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Filed Pursuant to Rule 424(b)(4)
Registration No. 333-204833

PROSPECTUS

9,090,909 Shares

Common Stock

We are offering 9,090,909 shares of our common stock.

Our common stock is quoted on the OTC Markets, OTCQB tier of OTC Markets Group, Inc., or OTCQB, under the symbol “PIRS.” On June 29, 2015, the last reported sale price for our common stock as reported on the OTCQB was $3.26 per share. Our common stock has been approved for listing on the NASDAQ Capital Market under the symbol “PIRS,” beginning on June 30, 2015.

Investing in our common stock involves a high degree of risk. See “Risk Factors” beginning on page 10.

We are an “emerging growth company” as that term is used in the Jumpstart Our Business Startups Act of 2012 and, as such, have elected to comply with certain reduced public company reporting requirements for this prospectus and future filings. See “Prospectus Summary — Implications of Being an Emerging Growth Company.”

Neither the Securities and Exchange Commission nor any state securities commission has approved or disapproved of these securities or determined if this prospectus is truthful or complete. Any representation to the contrary is a criminal offense.

We have granted an over-allotment option to the underwriters. Under this option, the underwriters may elect to purchase a maximum of 1,363,636 additional shares from us, at the public offering price less underwriting discounts and commissions, within 30 days following the date of this prospectus to cover over-allotments. If the over-allotment option is exercised in full, the total proceeds to us, after deducting underwriting discounts and commissions and before expenses, will be $26.7 million.

We expect that the delivery of the shares of common stock will be made on or about July 6, 2015.

Joint Book-Running Managers

Co-Managers

The date of this prospectus is June 30, 2015

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About This Prospectus

You should rely only on the information that we have provided or incorporated by reference in this prospectus, any applicable prospectus supplement and any related free writing prospectus that we may authorize to be provided to you. We have not authorized anyone to provide you with different information. No dealer, salesperson or other person is authorized to give any information or to represent anything not contained in this prospectus, any applicable prospectus supplement or any related free writing prospectus that we may authorize to be provided to you. You must not rely on any unauthorized information or representation. This prospectus is an offer to sell only the securities offered hereby, but only under circumstances and in jurisdictions where it is lawful to do so. You should assume that the information in this prospectus, any applicable prospectus supplement or any related free writing prospectus is accurate only as of the date on the front of the document and that any information we have incorporated by reference is accurate only as of the date of the document incorporated by reference, regardless of the time of delivery of this prospectus, any applicable prospectus supplement or any related free writing prospectus, or any sale of a security registered under the registration statement of which this prospectus is a part.

This prospectus contains summaries of certain provisions contained in some of the documents described herein, but reference is made to the actual documents for complete information. All of the summaries are qualified in their entirety by the actual documents. Copies of some of the documents referred to herein have been filed, will be filed or will be incorporated by reference as exhibits to the registration statement of which this prospectus is a part, and you may obtain copies of those documents as described below under the heading “Where You Can Find Additional Information.”

As used in this prospectus, unless the context indicates or otherwise requires, “our Company,” “the Company,” “Pieris,” “we,” “us,” and “our” refer to Pieris Pharmaceuticals, Inc., a Nevada corporation, and its consolidated subsidiaries, and the term “Pieris Operating” refers to Pieris AG, a company organized under the laws of Germany that, through a share exchange transaction completed on December 17, 2014, became our wholly owned subsidiary.

Pieris effected a forward stock split of its capital stock at the ratio of 2.272727-for-1 on December 5, 2014. Unless the context indicates or otherwise requires, all share numbers and share price data included in this prospectus have been adjusted to give effect to this forward stock split.

We have registered trademarks for Pieris^®, Anticalin^® and Pocket Binding^®. All other trademarks, trade names and service marks included in this prospectus are the property of their respective owners. Use or display by us of other parties’ trademarks, trade dress or products is not intended to and does not imply a relationship with, or endorsements or sponsorship of, us by the trademark or trade dress owner.

Currency Presentation and Currency Translation

Unless otherwise indicated, all references to “dollars,” “$,” “U.S. $” or “U.S. dollars” are to the lawful currency of the United States. All references in this prospectus to “euro” or “€” are to the currency introduced at the start of the third stage of the European Economic and Monetary Union pursuant to the Treaty establishing the European Community, as amended. We prepare our financial statements in U.S. dollars.

The functional currency for our operations is the euro. With respect to our financial statements, the translation from the euro to U.S. dollars is performed for balance sheet accounts using exchange rates in effect at the balance sheet date and for revenue and expense accounts using a weighted average exchange rate during the period. The resulting translation adjustments are recorded as a component of other comprehensive income.

Where in this prospectus we refer to amounts in euros, we have for your convenience also in certain cases provided a conversion of those amounts to U.S. dollars in parentheses. Where the numbers refer to a specific

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balance sheet account date or financial statement account period, we have used the exchange rate that was used to perform the conversions in connection with the applicable financial statement. In all other instances, unless otherwise indicated, the conversions have been made using the noon buying rate of €1.00 to U.S. $1.2101 in The City of New York for cable transfers of euro as certified for customs purposes by the Federal Reserve Bank of New York as of December 31, 2014. As of March 31, 2015, the date of the most recent consolidated financial statements included in this prospectus, the noon buying rate was €1.00 to U.S. $1.0741 in The City of New York for cable transfers of euro as certified for customs purposes by the Federal Reserve Bank of New York.

Market, Industry and Other Data

Unless otherwise indicated, information contained in this prospectus concerning our industry and the markets in which we operate, including our general expectations and market position, market opportunity, and market size, is based on information from various sources, on assumptions that we have made that are based on those data and other similar sources, and on our knowledge of the markets for our drug candidates. These data involve a number of assumptions and limitations, and you are cautioned not to give undue weight to such estimates. In addition, projections, assumptions, and estimates of our future performance and the future performance of the industry in which we operate are necessarily subject to a high degree of uncertainty and risk due to a variety of factors, including those described in “Risk Factors” and elsewhere in this prospectus. These and other factors could cause results to differ materially from those expressed in the estimates made by third parties and by us.

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RISK FACTORS

Investing in our common stock involves a high degree of risk. You should carefully consider the risks described below, together with the other information contained in this prospectus, including our consolidated financial statements and the related notes, before making any decision to invest in shares of our common stock. This prospectus contains forward-looking statements. If any of the events discussed in the risk factors below occurs, our business, prospects, results of operations, financial condition and cash flows could be materially harmed. If that were to happen, the trading price of our common stock could decline, and you could lose all or part of your investment. The risks and uncertainties described below are not the only ones we face. Additional risks not currently known to us or other factors not perceived by us to present significant risks to our business at this time also may impair our business operations.

Risks Related to Our Business, Financial Position and Capital Requirements

We have incurred significant losses since our inception and anticipate that we will continue to incur losses for the foreseeable future. We currently have no product revenues and no approved products, and will need to raise additional capital to operate our business.

We are a clinical-stage biopharmaceutical company. To date, we have not generated any product revenue and are not profitable, and have incurred losses since our inception in August 2000. For the years ended December 31, 2014 and 2013 we reported net loss of $9.8 million and net income of $0.1 million, respectively. Our net profit for the year ended December 31, 2013 is not indicative of a trend. As of March 31, 2015 and December 31, 2014, we had an accumulated deficit of $69.5 million and $65.8 million, respectively. We expect to continue to incur losses for the foreseeable future, and we expect these losses to increase as we continue our development of, and seek regulatory approvals for, our drug candidates and the commercialization of approved products, if any.

We are currently focused primarily on the development of our lead drug candidates, PRS-080, PRS-060 and our 300-Series programs, as well as our other programs, which we believe will result in our continued incurrence of significant research, development and other expenses related to those programs. If preclinical studies or the clinical trials for any of our drug candidates fail or produce unsuccessful results and those drug candidates do not gain regulatory approval, or if any of our drug candidates, if approved, fail to achieve market acceptance, we may never become profitable. Even if we achieve profitability in the future, we may not be able to sustain profitability in subsequent periods. Our prior losses, combined with expected future losses, have had and will continue to have an adverse effect on our stockholders’ equity and working capital.

We will need substantial additional funding to continue our operations, which could result in significant dilution or restrictions on our business activities. We may not be able to raise capital when needed, if at all, or on terms acceptable to us, which would force us to delay, reduce or eliminate our product development programs or commercialization efforts and could cause our business to fail.

Our operations have consumed substantial amounts of cash since inception. We expect to need substantial additional funding to pursue the clinical development of our drug candidates and launch and commercialize any drug candidates for which we receive regulatory approval.

Even after giving effect to our recent private placement and the proceeds of this offering, we will require additional capital for the further development and commercialization of our drug candidates and may need to raise additional funds sooner than we currently anticipate if we choose to and are able to expand more rapidly than we currently anticipate. Further, we expect our expenses to increase in connection with our ongoing activities, particularly as we advance PRS-080 through clinical trials, prepare for a potential Phase I clinical trial of PRS-060 and advance preclinical development of our 300-Series programs. In addition, if we obtain regulatory approval for any of our drug candidates, we expect to incur significant commercialization expenses related to regulatory requirements, product manufacturing, marketing, sales and distribution.

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Furthermore, we expect to incur additional costs associated with operating as a public company. We may also encounter unforeseen expenses, difficulties, complications, delays and other unknown factors that may increase our capital needs and/or cause us to spend our cash resources faster than we expect. Accordingly, we will need to obtain substantial additional funding in order to continue our operations.

To date, we have financed our operations through a mix of equity investments from private investors, the incurrence of debt, grant funding and technology licensing revenues, and we expect to continue to utilize such means of financing for the foreseeable future. Additional funding from those or other sources may not be available when or in the amounts needed, on acceptable terms, or at all.

If we raise additional capital through the incurrence of indebtedness, we would likely become subject to covenants restricting our business activities, and holders of debt instruments may have rights and privileges senior to those of our equity investors. In addition, servicing the interest and principal repayment obligations under debt facilities could divert funds that would otherwise be available to support research and development, clinical or commercialization activities.

If we obtain capital through collaborative arrangements, these arrangements could require us to relinquish rights to our Anticalin^®-brand technology or drug candidates and could result in our receipt of only a portion of the revenues associated with the partnered drug.

If we are unable to raise capital when needed or on attractive terms, we could be forced to delay, reduce or eliminate our research and development for our drug candidates or any future commercialization efforts. Any of these events could significantly harm our business, financial condition and prospects.

Our limited operating history as a clinical stage company may hinder our ability to successfully meet our objectives.

We were formed in August 2000 and, since that time our focus has been on discovery of Anticalin^®-brand drug candidates. We are currently conducting clinical development of PRS-080, and are continuing preclinical development of our other drug candidates, as well as exploring additional indications that may be suitable for Anticalin-brand drug therapeutics, such as immuno-oncology. Our drug candidates are in early stages of development, have not obtained marketing approval, have never generated any revenue from sales and will require extensive testing before commercialization. We have limited operating experience with respect to clinical-stage operations and have not yet demonstrated an ability to successfully overcome many of the risks and uncertainties frequently encountered by companies in new and rapidly evolving fields, particularly in the biopharmaceutical area. In addition, the early-stage nature of our drug development operations can only provide limited operating results upon which you can evaluate our business and prospects.

Our limited operating history may adversely affect our ability to implement our business strategy and achieve our business goals, which include, among others, the following activities:

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If we are unsuccessful in accomplishing these objectives, we may not be able to develop drug candidates, raise capital, expand our business or continue our operations.

Our global operations subject us to various risks, and our failure to manage these risks could adversely affect our results of operations.

Our business is subject to certain risks associated with doing business globally. One of our growth strategies is to pursue opportunities for our business in several areas of the world, both inside and outside of the United States, Germany and Europe, any or all of which could be adversely affected by the risks set forth below. Accordingly, we face significant operational risks as a result of doing business internationally, such as:

Our failure to manage the market and operational risks associated with our international operations effectively could limit the future growth of our business and adversely affect our results of operations.

Our international operations pose currency risks, which may adversely affect our operating results and net income.

Our operating results may be affected by volatility in currency exchange rates and our ability to effectively manage our currency transaction risks. Our reporting currency is the U.S. dollar and our functional currency is the euro. As such, the financial statements are translated for reporting purposes as follows: (1) asset and liability accounts at year-end rates, (2) income statement accounts at weighted average exchange rates for the year and (3) stockholders’ equity accounts at historical rates. Corresponding translation gains or losses are recorded in stockholders’ equity.

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In 2014, 96.3% of our revenues were generated and 67% of our costs were incurred in euros. As we realize upon our strategy to expand internationally, our exposure to currency risks will increase. We do not manage our foreign currency exposure in a manner that would eliminate the effects of changes in foreign exchange rates. Therefore, changes in exchange rates between these foreign currencies and the euro will affect our revenues and expenses and could result in exchange losses in any given reporting period.

We incur currency transaction risks whenever we enter into either a purchase or a sale transaction using a different currency other than the euro, our functional currency, in particular our arrangements for the purchase of supplies or licensing and collaboration agreements with partners outside of the euro zone. In such cases we may suffer an exchange loss because we do not currently engage in currency swaps or other currency hedging strategies to address this risk.

Given the volatility of exchange rates, we can give no assurance that we will be able to effectively manage our currency transaction risks or that any volatility in currency exchange rates will not have an adverse effect on our results of operations.

If we fail to comply with environmental, health and safety laws and regulations that apply to us, we could become subject to fines or penalties or incur costs that could harm our business.

We are subject to numerous environmental, health and safety laws and regulations, including those governing laboratory procedures and the handling, use, storage, treatment and disposal of hazardous materials and wastes. Our operations involve the use of hazardous and flammable materials, including chemicals and biological materials. Our operations also produce hazardous waste products. We generally contract with third parties for the disposal of any hazardous materials we use and wastes we produce. The use of these materials in our business could result in contamination or injury, which could cause damage for which we may be responsible but may not have sufficient resources to pay. We also could incur significant costs associated with civil or criminal fines and penalties for failure to comply with these laws and regulations, which we may not be able to afford.

Although we maintain workers’ compensation insurance for our operations in Germany to cover us for costs and expenses we may incur due to injuries to our employees resulting from the use of hazardous materials, this insurance may not provide adequate coverage against potential liabilities. We do not maintain insurance for environmental liability or toxic tort claims that may be asserted against us in connection with our storage or disposal of biological, hazardous or radioactive materials.

In addition, we may incur substantial costs in order to comply with current or future environmental, health and safety laws and regulations applicable to us. These current or future laws and regulations may impair our research, development or production efforts or impact the research activities we pursue, particularly with respect to research involving human subjects or animal testing. Our failure to comply with these laws and regulations also may result in substantial fines, penalties or other sanctions, which could cause our financial condition to suffer.

Health and safety regulations in the United States, Germany and in the countries where our technology and potential products are licensed or sold may prevent the sale or use of our technology or products in the future.

We are subject to a variety of regulations regarding worker health and safety in the United States, Germany, Australia and in the countries where our technology and potential products are licensed or sold. Because our technology and potential products may frequently involve the manufacture or use of certain chemical or biological compounds, we are required to certify their safety for industrial use and development in a variety of countries and contexts. As there has not been sufficient testing to determine the long-term health and environmental risks of all of the materials used in the production of Anticalin^® drug candidates and any future products, future regulations may ban the use of our products due to the potential risk they pose to workers or may limit the use of our drug candidates in research and commercial settings. Any such regulations may have a

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substantial negative impact on our business and revenues, and may cause our business to fail. Because we cannot guarantee the long-term safety of use or exposure to materials used during development or manufacture of our products, we may face liability for health risks or harms caused as a result of developing, manufacturing or other processes that use such materials. Any such claims may have a negative impact on our revenues and may prove substantially disruptive to our business in the future.

In addition, under the European Union regulation on classification, labeling and packaging of substances and mixtures, or CLP, we may be required to publicly disclose the composition of our proprietary products or substances, which may facilitate infringement or avoidance of our intellectual property by third parties and may potentially reduce the margin we are able to charge for our products by allowing competitors to more accurately determine our production costs. Future development of the CLP regulation may have a further negative impact our revenues and a substantial negative impact on our business.

Our ability to utilize our net operating loss carryforwards and certain other tax attributes may be limited.

We have incurred substantial losses during our history and do not expect to become profitable in the foreseeable future and may never achieve profitability. Our net profit of $0.1 million for the year ended December 31, 2013 is not indicative of a trend. To the extent we continue to generate taxable losses, unused losses will carry forward to offset future taxable income, if any, until such unused losses expire or forfeit.

Tax losses under German corporate income tax and trade tax may be used to offset taxable income and trade profit attributable to the same taxpayer, or loss holding entity, within the boundaries of German tax law. As of March 31, 2015 and December 31, 2014, Pieris Operating had net operating loss carryforwards of German corporate income tax of $35.6 million and $34.2 million, respectively, and of trade tax of $35.6 million and $34.2 million, respectively. Under current laws, tax loss carryforwards may only be used to offset in any relevant later assessment period (calendar year) €1,000,000 ($1,210,100) plus 60% of the exceeding taxable income and trade profit of such period. Also, certain transactions, including transfers of shares or interest in the loss holding entity, may result in the partial or total forfeiture of tax losses existing at that date. Partial or total forfeiture of tax losses may further occur in corporate reorganizations of the loss holding entity.

Pieris Operating experienced an ownership change as a result of the Acquisition and/or the December 2014 private placement of our common stock and may experience one or more ownership changes as a result of this offering or future transactions in our stock, and as a result have lost some, and may in the future lose some or all, of the unused German corporate income and trade tax losses carryforwards existing or realized at the time of the Acquisition and/or the private placement (including carryforwards). Any forfeiture of such tax losses due to the Acquisition and/or the private placement, or due to any other such ownership change, could potentially result in increased future tax liability to us and have an adverse effect on our results of operations.

Our business and operations would suffer in the event of system failures, and our operations are vulnerable to interruption by natural disasters, terrorist activity, power loss and other events beyond our control, the occurrence of which could materially harm our business.

Despite the implementation of security measures, our internal computer systems and those of our contractors and consultants are vulnerable to damage from computer viruses, unauthorized access as well as telecommunication and electrical failures. While we have not experienced any such system failure, accident or security breach to date, if such an event were to occur and cause interruptions in our operations, it could result in a material disruption of our drug development programs. For example, the loss of clinical trial data from completed or ongoing or planned clinical trials could result in delays in our regulatory approval efforts and we may incur substantial costs to attempt to recover or reproduce the data. If any disruption or security breach resulted in a loss of or damage to our data or applications, or inappropriate disclosure of confidential or proprietary information, we could incur liability and/or the further development of our drug candidates could be delayed.

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We are also vulnerable to accidents, electrical blackouts, labor strikes, terrorist activities, war and other natural disasters and other events beyond our control, and we have not undertaken a systematic analysis of the potential consequences to our business as a result of any such events and do not have an applicable recovery plan in place. Except for our operations in Germany, where we have business interruption insurance against losses or damages resulting from fire, we do not carry other business interruption insurance that would compensate us for actual losses from interruptions of our business that may occur, and any losses or damages incurred by us could cause our business to materially suffer.

There could be an adverse change or increase in the laws and/or regulations governing our business.

We and our operating subsidiary are subject to various laws and regulations in different jurisdictions, and the interpretation and enforcement of laws and regulations are subject to change. We are also subject to different tax regulations in each of the jurisdictions where we conduct our business or where our management or the management of our operating subsidiary is located. We expect the scope and extent of regulation in the jurisdictions in which we conduct our business, or where our management or the management of our operating subsidiary is located, as well as regulatory oversight and supervision, to generally continue to increase. There can be no assurance that future regulatory, judicial and legislative changes in any jurisdiction will not have a material adverse effect on us or hinder us in the operation of its business.

Risks Related to the Discovery and Development of Our Drug Candidates

We are heavily dependent on the success of PRS-080, PRS-060 and our 300-Series programs, our early-stage lead drug candidates which are still in clinical and /or preclinical development, and we cannot be certain that PRS-080, PRS-060 and our 300-Series programs will receive regulatory approvals or be successfully commercialized even if we receive regulatory approvals.

We currently have no products that are approved for commercial sale. We expect that a substantial portion of our efforts and expenditures over the next few years will be devoted to our lead drug candidates, PRS-080, PRS-060, and our 300-Series programs, as well as our other programs. We completed dosing of healthy volunteers in a Phase I clinical trial with PRS-080 in June 2015 and PRS-060 is in preclinical development. We are also conducting preclinical experiments on a number of 300-Series lead candidates and by the second half of 2015 intend to choose a candidate for pre-clinical studies to support the IND for potential clinical trials in oncology. All of our other drug candidates are in the discovery or early preclinical stage. Accordingly, our business is currently substantially dependent on the successful development, clinical testing, regulatory approval and commercialization of PRS-080, PRS-060 and our 300-Series programs, which may never occur.

Before we can generate any revenues from sales of our lead drug candidates, we must complete the following activities for each of them, any one of which we may not be able to successfully complete:

If the results of the PRS-080 Phase I clinical trial are not successful, we may not be able to use those results as the basis for advancing the drug candidate into further clinical development. In that case, we may not have the resources to conduct new clinical trials, and/or we may determine that further clinical development of this drug candidate is not justified and may decide to discontinue the program. Clinical testing of PRS-060 and our 300-

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Series programs has not yet commenced, and the results of any future preclinical studies or clinical trials of PRS-060 and our 300-Series programs, if unsuccessful, could lead to our abandonment of the development of those drug candidates as well. If studies of these drug candidates produce unsuccessful results and we are forced or elect to cease their development, our business and prospects would be substantially harmed.

Preclinical and clinical testing of our drug candidates that have been conducted to date or will be conducted in future may not have been or may not be performed in compliance with applicable regulatory requirements, which could lead to increased costs or material delays for their further development.

Given the complexity as well as the uncertainty inherent in biopharmaceutical preclinical studies and clinical trials, and because of our limited operating experience, we may discover that our own development activities have not been or are not in compliance with applicable regulatory requirements or have otherwise been or are deficient, and, therefore, advancement of the development of the drug candidates on the basis of those trials and studies is not warranted or will be delayed.

We have also entered into license and partnership arrangements, such as with Allergan Inc., or Allergan, Daiichi Sankyo Company Limited, or Daiichi Sankyo, Sanofi Group (formerly Sanofi-Aventis and Sanofi-Pasteur SA), or Sanofi, Cadila Healthcare Limited (Zydus Cadila), or Zydus, and Strides Arcolab Limited, or Stelis, relating to certain of our drug candidates, and may continue to do so in the future. Under certain of such arrangements, the development of those drug candidates has been, or in the future may be, conducted wholly by such partners or any third parties with which the partners contract. As a result, we have not been or may not be closely involved with or have any control over those development activities. Although certain of such partners have provided information regarding those drug candidates and the related preclinical studies conducted to date, including certain data that is included in this prospectus, we have not received and do not yet have access to comprehensive information regarding those development activities, including the raw data from the studies that have been conducted, information regarding the design, procedural implementation and structure and information regarding the manufacture of the drug candidates used in the studies. Because we have had no input on the development to date of these drug candidates, we may discover that all or certain elements of the trials and studies our partners have performed have not been, or may not in the future be, in compliance with applicable regulatory standards or have otherwise been or may be deficient, and that advancement of the development of these drug candidates on the basis of those trials and studies is not warranted.

Further, the majority of our development activities for each of our drug candidates to date, including our Phase I clinical trial with PRS-080 in healthy volunteers, which was conducted in Germany, have been or are being conducted outside the United States, primarily in Europe as well as in Australia, and we may conduct some of our future development activities in other countries or regions. As a result, although those studies may meet the standards of certain applicable foreign regulatory bodies, the structure and design of those clinical trials and preclinical studies may not meet applicable U.S. Food and Drug Administration, or FDA, standards to allow immediate further development of those drug candidates in the United States, and also may not meet the standards of the applicable regulatory authorities in foreign countries in which we desire to pursue marketing approval for these drug candidates.

If the studies conducted by us or our partners or collaborators have not been in full compliance with applicable regulatory requirements or are otherwise not eligible for continued development in the United States, then we or our partners may be forced to conduct new studies in order to progress the development of our drug candidates. We, or our partners, may not have the funding or other resources to conduct or complete these new studies, which would severely delay the development plans for these drug candidates and their commercialization. Any such deficiency and delay in the development of these drug candidates would significantly harm our business plans, product revenues and prospects.

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Our research and development is based on a rapidly evolving area of science, and our approach to drug discovery and development is novel and may never lead to marketable products.

Biopharmaceutical product development is generally a highly speculative undertaking and by its nature involves a substantial degree of risk. Our specific line of business, the discovery of Anticalin^®-brand drug therapeutics for patients with a variety of diseases and conditions, such as anemia, asthma and cancer, is an emerging field, and the scientific discoveries that form the basis for our efforts to develop drug candidates are relatively new. Further, the scientific evidence to support the feasibility of developing drug candidates based on those discoveries is both preliminary and limited. In contrast with companies who focus on more traditional drug classes, such as antibodies and small molecules, we believe we are the first, if not the only company, to work with Anticalin-brand drug therapeutics and work to advance these to a clinical stage of development. We are not aware of any company that has successfully developed and obtained approval for a drug based on Anticalin proteins. As a result, identifying drug targets based in part on their suitability with Anticalin-brand drug therapeutics, which is a fundamental aspect of our business approach, may not lead to the discovery or development of any drugs that successfully treat patients with the diseases and conditions we intend to target. Moreover, the lack of successful precedents in the development of Anticalin proteins could result in added complexities or delays in our development efforts. The failure of the scientific underpinnings of our business model to produce viable drug candidates would substantially harm our operations and prospects.

We may not be successful in our efforts to build a pipeline of drug candidates.

A key element of our strategy is to use and expand our Anticalin^® drug platform to build a pipeline of drug candidates to address different targets, and progress those drug candidates through clinical development for the treatment of a variety of different types of diseases. Although our research efforts to date have resulted in identification of a series of targets, we may not be able to develop drug candidates that are safe and effective inhibitors or promoters of all or any of these targets. Even if we are successful in building a product pipeline, the potential drug candidates that we identify may not be suitable for clinical development for a number of reasons, including causing harmful side effects or demonstrating other characteristics that indicate a low likelihood of receiving marketing approval or achieving market acceptance. If our methods of identifying potential drug candidates fail to produce a pipeline of potentially viable drug candidates, then our success as a business will be dependent on the success of fewer potential drug candidates, which introduces risks to our business model and potential limitations to any success we may achieve.

Clinical drug development involves a lengthy and expensive process with uncertain outcomes, is very difficult to design and implement, and any of our clinical trials could produce unsuccessful results or fail at any stage in the process.

Clinical trials conducted on humans are expensive and can take many years to complete, and outcomes are inherently uncertain. Failure can occur at any time during the clinical trial process. Additionally, any positive results of preclinical studies and early clinical trials of a drug candidate may not be predictive of the results of later-stage clinical trials, such that drug candidates may reach later stages of clinical trials and fail to show the desired safety and efficacy traits despite having shown indications of those traits in preclinical studies and initial clinical trials. A number of companies in the biopharmaceutical industry have suffered significant setbacks in advanced clinical trials due to lack of efficacy or adverse safety profiles, notwithstanding promising results in earlier phases of the trials. Therefore, the results of any ongoing or future clinical trials we conduct may not be successful.

Although dosing of healthy volunteers in the clinical Phase I trial for PRS-080 was completed in June 2015, and although we are planning to initiate clinical trials for PRS-060 as early as the first quarter of 2017, we may experience delays in pursuing those or any other clinical trials, and any planned clinical trials may not begin on time, may require redesign, may not enroll sufficient healthy volunteers or patients in a timely manner, and may not be completed on schedule, if at all.

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Clinical trials may be delayed for a variety of reasons, including delays related to:

We rely and plan to continue to rely on CROs and clinical trial sites to ensure the proper and timely conduct of our clinical trials. Although we have and expect that we will have agreements in place with CROs governing their committed activities and conduct, we will have limited influence over their actual performance. As a result, we ultimately do not and will not have control over a CRO’s compliance with the terms of any agreement it may have with us, its compliance with applicable regulatory requirements, or its adherence to agreed time schedules and deadlines, and a future CRO’s failure to perform those obligations could subject any of our clinical trials to delays or failure.

Further, we may also encounter delays if a clinical trial is suspended or terminated by us, by any IRB or Ethics Committee at an institution in which such trials are being conducted, by the Data Safety Monitoring Board, or DSMB, for the trial, if applicable, or by the FDA, the European Medicines Agency, or EMA, or other regulatory authorities. Such authorities may impose such a suspension or termination due to a number of factors, including failure to conduct the clinical trial in accordance with regulatory requirements, inspection of the clinical trial operations or trial site by the FDA, EMA or other regulatory authorities resulting in the imposition of a clinical hold, exposing participants to health risks caused by unforeseen safety issues or adverse side effects, development of previously unseen safety issues, failure to demonstrate a benefit from using a drug candidate, changes in governmental regulations or administrative actions or lack of adequate funding to continue the clinical trial. Therefore, we cannot predict with any certainty the schedule for commencement or completion of any currently ongoing, planned or future clinical trials.

If we experience delays in the commencement or completion of, or suspension or termination of, any clinical trial for our drug candidates, the commercial prospects of the drug candidate could be harmed, and our ability to generate product revenues from the drug candidate may be delayed or eliminated. In addition, any delays in completing our clinical trials will increase our costs, slow down our drug candidate development and approval process and jeopardize regulatory approval of our drug candidates and our ability to commence sales and generate revenues. The occurrence of any of these events could harm our business, financial condition, results of operations and prospects significantly.

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If we experience delays or difficulties in the enrollment of research subjects in clinical trials, those clinical trials could take longer than expected to complete and our receipt of necessary regulatory approvals could be delayed or prevented.

We may not be able to initiate or continue clinical trials for our drug candidates if we are unable to locate and enroll a sufficient number of research subjects to participate in these trials. In particular, for some diseases and conditions we are or will be focused on, our pool of suitable patients may be smaller and more selective and our ability to enroll a sufficient number of suitable patients may be limited or take longer than anticipated. In addition, some of our competitors have ongoing clinical trials for drug candidates that treat the same indications as our drug candidates, and volunteers or patients who would otherwise be eligible for our clinical trials may instead enroll in clinical trials of our competitors’ drug candidates.

Patient enrollment for any of our clinical trials may also be affected by other factors, including without limitation:

Our inability to enroll a sufficient number of patients for our clinical trials would result in significant delays and could require us to abandon one or more clinical trials altogether. Enrollment delays in our clinical trials may result in increased development costs for our drug candidates, and we may not have or be able to obtain sufficient cash to fund such increased costs when needed, which could result in the further delay or termination of the trial.

The review processes of regulatory authorities are lengthy, time consuming, expensive and inherently unpredictable. If we are unable to obtain approval for our drug candidates from applicable regulatory authorities, we will not be able to market and sell those drug candidates in those countries or regions and our business could be substantially harmed.

The research, testing, manufacturing, labeling, approval, sale, marketing and distribution of drug products are, and will remain, subject to extensive regulation by the FDA in the United States and by the respective regulatory authorities in other countries, which regulations differ from country to country. We are not permitted to market our drug candidates in the United States until we receive the respective approval of a biologics license application, or BLA, from the FDA, or in any foreign countries until we receive the requisite approval from the respective regulatory authorities in such countries. The time required to obtain approval, if any, by the FDA, EMA and comparable foreign authorities is unpredictable, but typically takes many years following the commencement of clinical trials and depends upon numerous factors, including the substantial discretion of the regulatory authorities. We have not submitted a BLA or similar filing (such as marketing authorization, or MA, from the EMA for commercial sale in the European Union) or obtained regulatory approval for any drug candidate in any jurisdiction and it is possible that none of our existing drug candidates or any drug candidates we may seek to develop in the future will ever obtain regulatory approval.

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Our drug candidates could fail to receive regulatory approval for many reasons, including any one or more of the following:

The time and expense of the approval process, as well as the unpredictability of future clinical trial results and other contributing factors, may result in our failure to obtain regulatory approval to market, in one or more jurisdictions, PRS-080, PRS-060, our 300-Series programs, our discovery stage programs or any other drug candidates we may seek to develop in the future, which would significantly harm our business, results of operations and prospects. In such case, we may also not have the resources to conduct new clinical trials and/or we may determine that further clinical development of any such drug candidate is not justified and may discontinue any such programs.

In order to market and sell our products in any jurisdiction, we or our third party collaborators must obtain separate marketing approvals in that jurisdiction and comply with its regulatory requirements. The review and approval procedures can vary drastically among jurisdictions, and each jurisdiction may impose different testing and other requirements to obtain and maintain marketing approval. Further, the time required to obtain those approvals, if any, may differ substantially among jurisdictions. In addition, in many countries or regions outside the United States, it is required that the product be approved for reimbursement before the product can be approved for sale in that country or region. Moreover, approval by the FDA or an equivalent foreign authority does not ensure approval by regulatory authorities in any other countries or regions. As a result, the ability to market and sell a drug candidate in more than one jurisdiction can involve significant additional time, expense and effort, and would subject us and our collaborators to the numerous and varying post-approval requirements of each jurisdiction governing commercial sales, manufacturing, pricing and distribution of our drug candidates. We or any third parties with whom we may collaborate may not have the resources to pursue those approvals, and we or they may not be able to obtain any approvals that are pursued.

The failure to obtain marketing approval for our drug candidates in foreign jurisdictions could severely limit their potential market and ability to generate revenue.

In addition, even if we were to obtain regulatory approval in one or more jurisdictions, regulatory authorities may approve any of our drug candidates for fewer or more limited indications than we request, may not approve

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the prices we may propose to charge for our products, may grant approval contingent on the performance of costly post-marketing clinical trials, or may approve a drug candidate with a label that does not include the labeling claims necessary or desirable for the successful commercialization of that drug candidate. Any of the foregoing circumstances could materially harm the commercial prospects for our drug candidates.

We may expend our limited resources to pursue a particular drug candidate or indication that does not produce any commercially viable products and may fail to capitalize on drug candidates or indications that may be more profitable or for which there is a greater likelihood of success.

Because we have limited financial and managerial resources, we must focus our efforts on particular research programs and drug candidates for specific indications. As a result, we may forego or delay pursuit of opportunities with other drug candidates or for other indications that later prove to have greater commercial potential. Further, our resource allocation decisions may result in our use of funds for research and development programs and drug candidates for specific indications that may not yield any commercially viable products.

If we do not accurately evaluate the commercial potential or target market for a particular drug candidate, we may relinquish valuable rights to that drug candidate through collaboration, licensing or other royalty arrangements in cases in which it would have been more advantageous for us to retain sole development and commercialization rights to such drug candidate. Any such failure to improperly assess potential drug candidates could result in missed opportunities and/or our focus on drug candidates with low market potential, which would harm our business and financial condition.

Risks Related to Our Dependence on Third Parties

We rely on third parties to conduct our preclinical studies and clinical trials. If these third parties do not successfully carry out their contractual duties or meet expected deadlines, we may not be able to obtain regulatory approval for our drug candidates and our business could be substantially harmed.

We depend upon independent investigators and contractors, such as CROs, universities and medical institutions, to conduct our preclinical studies and clinical trials. We rely upon, and plan to continue to rely upon, such third-party entities to execute our preclinical studies and clinical trials and to monitor and manage data produced by and relating to those studies and trials. However, we may not be able to in the future establish arrangements with CROs when needed or on terms that are acceptable to us, or at all, which could negatively affect our development efforts with respect to our drug candidates and materially harm our business, operations and prospects. As a result of the use of third-party contractors, we will have only limited control over certain aspects of their activities. Nevertheless, we are responsible for ensuring that each of our studies, including each of our clinical trials, is conducted in accordance with the applicable protocol, legal and regulatory requirements as well as scientific standards, and our reliance on any third-party entity will not relieve us of our regulatory responsibilities.

Based on our present expectations, we and our third-party contractors will be required to comply with current Good Clinical Practice, or cGCP, for all of our drug candidates in clinical development. Regulatory authorities enforce cGCP through periodic inspections of trial sponsors, clinical investigators and trial sites. If we or any of our contractors fail to comply with applicable cGCP, the clinical data generated in the applicable trial may be deemed unreliable and the FDA, EMA or comparable foreign regulatory authorities may require us to perform additional clinical trials before approving a drug candidate for marketing, which we may not have sufficient cash or other resources to support and which would delay our ability to generate revenue from any sales of such drug candidate. Any agreements governing our relationships with outside contractors such as CROs, or CROs or other contractors we may engage in the future, may provide those outside contractors with certain rights to terminate a clinical trial under specified circumstances. If such an outside contractor terminates its relationship with us during the performance of a clinical trial, we would be forced to seek an engagement with a substitute contractor, which we may not be able to do on a timely basis or on commercially reasonable terms, if at all, and the applicable clinical trial would experience delays or may not be completed.

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If our contractors do not successfully carry out their contractual duties or obligations or meet expected deadlines, if they need to be replaced or if the quality or accuracy of the data they obtain is compromised due to a failure to adhere to our clinical protocols, legal and regulatory requirements or for other reasons, our clinical trials may be extended, delayed or terminated and we may not be able to obtain regulatory approval for, or successfully commercialize, the affected drug candidates. In addition, we will be unable to control whether or not they devote sufficient time and resources to our preclinical and clinical programs. These outside contractors may not assign as great a priority to our programs or pursue them as diligently as we would if we were undertaking such programs ourselves. As a result, our operations and the commercial prospects for the effected drug candidates would be harmed, our costs could increase and our ability to generate revenues could be delayed. These contractors may also have relationships with other commercial entities, some of whom may compete with us. If our contractors assist our competitors to our detriment, our competitive position would be harmed.

We rely and expect to continue to rely completely on third parties to formulate and manufacture our preclinical, clinical trial and post-approval drug supplies. The development and commercialization of any of our drug candidates could be stopped, delayed or made less profitable if those third parties fail to provide us with sufficient quantities of such drug supplies or fail to do so at acceptable quality levels, including in accordance with applicable regulatory requirements or contractual obligations and our operations could be harmed as a result.

We have no experience in drug formulation or manufacturing. We do not currently have, nor do we plan to acquire, the infrastructure or capability internally, such as our own manufacturing facilities, to manufacture our preclinical and clinical drug supplies for use in the conduct of our preclinical studies and clinical trials or commercial quantities of any drug candidates that may obtain regulatory approval. Therefore, we lack the resources and expertise to formulate or manufacture our own drug candidates. We have entered into agreements with third-party manufacture contractors, or CMOs, for the clinical-stage manufacture of certain of our drug candidates, including PRS-080. We plan to enter into agreements with one or more manufacturers to manufacture, supply, store and distribute drug supplies for our current and future clinical trials and/or commercial sales. We intend to establish or continue those relationships for the supply of our drug candidates, however, there can be no assurance that we will be able to retain those relationships on commercially reasonable terms, if at all. If we are unable to maintain those relationships, we could experience delays in our development efforts as we locate and qualify new CMOs. If any of our current drug candidates or any drug candidates we may develop or acquire in the future receive regulatory approval, we will rely on one or more CMOs to manufacture the commercial supply of such drugs.

Our reliance on a limited number of CMOs exposes us to the following risks:

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Each of these risks could delay our clinical trials, the approval, if any, of our drug candidates by the FDA or the commercialization of our drug candidates or result in higher costs or deprive us of potential product revenues.

We expect to have no control over the ability of our contract manufacturers to maintain adequate quality control, quality assurance and qualified personnel. If any of our contract manufacturers cannot successfully manufacture material that conforms to our specifications and the strict regulatory requirements of the FDA, EMA or other comparable foreign authorities, we would be prevented from obtaining regulatory approval for our drug candidates unless and until we engage a substitute contract manufacturer that can comply with such requirements, which we may not be able to do. Any such failure by any of our contract manufacturers would significantly impact our ability to develop, obtain regulatory approval for or market our drug candidates, if approved.

Further, we plan to rely on our manufacturers to purchase from third-party suppliers the materials necessary to produce our drug candidates for our clinical trials. We do not have, nor do we expect to enter into, any agreements for the commercial production of these raw materials, and we do not expect to have any control over the process or timing of our contract manufacturers’ acquisition of raw materials needed to produce our drug candidates. Any significant delay in the supply of a drug candidate or the raw material components thereof for an ongoing clinical trial due to a manufacturer’s need to replace a third-party supplier of raw materials could considerably delay completion of our clinical trials, product testing and potential regulatory approval of our drug candidates. Additionally, if our future manufacturers or we are unable to purchase these raw materials to commercially produce any of our drug candidates that gains regulatory approvals, the commercial launch of our drug candidates would be delayed or there would be a shortage in supply, which would impair our ability to generate revenues from the sale of our drug candidates.

Disagreements with respect to the commercial terms of our sales, licensing, purchase or manufacturing agreements may limit our commercial success.

The rights and obligations of the partners to which we may license our Anticalin^® technology are governed by the licensing and collaboration agreements we enter into with those partners. In addition, our relationships with CROs and CMOs are governed by the service agreements between us and each manufacturer. Although we attempt to address the full range of possible events that may occur during the development or the manufacturing of Anticalin drug candidates and products, unanticipated or extraordinary events may occur beyond those contemplated by said agreements. Furthermore, our business relationships with our product manufacturers and our collaborators may include assumptions, understandings or agreements that are not included in our agreements with them, or that are inaccurately or incompletely represented by their terms. In addition, key terms in such agreements may be misunderstood or contested, even when both we and the other party previously believed that we had a mutual understanding of our obligations.

Any differences in interpretation or misunderstandings between us and other parties may result in substantial costs and delays with respect to the development, manufacturing or sale of Anticalin^® drugs, and may negatively impact our revenues and operating results. Product manufacturers may fail to produce the products and partners may fail to develop the drug candidates under the timeline or in the manner we anticipated, and results may differ from the terms upon which we had agreed. As a result, we may be unable to supply drugs of the quality or in the quantity demanded or required. We may suffer harm to our reputation in the market from missed development goals or deadlines, and may be unable to capitalize upon market opportunities as a result. Resolution of these problems may entail costly and lengthy litigation or dispute resolution procedures. In addition, there is no guarantee that we will prevail in any such dispute or, if we do prevail, that any remedy we receive, whether legal or otherwise, will adequately redress the harm we have suffered. The delays and costs associated with such disputes may themselves harm our business and reputation and limit our ability to successfully compete in the market going forward.

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Risks Related to the Commercialization of Our Drug Candidates

Even if we receive regulatory approval for any of our drug candidates, we will be subject to ongoing regulatory obligations and review. Maintaining compliance with ongoing regulatory requirements may result in significant additional expense to us, and any failure to maintain such compliance could subject us to penalties and cause our business to suffer.

Any regulatory approvals that we receive for our drug candidates may be subject to limitations on the approved indicated uses for which the products may be marketed, or contain requirements for potentially costly post- marketing testing, including Phase IV clinical trials. In addition, if the FDA, EMA or a comparable foreign regulatory authority approves any of our drug candidates, the manufacturing processes, labeling, packaging, distribution, adverse event reporting, storage, advertising, promotion and recordkeeping for the products will be subject to extensive and ongoing regulatory requirements. These requirements include submissions of safety and other post-marketing information and reports, registration, as well as continued compliance with cGMP. Later discovery of previously unknown problems with a product, including adverse events of unanticipated severity or frequency, or with our third-party manufacturers or manufacturing processes, or failure to comply with regulatory requirements, may result in, among other things:

In addition, regulatory authorities’ policies (such as those of the FDA or EMA) may change and additional government regulations may be enacted that could prevent, limit or delay regulatory approval of our drug candidates. If we are slow or unable to adapt to changes in existing requirements or the adoption of new requirements or policies, or if we are otherwise not able to maintain regulatory compliance, we may lose any marketing approval that we may have obtained, which would adversely affect our business, prospects and ability to achieve or sustain profitability.

Our commercial success depends upon attaining significant market acceptance of our drug candidates, if approved, among physicians, patients, healthcare payors and other members of the medical community.

Even if we obtain regulatory approval for our drug candidates, the products may not gain market acceptance among physicians, health care payors, patients and other members of the medical community, which is critical to commercial success. Market acceptance of any drug candidate for which we receive approval depends on a number of factors, including:

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If our drug candidates are approved but fail to achieve an adequate level of acceptance by key market participants, we will not be able to generate significant revenues, and we may not become or remain profitable, which may require us to seek additional financing.

Reimbursement may be limited or unavailable in certain market segments for our drug candidates, which could make it difficult for us to sell on a profitable basis any products for which we obtain marketing approvals.

There is significant uncertainty related to the third-party coverage and reimbursement of newly approved drugs. Market acceptance and successful commercialization of any of our drug candidates that obtain regulatory approval in domestic or international markets will depend significantly on the availability of adequate coverage and reimbursement from governmental authorities, private health insurers and other third-party payors for any of our drug candidates, and may be affected by existing and future healthcare reform measures.

Pricing and reimbursement for any of our drug candidates that obtain regulatory approval is uncertain. Government authorities, private health insurers and other third-party payors decide which drugs they will cover and establish reimbursement levels for them, and obtaining coverage and reimbursement approval for a product from any such third-party payors is a time consuming and costly process. Third-party payors also are increasingly challenging the effectiveness of and prices charged for medical products and services. As a result, any denial of private or government payor coverage or inadequate reimbursement for our drug candidates, if any are commercialized, could harm our business and reduce our prospects for generating revenue.

Further, there have been, and may continue to be, legislative and regulatory proposals at the federal and state levels and in foreign jurisdictions directed at broadening the availability and containing or lowering the cost of healthcare. The continuing efforts of the government, insurance companies, managed care organizations and other third-party payors to contain or reduce costs of healthcare may adversely affect our ability to set prices for our products that would allow us to achieve or sustain profitability. In addition, governments may impose price controls on any of our products that obtain marketing approval, which may adversely affect our future profitability.

In some foreign countries, particularly in the European Union, the pricing of prescription pharmaceuticals is subject to governmental control. In these countries, pricing negotiations with governmental authorities can be a long and expensive process after the receipt of marketing approval for a drug candidate. To obtain reimbursement or pricing approval in some countries, we may be required to conduct additional clinical trials that compare the cost-effectiveness of our drug candidates to other available therapies. If reimbursement of our drug candidates is unavailable or limited in scope or amount in a particular country, or if pricing is set at unsatisfactory levels, we may be unable to achieve or sustain profitability for sales of any of our drug candidates that are approved for marketing in that country.

We have no experience selling, marketing or distributing products and currently have no internal marketing and sales force. If we are unable to establish effective marketing and sales capabilities or enter into agreements with third parties to market and sell our drug candidates, we may not be able to effectively market and sell our drug candidates, if approved, or generate product revenues.

We currently have no sales, marketing or distribution capabilities and there can be no assurance that we will be able to market and sell our products in the United States or overseas. In order to commercialize any drug candidates, we must build on a territory-by-territory basis marketing, sales, distribution, managerial and other non-technical capabilities or make arrangements with third parties to perform these services, and we may not be

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successful in doing so. Therefore, with respect to the commercialization of all or certain of our drug candidates, we may choose to collaborate, either globally or on a territory-by-territory basis, with third parties that have direct sales forces and established distribution systems, either to augment our own sales force and distribution systems or in lieu of our own sales force and distribution systems. If so, our success will depend, in part, on our ability to enter into and maintain collaborative relationships for such capabilities, such collaborator’s strategic interest in the products under development and such collaborator’s ability to successfully market and sell any such products.

If we are unable to enter into such arrangements when needed on acceptable terms or at all, we may not be able to successfully commercialize any of our drug candidates that receive regulatory approval or any such commercialization may experience delays or limitations. Further, to the extent that we depend on third parties for marketing and distribution, any revenues we receive will depend upon the efforts of such third parties, and there can be no assurance that such efforts will be successful.

To the extent that we decide not to, or are unable to, enter into collaborative arrangements with respect to the sales and marketing of our products, we may in the future need to establish an internal sales and marketing team with technical expertise and supporting distribution capabilities to commercialize our drug candidates, which could be expensive and time consuming and which would require significant attention of our executive officers to manage. Further, may not have sufficient resources to allocate to the sales and marketing of our products.

Any failure or delay in the development of sales, marketing and distribution capabilities, either through collaboration with one or more third parties or through internal efforts, would adversely impact the commercialization of any of our products that we obtain approval to market. As a result, our future product revenue will suffer and we may incur significant additional losses.

We face significant competition from other biotechnology and pharmaceutical companies, and our operating results will suffer if we fail to compete effectively.

The biotechnology and pharmaceutical industries are intensely competitive and subject to rapid and significant technological advances. In addition, the competition in the anemia and asthma markets is intense. We have competitors both in the United States and internationally, including major multinational pharmaceutical companies, fully integrated pharmaceutical or biotechnology companies, smaller companies that are collaborating with larger pharmaceutical companies, academic institutions, and other public and private research organizations.

There are several third-party drug candidates that could be competitive with drug candidates in our pipeline.

Drug candidates interfering with hepcidin function and thus competing with PRS-080 include those that are being developed by Noxxon (NOX-H94), Lilly (LY-2787106, LY-2928057), Ferrumax (FMX-8), ISIS/Xenon (XEN701), and Alnylam (ALN-HPN). Drug candidates interfering with the function of type 2 helper T cells, or Th2, the biological pathway for PRS-060, and thus competing with PRS-060, include those that are being developed by Sanofi/Regeneron (dupilimab), Roche/Genentech (lebrikizumab), Astra-Zeneca (tralokizumab, benralizumab), GSK (mepolizumab) and Teva (reslizumab). Drugs targeting immunomodulatory targets and thus competing with our 300-Series programs include those that are currently marketed by Bristol- Myers Squibb (Yervoy/ipilimumab, Opdivo/ nivolumab) and Merck (Keytruda/pembrolizumab) and drug candidates are developed by Bristol-Myers Squibb (Urelumab / anti-CD137; anti-LAG3; Anti-CD40; Lirilumab/ anti-KIR), Roche / Genentech (MPDL3280A/anti- PDL-1; RG7888 /anti-Ox40), Merck Serono (Avelumab / anti-PDL-1) and AstraZeneca (MEDI4736 /anti-PDL-1; MEDI0680 / anti-PD-1; MEDI6469/ Ox-40; tremelimumab/anti-CTLA-4). Drug candidates targeting cMet and thus competing with PRS-110 include those that are being developed by Roche / Genentech (MetMab), Eli Lilly (LY2875359) and Abbvie (ABT700). For additional information about our third party drug candidates which could be competitive with the drug candidates in our pipeline, see “Business—Competition.”

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These existing or future competing products may provide greater therapeutic convenience or clinical or other benefits for a specific indication than our products, or may offer comparable performance at a lower cost. If our products fail to capture and maintain market share, we may not achieve sufficient product revenue and our business will suffer.

Many of our competitors have substantially greater financial, technical and other resources than we do, such as larger research and development staff and experienced marketing and manufacturing organizations, as well as significantly greater experience in:

Established pharmaceutical companies may invest heavily to accelerate discovery and development of or in-license novel compounds that could make our drug candidates less competitive. In addition, any new product that competes with an approved product must demonstrate compelling advantages in efficacy, convenience, tolerability and safety in order to overcome price competition and to be commercially successful. Accordingly, our competitors may succeed in obtaining patent protection, receiving FDA, EMA or other regulatory approval, or discovering, developing and commercializing medicines before we do, which would have a material adverse effect on our business and ability to achieve profitability from future sales of our approved drug candidates, if any. For additional information about our competitors, please see “Business—Competition.”

We could be subject to product liability lawsuits based on the use of our drug candidates in clinical testing or, if obtained, following marketing approval and commercialization. If product liability lawsuits are brought against us, we may incur substantial liabilities and may be required to cease clinical testing or limit commercialization of our drug candidates.

We could be subject to product liability lawsuits if any drug candidate we develop allegedly causes injury or is found to be otherwise unsuitable for human use during product testing, manufacturing, marketing or sale. Any such product liability claims may include allegations of defects in manufacturing, defects in design, a failure to warn of dangers inherent in the product, negligence, strict liability and a breach of warranties. Claims could also be asserted under state consumer protection acts.

Our inability to obtain and retain sufficient product liability insurance at an acceptable cost to protect against potential product liability claims could prevent or inhibit the clinical testing and commercialization of products we develop on our own or with collaborators. We do not currently carry general product liability insurance. We have put in place applicable product liability insurance, covering us as sponsor and the investigators involved in our Phase I clinical trial of PRS-080 in healthy volunteers, in an amount of up to the lesser of €0.5 million ($0.6 million) per enrolled subject or €10 million ($12.1 million) for the Phase I clinical trial in its entirety. In the future, we will seek to obtain similar insurance coverage with respect to any future clinical trials of our other drug candidates, such as PRS-060 and our 300-Series programs, but we may not be able to obtain the levels of coverage desired on acceptable terms, or at all. If we do secure product liability insurance, we may subsequently determine that additional amounts of coverage would be desirable at later stages of clinical development of our drug candidates or upon commencing commercialization of any drug candidate that obtains required approvals, but we may not be able to obtain such additional coverage amounts when needed on acceptable terms, or at all. Unless and until we obtain such insurance, we would be solely responsible for any product liability claims relating to our preclinical and clinical development activities. Further, even after any such insurance coverage is obtained, any claim that may be brought against us could result in a court judgment

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or settlement in an amount that is not covered, in whole or in part, by any insurance policies we may then have or that is in excess of the limits of our insurance coverage. We would be required to pay any amounts awarded by a court or negotiated in a settlement that exceed the coverage limitations or that are not covered by any product liability insurance we may obtain, and we may not have, or be able to obtain, sufficient capital to pay such amounts.

Risks Related to Managing Any Growth We May Experience

We will need to grow the size of our organization, and we may not successfully manage any growth we may achieve.

Our success will depend upon the expansion of our operations and our ability to successfully manage our growth. Our future growth, if any, may place a significant strain on our management and on our administrative, operational and financial resources and require us to implement and improve our operational, financial and management systems.

In addition, our ability to manage our growth effectively will hinge upon our ability to expand, train, manage and motivate our employees. As of June 17, 2015, we have 29 full-time employees and five part-time employees. As our development and commercialization plans and strategies develop, these demands may also require the hiring of additional research, development, managerial, operational, sales, marketing, financial, accounting, legal and other personnel.

Moreover, future growth could require the development of additional expertise by management and impose significant added responsibilities on members of management, including:

We may not be able to accomplish any of those tasks, and our failure to do so could prevent us from effectively managing future growth, if any, and successfully growing our company.

Any increase in resources devoted to research and product development without a corresponding increase in our operational, financial and management systems, could have a material adverse effect on our business, financial condition and results of operations.

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We may make future acquisitions that could disrupt our business, cause dilution to our stockholders and harm our financial condition and operating results.

While we currently have no specific plans to acquire any other businesses, we may, in the future, make acquisitions of, or investments in, companies that we believe have products or capabilities that are a strategic or commercial fit with our current business or otherwise offer opportunities for our company. In connection with these acquisitions or investments, we may:

We may not be able to complete acquisitions on favorable terms, if at all. If we do complete an acquisition, we cannot assure you that it will ultimately strengthen our competitive position or that it will be viewed positively by customers, financial markets or investors. Furthermore, future acquisitions could pose numerous additional risks to our operations, including:

Risks Related to Our Intellectual Property

If we breach any of the agreements under which we license from third parties the intellectual property rights or commercialization rights to our drug candidates, particularly our license agreement with TUM, we could lose license rights that are important to our business and our operations could be materially harmed.

Under the TUM License Agreement, we in-license significant intellectual property related to our Anticalin^® platforms from Technische Universität München, or TUM. Under the terms of the agreement, TUM assigns to us certain materials and records resulting from the research. We retain rights to inventions made by our employees, and TUM assigns to us all inventions made under the agreement jointly by our employees and TUM personnel, provided that our employees have made a certain inventive contribution. With respect to all other inventions made in the course of the research, TUM grants to us worldwide exclusive license rights under patents and patent applications claiming such inventions. TUM retains rights to practice these inventions for research and teaching purposes. We bear the costs of filing, prosecution and maintenance of patents assigned or licensed to us under the agreement.

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As consideration for the assignments and licenses we are obliged to pay to TUM milestone payments on development of our proprietary products claimed by patents assigned or licensed to us by TUM. We also are obliged to pay low single-digit royalties, including annual minimum royalties, on sales of such products. Should we grant licenses or sublicenses to those patents to third parties, we are obliged to pay to TUM certain undisclosed variable fees as a function of out-licensing revenues, or the Out-License Fee, where such Out-License Fees are creditable against annual license payments to TUM. Our payment obligations are reduced by our proportionate contribution to a joint invention. Payment obligations terminate on expiration or annulment of the last patent covered by the agreement.

We are also currently in a dispute with TUM. On March 20, 2014, Pieris Operating instituted arbitration proceedings, or the TUM Arbitration, against TUM to address issues regarding the calculation of payments due from Pieris Operating to TUM under the TUM License Agreement. Pursuant to the terms of the TUM License Agreement, the arbitration is proceeding in Munich, Germany and governed by German law, in accordance with the arbitration rules of the Deutsche Institution für Schiedsgerichtsbarkeit.

As required by the TUM License Agreement, Pieris Operating provided to TUM its calculation of the Out-License Fee owed by Pieris Operating to TUM for the period beginning on the effective date of the agreement and ending on December 31, 2012, the Dispute Period, in the amount of $0.4 million excluding value-added tax. TUM has asserted that, under the TUM License Agreement, the Out-License Fee due to TUM for the Dispute Period amounts to $3.4 million excluding value-added tax in the aggregate and has threatened to terminate the TUM License Agreement if the Out-License Fee is not paid. We believe that if TUM sought to terminate the license agreement for cause as a result of this dispute, it would potentially face wrongful termination claims for substantial damages if the arbitral tribunal in the TUM Arbitration sides with Pieris in its final decision regarding the proper amount of the Out-License Fee, but we can provide no assurance regarding the timing, nature or consequences of such decision. Pieris Operating instituted the TUM Arbitration to request the arbitration tribunal to hold that Pieris Operating’s calculation of the payments owed to TUM is accurate and shall govern all current and future payments due in respect of the Out-License Fee under the TUM License Agreement. Pieris Operating has reserved a liability on its balance sheet in respect of such payment in the amount of €271,000 ($327,937). An adverse ruling in the TUM Arbitration could have a material adverse effect on Pieris Operating’s results of operations and financial condition.

In addition to the TUM License Agreement, we may seek to enter into additional agreements with other third parties in the future granting similar license rights with respect to other potential drug candidates. If we fail to comply with any of the conditions or obligations or otherwise breach the terms of our license agreement with TUM, or any future license agreement we may enter on which our business or drug candidates are dependent, TUM or other licensors may have the right to terminate the applicable agreement in whole or in part and thereby extinguish our rights to the licensed technology and intellectual property and/or any rights we have acquired to develop and commercialize certain drug candidates, including, with respect to our license agreement with TUM, our Anticalin^® drug therapies. Under the TUM License Agreement, we can terminate the licenses to any or all licensed patents upon specified advance notice to TUM. TUM may terminate the license provisions of the agreement only for cause. Termination of the agreement does not terminate our rights in patents assigned to us but would terminate our rights to patents licensed to us under the agreement. The loss of the rights licensed to us under our license agreement with TUM, or any future license agreement that we may enter granting us rights on which our business or drug candidates are dependent, would eliminate our ability to further develop the applicable drug candidates and would materially harm our business, prospects, financial condition and results of operations.

If our efforts to protect the proprietary nature of the intellectual property related to our technologies are not adequate, we may not be able to compete effectively and our business would be harmed.

We rely upon a combination of patents, trade secret protection and confidentiality agreements to protect the intellectual property related to our technologies. Any disclosure to, or misappropriation by, third parties of our

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trade secret or other confidential or proprietary information could enable competitors to quickly duplicate or surpass our technological achievements, thus eroding any competitive advantage we may derive from the proprietary information.

The strength of patents in the biotechnology and pharmaceutical fields can be uncertain and involve complex legal and scientific questions. No consistent policy regarding the breadth of claims allowed in patents has emerged to date in the United States. Accordingly, we cannot predict the breadth of claims that may be allowed or enforced, or that the scope of any patent rights could provide a sufficient degree of protection that could permit us to gain or keep our competitive advantage with respect to these products and technologies. For example, we cannot predict:

As a result, the patent applications we own or license may fail to result in issued patents in the United States or in foreign countries. Third parties may challenge the validity, enforceability or scope of any issued patents we own or license or any applications that may issue as patents in the future, which may result in those patents being narrowed, invalidated or held unenforceable. Even if they are unchallenged, our patents and patent applications may not adequately protect our intellectual property or prevent others from developing similar products that do not fall within the scope of our patents. If the breadth or strength of protection provided by the patents we hold or pursue is threatened, our ability to commercialize any drug candidates with technology protected by those patents could be threatened. Further, if we encounter delays in our clinical trials, the period of time during which we would have patent protection for any covered drug candidates that obtain regulatory approval would be reduced. Since patent applications in the United States and most other countries are confidential for a period of time after filing, we cannot be certain at the time of filing that we are the first to file any patent application related to our drug candidates.

While patent term extensions under the Hatch-Waxman Act in the United States and under supplementary protection certificates in Europe may be available to extend our patent exclusivity for our drug candidates, the applicable patents may not meet the specified conditions for eligibility for any such term extension and, even if eligible, we may not be able to obtain any such term extension. Further, because filing, prosecuting, defending and enforcing patents in multiple jurisdictions can be expensive, we may elect to pursue patent protection relating to our drug candidates in only certain jurisdictions. As a result, competitors would be permitted to use our technologies in jurisdictions where we have not obtained patent protection to develop their own products, any of which could compete with our drug candidates.

In addition to the protection afforded by patents, we seek to rely on trade secret protection and confidentiality agreements to protect proprietary know-how that is not patentable, processes for which patents are difficult to enforce and any other elements of our discovery platform and drug development processes that involve proprietary know-how, information or technology that is not covered by patents or not amenable to patent protection. Although we require all of our employees and certain consultants and advisors to assign inventions to us, and all of our employees, consultants, advisors and any third parties who have access to our proprietary know-how, information or technology to enter into confidentiality agreements, our trade secrets and other proprietary information may be disclosed or competitors may otherwise gain access to such information or

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independently develop substantially equivalent information. Further, the laws of some foreign countries do not protect proprietary rights to the same extent or in the same manner as the laws of the United States. As a result, we may encounter significant difficulty in protecting and defending our intellectual property both in the United States and abroad. If we are unable to prevent material disclosure of the trade secret intellectual property related to our technologies to third parties, we may not be able to establish or maintain the competitive advantage that we believe is provided by such intellectual property, which could materially adversely affect our market position and business and operational results.

Claims that we infringe the intellectual property rights of others may prevent or delay our drug discovery and development efforts.

Our research, development and commercialization activities, as well as any drug candidates or products resulting from those activities, may infringe or be accused of infringing a patent or other form of intellectual property under which we do not hold a license or other rights. Third parties may assert that we are employing their proprietary technology without authorization.

There may be third-party patents of which we are currently unaware with claims that cover the use or manufacture of our drug candidates or the practice of our related methods. Because patent applications can take many years to issue, there may be currently pending patent applications that may later result in issued patents that our drug candidates may infringe. In addition, third parties may obtain patents in the future and claim that use of our drug candidates infringes upon one or more claims of these patents. If our activities or drug candidates infringe the patents or other intellectual property rights of third parties, the holders of such intellectual property rights may be able to block our ability to commercialize such drug candidates or practice our methods unless we obtain a license under the intellectual property rights or until any applicable patents expire or are determined to be invalid or unenforceable.

Defense of any intellectual property infringement claims against us, regardless of their merit, would involve substantial litigation expense and would be a significant diversion of resources from our business. In the event of a successful claim of infringement against us, we may have to pay substantial damages, obtain one or more licenses from third parties, limit our business to avoid the infringing activities, pay royalties and/or redesign our infringing drug candidates or alter related formulations, processes, methods or other technologies, any or all of which may be impossible or require substantial time and monetary expenditure. Further, if we were to seek a license from the third party holder of any applicable intellectual property rights, we may not be able to obtain the applicable license rights when needed or on reasonable terms, or at all. Some of our competitors may be able to sustain the costs of complex patent litigation or proceeding more effectively than us because they have substantially greater resources. The occurrence of any of the above events could prevent us from continuing to develop and commercialize one or more of our drug candidates and our business could materially suffer.

We may desire to, or be forced to, seek additional licenses to use intellectual property owned by third parties, and such licenses may not be available on commercially reasonable terms or at all.

In addition to TUM, other third parties may also hold intellectual property, including patent rights, that are important or necessary to the development of our drug candidates, in which case we would need to obtain a license from that third party or develop a different formulation of the product that does not infringe upon the applicable intellectual property, which may not be possible. Additionally, we may identify drug candidates that we believe are promising and whose development and other intellectual property rights are held by third parties. In such a case, we may desire to seek a license to pursue the development of those drug candidates. Any license that we may desire to obtain or that we may be forced to pursue may not be available when needed on commercially reasonable terms or at all. Any inability to secure a license that we need or desire could have a material adverse effect on our business, financial condition and prospects.

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The patent protection covering some of our drug candidates may be dependent on third parties, who may not effectively maintain that protection.

While we expect that we will seek to gain the right to fully prosecute any patents covering drug candidates we may in-license from third-party owners, it is possible that the platform technology patents that cover our drug candidates remain controlled by our licensors. Similarly, some of our future licensing partners may retain the right, or may seek the rights, to prosecute patents covering the drug candidates we license to them and we may grant such rights to those partners for business reasons. If such third parties fail to appropriately maintain that patent protection, we may not be able to prevent competitors from developing and selling competing products or practicing competing methods and our ability to generate revenue from any commercialization of the affected drug candidates may suffer.

Certain technologies and patents have been developed with partners and we may face restrictions on this jointly-developed intellectual property.

We have entered into agreements with a number of commercial partners, including university partners, which cover intellectual property. We have, in some cases individually and in other cases along with our partners, filed for patent protection for a number of technologies developed under these agreements and may in the future file for further intellectual property protection and/or seek to commercialize such technologies. Under some of these agreements, certain intellectual property developed by us and the relevant partner may be subject to joint ownership by us and the partner and our commercial use of such intellectual property may be restricted, or may require written consent from, or a separate agreement with, the partner. In other cases, we may not have any rights to use intellectual property solely developed and owned by the partner. If we cannot obtain commercial use rights for such jointly-owned intellectual property or partner-owned intellectual property, our future product development and commercialization plans may be adversely affected.

We may be involved in lawsuits to protect or enforce our patents or the patents of our licensors, which could be expensive, time-consuming and unsuccessful.

Competitors may infringe our patents or the patents of our current or potential licensors. To attempt to stop infringement or unauthorized use, we may need to enforce one or more of our patents, which can be expensive and time-consuming and distract management.

If we pursue any litigation, a court may decide that a patent of ours or any of our licensor’s is not valid or is unenforceable, or may refuse to stop the other party from using the relevant technology on the grounds that our patents do not cover the technology in question. Further, the legal systems of certain countries, particularly certain developing countries, do not favor the enforcement of patents, which could reduce the likelihood of success of, or the amount of damages that could be awarded resulting from, any infringement proceeding we pursue in any such jurisdiction. An adverse result in any infringement litigation or defense proceedings could put one or more of our patents at risk of being invalidated, held unenforceable, or interpreted narrowly and could put our patent applications at risk of not issuing, which could limit our ability to exclude competitors from directly competing with us in those jurisdictions.

Interference proceedings provoked by third parties or brought by the USPTO or at its foreign counterparts (such as the EPO) to determine the priority of inventions with respect to our patents or patent applications or those of our licensors. An unfavorable outcome could require us to cease using the related technology or to attempt to license rights to use it from the prevailing party. Our business could be harmed if the prevailing party does not offer us a license on commercially reasonable terms, or at all.

Litigation or interference proceedings may fail and, even if successful, may result in substantial costs and distract our management and other employees.

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If we are unsuccessful in obtaining or maintaining patent protection for intellectual property in development, our business and competitive position would be harmed.

We are seeking patent protection for our technology and drug candidates that are not trade secrets. Patent prosecution is a challenging process and is not assured of success. If we are unable to secure patent protection for our technology and drug candidates, our business may be adversely impacted.

In addition, issued patents and pending applications require regular maintenance. Failure to maintain our portfolio may result in loss of rights that may adversely impact our intellectual property rights, for example by rendering issued patents unenforceable or by prematurely terminating pending applications.

If we are unable to protect the confidentiality of our trade secrets, our business and competitive position would be harmed.

In addition to seeking patents for our Anticalin^®-brand technology and some of our drug candidates, we also rely on trade secrets, including unpatented know-how, technology and other proprietary information, to maintain our competitive position. We currently, and expect in the future to continue to, seek to protect these trade secrets, in part, by entering into confidentiality agreements with parties who have access to them, such as our employees, collaborators, contract manufacturers, consultants, advisors, investigators and other third parties. We also enter into confidentiality and invention or patent assignment agreements with our employees and consultants. Despite these efforts, any of these parties may breach the agreements and disclose our proprietary information, including our trade secrets, and we may not be able to obtain adequate remedies for any such disclosure. Enforcing a claim that a party illegally disclosed or misappropriated a trade secret is difficult, expensive and time-consuming, and the outcome is unpredictable. In addition, some courts inside and outside the United States are less willing or unwilling to protect trade secrets. If any of our trade secrets were to be lawfully obtained or independently developed by a competitor, we would have no right to prevent them, or those to whom they disclose the trade secrets, from using that technology or information to compete with us. If any of our trade secrets were to be disclosed to or independently developed by a competitor, our competitive position would be harmed.

If we fail to protect our trademark rights, competitors may be able to take advantage of our goodwill, which would weaken our competitive position, reduce our revenues and increase our costs.

We believe that the protection of our trademark rights is an important factor in product recognition, maintaining goodwill, and maintaining or increasing market share. We may expend substantial cost and effort in an attempt to register, maintain and enforce our trademark rights. If we do not adequately protect our rights in our trademarks from infringement, any goodwill that we have developed in those trademarks could be lost or impaired.

Third parties may claim that the sale or promotion of our products, when and if we have any, may infringe on the trademark rights of others. Trademark infringement problems occur frequently in connection with the sale and marketing of pharmaceutical products. If we become involved in any dispute regarding our trademark rights, regardless of whether we prevail, we could be required to engage in costly, distracting and time-consuming litigation that could harm our business. If the trademarks we use are found to infringe upon the trademark of another company, we could be liable for damages and be forced to stop using those trademarks, and as result, we could lose all the goodwill that has been developed in those trademarks.

Certain of our employees and their inventions are subject to German law.

The employees of Pieris Operating work in Germany and are subject to German employment law. Ideas, developments, discoveries and inventions made by such employees and consultants are subject to the provisions of the German Act on Employees’ Inventions (Gesetz über Arbeitnehmererfindungen), which regulates the ownership of, and compensation for, inventions made by employees. We face the risk that disputes can occur

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between us and such employees or ex-employees pertaining to alleged non-adherence to the provisions of this act that may be costly to defend and take up our management’s time and efforts whether we prevail or fail in such dispute. In addition, under the German Act on Employees’ Inventions, certain employees retained rights to patents they invented or co-invented prior to 2009. Although most of these employees have subsequently assigned their interest in these patents to us, there is a risk that the compensation we provided to them may be deemed to be insufficient and we may be required under German law to increase the compensation due to such employees for the use of the patents. In those cases where employees have not assigned their interests to us, we may need to pay compensation for the use of those patents. If we are required to pay additional compensation or face other disputes under the German Act on Employees’ Inventions, our results of operations could be adversely affected.

The future growth of our business may expose our intellectual property to a high risk of counterfeiting or unauthorized use.

As part of our business strategy, we intend to license our Anticalin^® technology and sell our potential products, if any, in many different countries. As a result, we may do business with third parties in countries where intellectual property rights have been or are routinely disregarded, and the future growth of our business may expose our intellectual property to a high risk of counterfeiting or unauthorized use. Although we attempt to obtain broad international intellectual property rights for our Anticalin technology and proteins, we cannot guarantee that such rights, to the extent we can obtain them, will be enforceable in a timely fashion or at all in any particular country or jurisdiction, or that if enforced, will offer us adequate commercial protection or adequate redress for any harm suffered. Counterfeiting or unauthorized use of our technologies or products may also expose our business to harm for which no adequate monetary redress exists, and to the extent we are unable to stop such use, may cause us to lose rights with respect to intellectual property that is crucial to our business. Any such misuse of our intellectual property may have a substantial negative impact on our business and revenues, and may cause our business to fail.

Risks Related to our Employees

If we are not able to attract and retain highly qualified personnel, we may not be able to successfully implement our business strategy.

Our ability to compete in the highly competitive biotechnology and pharmaceuticals industries depends upon our ability to attract and retain highly qualified personnel. We are highly dependent on our management, scientific and medical personnel, especially Stephen S. Yoder, our Chief Executive Officer and President, whose services are critical to the successful implementation of our drug candidate development, our business development and partnerships, and our regulatory and commercialization strategies. Further, as our approach is built in part upon the drug discovery and development experience of our drug development team, which we believe is a significant contributor to our competitive advantage, we are dependent on the maintenance and growth of that team with qualified members containing high levels of expertise in specific scientific fields. We currently have 34 employees, and we may in the future hire additional employees for research and development or general and administrative activities.

We are not aware of any present intention of any of our executive officers or other members of our senior management team to leave our company, but our industry tends to experience a high rate of turnover of management personnel and our employees are generally able to terminate their relationships with us on short notice. Pursuant to German employment law, our employment arrangements with employees of Pieris Operating are governed by employment contracts which provide certain defined terms for either party to terminate the employment relationship. Additionally, some members of our team, including our Acting Chief Financial Officer Darlene Deptula-Hicks, are consultants rather than employees, and could terminate their consulting relationship with us at any time or with short notice, depending on the terms of their respective consulting agreements with us.

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The loss of the services of any of our executive officers, in particular Mr. Yoder, or other key employees and our inability to find suitable replacements could potentially harm our business, financial condition and prospects. Our success also depends on our ability to continue to attract, retain and motivate highly skilled junior and mid-level managers as well as junior and mid-level scientific and medical personnel.

Moreover, there is intense competition for a limited number of qualified personnel among biopharmaceutical, biotechnology, pharmaceutical and other related businesses. Many of the other companies against which we compete for qualified personnel have greater financial and other resources, different risk profiles, longer histories in the industry and greater ability to provide valuable cash or stock incentives to potential recruits than we do. They also may provide more diverse opportunities and better chances for career advancement. Some of these characteristics may be more appealing to high quality candidates than what we are able to offer as an early stage company. If we are unable to continue to attract and retain high quality personnel, the rate and success at which we can develop and commercialize drug candidates will be limited.

We may be subject to labor claims brought by our employees against us.

In the United States, an employment relationship with no specified duration is presumed to be employment “at- will” and the employer or employee may terminate the employment relationship at any time, with or without cause, except for public policy reasons including discrimination, participating in union activity or refusing to carry out an activity that violates the law.

In contrast, in Germany, there is no analogous doctrine of “employment at will.” By law, German employees must have written employment contracts that reflect the key aspects of the employment relationship. With respect to Pieris Operating, relations between German employers and employees are extensively regulated under German labor and employment laws and regulations. German employees enjoy, in particular, special protection against dismissals provided the employee has been employed by a company for more than six months and such company employs more than 10 employees.

German employment termination law is regulated by various codes, in particular the Kündigungsschutzgesetz (German Termination Protection Act) and is intended to give the employee maximum protection against unfair dismissal, including among other things:

In this regard, if we downsize Pieris Operating for any reason and fail to adhere to the complex requirements articulated by the employee protection law, we could face legal actions brought by affected employees or former employees, and, as a result, we may incur operational or financial losses and the attention of our executive officers may be distracted from managing our business.

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We may be subject to claims by third parties asserting that our employees or we have misappropriated their intellectual property, or claiming ownership of what we regard as our own intellectual property.

Many of our employees were previously employed at universities or other biotechnology or pharmaceutical companies, including our competitors or potential competitors. We may be subject to claims that these employees or we have used or disclosed intellectual property, including trade secrets or other proprietary information, of any such employee’s former employers. Litigation may be necessary to defend against any such claims.

In addition, while it is our policy to require our employees and contractors who may be involved in the development of intellectual property to execute agreements assigning such intellectual property to us, we may be unsuccessful in executing such an agreement with each party who in fact contributes to the development of intellectual property that we regard as our own. Further, the terms of such assignment agreements may be breached and we may not be able to successfully enforce their terms, which may force us to bring claims against third parties, or defend claims they may bring against us, to determine the ownership of intellectual property rights we may regard and treat as our own.

Our employees may engage in misconduct or other improper activities, including noncompliance with regulatory standards and requirements, which could cause our business to suffer.

We are exposed to the risk of employee fraud or other misconduct. Misconduct by employees could include intentional failures to comply with FDA or EMA regulations, provide accurate information to the FDA or EMA, comply with manufacturing standards we have established, comply with federal, state and international healthcare fraud and abuse laws and regulations as they may become applicable to our operations, report financial information or data accurately or disclose unauthorized activities to us. Employee misconduct could also involve the improper use of information obtained in the course of clinical trials, which could result in regulatory sanctions and serious harm to our reputation. It is not always possible to identify and deter employee misconduct, and the precautions and procedures we currently take or may establish in the future as our operations and employee base expand to detect and prevent this type of activity may not be effective in controlling unknown or unmanaged risks or losses or in protecting us from governmental investigations or other actions or lawsuits stemming from a failure by our employees to comply with such laws or regulations. If any such actions are instituted against us, and we are not successful in defending ourselves or asserting our rights, those actions could have a significant impact on our business and results of operations, including the imposition of significant fines or other sanctions.

Risks Related to the Ownership of our Common Stock and this Offering

There is not now, and there may never be, an active, liquid and orderly trading market for our common stock, which may make it difficult for you to sell your shares of our common stock.

There is not now, nor has there been since our inception, any significant trading activity in our common stock or a market for shares of our common stock, and an active trading market for our shares may never develop or be sustained after this offering. As a result, investors in our common stock must bear the economic risk of holding those shares for an indefinite period of time. Our common stock has been quoted on the OTC Markets OTCQB tier, or OTCQB, of OTC Markets Group Inc., an over-the-counter quotation system. Although in connection with this offering, our common stock has been approved for listing on the NASDAQ Capital Market beginning on June 30, 2015, an active market for our common stock may never develop or be sustained. If an active market for our common stock does not develop, it may be difficult for you to sell the shares you purchase in this offering without depressing the market price for the shares or at all. Further, an inactive market may also impair our ability to raise capital by selling additional equity in the future, and may impair our ability to enter into strategic partnerships or acquire companies or products by using shares of our common stock as consideration.

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Our share price is expected to be volatile and may be influenced by numerous factors, some of which are beyond our control.

Market prices for shares of biotechnology companies such as ours are often volatile, and the quoted price of our common stock is therefore likely to be highly volatile and could be subject to wide fluctuations in response to various factors, some of which are beyond our control. In addition to the factors discussed in this “Risk Factors” section and elsewhere in prospectus, these factors include:

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In addition, the stock market in general, and the stocks of small-cap biotechnology companies in particular, have experienced extreme price and volume fluctuations that have often been unrelated or disproportionate to the operating performance of these companies. Broad market and industry factors may negatively affect the market price of our common stock, regardless of our actual operating performance. In addition other biotechnology companies or our competitors’ programs could have positive or negative results that impact their stock prices and their results or stock fluctuations could have a positive or negative impact on our stock price regardless of whether such impact is direct or not. The realization of any of the above risks or any of a broad range of other risks, including those described in these “Risk Factors,” could have a dramatic and material adverse impact on the market price of our common stock.

Our common stock is subject to the “penny stock” rules of the SEC and the trading market in the securities is limited, which makes transactions in the stock cumbersome and may reduce the value of an investment in the stock.

Rule 15g-9 under the Securities Exchange Act of 1934, as amended, or the Exchange Act, establishes the definition of a “penny stock,” for the purposes relevant to us, as any equity security that has a market price of less than $5.00 per share or with an exercise price of less than $5.00 per share, subject to certain exceptions. For any transaction involving a penny stock, unless exempt, the rules require: (i) that a broker or dealer approve a person’s account for transactions in penny stocks in accordance with the provisions of Rule 15g-9; and (ii) the broker or dealer receive from the investor a written agreement to the transaction, setting forth the identity and quantity of the penny stock to be purchased, provided that any such purchase shall not be effected less than two business days after the broker or dealer sends such written agreement to the investor.

In order to approve a person’s account for transactions in penny stocks, the broker or dealer must: (i) obtain financial information, investment experience and investment objectives of the person and (ii) make a reasonable determination that the transactions in penny stocks are suitable for that person and the person has sufficient knowledge and experience in financial matters to be reasonably expected to be capable of evaluating the risks of transactions in penny stocks.

The broker or dealer must also deliver, prior to any transaction in a penny stock, a disclosure schedule prescribed by the SEC relating to the penny stock market, which: (i) sets forth the basis on which the broker or dealer made the suitability determination; and (ii) in highlight form, confirms that the broker or dealer received a signed, written agreement from the investor prior to the transaction. Generally, brokers may be less willing to execute transactions in securities subject to the “penny stock” rules. This may make it more difficult for investors to dispose of our common stock and cause a decline in the market value of our common stock.

Disclosure also has to be made about the risks of investing in penny stocks in both public offerings and in secondary trading and about the commissions payable to both the broker or dealer and the registered representative, current quotations for the securities and the rights and remedies available to an investor in cases of fraud in penny stock transactions. Finally, monthly statements have to be sent disclosing recent price information for the penny stock held in the account and information on the limited market in penny stocks. As a result, it may be more difficult to execute trades of our common stock which may have an adverse effect on the liquidity of our common stock and your investment.

If securities or industry analysts do not publish, or cease publishing, research or publish inaccurate or unfavorable research about our business or our market, or if they change their recommendations regarding our stock adversely, our stock price and any trading volume could decline.

Any trading market for our common stock that may develop will depend in part on the research and reports that securities or industry analysts publish about us or our business, markets or competitors. Securities and industry analysts do not currently, and may never, publish research on us or our business. If no securities or industry analysts commence coverage of our company, the trading price for our stock would be negatively affected. If securities or industry analysts initiate coverage, and one or more of those analysts downgrade our stock or

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publish inaccurate or unfavorable research about our business or our market, our stock price would likely decline. If one or more of these analysts cease coverage of our company or fail to publish reports on us regularly, demand for our stock could decrease, which might cause our stock price and any trading volume to decline.

We may have material liabilities that were not discovered before, and have not been discovered since, the closing of the Acquisition.

As a result of the Acquisition, the former business plan and management of Pieris, previously known as Marika Inc., have been abandoned and replaced with the business and management team of Pieris Operating. Prior to the Acquisition, there were no relationships or other connections among the businesses or individuals associated with those two entities. As a result, Pieris may have material liabilities based on activities before the Acquisition that have not been discovered or asserted. We could experience losses as a result of any such undisclosed liabilities that are discovered in the future, which could materially harm our business and financial condition. Although the acquisition agreement entered into in connection with the Acquisition contains customary representations and warranties from Pieris concerning its assets, liabilities, financial condition and affairs, there may be limited or no recourse against Pieris’ pre-Acquisition stockholders or principals in the event those representations prove to be untrue. As a result, our current and future stockholders will bear some, or all, of the risks relating to any such unknown or undisclosed liabilities.

We are exposed to additional risks as a result of “going public” by means of a reverse acquisition transaction.

We are exposed to additional risks because the business of Pieris Operating has become a public company through a “reverse acquisition” transaction. There has been increased focus in recent years by government agencies on transactions such as the Acquisition in recent years, and we may be subject to increased scrutiny by the SEC and other government agencies and holders of our securities as a result of the completion of that transaction. Further, as a result of our existence as a “shell company” under applicable rules of the SEC prior to the closing of the Acquisition on December 17, 2014, we are subject to certain restrictions and limitations for certain specified periods of time relating to potential future issuances of our securities and compliance with applicable SEC rules and regulations. Additionally, our “going public” by means of a reverse acquisition transaction may make it more difficult for us to obtain coverage from securities analysts of major brokerage firms following the Acquisition because there may be little incentive to those brokerage firms to recommend the purchase of our common stock. Further, investment banks may be less likely to agree to underwrite secondary offerings on our behalf than they might if we became a public reporting company by means of an initial public offering, or IPO, because they may be less familiar with our company as a result of more limited coverage by analysts and the media, and because we became public at an early stage in our development. The failure to receive research coverage or support in the market for our shares will have an adverse effect on our ability to develop a liquid market for our common stock. The occurrence of any such event could cause our business or stock price to suffer.

If we continue to fail to maintain proper and effective internal controls, our ability to produce accurate and timely financial statements could be impaired, which could harm our operating results, our ability to operate our business and investors’ views of us.

We are required to comply with Section 404 of the Sarbanes-Oxley Act of 2002, as amended, or the Sarbanes- Oxley Act, subject to certain exceptions. Section 404 of the Sarbanes-Oxley Act requires public companies to conduct an annual review and evaluation of their internal controls and to obtain attestations of the effectiveness of internal controls by independent auditors. However, as discussed in detail below, as an emerging growth company, we are not required to obtain an auditor attestation. As a private company, Pieris Operating was not subject to requirements to establish, and did not establish, internal control over financial reporting and disclosure controls and procedures prior to the Acquisition. Our management team and Board of Directors will need to devote significant efforts to maintaining adequate and effective disclosure controls and procedures and

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internal control over financial reporting in order to comply with applicable regulations, which may include hiring additional legal, financial reporting and other finance and accounting staff. Additionally, any of our efforts to improve our internal controls and design, implement and maintain an adequate system of disclosure controls may not be successful and will require that we expend significant cash and other resources.

Under the Jumpstart Our Business Startups Act of 2012, or the JOBS Act, issuers that qualify as “emerging growth companies” under the JOBS Act will not be required to provide an auditor’s attestation report on internal controls for so long as the issuer qualifies as an emerging growth company. We currently qualify as an emerging growth company under the JOBS Act, and we may choose not to provide an auditor’s attestation report on internal controls. However, if we cannot favorably assess the effectiveness of our internal control over financial reporting, or if we require an attestation report from our independent registered public accounting firm in the future and that firm is unable to provide an unqualified attestation report on the effectiveness of our internal controls over financial reporting, investor confidence and, in turn, our stock price could be materially adversely affected.

Ensuring that we have adequate internal financial and accounting controls and procedures in place so that we can produce accurate financial statements on a timely basis is a costly and time-consuming effort that will need to be evaluated frequently. Our failure to maintain the effectiveness of our internal controls in accordance with the requirements of the Sarbanes-Oxley Act could have a material adverse effect on the tradability of our common stock, which in turn would negatively impact our business. We could lose investor confidence in the accuracy and completeness of our financial reports, which could have an adverse effect on the price of our common stock. In addition, if our efforts to comply with new or changed laws, regulations, and standards differ from the activities intended by regulatory or governing bodies due to ambiguities related to practice, regulatory authorities may initiate legal proceedings against us and our business may be harmed.

We do not have sufficient accounting and supervisory personnel with the appropriate level of technical accounting experience and training necessary or adequate accounting policies, processes and procedures, particularly in the areas of revenue recognition, equity related transactions and other complex, judgmental areas for U.S. GAAP financial reporting and SEC reporting purposes and consequently, we must rely on third party consultants. These deficiencies represent a material weakness (as defined under the Exchange Act) in our internal control over financial reporting in both design and operation. We may identify additional material weaknesses in the future. Under the Exchange Act, a material weakness is defined as a deficiency, or a combination of deficiencies, in internal control over financial reporting, such that there is a reasonable possibility that a material misstatement of a company’s annual or interim financial statements will not be prevented or detected on a timely basis by the company’s internal controls. We are currently developing a plan to design, review, implement and refine internal control over financial reporting and we have retained the services of Darlene Deptula-Hicks, as our Acting Chief Financial Officer, to help us with this process. However, we may identify deficiencies and weaknesses or fail to remediate previously identified deficiencies in our internal controls. As permitted by Section 215.02 of the SEC’s Compliance and Disclosure Interpretations, management excluded its assessment of internal controls over financial reporting for the year ended December 31, 2014, which is the year the Acquisition was completed, and we do not expect to have to include such assessment until the year ended December 31, 2015. If material weaknesses or deficiencies in our internal controls exist and go undetected or unremediated, our financial statements could contain material misstatements that, when discovered in the future, could cause us to fail to meet our future reporting obligations and cause the price of our common stock to decline.

Shares of our common stock that have not been registered under federal securities laws are subject to resale restrictions imposed by Rule 144, including those set forth in Rule 144(i) which apply to a former “shell company.”

Prior to the closing of the Acquisition, we were deemed a “shell company” under applicable SEC rules and regulations because we had no or nominal operations and either no or nominal assets, assets consisting solely of cash and cash equivalents, or assets consisting of any amount of cash and cash equivalents and nominal other

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assets. Pursuant to Rule 144 promulgated under the Securities Act of 1933, as amended, or the Securities Act, sales of the securities of a former shell company, such as us, under that rule are not permitted (i) until at least 12 months have elapsed from December 18, 2014, the date on which our Current Report on Form 8-K reflecting our status as a non-shell company, was filed with the SEC and (ii) unless at the time of a proposed sale, we are subject to the reporting requirements of Section 13 or 15(d) of the Exchange Act and have filed all reports and other materials required to be filed by Section 13 or 15(d) of the Exchange Act, as applicable, during the preceding 12 months, other than Form 8-K reports. Additionally, our previous status as a shell company could also limit our use of our securities to pay for any acquisitions we may seek to pursue in the future (although none are currently planned). The lack of liquidity of our securities as a result of the inability to sell under Rule 144 for a longer period of time than a non-former shell company could cause the market price of our securities to decline.

If we issue additional shares of our capital stock in the future, our existing stockholders will be diluted.

Our Amended and Restated Articles of Incorporation authorize the issuance of up to 300,000,000 shares of our common stock and up to 10,000,000 shares of preferred stock with the terms, limitations, voting rights, relative rights and preferences and variations of each series that our Board of Directors may determine from time to time. Upon the closings of the private placement of our common stock on December 17, 18 and 23, 2014, we issued an aggregate of 6,779,510 shares of our common stock and in connection with the private placement, we issued 542,360 shares of common stock issuable upon exercise of common stock purchase warrants issued to the placement agents thereof and their designees, which equals approximately 25% of our issued and outstanding capital stock as of June 17, 2015. Possible business and financial uses for our authorized capital stock include, without limitation, equity financing, such as the offering described in this prospectus, future stock splits, acquiring other companies, businesses or products in exchange for shares of our capital stock, issuing shares of our capital stock to partners or other collaborators in connection with strategic alliances, attracting and retaining employees by the issuance of additional securities under our equity compensation plan, or other transactions and corporate purposes that our Board of Directors deems are in the interests of our company. Additionally, issuances of shares of our capital stock could have the effect of delaying or preventing changes in control or our management. Any future issuances of shares of our capital stock may not be made on favorable terms or at all, they may have rights, preferences and privileges that are superior to those of our common stock, and may have an adverse effect on our business or the trading price of our common stock. The issuance of any additional shares of our common stock will reduce the book value per share and may contribute to a reduction in the market price of the outstanding shares of our common stock. Additionally, any such issuance will reduce the proportionate ownership and voting power of all of our current stockholders.

If you purchase shares of our common stock in this offering, you will suffer immediate dilution of your investment.

The public offering price of our common stock is substantially higher than the net tangible book value per share of our common stock. Therefore, if you purchase shares of our common stock in this offering, you will pay a price per share that substantially exceeds our net tangible book value per share after this offering. To the extent outstanding options or warrants are exercised, you will incur further dilution. Based on the public offering price of $2.75 per share, you will experience immediate dilution of $1.79 per share, representing the difference between our as adjusted net tangible book value per share after giving effect to this offering and the public offering price. In addition, purchasers of common stock in this offering will have contributed approximately 29.8% of the aggregate price paid by all purchasers of our stock but will own only approximately 23.6% of our common stock outstanding after this offering. For further information on this calculation, see “Dilution” elsewhere in this prospectus.

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We have broad discretion in the use of the net proceeds from this offering and may not use them effectively.

Our management will have broad discretion in the application of the net proceeds from this offering and could spend the proceeds in ways that do not improve our results of operations or enhance the value of our common stock. The failure by our management to apply these funds effectively could result in financial losses that could have a material adverse effect on our business, cause the price of our common stock to decline and delay the development of our drug candidates. Pending their use, we may invest the net proceeds from this offering in a manner that does not produce income or that loses value.

Sales of a substantial number of shares of our common stock in the public market, or the perception that such sales could occur, could cause our stock price to fall.

If our existing stockholders sell, or indicate an intention to sell, substantial amounts of our common stock in the public market, the trading price of our common stock could decline. As of June 17, 2015, a total of 29,429,522 shares of our common stock were outstanding. Of those shares, 29,279,522 were freely tradable, without restriction, in the public market. Such shares represent approximately 99% of our outstanding shares of common stock as of that date. Any sales of those shares or any perception in the market that such sales may occur could cause the trading price of our common stock to decline.

In addition, shares of common stock that are either subject to outstanding options or reserved for future issuance under our equity incentive plan will be eligible for sale in the public market to the extent permitted by the provisions of various vesting schedules. If these additional shares of common stock are sold, or if it is perceived that they will be sold, in the public market, the trading price of our common stock could decline.

The resale of shares covered by our effective resale registration statement could adversely affect the market price of our common stock in the public market, should one develop, which result would in turn negatively affect our ability to raise additional equity capital.

The sale, or availability for sale, of our common stock in the public market may adversely affect the prevailing market price of our common stock and may impair our ability to raise additional equity capital. We filed a registration statement with the SEC, which was declared effective on May 11, 2015, to register the resale of 27,321,870 shares of our common stock, which represents all of the shares of our common stock issued and sold in our private placement consummated in December 2014, shares of our common stock issued to former stockholders of Pieris Operating in connection with the closing of the Acquisition on December 17, 2014, and shares of common stock issuable upon exercise of common stock purchase warrants issued in connection with the closings of the private placement on December 17, 18 and 23, 2014. Such shares represent approximately 93% of our outstanding shares of common stock as of June 17, 2015. The resale registration statement permits the resale of these shares at any time without restriction. The resale of a substantial number of shares of our common stock in the public market could adversely affect the market price for our common stock and make it more difficult for you to sell shares of our common stock at times and prices that you feel are appropriate. Furthermore, because there are a large number of shares registered pursuant to the resale registration statement, we may continue to offer shares covered by the resale registration statement for a significant period of time, the precise duration of which cannot be predicted. Accordingly, the adverse market and price pressures resulting from an offering pursuant to the resale registration statement may continue for an extended period of time and continued negative pressure on the market price of our common stock could have a material adverse effect on our ability to raise additional equity capital.

Future sales and issuances of our common stock or rights to purchase common stock, including pursuant to our equity incentive plans or otherwise, could result in dilution of the percentage ownership of our stockholders and could cause our stock price to fall.

Even after giving effect to the funds raised in this offering, we expect that significant additional capital will be needed in the future to continue our planned operations. To raise capital, we may sell common stock,

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convertible securities or other equity securities in one or more transactions at prices and in a manner we determine from time to time. If we sell common stock, convertible securities or other equity securities in more than one transaction, investors in a prior transaction may be materially diluted. Additionally, new investors could gain rights, preferences and privileges senior to those of existing holders of our common stock. Further, any future sales of our common stock by us or resales of our common stock by our existing stockholders could cause the market price of our common stock to decline.

Pursuant to the Pieris Plan, we are authorized to grant equity awards to our employees, directors and consultants for up to an aggregate of 3,200,000 shares of our common stock and, as of June 17, 2015, we have granted options to purchase 2,616,735 shares of our common stock. The Pieris Plan also includes an “evergreen” provision which provides that the number of shares of our common stock reserved for issuance under the Pieris Plan shall be automatically increased on January 1 of each of year commencing in fiscal 2016 by the lesser of (i) 1,000,000 shares, (ii) 4% of the number shares of our common stock outstanding on such date, and (iii) such other amount determined by the Board of Directors. Any future grants of options, warrants or other securities exercisable or convertible into our common stock, or the exercise or conversion of such shares, and any sales of such shares in the market, could have an adverse effect on the market price of our common stock.

Anti-takeover provisions in our organizational documents could delay or prevent a change of control.

Certain provisions of our Amended and Restated Articles of Incorporation and Amended and Restated Bylaws may have an anti-takeover effect and may delay, defer or prevent a merger, acquisition, tender offer, takeover attempt or other change of control transaction that a stockholder might consider to be in its interests, including attempts that might result in a premium over the market price for the shares held by our stockholders.

These provisions provide, among other things:

These anti-takeover provisions, including those noted above, could make it more difficult for a third party to acquire us, even if the third party’s offer may be considered beneficial by many of our stockholders. As a result, our stockholders may be limited in their ability to obtain a premium for their shares. See “Description of Capital Stock.”

Our Amended and Restated Articles of Incorporation designate the Eighth Judicial District Court of Clark County, Nevada, as the sole and exclusive forum for certain types of actions and proceedings that may be initiated by our stockholders, and therefore limit our stockholders’ ability to choose a forum for disputes with us or our directors, officers, employees or agents.

Our Amended and Restated Articles of Incorporation provide that, to the fullest extent permitted by law, and unless we consent to the selection of an alternative forum, the Eighth Judicial District Court of Clark County, Nevada shall be the sole and exclusive forum for any (i) derivative action or proceeding brought in the name or

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right of the corporation or on its behalf, (ii) action asserting a claim of breach of a fiduciary duty owed by any of our directors, officers, employees or agents to the corporation or any of our stockholders, (iii) any action arising or asserting a claim arising pursuant to any provision of Chapters 78 or 92A of the NRS or any provision of our articles of incorporation or bylaws, (iv) any action to interpret, apply, enforce or determine the validity of our articles of incorporation or bylaws or (v) any action asserting a claim governed by the internal affairs doctrine. Our Amended and Restated Articles of Incorporation further provide that any person purchasing or otherwise acquiring any interest in shares of our capital stock shall be deemed, to the fullest extent permitted by law, to have notice of and consented to the foregoing provision.

We believe the choice-of-forum provision in our Amended and Restated Articles of Incorporation will help provide for the orderly, efficient and cost-effective resolution of Nevada-law issues affecting us by designating courts located in the State of Nevada (our state of incorporation) as the exclusive forum for cases involving such issues. However, this provision may limit a stockholder’s ability to bring a claim in a judicial forum that it believes to be favorable for disputes with us or our directors, officers, employees or agents, which may discourage such actions against us and our directors, officers, employees and agents. While there is no Nevada case law addressing the enforceability of this type of provision, Nevada courts have on prior occasion found persuasive authority in Delaware case law in the absence of Nevada statutory or case law specifically addressing an issue of corporate law. The Court of Chancery of the State of Delaware has ruled in June 2013 that choice-of-forum provisions of a type similar to those included in our Amended and Restated Articles of Incorporation are not facially invalid under corporate law and constitute valid and enforceable contractual forum selection clauses. However, if a court were to find the choice-of-forum provision in our Amended and Restated Articles of Incorporation inapplicable to, or unenforceable in respect of, one or more of the specified types of actions or proceedings, we may incur additional costs associated with resolving such matters in other jurisdictions, which could adversely affect our business, financial condition or results of operations.

The elimination of personal liability of our directors and officers under Nevada law and the existence of indemnification rights held by our directors, officers and employees may result in substantial expenses.

Our Amended and Restated Articles of Incorporation eliminate to the furthest extent permitted under Nevada law the personal liability of our directors and officers to us, our stockholders and creditors for damages as a result of any act or failure to act in his or her capacity as a director or officer. Further, our Amended and Restated Articles of Incorporation, our Amended and Restated Bylaws and individual indemnification agreements that we have entered with each of our directors and officers provide that we are obligated to indemnify, subject to certain exceptions, each of our directors or officers to the fullest extent authorized by Nevada law and, subject to certain conditions, to advance the expenses incurred by any director or officer in defending any action, suit or proceeding prior to its final disposition. Those indemnification obligations could expose us to substantial expenditures to cover the cost of settlement or damage awards against our directors or officers, which we may be unable to afford. Further, those provisions and resulting costs may discourage us or our stockholders from bringing a lawsuit against any of our current or former directors or officers for such damages, even if such actions might otherwise benefit our stockholders.

We do not intend to pay cash dividends on our capital stock in the foreseeable future.

We have never declared or paid any cash dividends on our common stock and do not anticipate paying any dividends in the foreseeable future. We currently intend to retain all future earnings to fund the development and growth of our business. Any future payment of cash dividends in the future will be at the discretion of our Board of Directors and will depend on, among other things, our earnings, financial condition, capital requirements, level of indebtedness, statutory and contractual restrictions applying to the payment of dividends and other considerations that the Board of Directors deems relevant. Our stockholders should not expect that we will ever pay cash or other dividends on our outstanding capital stock.

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We will incur increased costs associated with, and our management will need to devote substantial time and effort to, compliance with public company reporting and other requirements.

Our common stock has been approved for listing on the NASDAQ Capital Market under the symbol “PIRS” beginning on June 30, 2015. As a public company listed on the NASDAQ Capital Market, and particularly if and after we cease to be a an “emerging growth company” or a “smaller reporting company,” we will incur significant legal, accounting and other expenses that Pieris Operating did not incur as a private company and that we did not incur prior to the listing of our common stock on the NASDAQ Capital Market, including costs associated with public company reporting requirements. In addition, the rules and regulations of the SEC and the NASDAQ Capital Market impose numerous requirements on public companies, including requirements relating to our corporate governance practices and requirements under Section 404 and other provisions of the Sarbanes-Oxley Act, with which we will now need to comply. Further, since we are subject to the Exchange Act, we are required to, among other things, file annual, quarterly and current reports with respect to our business and operating results. Our management and other personnel will need to devote substantial time to gaining expertise regarding operations as a public company and compliance with applicable laws and regulations, and our efforts and initiatives to comply with those requirements could be expensive. The expenses incurred by public companies for reporting and corporate governance purposes have increased dramatically in recent years. We are unable currently to estimate these costs with any degree of certainty.

We are an emerging growth company and we cannot be certain if the reduced disclosure requirements applicable to emerging growth companies will make our common stock less attractive to investors.

We are an emerging growth company under the JOBS Act. For as long as we continue to be an emerging growth company, we intend to take advantage of certain exemptions from various reporting requirements that are applicable to other public companies including, but not limited to, reduced disclosure obligations regarding executive compensation in our periodic reports and proxy statements, exemptions from the requirements of holding a nonbinding advisory stockholder vote on executive compensation and any golden parachute payments not previously approved, exemption from the requirement of auditor attestation in the assessment of our internal control over financial reporting and exemption from any requirement that may be adopted by the Public Company Accounting Oversight Board. If we do, the information that we provide stockholders may be different than what is available with respect to other public companies. We cannot predict if investors will find our common stock less attractive because we will rely on these exemptions. If some investors find our common stock less attractive as a result, there may be a less active trading market for our common stock and our stock price may be more volatile.

Under the JOBS Act, emerging growth companies can delay adopting new or revised accounting standards until such time as those standards apply to private companies. We have irrevocably elected to take advantage of this extended transition period. Since we will not be required to comply with new or revised accounting standards on the relevant dates on which adoption of such standards is required for other public companies, our financial statements may not be comparable to the financial statements of companies that comply with the effective dates of those accounting standards.

We will remain an emerging growth company until the earliest of (1) the end of the fiscal year in which the market value of our common stock that is held by non-affiliates exceeds $700 million as of the end of the second fiscal quarter, (2) the end of the fiscal year in which we have total annual gross revenues of $1 billion or more during such fiscal year, (3) the date on which we issue more than $1 billion in non-convertible debt in a three-year period or (4) December 31, 2019, the end of the fiscal year following the fifth anniversary of the date of the first sale of our common stock pursuant to an effective registration statement filed under the Securities Act. Decreased disclosures in our SEC filings due to our status as an “emerging growth company” may make it harder for investors to analyze our results of operations and financial prospects.

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We are a smaller reporting company, and we cannot be certain if the reduced disclosure requirements applicable to smaller reporting companies will make our common stock less attractive to investors.

We are currently a “smaller reporting company,” meaning that we are not an investment company, an asset- backed issuer, or a majority-owned subsidiary of a parent company that is not a smaller reporting company and have a public float of less than $75 million and annual revenues of less than $50 million during the most recently completed fiscal year. In the event that we are still considered a “smaller reporting company,” at such time we cease being an “emerging growth company,” we will be required to provide additional disclosure in our SEC filings. However, similar to “emerging growth companies,” “smaller reporting companies” are able to provide simplified executive compensation disclosures in their filings; are exempt from the provisions of Section 404(b) of the Sarbanes-Oxley Act requiring that independent registered public accounting firms provide an attestation report on the effectiveness of internal control over financial reporting; and have certain other decreased disclosure obligations in their SEC filings, including, among other things, only being required to provide two years of audited financial statements in annual reports and in a registration statement under the Exchange Act on Form 10. Decreased disclosures in our SEC filings due to our status as a “smaller reporting company” may make it harder for investors to analyze our results of operations and financial prospects.

Although we have been approved for listing on the NASDAQ Capital Market, there can be no assurance that we will be able to comply with continued listing standards of the NASDAQ Capital Market.

We cannot assure you that we will be able to continue to comply with the minimum bid price and the other standards that we are required to meet in order to maintain a listing of our common stock on the NASDAQ Capital Market. Our failure to continue to meet these requirements may result in our common stock being delisted from the NASDAQ Capital Market.

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SPECIAL NOTE REGARDING FORWARD-LOOKING STATEMENTS

This prospectus contains forward-looking statements concerning our business, operations and financial performance and condition as well as our plans, objectives and expectations for our business operations and financial performance and condition. Any statements that are not of historical facts may be deemed to be forward-looking statements. You can identify these forward-looking statements by words such as “believes,” “estimates,” “anticipates,” “expects,” “plans,” “intends,” “may,” “could,” “might,” “will,” “should,” “aims,” “seeks,” or other similar expressions that convey uncertainty of future events or outcomes. Forward-looking statements appear in a number of places throughout this prospectus and include statements regarding our intentions, beliefs, assumptions, projections, outlook, analyses or current expectations concerning, among other things, our intellectual property position, results of operations, cash needs, spending of the proceeds from this offering, financial condition, liquidity, prospects, growth and strategies, the industry in which we operate and the trends that may affect the industry or us.

By their nature, forward-looking statements involve risks and uncertainties because they relate to events, competitive dynamics and industry change, and depend on economic circumstances that may or may not occur in the future or may occur on longer or shorter timelines than anticipated. Although we believe that we have a reasonable basis for each forward-looking statement contained in this prospectus, we caution you that forward- looking statements are not guarantees of future performance and involve known and unknown risks, uncertainties and other factors that are in some cases beyond our control. All of our forward-looking statements are subject to risks and uncertainties that may cause our actual results to differ materially from our expectations.

Actual results could differ materially from our forward-looking statements due to a number of factors, including, without limitation, risks related to:

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Any forward-looking statements that we make in this prospectus speak only as of the date of such statement, and we undertake no obligation to update such statements to reflect events or circumstances after the date of this prospectus or to reflect the occurrence of unanticipated events. Comparisons of results for current and any prior periods are not intended to express any future trends or indications of future performance, unless expressed as such, and should only be viewed as historical data. You should, however, review the factors and risks we describe in the reports we will file from time to time with the SEC after the date of this prospectus. See “Where You Can Find More Information.”

You should also read carefully the factors described in the “Risk Factors” section of this prospectus and elsewhere to better understand the risks and uncertainties inherent in our business and underlying any forward- looking statements. As a result of these factors, we cannot assure you that the forward-looking statements in this prospectus will prove to be accurate. Furthermore, if our forward-looking statements prove to be inaccurate, the inaccuracy may be material. In light of the significant uncertainties in these forward-looking statements, you should not regard these statements as a representation or warranty by us or any other person that we will achieve our objectives and plans in any specified timeframe, or at all.

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USE OF PROCEEDS

We estimate that we will receive net proceeds of approximately $22.7 million (or approximately $26.2 million if the underwriters’ option to purchase additional shares is exercised in full) from the sale of the shares of common stock offered by us in this offering, after deducting the underwriting discounts and commissions and estimated offering expenses payable by us.

The principal purpose of this offering is to obtain additional capital to support our operations. We intend to use the net proceeds of this offering to fund research and development, including preclinical and clinical research and development of our drug candidates, working capital and general corporate purposes. We may also use a portion of the net proceeds to acquire or invest in complementary businesses or products or to obtain rights to such complementary technologies. We have no commitments with respect to any such acquisitions or investments.

We believe that our existing cash and cash equivalents, together with the net proceeds from this offering, will be sufficient to fund our operating expenses and capital expenditure requirements for at least the next 18 months. The amount and timing of our actual expenditures will depend upon numerous factors, including the status of our preclinical studies and clinical trials, and other factors described under “Risk Factors” in this prospectus, as well as the amount of cash used in our operations. We may find it necessary or advisable to use the net proceeds for other purposes, and we will have broad discretion in the use of the net proceeds from this offering and could spend the proceeds in ways that do not improve our results of operations or enhance the value of our stock. Pending their use, we plan to invest the net proceeds from this offering in money market funds short- and intermediate-term, interest-bearing obligations, investment-grade instruments, certificates of deposit or direct or guaranteed obligations of the U.S. government.

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PRICE RANGE OF OUR COMMON STOCK

Market Information

Our common stock has been quoted on the OTC Markets OTCQB tier, or OTCQB, of OTC Markets Group, Inc. under the symbol “PIRS.” Our common stock has been approved for listing on the NASDAQ Capital Market under the symbol “PIRS” beginning on June 30, 2015.

Our common stock commenced public trading on January 28, 2014 on the OTC Markets, OTCPink (Current Information) tier of the OTC Markets Group, Inc. Although our common stock has been quoted on the OTCQB, there has been limited trading market for our common stock and there have been few trades in our common stock to date. Because our common stock has been thinly traded, any reported sale prices may not be a true market-based valuation of our common stock. The following table sets forth, for the periods indicated, the high and low closing bid quotations for our common stock, as reported by OTCQB, since the common stock commenced public trading:

Source: OTCMarkets

On June 29, 2015, the closing bid price for our common stock as reported on the OTCQB was $3.26 per share. As of June 29, 2015, there are: (i) outstanding options to purchase 2,616,735 shares of our common stock; (ii) outstanding warrants to purchase 542,360 shares of our common stock; and (iii) 29,429,522 outstanding shares of our common stock, 29,279,522 of which have been registered under the Securities Act and are freely tradable.

Holders

As of June 29, 2015, there were 169 holders of record of our common stock.

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DIVIDEND POLICY

We have never declared nor paid any cash dividends to stockholders. We do not intend to pay cash dividends on our common stock for the foreseeable future, and currently intend to retain any future earnings, if any, to fund our operations and the development and growth of our business. The declaration of any future cash dividend, if any, would be at the discretion of our Board of Directors (subject to limitations imposed under applicable Nevada law) and would depend upon our earnings, if any, our capital requirements and financial position, our general economic conditions, and other pertinent considerations.

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CAPITALIZATION

The following table sets forth our cash and cash equivalents as well as capitalization as of March 31, 2015:

You should read this table together with “Management’s Discussion and Analysis of Financial Condition and Results of Operations” included elsewhere in this prospectus, and our financial statements and related notes thereto.

The number of shares of common stock to be outstanding after this offering is based on an aggregate of 29,429,522 shares outstanding as of March 31, 2015. The table above does not include:

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DILUTION

Investors purchasing shares of our common stock in this offering will experience immediate and substantial dilution in the as adjusted net tangible book value of their shares of common stock. Dilution in as adjusted net tangible book value represents the difference between the public offering price per share and the as adjusted net tangible book value per share of our common stock immediately after the offering.

The historical net tangible book value of our common stock as of March 31, 2015 was $14,227,353, or $0.48 per share. Historical net tangible book value per share of our common stock represents our total tangible assets (total assets less intangible assets) less total liabilities divided by the number of shares of common stock outstanding as of that date.

After giving effect to the sale of 9,090,909 shares of our common stock in this offering at the public offering price of $2.75 per share, and after deducting underwriting discounts and commissions and estimated offering expenses payable by us, our net tangible book value as of March 31, 2015 would have been $36.9 million, or $0.96 per share. This amount represents an immediate increase in net tangible book value of $0.48 per share to our existing stockholders and an immediate dilution in net tangible book value of approximately $1.79 per share to new investors purchasing shares of our common stock in this offering. We determine dilution by subtracting the net tangible book value per share after the offering from the amount of cash that a new investor paid for a share of common stock.

The following table illustrates this dilution on a per share basis:

If the underwriters exercise their option to purchase additional shares in full, the net tangible book value per share after giving effect to the offering would be $1.01 per share. This represents an immediate increase in as adjusted pro forma net tangible book value of $0.53 per share to existing stockholders and an immediate dilution in net tangible book value of $1.74 per share to new investors purchasing shares of our common stock in this offering.

The table above does not include:

To the extent that outstanding options or warrants are exercised, you will experience further dilution. In addition, we may choose to raise additional capital due to market conditions or strategic considerations even if we believe we have sufficient funds for our current or future operating plans. To the extent that additional capital is raised through the sale of equity or convertible debt securities, the issuance of these securities may result in further dilution to our stockholders.

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MANAGEMENT’S DISCUSSION AND ANALYSIS OF FINANCIAL CONDITION AND RESULTS OF OPERATIONS

The following discussion and analysis of our financial condition and results of operations should be read in conjunction with our consolidated financial statements and the related notes and other financial information appearing elsewhere in this prospectus. Some of the information contained in this discussion and analysis or set forth elsewhere in this prospectus, including information with respect to our plans and strategy for our business, includes forward-looking statements that involve risks and uncertainties as described under the heading “Forward-Looking Statements” elsewhere in this prospectus. You should review the disclosure under the heading “Risk Factors” in this prospectus for a discussion of important factors that could cause actual results to differ materially from the results described in or implied by the forward-looking statements contained in the following discussion and analysis.

Overview

We are a clinical-stage biopharmaceutical company dedicated to the discovery and development of our Anticalin^® class of biotherapeutics for patients with diseases in which we believe there is high unmet medical need. Our current development plans focus mainly on our Anticalin drug candidates PRS-080, PRS-060, as well as our 300-Series “platform within a product” opportunity in immuno-oncology, as discussed in more detail below. Anticalin proteins are a class of low molecular-weight therapeutic proteins derived from lipocalins, which are naturally occurring low-molecular weight human proteins typically found in blood plasma and other bodily fluids. PRS-080 is a PEGylated Anticalin protein that binds to hepcidin, a natural regulator of iron in the blood. PRS-080 has been designed to target hepcidin for the treatment of functional iron deficiency, or FID, in anemic patients with chronic kidney disease, or CKD, particularly in end-stage renal disease patients requiring dialysis. PRS-060 is a drug candidate that binds to the IL-4RA receptor, thereby inhibiting IL-4 and IL-13, two cytokines, small proteins mediating signaling between cells within the human body, known to be key mediators in the inflammatory cascade that causes asthma and other inflammatory diseases. We completed dosing of healthy volunteers in a Phase I clinical trial with PRS-080 in June 2015, and we expect to report the data from this trial in the second half of 2015. In the trial, no dose-limiting toxicities were observed and a maximum tolerated dose was not reached. PRS-060 is currently in preclinical development, and we intend to begin a Phase I clinical trial with PRS-060 in the first quarter of 2017.

Our 300-Series oncology drug candidates are multispecific Anticalin^®-based proteins designed to engage immunomodulatory targets and consist of a variety of multifunctional biotherapeutics that genetically link an antibody with one or more Anticalin proteins, thereby constituting a multispecific protein. We are conducting preclinical experiments on a number of 300-Series lead candidates and by the second half of 2015 intend to choose a candidate for pre-clinical studies to support the IND for potential clinical trials in oncology. We are also developing PRS-110 in oncology. PRS-110 is a monovalent antagonist, a polypeptide molecule with one target-binding domain, that is designed to block both ligand- dependent and ligand-independent activity of cMet. cMet is a receptor tyrosine kinase, a well-known high- affinity cell surface receptor that transmits signals into the cell when a corresponding ligand binds to it, which is essential for embryonic development and wound healing and has been associated with several different cancers, including renal, gastric and lung carcinomas, central nervous system tumors and sarcomas.

Our core Anticalin^® technology and platform was developed in Germany, and we have partnership arrangements with major multi-national pharmaceutical companies headquartered in the U.S., Europe and Japan and with regional pharmaceutical companies headquartered in India. These include existing agreements with Daiichi Sankyo Company Limited, or Daiichi Sankyo, and Sanofi Group (formerly Sanofi-Aventis and Sanofi-Pasteur SA), or Sanofi, pursuant to which our Anticalin platform has consistently achieved its development milestones. We have discovery and preclinical collaboration and service agreements with both academic institutions and private firms in Australia. We also intend to establish a greater U.S. presence and take advantage of the U.S. capital markets, additional potential corporate partners, and the broad expertise found in the biotechnology industry in the United States.

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Since inception, we have devoted nearly all of our efforts and resources to our research and development activities. We have incurred significant net losses since inception. For the three months ended March 31, 2015 and for the years ended December 31, 2014 and 2013, we reported net loss of $3.7 million, net loss of $9.8 million and net income of $0.1 million, respectively. As of March 31, 2015 and December 31, 2014, we had an accumulated deficit of $69.5 million and $65.8 million, respectively. Our net profit for the year ended December 31, 2013 is not indicative of a trend. We expect to continue incurring substantial losses for the foreseeable future as we continue to develop our clinical and preclinical drug candidates and programs. Our operating expenses are comprised of research and development expenses and general and administrative expenses.

We have not generated any revenues from product sales to date, and we do not expect to generate revenues from product sales for at least the next several years. Our revenues for the three months ended March 31, 2015 and 2014 and the fiscal years ended December 31, 2014 and 2013 were primarily from license and collaboration agreements with our partners, and, to a lesser extent, from grants from government agencies.

The U.S. dollar is the reporting currency for all periods presented. The functional currency for Pieris Operating is euros. All assets and liabilities denominated in euros are translated into U.S. dollars at the exchange rate on the balance sheet date. Revenues and expenses are translated at the average rate during the period. Equity transactions are translated using historical exchange rates. Adjustments resulting from translating foreign currency financial statements into U.S. dollars are included in accumulated other comprehensive loss. Pieris is a holding company without operations and the sole stockholder of Pieris Operating. The current corporate headquarters and research facility of Pieris Operating are located in Freising, Germany. Pieris intends to relocate its corporate headquarters to Boston, Massachusetts by the second half of 2015. Pieris Australia Pty Ltd., a wholly owned subsidiary of Pieris Operating, was formed on February 14, 2014 to conduct research and development in Australia.

Private Placement

On December 17, 2014, we entered into a securities purchase agreement, or the Securities Purchase Agreement, with certain accredited investors, or the Investors, providing for the issuance and sale to such Investors of an aggregate of 6,779,510 shares of our common stock in a private placement which closed in a series of closings on December 17, 18 and 23, 2014, or the Private Placement. All shares issued in the Private Placement were sold at a purchase price per share of $2.00, for aggregate gross proceeds of $13.56 million. After deducting for placement agent and other fees and expenses, the aggregate net proceeds from the Private Placement were $12.04 million. Northland Securities, Inc. and Katalyst Securities, LLC served as co-exclusive placement agents, or the Placement Agents, for the Private Placement. At the closings of the Private Placement we issued to the Placement Agents and their designees warrants, or the Placement Warrants, to acquire up to 542,360 shares of our common stock at an exercise price of $2.00 per share. Each of the Placement Warrants is exercisable at any time at the option of the holder until the five-year anniversary of its date of issuance. In connection with the Private Placement, we entered into a registration rights agreement, or the Registration Rights Agreement, with the investors that participated in the Private Placement, pursuant to which we agreed to file with the SEC a registration statement relating to the resale of the shares of our common stock issued and sold in the Private Placement as well the shares of the Company’s common stock issued to the former stockholders of Pieris Operating, which such shareholders received in connection with the Acquisition, as defined below, and shares of the Company’s common stock issuable upon exercise of the Placement Warrants, which registration statement, as amended, was declared effective by the SEC on May 11, 2015.

Acquisition

On December 17, 2014, Pieris, Pieris Operating and the former stockholders of Pieris Operating entered into an Acquisition Agreement, or the Acquisition Agreement, pursuant to which the stockholders of Pieris Operating contributed all of their equity interests in Pieris Operating to Pieris in exchange for shares of Pieris common stock, which resulted in Pieris Operating becoming a wholly owned subsidiary of Pieris, which we refer to as

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the Acquisition. The Acquisition was consummated on December 17, 2014. On December 5, 2014, Pieris completed a 2.272727-for-1 forward split of its common stock in the form of a share dividend, with the result that 6,100,000 shares of common stock outstanding immediately prior to the stock split became 13,863,647 shares of common stock outstanding immediately thereafter. Effective December 16, 2014, prior to the closing of the Acquisition, Pieris amended and restated its Articles of Incorporation to, among other things, change its name from Marika Inc. to “Pieris Pharmaceuticals, Inc.,” and increased its authorized capital stock from 75,000,000 shares of common stock, par value $0.001 per share, to 300,000,000 shares of common stock, par value $0.001 per share, and 10,000,000 shares of “blank check” preferred stock, par value $0.001 per share. On December 17, 2014, Pieris transferred its pre-Acquisition assets and liabilities to its former majority stockholder, Aleksandrs Sviks, in exchange for the surrender by him and cancellation of 11,363,635 shares of Pieris common stock. All share and per share numbers in this prospectus relating to our shares of common stock have been adjusted to give effect to the stock split described above, unless otherwise stated.

At the closing of the Acquisition, Pieris issued an aggregate of 20,000,000 shares of its common stock to the former stockholders of Pieris Operating in exchange for all of the outstanding shares (common and preferred) of Pieris Operating’s capital stock. Pieris Operating became a wholly owned subsidiary of Pieris, and the former stockholders of Pieris Operating collectively own approximately 68% of the outstanding shares of Pieris’ common stock.

In accordance with Financial Accounting Standards Board, or FASB, Accounting Standards Codification, or ASC, section 805 entitled, “Business Combinations,” Pieris Operating is considered the accounting acquirer in the Acquisition and will account for the transaction as a capital transaction. Consequently, the assets and liabilities and the historical operations that will be reflected in our financial statements will be those of Pieris Operating and will be recorded at the historical cost basis of Pieris Operating.

2014 Series C Financing

In December 2014, Pieris Operating concluded a Series C financing round, or the 2014 Series C Financing, in which Pieris Operating issued Series C preferred shares for €5,970,149.15 ($7,224,477.49) in cash and the conversion of €3,000,000 ($3,630,300) outstanding under an existing convertible loan agreement dated November 12, 2012, or the 2012 Bridge Loan and a second convertible loan agreement dated April 14, 2014, or the 2014 Bridge Loan. The convertible loan agreements were terminated in the course of the 2014 Series C Financing.

As part of the 2014 Series C Financing, parties to existing investment agreements and shareholders agreement relating to prior rounds of financing agreed to become parties to the investment agreement and the consolidated shareholders’ agreement for the 2014 Series C Financing and the prior agreements were terminated.

Prior to the Series C Financing, Pieris Operating entered into agreements in April 2014 relating to the 2014 Bridge Loan with certain of its stockholders pursuant to which Pieris Operating received a commitment for financing in the aggregate amount of €2,000,000 ($2,420,200), which loan amount, if drawn down by Pieris Operating, would be convertible into preferred shares of Pieris Operating after the maturity date or upon occurrence of certain events. The 2014 Bridge Loan provided for two tranches of financing: (i) Tranche A of €1,500,000 ($1,815,150) and (ii) Tranche B of €500,000 ($605,050). In June 2014, Pieris Operating called 67% of Tranche A, or €1,000,000 ($1,210,100). Loan amounts outstanding under the 2014 Bridge Loan accrued interest at a rate of 12% per year and had a maturity date of December 31, 2015, after which the loan amounts would have accrued interest at a rate of 18% per year. The stockholders party to the 2014 Bridge Loan invested the €1,000,000 ($1,210,100) remaining commitment in cash directly in the 2014 Series C Financing.

In addition, in March 2014, Pieris Operating and the lenders under the 2012 Bridge Loan entered into an amendment, pursuant to which, among other things, the parties agreed to postpone the ultimate maturity date with respect to the remaining balance of the loan from December 31, 2013 to December 31, 2015. The stockholders party to the 2012 Bridge Loan participated in the 2014 Series C Financing and waived their claims for repayment of the 2012 Bridge Loan as consideration.

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TBG Loan

As of April 3, 2014, Pieris Operating and tbg Technologie-Beteiligungs-Gesellschaft mbH, or TBG, a subsidiary of KfW Bank, Frankfurt, signed a repayment agreement concerning Pieris Operating’s repayment of its liabilities to TBG outstanding at December 31, 2013 in a total amount of €1.2 million ($1.5 million) under a silent partnership agreement between Pieris Operating and TBG, dated May 13, 2003, pursuant to which TBG had invested €750,000 ($907,575) as a silent partner in Pieris Operating. The silent partnership agreement expired on December 31, 2013. The outstanding amount of €1.2 million ($1.5 million) consisted of (i) the investment by TBG of €750,000 ($907,757) which bore interest at a rate of 10.53% per year, and (ii) €450,000 ($544,545), which represents an exit premium under the silent partnership agreement and which did not accrue interest. Under the repayment agreement, Pieris Operating had agreed to a payment schedule pursuant to which it would make semi-annual payments on the outstanding amount and interest until 2016. As of December 11, 2014, €150,000 ($181,515) of the outstanding amount had been paid, and €1,050,000 ($1.3 million) remained outstanding.

On December 11, 2014, Pieris Operating and TBG entered into an accelerated repayment agreement in respect of the claims of TBG against Pieris Operating with a gross settlement amount of €1,050,000 ($1.3 million), the outstanding amount under the repayment agreement. Under the terms of the accelerated repayment agreement, the exit premium of €450,000 ($544,545) is subject to German income tax and a solidarity surcharge resulting in a potential net payment amount by Pieris Operating of €331,312.50 ($400,921). This amount may change if the competent German tax authorities have a differing opinion regarding the tax treatment of the profit-based payment, but in no event shall Pieris Operating have to pay more than the gross settlement amount of €450,000 ($544,545). Pursuant to the terms of the accelerated repayment agreement, Pieris Operating made two payments to satisfy the settlement as follows: a gross amount of €600,000 ($726,060) plus accrued interest on January 31, 2015 and a post-tax net amount of €331,312.50 ($400,921) on March 31, 2015, which may be adjusted by German tax authorities as described above. In addition, on April 9, 2015, Pieris Operating made a payment to the German tax authorities of €118,687.50 ($143,624). Upon full payment of the gross settlement amount of €1,050,000 ($1.3 million) and issuance of a tax confirmation by Pieris Operating to TBG, all claims of Pieris Operating and TBG against each other from or in connection with the silent partnership agreement dated May 13, 2003 and the repayment agreement entered into on April 3, 2014, shall be considered settled and repaid in full.

TUM Arbitration

On March 20, 2014, Pieris Operating instituted arbitration proceedings, against Technische Universität München, or TUM, to address issues regarding the calculation of payments due from Pieris Operating to TUM under Pieris Operating’s Research and Licensing Agreement with TUM, as amended. Under the agreement, TUM has exclusively licensed, or in some cases assigned, to Pieris Operating certain intellectual property and know-how that has become part of the Anticalin^® proprietary technologies. In return, Pieris Operating agreed to pay to TUM certain annual license fees, milestones and royalties for its own proprietary drug development and sales, as well as a variable fee as a function of out-licensing revenues, or the Out-License Fee, where such Out-License Fee is creditable against annual license payments to TUM. As required by the agreement, Pieris Operating provided to TUM its calculation of the Out-License Fee for the period beginning July 4, 2003 and ending on December 31, 2012 in the amount of $0.4 million excluding value-added tax. TUM has asserted that the Out-License Fee for this period amounts to €2.5 million ($3.0 million) excluding value-added tax and has threatened to terminate the license agreement if the Out-License Fee is not paid. We believe that if TUM sought to terminate the license agreement for cause as a result of this dispute, it would potentially face wrongful termination claims for substantial damages if the arbitral tribunal in the TUM Arbitration sides with Pieris in its final decision regarding the proper amount of the Out-License Fee. Pieris Operating instituted arbitration to request confirmation that Pieris Operating’s calculation of the payments owed to TUM is accurate and will govern all current and future payments due in respect of the Out-License Fee under the agreement.

In April 2014, TUM argued to the arbitrators that it is not the proper party to be sued under the action for a declaratory arbitration decision brought by Pieris Operating in relation to the agreement, and that instead, it is

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the Free State of Bavaria that is the proper respondent to the action. Pieris Operating has responded that TUM has capacity to be sued in relation to any disputes arising from and regarding contractual provisions of the agreement and is thus also the proper respondent in the action. In accordance with the arbitration rules of the Deutsche Institution für Schiedsgerichtsbarkeit, each party to the arbitration proceeding has appointed one arbitrator and the party-named arbitrators collectively selected the third arbitrator as the chairman of the arbitration panel. Pieris Operating has recorded a liability on its balance sheet in respect of such payment in the amount of €271,000 ($327,937).

On December 1, 2014, TUM filed its statement of defense, maintaining its earlier calculation of the Out-License Fee. On December 23, 2014, TUM filed a counterclaim in the amount of €2,529,400 ($3,060,827) to suspend the statute of limitations on its claims.

On January 12, 2015, Pieris Operating filed a reply brief in response to TUM’s statement of defense, filed on December 1, 2014. The arbitration panel held its first hearing in Munich, Germany on January 20, 2015, however the arbitration panel did not come to a conclusion on whether TUM is the proper respondent in the action or on the merits of the case. The panel had previously indicated that it will first decide the issue of whether TUM is the proper respondent in this action. The panel resolved that the value in dispute for both parties’ claims and counterclaims would be fixed at €3,500,000 ($4,235,350), as the calculation of the outstanding Out-Licensing Fee also impacts future payments. On March 3, 2015, Pieris Operating submitted a reply brief responding to TUM’s statement of defense and counterclaim. On March 31, 2015, TUM submitted a rebuttal brief. The panel requested that both Pieris Operating and TUM indicate to the panel by April 27, 2015 whether proceedings should be stayed as a result of settlement negotiations. On April 27, 2015, Pieris Operating submitted a reply brief requesting proceedings to continue without disruption and moving for leave to comment on TUM’s latest submission. Following an approved extension by the panel for TUM’s submission, TUM submitted its proposal on May 4, 2015, requesting that the panel conduct a mediation hearing and assist the parties in negotiating a settlement. On May 8, 2015, the arbitration tribunal set June 1, 2015 as the deadline for final briefs and offered to schedule another oral hearing in mid-June for the purpose of supporting further settlement negotiations if both parties are in favor of holding a hearing. Pieris Operating filed its final brief on June 1, 2015 and TUM refrained from submitting an additional brief. On June 8, 2015, the arbitration tribunal issued a procedural order indicating they will proceed with the arbitration without another oral hearing.

For more information about the TUM arbitration, see “Business—Legal Proceedings—Arbitration Proceeding with Technische Universität München,” “Business—TUM License Agreement” and “Management’s Discussion and Analysis of Financial Condition and results of Operations—Critical Accounting Policies and Estimates—Loss contingencies.”

Financial Operations Overview

The following discussion summarizes the key factors our management believes are necessary for an understanding of our consolidated financial statements.

Revenues

We have not generated any revenues from product sales to date, and we do not expect to generate revenues from product sales for at least the next several years. Our revenues for the last two years have been primarily from the license and collaboration agreements with Sanofi Group (formerly Sanofi-Aventis and Sanofi-Pasteur SA), or Sanofi, and Daiichi Sankyo Company Limited, or Daiichi Sankyo and, to a much lesser extent, grants from government agencies.

The revenues from Sanofi and Daiichi Sankyo have been comprised primarily of upfront payments, research and development services and, to a lesser extent, milestone payments. We recognized revenues from upfront payments under these agreements on a straight-line basis over the required service period because we determined that the licenses to which the payments related did not have standalone value. Research service

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revenue is recognized when the costs are incurred and the services have been performed. Revenue from milestone payments is recognized when all of the following conditions are met: (1) the milestone payments are non-refundable, (2) the achievement of the milestone involves substantial risk and was not reasonably assured at the inception of the arrangement, (3) substantive effort on our part is involved in achieving the milestone, (4) the amount of the milestone payment is reasonable in relation to the effort expended or the risk associated with achievement of the milestone, and (5) a reasonable amount of time passes between the up-front license payment and the first milestone payment.

We expect our revenues for the next several years to consist of upfront payments, research funding and milestone payments from strategic collaborations we currently have or may establish in the future. We also may apply for grants from government agencies and foundations funds in connection with our drug development efforts.

Expenses

The process of researching and developing drugs for human use is lengthy, unpredictable and subject to many risks. We expect to continue incurring substantial expenses for the next several years as we continue to develop our clinical and preclinical drug candidates and programs. We are unable with any certainty to estimate either the costs or the timelines in which those costs will be incurred. Our current development plans focus on our lead drug candidates: PRS-080, PRS-060 and our 300-Series programs. These programs consume a large proportion of our current, as well as projected, resources. We anticipate that our expenses will increase significantly compared to recent years as we advance PRS-080 through clinical trials, engage in first-in-man-enabling preclinical studies for PRS-060 and, subsequently, clinical development activities for this program, conducting preclinical experiments on a number of 300-Series lead candidates, including our efforts to choose by the second half of 2015 a candidate for potential clinical trials in oncology, and prepare drug supply for these and other drug candidates. We also expect to incur expenses associated with:

Any failure or delay in the advancement of PRS-080, PRS-060 or our 300-Series programs could require us to re-allocate resources from our other projects to the advancement of those drug candidates, which could have a material adverse impact on the advancement of other projects and on our operations.

Our operating expenses are comprised of research and development expenses and general and administrative expenses. Our research and development costs include costs that are directly attributable to the creation of certain of our Anticalin^® drug candidates and are comprised of:

General and administrative expenses consist primarily of salaries and benefits for employees in executive, finance, business development, legal, accounting, human resources and other support functions. Other significant general and administrative expenses include the costs associated with obtaining and maintaining our intellectual property portfolio, professional fees for accounting, auditing, consulting and legal services, travel and allocated expenses and stock-based compensation expense.

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Results of Operations

Comparison of the three months ended March 31, 2015 and March 31, 2014

The following table sets forth our revenues and operating expenses for the periods presented:

Revenues

The following table provides a comparison of revenues for the periods presented:

The $0.4 million decrease in revenues from upfront payments in the period ended March 31, 2015 compared to the period ended March 31, 2014 relates to the successful hand over to collaboration partners of collaboration projects in 2014. Recognition of upfront payments was spread over the expected time period in which we were performing research services for corresponding partner projects and until hand-over or termination of the projects. Thus, in the three months ended March 31, 2014 upfront payments for two projects were recognized. Accordingly, the $0.7 million decrease in revenues from research and development services in the period ended March 31, 2015 compared to the period ended March 31, 2014 relates to the successful hand over of all collaboration projects in 2014. We have not received research funding from collaboration partners since July 2014. In the period ended March 31, 2014, we received research funding from collaboration partners for two collaboration projects.

Pieris did not recognize any collaboration milestones in the three months ended March 31, 2015. In the three months ended March 31, 2014, we achieved one research milestone under a collaboration project. The increase in revenues from grants in the three months ended March 31, 2015 compared to the three months ended March 31, 2014 relates primarily to our significantly increased activities related to PRS-080’s development in 2015 compared to 2014, resulting in higher reimbursement from the European Commission for PRS-080’s development.

Research and Development Expenses

Total research and development expenses were $1.5 million for the three months ended March 31, 2015 as compared to $1.2 million for the three months ended March 31, 2014.

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The $0.3 million increase in total research and development expenses in the three months ended March 31, 2015 compared to the three months ended March 31, 2014 is primarily due to increased external clinical expenses associated with PRS-080 and increased internal expenses for our 300-Series programs in the three months ended March 31, 2015.

Our research and development expenses for advancing our proprietary and co-development projects and improving and maintaining our Anticalin^® platform technology were $1.5 million and $1.1 million during the three months ended March 31, 2015 and 2014, respectively. As of March 31, 2015, we employed 23 full-time and five part-time personnel in our research and development group compared to 26 full-time and four part-time personnel in our research and development group as of March 31, 2014. We incurred expenses of $0.6 million and $0.2 million during the three months ended March 31, 2015 and 2014, respectively, for amounts payable to external parties who performed research and development activities for our proprietary and co-development projects and platform technology.

The following table provides a comparison of the research and development expenses for our drug candidates and projects for the periods presented:

Research and development expenses related to PRS-080 increased by $0.4 million in three months ended March 31, 2015 as compared to the three month period ended March 31, 2014. This increase was a result of the Phase I clinical trial of PRS-080 in healthy volunteers which commenced in November 2014. In contrast, no activities related to clinical trials were carried out during the three month period ended March 31, 2014. As our 300-Series project activities were only first initiated during the three months ended March 31, 2014 the corresponding cost in three months ended March 31, 2015 activities relating to our 300-Series programs were significantly higher.

In addition to the amounts outlined above, we incurred $0.4 million and $0.8 million in connection with early stage research projects and platform technology development during the three months ended March 31, 2015 and 2014, respectively.

We incurred zero and $0.1 million of costs in relation to providing research and development services under the license and collaboration agreements with our collaboration partners for the three months ended March 31, 2015 and 2014, respectively.

General and Administrative Expenses

General and administrative expenses increased from $0.8 million for the three months ended March 31, 2014 to $2.4 million in the three months ended March 31, 2015. The increase resulted primarily from costs associated with being a public company in the United States, which consisted of legal fees, which increased by $0.5 million, stock based compensation expense, which increased by $0.5 million, consulting costs, which increased by $0.4 million and costs for business development, which increased by $0.2 million, each compared to the same period last year.

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Other Income (Expense)

Other expense decreased to $3,000 in the three months ended March 31, 2015 from $0.1 million for the three months ended March 31, 2014. This decrease primarily relates to reduced interest expense on shareholder loans which were converted into shares of common stock in the fourth quarter of 2014.

Comparison of the years ended December 31, 2014 and December 31, 2013

The following table sets forth our revenues and operating expenses for the fiscal years ended December 31, 2014 and 2013:

Revenues

The following table provides a comparison of revenues for the years ended December 31, 2014 and 2013:

The decrease in revenues from upfront payments in the fiscal year ended December 31, 2014 compared to the fiscal year ended December 31, 2013 related primarily to the successful hand over to collaboration partners of collaboration projects in June 2014, October 2014 and March 2013, and the termination of one collaboration project in November 2013. Because the recognition of upfront payments is spread over the expected time period in which we are performing research services for corresponding partner projects and until hand-over or termination of the projects, we realized more revenues from upfront payments for collaboration projects in 2013 than in 2014. In 2014, we only realized revenues from upfront payments for two collaboration projects from January to June 2014 and one of the two collaboration projects from July to October 2014, compared to realized revenues for upfront payments for four collaboration projects from January to March 2013 and three of the four collaboration projects from January to November 2013 in the fiscal year ended December 31, 2013.

The $2.7 million decrease in revenues from research and development services in the fiscal year ended December 31, 2014 compared to the fiscal year ended December 31, 2013 related primarily to a $2.1 million decrease in research funding from collaboration partners. In the fiscal year ended December 31, 2013, we received research funding from collaboration partners for four collaboration projects, whereas in the fiscal year ended December 31, 2014 we received research funding from collaboration partners for only two collaboration projects.

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The increase of $2.1 million in revenues from milestone payments is due to the achievement of later-stage, higher value milestones in the fiscal year ended December 31, 2014 compared to the fiscal year ended December 31, 2013. In the fiscal year ended December 31, 2013, we achieved four research milestones under collaboration projects with our collaboration partners whereas in the fiscal year ended December 31, 2014, we achieved three research milestones under collaboration projects with our collaboration partners.

The decrease in revenues from grants in the fiscal year ended December 31, 2014 compared to the fiscal year ended December 31, 2013 related primarily to our significantly decreased activities related to PRS-080’s development in 2014 compared to 2013, resulting in lower reimbursement from the European Commission for PRS-080’s development.

Research and Development Expenses

Total research and development expenses were $5.6 million for the fiscal year ended December 31, 2014 as compared to $9.4 million for the fiscal year ended December 31, 2013.

The $3.8 million decrease in total research and development expenses in the fiscal year ended December 31, 2014 compared to the fiscal year ended December 31, 2013 is primarily due to decreased external activities associated with PRS-080 in the fiscal year ended December 31, 2014.

Our research and development expenses for advancing our proprietary and co-development projects and improving and maintaining our Anticalin^® platform technology were $5.4 million and $8.4 million during the years ended December 31, 2014 and 2013, respectively. As of December 31, 2014, we employed 25 full-time and seven part-time personnel in our research and development group compared to 32 full-time and two part-time personnel in our research and development group as of December 31, 2013. We incurred expenses of $0.7 million and $3.3 million during the years ended December 31, 2014 and 2013, respectively, for amounts payable to external parties who performed research and development activities for our proprietary and co-development projects and platform technology.

The following table provides a comparison of the research and development expenses for our drug candidates and projects that are described in detail under “Business—Pipeline” for the years ended December 31, 2014 and 2013 (amounts in thousands):

Research and development expenses related to PRS-080 decreased $2.8 million in the fiscal year ended December 31, 2014 as compared to the fiscal year ended December 31, 2013. This decrease was a result of increased costs in fiscal 2013 related to chemistry, manufacturing and control, or CMC, development of PRS-080 as well as increased costs associated with Phase I clinical trial supplies and preparation at a third-party contract manufacturer relating to PRS-080 to prepare for the Phase I clinical trial with PRS-080 in healthy volunteers. In contrast, no substantial CMC activities were carried out during the fiscal year ended December 31, 2014. As our 300-Series project activities were only first initiated in fiscal 2014, no costs were incurred relating to our 300-Series programs in the fiscal year ended December 31, 2013.

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In addition to the amounts outlined above, we incurred $3.2 million and $3.9 million in connection with early stage research projects and platform technology development during the years ended December 31, 2014 and 2013, respectively.

We incurred $0.2 million and $1.0 million of costs in relation to providing research and development services under the license and collaboration agreements with our collaboration partners for the years ended December 31, 2014 and 2013, respectively.

General and Administrative Expenses

General and administrative expenses increased from $2.5 million for the year ended December 31, 2013 to $7.0 million in 2014. The increase resulted primarily from the completion of the Acquisition and the Private Placement.

Other Income (Expense)

Other expense increased to $2.7 million in the fiscal year ended December 31, 2014 from $0.5 million for the fiscal year ended December 31, 2013 due to the conversion of the convertible bridge loan we obtained in November 2012 into shares of common stock. The conversion was deemed to be in-the-money, since the effective exercise price for the converted shares was less than the share price sold to investors who invested in the 2014 Series C Financing in cash.

Liquidity and Capital Resources

Through March 31, 2015, we have funded our operations with $141.3 million of cash that has been obtained from the following main sources: $76.9 million from sales of equity; $6.5 million from loans; $14.1 million from grants from government agencies; and $43.8 million in total payments received under license and collaboration agreements, including $7.9 million for research and development services costs we received in 2012, 2013, 2014 and the first three months of 2015 from Daiichi Sankyo and Sanofi. We expect that reimbursements of our development costs by Daiichi Sankyo and Sanofi will decline going forward, and we do not expect such reimbursements to be a significant source of funding in the future.

As of March 31, 2015, we had a total of $13.2 million in cash and cash equivalents and $2.5 million of liabilities, including $2.3 million of current liabilities from operations.

Pieris Operating has experienced operating losses since its inception and had a total accumulated deficit of $69.5 million as of March 31, 2015. Pieris Operating expects to incur additional costs and require additional capital. We have incurred losses in nearly every year since inception and in the three months ended March 31, 2015. These losses have resulted in significant cash used in operations. During the three months ended March 31, 2015 and 2014, our cash used in operations was $3.7 million and $0.4 million, respectively. While we have several research and development programs underway, the PRS-080, PRS-060 and 300-Series programs have advanced the furthest and will continue to consume increasing amounts of cash for conducting clinical trials and the testing and manufacturing of product material. As we continue to conduct these activities necessary to pursue regulatory approval of PRS-080, PRS-060, our 300-Series programs and our other drug candidates, we expect the cash needed to fund operations to increase significantly over the next several years. We also expect to incur increased costs in connection with operating and growth as a public company.

On December 17, 2014 we entered into a the Securities Purchase Agreement, with the Investors, providing for the issuance and sale to such Investors of an aggregate of 6,779,510 shares of our common stock in the Private Placement for gross proceeds to us of $13.56 million. After deducting for placement agent and other fees and expenses, the aggregate net proceeds from the Private Placement were $12.04 million.

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Even after giving effect to the Private Placement and this offering, we will need to obtain additional funding in order to continue our operations and pursue our business plans. If we are unable to raise capital when needed or on attractive terms, we would be forced to delay, reduce or eliminate our research and development programs or future commercialization efforts.

We expect that, following this offering, our existing cash and cash equivalents will enable us to fund our operations and capital expenditure requirements for at least the next 18 months. Our requirements for additional capital will depend on many factors, including the following:

We cannot be sure that future funding will be available to us on acceptable terms, or at all. Due to the often volatile nature of the financial markets, equity and debt financing may be difficult to obtain. In addition, any unfavorable development or delay in the progress for our PRS-080, PRS-060 or 300-Series programs could have a material adverse impact on our ability to raise additional capital.

We may seek to raise any necessary additional capital through a combination of private or public equity offerings, debt financings, collaborations, strategic alliances, licensing arrangements and other marketing and distribution arrangements. To the extent that we raise additional capital through marketing and distribution arrangements or other collaborations, strategic alliances or licensing arrangements with third parties, we may have to relinquish valuable rights to our drug candidates, future revenue streams, research programs or drug candidates or to grant licenses on terms that may not be favorable to us. If we raise additional capital through private or public equity offerings, the ownership interest of our existing stockholders will be diluted, and the terms of these securities may include liquidation or other preferences that adversely affect our stockholders’ rights. If we raise additional capital through debt financing, we may be subject to covenants limiting or restricting our ability to take specific actions, such as incurring additional debt, making capital expenditures or declaring dividends.

If we cannot raise adequate capital in the future, we will be required to delay and possibly eliminate the research and development work not only of our lead drug candidates PRS-080, PRS-060 and our 300-Series programs, but also our other preclinical stage drug candidates. In this case, we could be required to relinquish greater or all rights to our drug candidates at an earlier stage of development and on less favorable terms than we would otherwise agree. Our cash is maintained in money market accounts and, to a lesser extent, in current cash accounts at major financial institutions. Due to the current low interest rates available for these instruments, we are earning limited interest income. Our investment portfolio has not been adversely impacted by the problems in the credit markets that have existed over the last several years, but there can be no assurance that our investment portfolio will not be adversely affected in the future.

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Off-Balance Sheet Arrangements

We do not have any off-balance sheet arrangements.

Critical Accounting Policies and Estimates

The discussion and analysis of our financial condition and results of operations are based on our financial statements, which have been prepared in accordance with accounting principles generally accepted in the United States, or GAAP. The preparation of these financial statements requires management to make estimates and assumptions that affect reported amounts of assets and liabilities as of the date of the balance sheet and reported amounts of revenues and expenses for the periods presented. Management makes estimates and exercises judgment in revenue recognition, share-based payments and income taxes. Judgments must also be made about the disclosure of contingent liabilities, and these estimates and assumptions form the basis for making judgments about the carrying values of assets and liabilities that are not readily apparent from other sources. We base our estimates on historical experience and on various other assumptions that we believe to be reasonable under the circumstances. Actual results may differ from those estimates and under different assumptions or conditions. We periodically evaluate our estimates and judgments, including those described in greater detail below, in light of changes in circumstances, facts and experience.

We have identified the following accounting policies that we believe require application of management’s most subjective judgments, often requiring the need to make estimates about the effect of matters that are inherently uncertain and may change in subsequent periods. Our actual results could differ from these estimates and such differences could be material.

Multiple-element arrangements

We enter into licensing and development agreements with collaboration partners for the development of Anticalin^® therapeutics against a variety of targets in diseases and conditions. The terms of these agreements contain multiple elements and deliverables, which may include (i) licenses, or options to obtain licenses, to our Anticalin technology and (ii) research and development activities with respect to one or more therapeutics related to such licenses. Payments to us under these agreements may include upfront fees (which include license and option fees), payments for research and development services, payments based upon the achievement of certain milestones and royalties on product sales. There are no performance, cancellation, termination or refund provisions in any of the arrangements that contain material financial consequences to us. We follow the provisions of the Financial Accounting Standards Board (FASB) Accounting Standards Codification (ASC)

Topic 605-25, Revenue Recognition—Multiple-Element Arrangements and ASC Topic 605-28, Revenue

Recognition—Milestone Method in accounting for these agreements.

When evaluating multiple-element arrangements, we identify the deliverables included within the agreement and evaluate which deliverables represent separate units of accounting based on whether certain criteria are met, including whether the delivered element has stand-alone value to the collaborator or if the arrangement includes a general right of return for delivered items.

The consideration received is allocated among the separate units of accounting using the relative selling price method, and the applicable revenue recognition criteria are applied to each of the separate units. We have used best estimate of selling price methodology to estimate the selling price for licenses and options to acquire additional licenses to our proprietary technology because we do not have Vendor Specific Objective Evidence or Third Party Evidence of selling price for these deliverables. To determine the estimated selling price of a license to our proprietary technology, we consider market conditions as well as entity-specific factors, including those factors contemplated in negotiating the agreements, terms of previous collaborative agreements, similar agreements entered into by third parties, market opportunity, estimated development costs, probability of

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success and the time needed to commercialize a product candidate pursuant to the license. Significant changes in key assumptions used to determine the best estimate of selling price could have a significant effect on the allocation of arrangement consideration, which could have a material effect on the timing of revenue recognition.

We typically receive upfront, nonrefundable payments when licensing our intellectual property in conjunction with a research and development agreement. In determining the units of accounting, management evaluates whether the license has stand-alone value from the undelivered elements to the collaboration partner based on the consideration of the relevant facts and circumstances for each arrangement. Factors considered in this determination include the stage of development of the license delivered, research capabilities of the partner and the availability of Anticalin^® technology research expertise in the general marketplace.

When management believes the license to our intellectual property does not have stand-alone value from the other deliverables to be provided in the arrangement, we generally recognize revenue attributed to the license on a straight-line basis over our contractual or estimated performance period, which is typically the term of our research and development obligations. When management believes the license to our intellectual property has stand-alone value, we recognize revenue attributed to the license upon delivery. The periods over which revenue should be recognized are subject to estimates by management and may change over the course of the research and development agreement. Such a change could have a material impact on the amount of revenue we record in future periods.

The accounting treatment for options granted to collaborators depends upon the nature of the option granted to the collaboration partner. Options are considered substantive if, at the inception of an agreement, we are at risk as to whether the collaboration partner will choose to exercise the options to secure additional licenses. Factors that are considered in evaluating whether options are substantive include the overall objective of the arrangement, the benefit the collaborator might obtain from the agreement without exercising the options, the cost to exercise the options relative to the total upfront consideration, and the additional financial commitments or economic penalties imposed on the collaborator as a result of exercising the options.

In arrangements where options to obtain additional licenses are considered substantive, we do not consider the additional licenses to be a deliverable at the inception of the agreement. When a collaborator exercises the option to acquire the additional license, the exercise fee is attributed to the additional license, and we apply the multiple-element revenue recognition criteria to all deliverables in the arrangement, which will be consistent with the treatment of up-front payments for licenses (i.e., license and research and development services). In the event an option expires and is not exercised, any deferred amounts attributable to the optional licenses are recognized into revenue upon expiration. For options that are non-substantive, the additional licenses to which the options pertain are considered deliverables upon inception of the arrangement, and we apply the multiple-element revenue recognition criteria to determine accounting treatment. None of our agreements has been determined to contain non-substantive options.

Payments or reimbursements resulting from our research and development efforts for those arrangements where such efforts are considered as deliverables are recognized as the services are performed and are presented on a gross basis so long as there is persuasive evidence of an arrangement, the fee is fixed or determinable, and collection of the related receivable is reasonably assured. Amounts received prior to satisfying the above revenue recognition criteria are recorded as deferred revenue.

Milestone payments

At the inception of each agreement that includes milestone payments, we evaluate whether each milestone is substantive and at risk to both parties on the basis of the contingent nature of the milestone. This evaluation includes an assessment of whether (a) the consideration is commensurate with either (1) the entity’s performance to achieve the milestone or (2) the enhancement of the value of the delivered item(s) as a result of a specific outcome resulting from the entity’s performance to achieve the milestone, (b) the consideration

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relates solely to past performance and (c) the consideration is reasonable relative to all of the deliverables and payment terms within the arrangement. We evaluate factors such as the scientific, regulatory, commercial and other risks that must be overcome to achieve the respective milestone, the level of effort and investment required to achieve the respective milestone and whether the milestone consideration is reasonable relative to all deliverables and payment terms in the arrangement in making this assessment.

We aggregate milestones into three categories (i) research milestones, (ii) development milestones and (iii) commercial milestones. Research milestones are typically achieved upon reaching certain success criteria as defined in each agreement related to developing an Anticalin^® protein against the specified target. Development milestones are typically reached when a compound reaches a defined phase of clinical research or passes such phase, or upon gaining regulatory approvals. Commercial milestones are typically achieved when an approved pharmaceutical product reaches the status for commercial sale or certain defined levels of net sales by the licensee, such as when a product first achieves global sales or annual sales of a specified amount.

Revenues from research and development milestone payments, if the milestones are deemed substantive and the milestone payments are nonrefundable, are recognized entirely upon successful accomplishment of the milestones. Milestones that are not considered substantive are accounted for as license payments and recognized on a straight-line basis over the remaining period of performance. Revenues from commercial milestone payments are accounted for as royalties and are recorded as revenue upon achievement of the milestone, assuming all other revenue recognition criteria are met.

Government grants

Government grants are recognized when there is reasonable assurance that all conditions will be complied with and the grant will be received. As government grants received by us generally represent subsidies for specified activities, they are recognized when earned as a reduction of the expenses recorded for the activity that the grants are intended to compensate. Thus, revenues from a grant relating to research and development expense are recognized over the same period in which the related costs are incurred.

Loss contingencies

We record accruals for loss contingencies to the extent that we conclude that it is probable that a liability has been incurred and the amount of the related loss can be reasonably estimated. We evaluate, on a quarterly basis, developments in legal proceedings and other matters that could cause an increase or decrease in the amount of the liability that has been accrued previously. We consider all claims on a quarterly basis in accordance with GAAP and based on known facts assess whether potential losses are considered reasonably possible, probable and estimable. Based upon this assessment, we then evaluate disclosure requirements and whether to accrue for such claims in our financial statements.

Under the Research and Licensing Agreement between Pieris Operating and Technische Universität München dated as of July 26, 2007, or the TUM License Agreement, Pieris Operating is required make payments to TUM based on the Pieris Operating’s revenues generated from entering into sub-licensing agreements with any third party with respect to both University Inventions and Joint Inventions (each as defined in the agreement). These revenues include up-front payments as well as milestone payments received by Pieris Operating from third parties.

As Pieris Operating signed six sub-licensing agreements between 2004 and 2012 under which it has recorded revenues, Pieris Operating acknowledges an obligation to TUM. However, the parties disagree regarding the amount due. Pieris Operating commenced arbitration proceedings to resolve the dispute.

Although it is not possible to predict the outcome of such arbitration, the Company has assessed the degree of probability and the potential losses that it could incur as a result of these matters, and the Company has estimated the probable loss and recorded the amount as a liability on its balance sheet as of December 31, 2014

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of €271,000 ($327,937). The Company has concluded that the potential of a loss above the estimated probable loss is remote, however it is possible that additional losses may occur. The estimated losses are based on currently available information and involve elements of judgment and significant uncertainties, and actual losses may differ from the accrual set for any such liabilities under the agreement.

The amount currently in dispute is €3.5 million ($4.2 million), as described in more detail under “Business—Legal Proceedings.”

Income taxes

We apply ASC 740—Income Taxes, which established financial accounting and reporting requirements for the effects of income taxes that result from our activities during the current and preceding years. Deferred tax assets and liabilities are recognized for the future tax consequences attributable to differences between the financial statement carrying amounts of existing assets and liabilities and their respective tax bases, and operating losses and tax credit carryforwards. Deferred tax assets and liabilities are measured using enacted statutory tax rates expected to apply to taxable income in the jurisdictions and years in which those temporary differences are expected to be recovered or settled. The effect on deferred tax assets and liabilities of a change in tax rates is recognized in income in the period that includes the enactment date.

Where we determine that it is more likely than not that some portion or all of the deferred tax assets will not be realized in the future, the deferred tax assets are reduced by a valuation allowance. The valuation allowance is sufficient to reduce the deferred tax assets to the amount that we determine is more likely than not to be realized.

Management’s evaluation with regard to the probability of realizing its deferred tax assets is that it is more likely than not that we may not realize the benefit of its deferred tax asset. This evaluation is based on our history of operating losses and an actual outlook that we will experience losses in the foreseeable future. The net profit for the year ended December 31, 2013 is not indicative of a trend. Accordingly deferred tax assets have been fully reserved as of December 31, 2013 and 2014.

Recently Issued Accounting Pronouncements

We review new accounting standards to determine the expected financial impact, if any, that the adoption of each such standard will have. For the recently issued accounting standards that we believe may have an impact on our consolidated financial statements, see “Note 2—Recent Accounting Pronouncements” in our unaudited condensed consolidated financial statements and “Note 2—Summary of Significant Accounting Policies” in our consolidated financial statements, each included in this prospectus.

Emerging Growth Company and Smaller Reporting Company Status

The Jumpstart Our Business Startups Act of 2012, or the JOBS Act, establishes a class of company called an “emerging growth company,” which generally is a company whose initial public offering was completed after December 8, 2011 and had total annual gross revenues of less than $1 billion during its most recently completed fiscal year. Additionally, Section 12b-2 of the Exchange Act establishes a class of company called a “smaller reporting company,” which generally is a company with a public float of less than $75 million as of the last business day of its most recently completed second fiscal quarter or, if such public float is $0, had annual revenues of less than $50 million during the most recently completed fiscal year for which audited financial statements are available. We currently qualify as both an emerging growth company and a smaller reporting company.

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As an emerging growth company and a smaller reporting company, we are eligible to take advantage of certain extended accounting standards and exemptions from various reporting requirements that are not available to public reporting companies that do not qualify for those classifications, including without limitation the following:

For as long as we continue to be an emerging growth company and/or a smaller reporting company, we expect that we will take advantage of the reduced disclosure obligations available to us as a result of those respective classifications. We will remain an emerging growth company until the earlier of (i) December 31, 2019, the last day of the fiscal year following the fifth anniversary of the date of the first sale of our common stock pursuant to an effective registration statement under the Securities Act; (ii) the last day of the fiscal year in which we have total annual gross revenues of $1 billion or more; (iii) the date on which we have issued more than $1 billion in nonconvertible debt during the previous three years; or (iv) the date on which we are deemed to be a large accelerated filer under applicable SEC rules. We expect that we will remain an emerging growth company for the foreseeable future, but cannot retain our emerging growth company status indefinitely and will no longer qualify as an emerging growth company on or before December 31, 2019. We will remain a smaller reporting company until we have a public float of $75 million or more as of the last business day of our most recently completed second fiscal quarter, and we could retain our smaller reporting company status indefinitely depending on the size of our public float. Emerging growth companies may elect to take advantage of the extended transition period provided in Section 7(a)(2)(B) of the Securities Act of 1933, as amended, for complying with new or revised accounting standards. This allows an emerging growth company to delay the adoption of certain accounting standards until those standards would otherwise apply to private companies. We have elected to take advantage of the benefits of this extended transition period. Our financial statements may therefore not be comparable to those of companies that comply with such new or revised accounting standards.

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BUSINESS

Overview

We are a clinical-stage biopharmaceutical company dedicated to the discovery and development of our Anticalin^® class of biotherapeutics for patients with diseases in which we believe there is high unmet medical need.

Anticalin^® proteins are a class of low molecular-weight therapeutic proteins derived from lipocalins, which are naturally occurring low-molecular weight human proteins typically found in blood plasma and other bodily fluids. Anticalin-branded proteins function similarly to monoclonal antibodies, or mAbs, by binding tightly and specifically to a diverse range of targets. An antibody is a large protein used by the immune system that recognizes a unique part of a foreign target molecule, called an antigen. We believe Anticalin proteins possess numerous advantages over antibodies in certain applications. For example, Anticalin proteins are small in size and are monomeric, meaning single protein units rather than a multi-protein complex. Therefore, we believe Anticalins are generally more stable biophysically than tetrameric monoclonal antibodies, composed of four protein subunits, potentially enabling unique routes of drug administration such as pulmonary delivery. Higher-molecular-weight entities such as antibodies are often too large to be delivered effectively through these methods. In addition, Anticalin proteins are monovalent in structure, which means they bind to a single cell surface receptor and which may avoid the risk of cross-linking of cell surface receptors where such receptors are a therapeutic target. Antibody-mediated cross-linking can occur when each of the two “arms” of an antibody binds to a cell surface receptor and brings these receptors into close proximity, which can lead to aggressive cell growth that is characteristic of cancer. While our basic Anticalin proteins have only a single binding site and are not subject to such cross-linking, our Anticalin-branded technology is also modular, which allows us to design Anticalin proteins to bind with specificity to multiple targets at the same time. This multispecificity offers advantages in biological settings where binding to multiple targets can enhance the ability of a drug to achieve its desired effects, such as killing cancer cells. Moreover, unlike antibodies, the pharmacokinetic, or PK, profile of Anticalin proteins can be adjusted to potentially enable program-specific optimal drug exposure. Such differentiating characteristics suggest that Anticalin proteins have the potential, in certain cases, to become first-in-class drugs.

We have access to intellectual property rights directed to various aspects of our Anticalin^® technology platform, allowing for development and advancement of our platform and drug candidates. We believe our ownership and/ or license of our Anticalin platform provides us with a strong intellectual property position, particularly where we are seeking to address targets and diseases in a novel way and for which there is existing monoclonal antibody intellectual property.

We believe that the drug-like properties of the Anticalin^® drug class were demonstrated in a Phase Ib clinical trial in solid tumor patients of our anti-VEGF-A Anticalin-branded drug candidate, PRS-050, designed to inhibit blood vessel growth in solid tumors. VEGF-A is a protein that induces growth of blood vessels, and anti-VEGF- A drug aim to inhibit the blood supply to solid tumors. In a multi-ascending dose trial performed under governance by the German Federal Institute for Drugs and Medical Devices (Bundesinstitut für Arzneimittel und Medizinprodukte, or BfArM), PRS-050 was shown to be generally safe and well-tolerated, and we were not able to detect any anti-drug antibodies, or ADAs, following administration of a total of 144 doses with five or more doses to 17 patients. We believe that these results demonstrated that there was no apparent immune response against PRS-050. Furthermore, dose-proportional pharmacokinetics, pharmacology and biomarker activity were observed in the trial, which we believe demonstrates that PRS-050 engaged with its intended target VEGF-A in those patients. Despite these results, we decided not to advance PRS-050 based on our belief that PRS-050’s mode of action (the way in which it functions in the body, namely, antagonizing VEGF-A) was not sufficiently differentiated over the modes of action of already-marketed therapies, such as bevacizumab and aflibercept, to create enough economic value in the drug market to support continued development of PRS-050 as a competitive product candidate. While we have not advanced development of PRS-050 since that time for the aforementioned strategic and economic reasons, we believe that the positive results from this clinical trial generally support continued investment in our Anticalin drug candidates.

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Our core Anticalin^® technology and platform was developed in Germany, and we have partnership arrangements with major multi-national pharmaceutical companies headquartered in the U.S., Europe and Japan and with regional pharmaceutical companies headquartered in India. These include existing agreements with Daiichi Sankyo Company Limited, or Daiichi Sankyo, and Sanofi Group (formerly Sanofi-Aventis and Sanofi-Pasteur SA), or Sanofi, pursuant to which our Anticalin platform has consistently achieved its development milestones. We have discovery and preclinical collaboration and service agreements with both academic institutions and private firms in Australia, which increasingly are being handled through Pieris Australia Pty Ltd., a wholly owned subsidiary of Pieris Operating. For example, the University of Melbourne received a $AUS 500,000 research grant from the National Health and Medical Research Council (NHMRC) to further develop PRS-060, which is described in further detail below, in immunological disease. We also intend to establish a greater U.S. presence and take advantage of the U.S. capital markets, additional potential corporate partners, and the broad expertise found in the biotechnology industry in the United States. Certain members of our management team, the current Chief Executive Officer, Chief Scientific Officer, Head of Discovery and Head of Business Development, have prior experience working together at MorphoSys, AG, a biotechnology company involved in the development and research of antibodies.

Our current development plans focus mainly on our Anticalin^® drug candidates, PRS-080, PRS-060 and our 300-Series programs. PRS-080 is a PEGylated Anticalin protein that binds to hepcidin, a natural regulator of iron in the blood. An excess amount of hepcidin can cause functional iron deficiency, or FID, which often cannot be treated adequately with iron supplements and can lead to anemia. PRS-080 has been designed to target hepcidin for the treatment of FID in anemic patients with chronic kidney disease, or CKD, particularly in end-stage renal disease patients requiring dialysis. We believe that by blocking the actions of hepcidin, PRS-080 will serve to address anemia by mobilizing iron for incorporation into red blood cells. Furthermore, we engineered PRS-080 to have a half-life of less than a week, so that following administration, it is expected to clear from the human body in a much shorter timeframe than antibodies, which typically have a half-life of two weeks or greater. We believe a shorter residence time in the body may be a superior approach for countering excess hepcidin, as physiological levels of hepcidin in these patients are relatively high (nanomolar concentration), and in theory such high concentrations will quickly saturate an administered binding drug. As a result, frequent administration of a drug may be required in order to sufficiently antagonize, or suppress the effect of, the target. The longer residence time of a monoclonal antibody, or mAb, could lead to the accumulation of both the drug and the target beyond the typical residence time of hepcidin, resulting in large quantities of hepcidin bound to mAbs. We completed dosing of healthy volunteers in a Phase I clinical trial with PRS-080 in June 2015, and we expect to report the data from this trial in the second half of 2015. In the trial, no dose-limiting toxicities were observed and a maximum tolerated dose was not reached.

The second Anticalin^® drug candidate, PRS-060, binds to the IL-4 receptor alpha-chain ( IL-4RA), thereby inhibiting IL-4 and IL-13, two cytokines (small proteins mediating signaling between cells within the human body) known to be key mediators in the inflammatory cascade that causes asthma and other inflammatory diseases. The small size and biophysical stability of PRS-060 enable direct delivery to the lungs, such as through the use of an inhaler, which we believe will enable high concentrations of the drug candidate at the locus of disease at substantially lower doses than would be achievable with antibodies that are systemically delivered. Further, PRS-060 has a short systemic residence time in the body which we believe may avoid undesired target engagement outside of the desired area in the lungs. PRS-060 is currently in preclinical development, and we intend to begin a Phase I clinical trial with PRS-060 in the first quarter of 2017.

The third drug candidate is our 300-Series “platform within a product” opportunity in immuno-oncology. The 300-Series Anticalin^®-based proteins are multispecific proteins designed to engage immunomodulatory targets and consist of a variety of multifunctional biotherapeutics that genetically link an antibody with one or more Anticalin proteins, thereby constituting a multispecific protein. The 300-Series proteins are comprised of two components, one of which is directed to a tumor receptor and the other engages an immunomodulatory target, which is either an immune checkpoint or co-stimulatory molecule. Immune checkpoints are proteins that help the development of an immune response or downregulate the response, for example when an infection is

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eliminated. Co-stimulatory molecules also play a contributory role in the activation of immune cells. The design of a dual engagement approach seeks to traffic the 300-Series proteins to the tumor microenvironment through the engagement of the tumor receptor, acting as an antagonist, and thereafter augment an immune system response in such tumor microenvironment through the engagement of the immunomodulatory target, and in such context act as an agonist.

We are conducting preclinical experiments on a number of 300-Series lead candidates and by the second half of 2015 intend to choose a candidate for pre-clinical studies to support the IND for potential clinical trials in oncology. We plan to advance additional Series-300 programs into in vivo proof of concept through 2016 and 2017, with the goal of submitting a potential initial IND by the end of 2017. The 300-Series platform is modular, which we believe will permit rapid evaluation of unique combinations of validated tumor targets and immunomodulatory targets such as checkpoints and co-stimulatory molecules. For example, one panel of 300-Series Anticalin^®-based proteins, currently being evaluated in the preclinical stage of experiments, contains an Anticalin protein component directed with specificity and subnanomolar affinity against CTLA-4, a protein receptor that down-regulates the immune system and which is found on the surface of T cells, regulating T cells at their stage of initial activation, in effect turning “off” the attacking nature of the T cells. T cells are a type of white blood cell that play several central roles in the immune system. Inhibiting CTLA-4, and thus allowing T cells to attack cancer cells, has been validated with other biologics, including ipilimumab, which is marketed by Bristol-Myers Squibb as Yervoy. Another panel of 300-Series Anticalin-based proteins currently being evaluated in the preclinical stage of experiments contains an Anticalin protein component directed with specificity and low nanomolar affinity against CD137 (or 4-1BB), a member of the tumor necrosis factor receptor family which is increasingly associated with co-stimulatory activity for activated T cells, such as effector T cells and memory T cells, and assists in the up-regulation of the immune system. Agonizing CD137, and thus allowing T cells to attack cancer cells, has also been validated with other biologics, including urelumab, which is currently in clinical development by Bristol-Myers Squibb. We are currently evaluating in preclinical studies PRS-343, particular bispecific proteins, comprised of an anti-CD137 Anticalin protein genetically linked with a variant of trastuzumab, an anti-HER2 monoclonal antibody. Preclinical data has shown that several characterized CD137-engaging Anticalin proteins exhibit agonistic properties through target cross-linking and that such bispecific constructs maintain target engagement and desired stability. Based on the above, we believe that trafficking an anti-CD137 Anticalin-based therapeutic protein to the tumor microenvironment of HER2-implicated tumors may offer patients an improved therapeutic window for immunomodulatory treatment compared to a monospecific anti-CD137 antibody approach such as urelumab.

We are also developing PRS-110 in oncology. PRS-110 is a monovalent antagonist (a polypeptide molecule with one target-binding domain) that is designed to block cMet activity, independent of whether induced by hepatocyte growth factor, or HGF, the natural ligand for cMet, or mediated through intrinsic ligand-independent activity. cMet is a receptor tyrosine kinase, a well-known high-affinity cell surface receptor that transmits signals into the cell when a corresponding ligand binds to it, which is essential for embryonic development and wound healing and has been associated with several different cancers, including renal, gastric and lung carcinomas, central nervous system tumors and sarcomas. We have shown in preclinical in vivo studies that PRS-110 blocks both ligand-dependent and ligand-independent activity of cMet while also being devoid of any activating (agonistic) activity, likely due to the monovalent manner in which it engages cMet. Preclinical studies have also shown that PRS-110 both inhibits receptor activation and leads to receptor removal, highlighting its novel mechanism of action and potential for the treatment of cMet-driven tumors. In October 2013, we entered into a development and license agreement with Cadila Healthcare Limited (Zydus Cadila), or Zydus, for the preclinical development of PRS-110, pursuant to which we share certain commercial rights to PRS-110 with Zydus. For more information about the Zydus agreement, see “—Strategic Partnerships.”

In addition, in November 2013, Pieris Operating entered into a joint development and license agreement with Stelis BioPharma Private Limited, a subsidiary of Strides Arcolab Limited, or Stelis, establishing a collaboration for clinical development and commercialization of certain of our proprietary products, primarily focusing on use in ophthalmological applications. Under the terms of the agreement, we contribute certain proprietary assets to the development project, and Stelis agrees to establish a production process for preclinical

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and clinical supplies of product and to perform certain preclinical and a first-in-human clinical study. We agreed that upon reaching certain development stages for a product, we and Stelis would discuss the possible formation of a joint venture to further develop and commercialize such product. We believe the agreement pairs our drug discovery capabilities with Stelis’ bio-manufacturing and clinical development expertise. For more information about the Stelis agreement, see “—Strategic Partnerships” below.

Strategy

Our goal is to become a fully integrated biotechnology company by developing Anticalin^® therapeutics against a variety of targets in diseases and conditions with high unmet medical need, and later developing and commercializing our products. We intend to take advantage of our operational experience in technology development and our history of successful partnerships and collaborations to gain access to additional partnerships that will help provide us the experience we need to bring Anticalin drug candidates to market in a number of indications. We intend to engage with partners for many of our programs in a combination of geographic and indication-based arrangements to maximize our business opportunities. We also intend to retain certain development and commercial rights on selected products as our experience in drug development grows. Key elements of our strategy include:

Anticalin platform technology

Our platform technology focuses on low molecular-weight Anticalin^® proteins that bind tightly and specifically to a diverse range of targets. Anticalin proteins are derived from human proteins called lipocalins, which are

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naturally occurring low-molecular weight human proteins of approximately 18 to 20kDA molecular mass typically found in blood plasma and other bodily fluids. The lipocalin class of proteins defines a group of extracellular specific-binding proteins that, collectively, exhibit extremely high structural homology, yet have an uncharacteristically low amino acid sequence identity (less than 20%), making them attractive “templates” for amino acid diversification. Lipocalins naturally bind to, store and transport a wide spectrum of molecules. The defining attributes of the 12-member human lipocalin class and, by extension, Anticalin proteins, engineered from the lipocalin class of proteins, are a four-loop variable region and a rigidly conserved beta-barrel backbone, which, together, form a cup-like binding pocket. The below graphic shows both human tear (left) and neutrophil gelatinase-associated (right) lipocalins together with their natural ligands.

Anticalin^® proteins are created from either human tear lipocalin, found in human tear fluid, or human neutrophil gelatinase-associated liopcalin (or hNGAL), a protein involved in the innate immune system, by making discreet mutations in the genetic code for the binding regions. These mutations have the potential to lead to highly specific, high-affinity binding for both small and large molecular targets. Random mutations are introduced at pre-defined positions involved in endogenous ligand engagement, creating exponentially diverse pools of Anticalin proteins, the most potent and well behaved of which are selected and optimized in a customized manner through in vitro selection. Using techniques such as phage display, a successful technique in antibody-based drug discovery, to build and refine antibody libraries, the ability to introduce diversity and then select the best binders among a large pool of Anticalin proteins gives us the opportunity to select Anticalin proteins for a wide variety of targets. The flexibility inherent in the Anticalin proteins’ cup-like structure allows us to choose both small-molecule targets that fit inside the ‘cup’ as well as larger protein targets that can be bound by the Anticalin proteins’ outward-facing arms. Our Phase Ib trial for PRS-050 indicated that Anticalin proteins may be non-immunogenic and thereby have the potential to exhibit a favorable safety profile.

The below graphic demonstrates Anticalin^® drug candidates binding to a small molecule (left), a small protein target (hepcidin, center) and a large protein target (CTLA4, right):

To obtain a specific Anticalin^® protein, we take advantage of the breadth of our proprietary Anticalin libraries, generated through our protein engineering expertise. We have created, and will continue to create, proprietary Anticalin libraries by rationally diversifying the lipocalin regions that are responsible for ligand binding, applying different libraries to different types of targets. For each program, after conception of a research plan,

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we use an automated process to screen Anticalin libraries against targets of interest. Different assays are established to characterize lead Anticalin proteins by their functionality and biophysical and pharmacological properties. After lead Anticalin proteins are identified, optimization is performed to further improve the potency and drug-like properties of the Anticalin proteins, resulting in the selection and characterization of one or more drug candidates. For certain programs, we also generate and characterize multispecific constructs in different formats based on such drug candidates. This is a repeatable process that is typically completed within 12 to 18 months. By utilizing bacterial production from the earliest stages of drug discovery through Current Good Manufacturing Practice, or cGMP, manufacturing, we have created a seamless platform that improves the quality, yield and cost-effectiveness of our drug candidates. However, Anticalin protein manufacturing is not limited to bacterial systems, with the underlying expression system being driven on a program-by-program basis. See “—Manufacturing” below.

As targeted, protein-based molecules, Anticalin^® proteins also function similarly to monoclonal antibodies, thereby offering many of the same favorable qualities, including:

While often compared to monoclonal antibodies, Anticalin^® proteins, we believe, offer several advantages over antibodies, including:

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We believe that drug-like properties of the Anticalin^® drug class were demonstrated in a Phase Ib clinical trial for PRS-050 in solid tumor patients, our anti-VEGF-A Anticalin-branded drug candidate designed to inhibit blood vessel growth in solid tumors. Although we are not advancing the development of PRS-050 in oncology for strategic and economic reasons, we were able to demonstrate in 26 patients with advanced solid tumors that this drug candidate engaged its target with nanomolar affinity, did not generate any detectable ADAs, and has an activity that can be confirmed by biomarker activity, target engagement assays and known on-target effects such as hypertension. In this trial, 17 patients received five or more doses of PRS-050 and one patient received 17 doses. An analysis of this clinical trial led to a recommended Phase 2 dose ranging from weekly to every three weeks. We believe that the positive results from the Phase Ib clinical trial for PRS-050 lends support to the future success of our drug candidates currently in development.

Implementation of our Anticalin Platform Technology: Our Drug Candidates

Pipeline

Each of our drug candidates is in the early stage of development, and we anticipate that it will likely be several years before any of our drug candidates could be commercialized. The following table summarizes the status of our current drug candidates and programs:

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PRS-080 targeting hepcidin in CKD-related FID-anemia

PRS-080 is a PEGylated Anticalin^® drug candidate targeting hepcidin, a peptide mediator that is an important negative regulator of iron absorption and storage, derived from the naturally occurring human lipocalin known as hNGAL. The normal function of hepcidin is to maintain equilibrium in iron supply for red blood cell production by binding to ferroportin, the protein that transports iron from the inside of a cell to the outside, inducing its internalization and subsequent degradation. The binding of hepcidin to ferroportin reduces the iron uptake from the intestine into the body and inhibits iron mobilization from cellular stores into red blood cells. An excess amount of hepcidin can cause functional iron deficiency, or FID, which often cannot be treated adequately with iron supplements and can lead to anemia. According to a 2009 publication by Young and Zaritsky in the Clinical Journal of the American Society of Nephrology, lowering hepcidin levels or antagonizing its actions would reverse the negative effects of inflammation on red blood cell formation by allowing mobilization of stored iron and improved iron absorption.

PRS-080 has been designed to target hepcidin for the treatment of FID in anemic patients with CKD, particularly in end-stage renal disease patients requiring dialysis, to allow them to mobilize iron that is trapped in iron storage cells for use in the creation of red blood cells. We have also engineered PRS-080 to have a half-life of less than a week, so that following administration, it is expected to clear from the human body in a much shorter timeframe than antibodies, which typically have a half-life of two weeks or greater. This half-life was achieved by covalently linking PRS-080 to a specific polyethylene glycol, or PEG, in order to extend the serum half-life of the combined molecule to desirable levels. Since hepcidin is constantly produced by the body, we believe that a frequent, e.g. once per week, dosing interval will be optimally suited to interfere with hepcidin function. A half-life of about three days and a shorter residence time than mAbs is then in turn more compatible with the dosing schedule. A longer mAb-like residence time is not seen as advantageous, but rather could lead to the accumulation of both the drug and the target beyond the typical residence time of hepcidin, resulting in large quantities of hepcidin bound to mAbs. We completed dosing of healthy volunteers in a Phase I clinical trial with PRS-080 in June 2015. In the trial, no dose-limiting toxicities were observed and a maximum tolerated dose was not reached. The trial was conducted in accordance with German law at a clinical site in Neu-Ulm, Germany that belongs to Nuvisan GmbH, our contract research organization, or CRO. The results from this trial, which we expect to report in the second half of 2015, are intended to provide clinical-trial support for subsequent applications in the U.S.

Chronic kidney disease

According to the American Kidney Fund, approximately 31 million individuals in the United States have CKD (Stages 1-5). The proportion of CKD patients with anemia increases with the severity and stage of CKD, however according to a September 2013 competitive landscape report conducted by Tech Atlas Group, overall rates of individuals with anemia among the CKD population are approximately 30%, and according to a 2004 study by McClellan et al., Current Medical Research and Opinion, approximately 47% of the CKD patients studied were found to be anemic. Extrapolating these percentages based on the CKD population of 31 million individuals, we believe that approximately 9.3 to 14.6 million individuals in the United States with CKD are anemic. CKD (Stage 5), also known as End-Stage Renal Disease, or ESRD, is the final stage of chronic kidney disease with approximately 0.64 million patients in the US as of December 31, 2012 according the U.S. Renal Data System, USRDS 2014 Annual Data Report. The Tech Atlas Group report also estimates that approximately 70%, or approximately 0.45 million, of CKD (Stage 5) patients suffer from anemia. Anemia related to CKD is currently treated by injectable recombinant protein erythropoiesis, or red blood cell production, stimulating agents, or rESAs—including Epogen, Aranesp, and Procrit—with iron supplementation or a red blood cell transfusion. Based on the reported revenues of companies that market and sell rESAs, we believe that global sales of injectable rESAs were approximately $6.5 billion in 2012, the vast majority of which were for renal indications.

Anemia and functional iron deficiency in the CKD population

Anemia is a serious medical condition in which blood is deficient in red blood cells, or RBCs, and hemoglobin, leading to inadequate oxygen delivery to tissues and cells throughout the body. Anemia is generally said to

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exist when hemoglobin is less than 13 g/dL in men and 12 g/dL in women. Anemia has a number of potential causes, including nutritional deficiencies, iron deficiency, bone marrow disease, medications, and abnormalities in production of or sensitivity to erythropoietin, a hormone that controls red blood cell production. Anemia is a frequent and severe consequence of CKD. In addition, within the CKD population, anemia may be caused by functional iron deficiency, or FID. FID exists when, despite adequate stores, iron cannot be mobilized for erythropoiesis. In this case, despite treatment with exogenous erythropoietin and iron supplements, iron is still deficient. FID-anemic patients can be identified and selected for therapy using marketed laboratory tests for iron metabolism. According to the results of a 2013 research analysis conducted for us by Artisan Healthcare Consulting, which, among other things, pooled research results from nephrologists in the United States, approximately 70% of the hemodialysis patient population is anemic, and that among the anemic hemodialysis patient population, up to 20% are FID-anemic. Based on the estimated 0.45 million CKD (Stage 5) patients with anemia approximately 0.09 million individuals are FID-anemic.

Untreated anemia is associated with chronic fatigue, increased risk of progression of multiple diseases, and death. These morbidity and mortality risks have been clearly shown in the CKD population, where in patients age 66 and older, anemic patients with mid-stage CKD (Stage 3) have a 149% increase in cardiovascular events, and patients with severe CKD (Stage 4 and 5) have a 24% increase in cardiovascular events, in each case versus non-anemic patients in the same group, according to a paper published in 2006 in the peer-reviewed journal Blood. Similarly, compared to non-anemic patients, anemia increases the mortality rate by 199% in mid-stage CKD, and 59% in severe CKD. Successful treatment of anemia significantly improves patients’ quality of life, especially with respect to vitality, fatigue and physical function. In addition, patients whose anemia has been successfully treated have demonstrated lower mortality rates, less frequent hospitalization, and decreases in cardiovascular morbidity.

Challenges in using conventional therapy

We believe CKD patients with FID-anemia are especially poorly served. These patients have adequate stores of iron but this iron is not efficiently incorporated into red blood cell precursors through rESAs and iron supplements. According to the 2009 publication by Young and Zaritsky in the Clinical Journal of the American Society of Nephrology, this imbalance in iron metabolism is a result of a high level of circulating hepcidin in the blood stream. We believe existing therapies are limited in that they do not have an impact on hepcidin or, in the case of rESAs, patients often become resistant to the therapy.

Our potential solution: binding hepcidin with PRS-080

We have engineered PRS-080 so that it binds to hepcidin and reduces the impact of hepcidin’s negative regulation on iron mobilization. We believe that by blocking the actions of hepcidin, PRS-080 will serve to address anemia by mobilizing iron for incorporation into red blood cells.

In patients suffering from anemia of CKD, and specifically in patients with FID, hepcidin is frequently produced by the body in abnormally large amounts. Therefore, we believe that the best way to inhibit its function is to administer an inhibitor frequently, such as once a week. Our approach will use PRS-080 in connection with a conjugated PEG30 molecule, a well-known half-life extender, potentially allowing the drug sufficient residence time. Once coupled to PEG30, PRS-080 is intended to have a half-life that will be optimally suited for dosing anemic patients with CKD. In contrast, antibodies typically have a half-life of two to three weeks. Such a long half-life renders antibodies unsuitable for frequent administration and elimination of a circulating target protein like hepcidin because such antibodies tend to accumulate the target after binding due to their own long residence time in the body with the associated risk of bound hepcidin being released by antibodies that are still circulating in the blood.

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Preclinical data

Our preclinical studies targeted the cynomolgus monkey orthologue of hepcidin, which has a high degree of similarity (96% identity) with human hepcidin. PRS-080 was found to bind with high affinity to the cynomolgus monkey version of hepcidin. We performed a dose finding study in cynomolgus monkeys, testing intravenous 30-minute infusions as well as subcutaneous injections of PRS-080. We also carried out a 4-week repeated dose toxicology study with intravenous infusions of PRS-080 for 30 minutes every other day. Our work included toxicokinetic and ADA measurements. During the study, safety pharmacology parameters on the cardiovascular system and respiration were monitored and all safety endpoints were met. Our preclinical studies also examined a different hNGAL-derived Anticalin^®, or surrogate molecule, which targets rat hepcidin in a rat model of inflammation-induced anemia. In these studies, administration of the surrogate molecule once per day or every other day inhibited the manifestation of anemia in the rats over the course of a three-week period.

Hepcidin binds to ferroportin and induces its internalization and subsequent degradation, thus disabling iron mobilization from cells. PRS-080 binds strongly to hepcidin and inhibits its activity as shown in potency assays. These in vitro potency studies showed that the hepcidin-induced internalization of ferroportin is inhibited by PRS-080 in a dose-dependent manner. PRS-080 allowed for the restoration of ferroportin expression, overcoming the hepcidin-induced down-regulation, whereas hNGAL alone did not have a similar effect on ferroportin expression.

The below chart demonstrates the percentage of expression of ferroportin, % FPN1, by PRS-080 mediated inhibition of hepcidin in an in vitro potency assay with ferroportin transfected 293 cells, wherein at 20 nM, hepcidin induces internalization of ferroportin which is reversed by PRS-080 in a dose dependent manner:

We then studied the functional consequences of hepcidin inhibition on iron mobilization in cynomolgus monkeys. A dose of 1 mg/kg PRS-080 produced a robust, transient and reversible increase in total iron levels from approximately 36 µM at baseline to 52µM after 8 hours. Doses higher than 1 mg/kg elevated serum iron concentrations to comparable levels and, in a dose-dependent manner, prolonged the response. A linear correlation was observed over time between the PRS-080 dose and increase of serum iron concentrations.

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The below chart shows the increase in serum iron concentrations in cynomolgus monkeys following a single intravenous administration of PRS-080 at 10 mg/kg compared to wild-type hNGAL administered at the same dose:

The functional consequence of PRS-080 treatment on bone marrow activity and red blood cell production, or hematopoiesis, by means of hemoglobin (an oxygen transporting protein contained in red blood cells) concentration in reticulocytes, a precursor of red blood cells, was investigated in cynomolgus monkeys following repeated administration. As shown in the below chart, after administration of PRS-080 either intravenously (i.v. 150 mg/kg, **) or subcutaneously (s.c. 20 mg/kg, ***), elevated hemoglobin concentrations in reticulocytes (Retic CH) were observed on day 30 compared to pre-treatment (pre-dose).

The PK properties of PRS-080 were investigated in cynomolgus monkeys after a single administration at doses ranging from 20 mg/kg to 150 mg/kg. The concentration over time profiles of PRS-080 showed standard drug- like properties, as the kinetics were dose proportional and there was a low volume of distribution. Elimination of PRS-080 occurred with a terminal half-life of about 2 days which can be extrapolated to translate to 3 days in humans.

PRS-080 administration to cynomolgus monkeys was well tolerated up to the highest tested dose of 120 mg/kg. This dose was classified as producing no adverse events, routine laboratory tests and blood cell examinations did not demonstrate any adverse findings and safety pharmacology investigations were without adverse events. As a result of the hepcidin inhibition, the study showed increased iron uptake and storage, for example in the liver, and mobilization.

Phase I trial design

We completed dosing of healthy volunteers in a Phase I clinical trial with PRS-080 in June 2015. The trial was conducted in healthy volunteers at a clinical site in Neu-Ulm, Germany by Nuvisan GmbH, a CRO. The study was a single dose escalating, blinded, placebo controlled study at a dose range from 0.2 to 40 mg/kg (equivalent to 0.08 to 16.0 mg/kg based on protein content). Dosing of subjects began at the end of 2014. By June 2015, all 48 subjects were dosed with PRS-080 (36) or a placebo (12). This study is governed and was approved by the German Federal Institute for Drugs and Medical Devices (Bundesinstitut für Arzneimittel und Medizinprodukte, or BfArM) and the local Ethics Committee. In the trial, no dose-limiting toxicities were

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observed and a maximum tolerated dose was not reached. Evaluation of the study data is ongoing and we expect to report the data findings in the second half of 2015.

The first Phase Ib/IIa clinical trial enrolling patients is planned to be initiated by the fourth quarter of 2015 in end-stage renal disease patients, involving multiple sites in Europe. We first plan to enroll CKD patients to study pharmacokinetics in a single-dose format. We plan to subsequently dose repeatedly and study the effects of PRS-080 administration on iron mobilization and erythropoiesis in CKD patients.

Based on the results of the initial trials, our current intention is to design additional trials to examine dose response and longer treatment periods. Endpoints may include levels of circulating hemoglobin, which corresponds to the degree to which anemic patients with FID respond to PRS-080. Titration of intravenous iron and rESA doses will also be implemented in future trials. We intend to incorporate and utilize U.S. clinical sites in connection with such additional studies. We plan to submit an Investigational New Drug application, or IND, to the U.S. Food and Drug Administration, or FDA, for PRS-080 in 2017. We expect to complete Phase IIa clinical studies in the first half of 2017.

PRS-060 targeting IL-4RA in asthma

PRS-060 is an Anticalin^® drug candidate targeting IL-4RA, a cell surface receptor expressed on immune cells in the lung epithelium and mucosal layer. IL-4RA is specific to the circulating cytokines IL-4 and the closely related cytokine IL-13, both key drivers of the immune system that induce differentiation of naïve helper T cells to type 2 helper T cells, or Th2. PRS-060 is derived from human tear lipocalin, has picomolar affinity for human IL-4RA (20 pM) and has a favorable stability profile. We showed in vitro that PRS-060 can inhibit the activity of both IL-4 and IL-13. We have formulated PRS-060 supporting a delivery through inhalation, and we are actively preparing to carry out bioprocess optimization in preparation for Current Good Manufacturing Practice, or cGMP, manufacturing and preclinical safety and tolerability studies. Pending the results of our preclinical studies, we intend to pursue a first-in-man clinical trial for PRS-060 in the first quarter of 2017. Some of the development of PRS-060 is conducted in Australia, where we intend to access leading Australian pulmonologists for potential patient recruitment and to seek up to 40% or more in tax refunds from the Australian government in connection with research and development expenses related to PRS-060. We believe PRS-060 represents a first-in-class inhaled biologic for the treatment of asthma.

Asthma market

Asthma is a very common chronic airway disorder affecting approximately 300 million people worldwide according to the Global Initiative for Asthma and approximately 26 million Americans according to the U.S. Centers for Disease Control. Of these 26 million, about 7 million are children. Asthma is responsible for 13 million physician visits a year including about 2 million emergency visits in the United States, according to the American Lung Association. Asthma is responsible for $50 billion in direct healthcare costs each year in the United States, according to a 2011 publication by Barnett and Nurmagambetov in the Journal of Allergy and Clinical Immunology.

Challenges in using conventional therapy

According to a 2012 Artisan Health Care Consulting analysis, as of 2011 asthma affects approximately 195 million people in Brazil, China, Europe, India, Japan, Russia and the United States. The analysis determined that approximately 16%, or 32 million, of the group studied were considered to have moderate and severe uncontrolled asthma, while approximately 9%, or 19 million, of the group studied were considered to have moderate and severe uncontrolled asthma with an elevated Th2 signature. Extrapolating from these percentages to the global asthma population of 300 million individuals, we believe that approximately 48 million asthma sufferers worldwide are considered to have severe, persistent or uncontrolled disease and a large percentage of these patients, approximately 28 million, display inflammatory exacerbations associated with Th2 immunity. Inflammation brought about by Th2 immunity is not addressed by standard asthma therapies. Standard therapies are not able to address such patients, symptoms or they develop resistance to the inhaled steroids, currently considered the standard of care.

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The current standard of care for persistent, moderate to severe allergic asthma is omalizumab (Xolair from Roche). Omalizumab was approved for this condition in the United States in 2003. Outside of the United States, omalizumab is approved for severe asthma and it is currently the only biologic approved for asthma. Omalizumab works by binding to the immune mediator immunoglobulin E, or IgE, and inhibiting IgE-mediated activation of mast cells and basophils, types of white blood cells. It has also been shown to impact some diseases, such as asthma, that are driven by eosinophils, another important class of immune cells. However, patient response to omalizumab has been shown to be inconsistent, as reported in a publication by McNicholl and Heaney in 2008 in the journal Core Evidence, which explained that in only some studies did omalizumab improve lung function. Furthermore, general asthma symptoms are also typically unaffected by omalizumab. Finally, in 2007, the FDA issued a black box warning for omalizumab due to reported cases of anaphylaxis, a potentially life-threatening allergic reaction suffered by some patients who had taken the drug. Despite these shortcomings, in 2014, worldwide sales of Xolair (omalizumab) were reported to be approximately $1.8 billion.

The next generation of therapies beyond omalizumab targets a broader range than just IgE mediated mechanisms. These approaches target other immune mediators, including IL-5, IL-4 and IL-13 (which act in concert on eosinophils, B-cells, epithelial cells, goblet cells and others) and CRTH2. Asthma is associated with high levels of eosinophils, immune cells that play a role in protecting the body against infection. The creation of eosinophils can be interrupted at the early stages, while the cells are still maturing. Multiple products are in development that target eosinophils. However, eosinophils are only one of many cell types and immune system components that are involved with the body’s exaggerated inflammation response in asthma. Mast cells, basophils, goblet cells and other cells also play a role. These cells can be seen infiltrating the airways along with eosinophils, leading to the conclusion that more cell types are involved. We believe that targeting just one of these components is not likely to be as effective in resolving severe asthma as an approach that targets the broader Th2 (cell-mediated) pathway.

In 2013, Regeneron and its partner Sanofi reported proof-of-concept in a Phase IIa trial in persistent asthma with dupilumab, a currently unapproved monoclonal antibody that targets IL-4RA now in clinical development as a subcutaneously delivered agent. In a 2013 paper in the New England Journal of Medicine, Wenzel et al. reported that dupilumab showed a benefit on the asthma control questionnaire 5 (ACQ5) symptom score, a widely accepted measure for classifying the ability of a medication to control asthma. Patients dosed with dupilumab had fewer asthma attacks compared to placebo-treated patients when standard therapies, such as long-acting beta-agonists and inhaled glucocorticoids, were withdrawn, demonstrating the efficacy of dupilumab. Patients also showed improved lung function and reduced levels of Th2-associated inflammatory markers. Dupilumab is administered systemically through injection. In November 2014, Regeneron and Sanofi announced that in a Phase IIb study, dupilumab also demonstrated improved lung function and reduced exacerbations when administered together with standard of care. These effects were observed in both unselected severe asthma patients and selected patients presenting elevated Th2 responses. In May 2015, Regeneron and Sanofi announced interim analysis of a pivotal Phase IIb study of dupilumab in adult patients with moderate to severe asthma, who are uncontrolled despite treatment with inhaled corticosteroids and long-acting beta agonists (ICS/LABA). The announcement reported that the study met its primary endpoint of improving lung function in asthma patients with high blood eosinophil counts (greater than or equal to 300 eosinophilic cells per microliter), and also disclosed positive results in study patients with low blood eosinophil counts (less than 300 eosinophilic cells per microliter) who are thought to be less likely to suffer from “allergic” asthma and therefore less likely to respond to Th2-targeted therapies. We believe the results support the possibility of treating persistent uncontrolled asthma with a biologic therapy without narrowing the patient population based on the Th2 phenotype.

Another biologic in development for severe asthma is lebrikizumab, which blocks IL-13, a mechanism known to have a similar effect to that of dupilumab. Like dupilumab and other mediators of the Th2 pathway, lebrikizumab is a validating example for subcutaneously delivered Th2 intervention in treating uncontrolled asthmatics. In a 2011 publication in the New England Journal of Medicine, lebrikizumab was reported to improve lung function in severe asthma patients who were also receiving standard of care inhaled glucocorticoid therapy. At the same time, patients in the study who received lebrikizumab showed greater musculoskeletal side effects than patients receiving placebo. We believe that the ability to impact disease biology and improve lung function with biologics such as lebrikizumab is a promising result.

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We believe that there could also be significant advantages to other routes of administration, such as inhalation, of biologics that target asthma through the Th2 pathway. If delivered by inhalation, such biologics could be dosed at much lower levels and may preferentially direct the therapy to the site of the disease, in this case the lung.

Our proposed solution: binding IL-4RA with PRS-060

We propose to take PRS-060 forward into clinical trials first in healthy volunteers and then in severe asthma patients. These trials could accomplish two important goals: we could establish proof-of-concept for inhaled Anticalin^® proteins, opening up a second route of administration for our drug candidates beyond intravenous or subcutaneous injection. And if, based on data, we are able to enter a proof-of-concept trial in these patients, we will attempt to demonstrate that PRS-060 can improve patient symptoms. We intend to begin a Phase I clinical trial for PRS-060 in the first quarter of 2017.

Advantages to inhalation as a route of administration for PRS-060

We have performed inhalation studies in mice and observed that systemic concentrations of PRS-060 are minimal when dosed by inhalation, as a result of low doses and short systemic residence time. This offers the potential of a wider therapeutic window and possibly lower systemic side effects that may become prevalent with chronic, systemic Th2 interrogation. By our calculations, the dose of PRS-060 could potentially be lower than the doses being used for the monoclonal antibodies dupilumab and lebrikizumab. Furthermore, we believe that PRS-060 can be produced at a lower cost of goods than monoclonal antibodies because we intend to use manufacturing procedures that employ bacterial expression systems, which generally provides a cost advantage over mammalian production systems, typically used for mAbs. Since dosing by inhalation is a common route of administration in asthma patients, it represents a more convenient dosage regimen for patients than dosing of antibodies by injection and would not need to be administered in a physician’s office or other medical setting.

Preclinical data

In in vitro assays, PRS-060 specifically bound to immobilized targets such as human IL-4RA in a concentration-dependent manner. We tested the binding of PRS-060 to various targets in enzyme-linked immunosorbent assay, or the ELISA, a standard in vitro assay platform. In these tests, PRS-060 bound to IL-4RA with subnanomolar affinity and it did not bind to three other human cell-surface interleukin receptors (IL-6R, IL-18RA, IL-23RA). Furthermore, the activity of IL-4 and IL-13 was inhibited by PRS-060 in a dose-dependent manner. The below charts show the inhibition of IL-4 (left) or IL-13 (right) induced proliferation in human TF-1 cells in vitro by PRS-060.

In in vivo assays in mice genetically altered to express human IL-4RA and IL-13R, PRS-060 inhibited the induction of eotaxin protein, a marker or airway inflammation, in lung tissue following pulmonary delivery. We observed this inhibition at both the RNA and protein levels compared both to buffer and to tear lipocalin.

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The below chart shows the duration of PRS-060-mediated inhibition of eotaxin protein, a marker of airway inflammation, in lung tissue by a single pulmonary dose in mice:

When we administered IL-13 into the lung, inflammation was induced as determined by eotaxin expression, which was not inhibited when phosphate buffered saline, or PBS, was administered into the lung. In contrast to the PBS administration, eotaxin expression and, as a result, inflammation was prevented when PRS-060 was administered into the lung before IL-13. As demonstrated in the above chart, the model showed the inhibitory potential lasts for up to 24 hours after PRS-060 administration.

300-Series

Current antibody-based therapies targeting tumor cell destruction or immune activation are hampered by, among other factors, low response rates and the induction of immune-related adverse events. The 300-Series Anticalin^®-based proteins are multispecific proteins designed to engage immunomodulatory targets and consist of a variety of multifunctional biotherapeutics that can combine antibodies with Anticalin proteins. These combined molecules have the potential to build upon current therapies through the capability of modifying or regulating one or more immune functions on a single fusion protein, thereby having the potential to elevate immune responses within a tumor microenvironment. The 300-Series proteins are comprised of two components, one of which is directed to a tumor receptor and the other engages an immunomodulatory target, which is either an immune checkpoint or co-stimulatory molecule. First, the tumor receptor-targeting component of this multispecific construct will be able to directly attack tumor cells, causing signal attenuation, tumor debulking and, as a result, antigen presentation. Second, we believe that a tethered Anticalin protein directed at immunomodulatory targets can preferentially activate the immune system at the site of the tumor microenvironment. We believe that the 300-Series Anticalin-based proteins represent a “platform within a product” opportunity in immuno-oncology since it may be possible to apply a single combined Anticalin-antibody molecule in a number of different cancers. This is based on the shared underlying biology such as checkpoint biology found within tumors arising in different organs.

This platform is modular, which we believe will permit rapid evaluation of unique combinations of validated tumor targets and immunomodulatory targets. For example, one panel of 300-Series Anticalin^® proteins, currently being evaluated in the preclinical stage of experiments, contains an Anticalin protein component directed with specificity and subnanomolar affinity against CTLA-4, a protein receptor that down-regulates the immune system and which is found on the surface of T cells, regulating T cells at their stage of initial activation, in effect turning “off” the attacking nature of the T cells. Another panel of 300-Series Anticalin^® proteins currently being evaluated in the preclinical stage of experiments contains an Anticalin protein component directed with specificity and low nanomolar affinity against CD137 (or 4-1BB), a member of the tumor necrosis factor receptor family which is increasingly associated with co-stimulatory activity for activated T cells, such as effector T cells and memory T cells, and assists in the up-regulation of the immune system.

We are currently evaluating in preclinical studies PRS-343, particular bispecific proteins, comprised of an anti-CD137 Anticalin^® protein genetically linked with a variant of trastuzumab, an anti-HER2 monoclonal antibody. Preclinical data has shown that several characterized CD137-engaging Anticalin proteins exhibit agonistic

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properties through target cross-linking and that such bispecific constructs maintain target engagement and desired stability. Specifically, the Anticalin proteins can be linked to different points on the antibody backbone, resulting in bispecific proteins with multiple geometric formats. The varying formats may influence the target binding and functionality of such bispecific constructs in unique ways. We believe that these potentially distinct properties could result in different pharmacodynamics effects. For example, the positioning of a CD137-engaging Anticalin protein at different points on a HER2-engaging antibody can potentially result in different distances between a HER2-binding site of an antibody and a CD137-binding site of the Anticalin protein.

The below graphic demonstrates how the CD137-specific Anticalin^®- proteins can be linked, through a peptide bond, to various regions of an HER2-targeting antibody (left to right: the C-terminus of the immunoglobulin heavy chain domain (VH), the N-terminus of the VH, the C-terminus of the immunoglobulin light chain (VL), and the N-terminus of the VL).

We have identified a lead CD137-engaging Anticalin^® protein, which has a binding affinity of 2 nanomolar (nM) dissociation constant (KD) to recombinant CD137. We believe CD137 is engaged in a “non-competitive” manner, meaning that following CD137 binding by the Anticalin protein, CD137’s ability to bind to its ligand is preserved. This represents the immunomodulatory component of the PRS-343 bispecific proteins. The ability of the CD137-specific Anticalin^® protein to activate T cells was tested in experiments using fresh human donor T cells. During such experiments, we used an industry standard T cell activation assay, measuring secretion of interleukin 2 (IL-2), a cytokine secreted by activated T cells.

As shown in the graph above, a dose-dependent co-stimulation of T cells was observed when a CD137-specific Anticalin protein was coated on a plate. This demonstrates that Anticalin proteins may possess agonistic

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properties, providing the basis to make multiple formats of proteins using CD137-specific Anticalin proteins as functional building blocks.

To assess simultaneous target engagement for PRS-343 bispecific formats, we tested whether affinity for HER2 and CD137 is retained in the bispecific configuration. We employed an enzyme-linked immunosorbent assay, or ELISA-based dose titration experiment to determine the affinity of the fusion proteins to recombinant HER2 and observed affinity of the bispecific formats to HER2 was within the same range as the HER2-targeting antibody. Additionally, an ELISA-based dose titration experiment was performed to assess the affinity of the bispecific formats to recombinant CD137. Results showed that the bispecific formats behaved similarly to the CD137-specific Anticalin^® proteins.

To test the drug-like properties of PRS-343 bispecific formats, we performed a stability assessment. PRS-343 bispecific formats were incubated for one week at 37 degrees Celsius in phosphate-buffered saline at 1 milligram per milliliter (mg/ml). Size Exclusion Chromatography, or SEC, showed that the monomer profile of each protein was similar before and after incubation, demonstrating that the PRS-343 bispecific formats exhibited stable biophysical properties. In addition, we also observed stability of the PRS-343 bispecific formats when placed in human plasma in a dual binding ELISA-based experiment.

Preclinical data reported from Pastor et al (Molecular Therapy, 2011; 1878-86) showed that localized activation of CD137 (also referred to therein as 4-1BB) using a tumor targeting bispecific molecule based on aptamers, a group of target-specific binding oligonucleotide or peptide molecules, led to strong anti-tumor responses, similar to the mechanism of action currently employed by us in connection with PRS-343. Further, systemic delivery of an agonistic CD137-specific aptamer conjugated to a tumor-targeting aptamer that binds to prostate specific membrane antigens (PSMA) led to inhibition of tumor growth. In contrast, a combination delivery of the single aptamers had no effect. The data also showed that the administration of the bispecific molecule led to a survival advantage with a durable anti-tumor response in 50% of mice and impacted distal lung metastasis.

Based on the above, we believe that trafficking an anti-CD137 Anticalin-based therapeutic protein to the tumor microenvironment of HER2-implicated tumors may offer patients an improved therapeutic window for immunomodulatory treatment compared to a monospecific anti-CD137 antibody approach such as urelumab.

In addition, we are testing the potential of antagonizing certain other immune checkpoints and agonizing other co-stimulatory molecules through Anticalin^® proteins and building combined Anticalin-antibody multispecific proteins based on such Anticalin proteins. These latter studies are currently in the research phase. In May 2015 we engaged Dr. Holbrook Kohrt, M.D., PhD., of Stanford University as Senior Advisor Translational Medicine Immuno-oncology and entered into a collaboration with his research laboratory. As part of that alliance, we gain access to the laboratory’s capabilities, including access to tumor tissue samples and translational mouse tumor models; in return, we fund certain research activities performed at the laboratory. We believe the collaboration will enable us to quickly advance our 300-Series programs into in vivo proof of concept. Additionally, the collaboration provides a channel for evaluating and in-licensing novel immunomodulatory targets which could serve as the basis for new Anticalin drug discovery programs.

Pipeline products: PRS-110 in cMet-related cancer

PRS-110 is an Anticalin^® protein-based antagonist of cMet that blocks both ligand-dependent and ligand- independent activity of cMet. cMet is a receptor tyrosine kinase, a well-known high-affinity cell surface receptor which is essential for embryonic development and wound healing. Hepatocyte growth factor, or HGF, is the only known ligand of the cMet receptor, and upon HGF stimulation, cMet induces several biological responses that collectively give rise to a program known as invasive growth, which can in some cases trigger cancer formation or growth. cMet has been associated with several different cancers, including renal, gastric and lung carcinomas, central nervous system tumors and sarcomas. However, abnormal cMet activity, consisting of cMet amplification or mutation through cell overexpression or interaction with other membrane proteins or receptors, can also lead to HGF-independent tumor formation. Therefore, optimal targeting of the cMet pathway requires a drug with both ligand-dependent and ligand-independent efficacy. We have shown in

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preclinical in vivo studies that PRS-110 blocks both ligand-dependent and ligand-independent activity of cMet while also being devoid of any activating (agonistic) activity, likely due to the monovalent manner in which it engages cMet. Preclinical studies have also shown that PRS-110 inhibits receptor activation and leads to receptor degradation, highlighting its novel mechanism of action and potential for the treatment of cMet-driven tumors. Moreover, inhibition of other receptor tyrosine kinases, such as Bcr-Abl in chronic myeloid leukemia, c-kit in gastrointestinal stromal tumor and HER2 in breast cancer, by targeted therapies has been shown to have a significant clinical impact. Therefore, receptor tyrosine kinases targets such as cMet are currently a focus for drug discovery efforts in order to try to identify specific inhibitors. In October 2013, we entered into a development and license agreement with Zydus for the preclinical development of PRS-110, pursuant to which we share certain commercial rights to PRS-110. For more information about the Zydus agreement, see “—Strategic Partnerships”.

Several experimental drugs targeting various aspects of the cMet pathway, including both small molecule drugs and biologics, have shown tumor growth inhibition or tumor regression in preclinical models using human tissue transplanted into mice and are currently undergoing clinical evaluation. To date, small molecule receptor tyrosine kinase inhibitors have been hampered by lack of specificity for the cMet target. It has also proven difficult to generate antibodies that are completely inhibitory against the cMet receptor because the antibody structures themselves can lead to pathological activation of the receptors. There are several bivalent antibodies targeting cMet receptors that are undergoing preclinical or early clinical evaluation, but these bivalent antibodies can contribute to this pathological activation, thereby creating a potential safety risk. By contrast, in our in vitro studies, PRS-110 inhibits receptor activation and leads to receptor degradation, pointing to its potential to treat tumors linked to the cMet pathway based on what we believe to be its novel mechanism of action.

Competition

The pharmaceutical and biotechnology industries are characterized by rapidly advancing technologies, intense competition and a strong emphasis on proprietary products. While we believe that our technology, development experience, scientific knowledge and strategies provide us with competitive advantages, we face and will continue to face intense competition from many different sources, including major pharmaceutical, specialty pharmaceutical and biotechnology companies, academic institutions and governmental agencies and public and private research institutions, both in the United States and abroad.

We compete, or will compete, with existing and new therapies that may become available in the future. Some of our competitors are pursuing the development of pharmaceuticals that target the same diseases and conditions that our drug candidates target. Any drug candidates that we are able to develop and commercialize will compete with existing and new drugs being developed by our competitors. Our competitors may develop or market products or other novel technologies that are more effective, safer, more convenient or less costly than any that may be commercialized by us, or may obtain regulatory approval for their products more rapidly than we may obtain approval for ours.

The acquisition or licensing of pharmaceutical products is also very competitive, and a number of more established companies, some of which have acknowledged strategies to license or acquire products and many of which are bigger than us and have more institutional experience and greater cash flows than we have, may have competitive advantages over us, as may other emerging companies taking similar or different approaches to product licenses and/or acquisitions. In addition, a number of established research-based pharmaceutical and biotechnology companies may acquire products in late stages of development to augment their internal product lines, which may provide those companies with an even greater competitive advantage.

There are a number of other companies presently working to develop therapies for anemia, asthma and oncology, including divisions of large pharmaceutical companies and biotechnology companies of various sizes. There are also a variety of available drug therapies marketed for these diseases. Our drug candidates, if any are approved, may compete with these existing drug and other therapies, and to the extent they are ultimately used in combination with

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or as an adjunct to these therapies, our drug candidates may not be competitive with them. Some of the currently approved drug therapies are branded and subject to patent protection, and others are available on a generic basis. Many of these approved drugs are well established therapies and are widely accepted by physicians, patients and third-party payors. As a result, market acceptance of, and a significant share of the market for, any of our drug candidates that we successfully introduce to the market will pose challenges.

In addition to currently marketed therapies, there are also a number of medicines in clinical development to treat anemia, asthma or cancer. These medicines in development may provide efficacy, safety, convenience and other benefits that are not provided by currently marketed therapies and may not be provided by any of our current or future drug candidates. As a result, they may provide significant competition for any of our drug candidates.

Many of our competitors will have substantially greater financial, technical and human resources than we have. Additional mergers and acquisitions in the pharmaceutical industry may result in even more resources being concentrated in some of our competitors. Competition may increase further as a result of advances made in the commercial applicability of technologies and greater availability of capital for investment in these fields. Our success will be based in part on our ability to build, obtain regulatory approval for and market acceptance of, and actively manage a portfolio of drugs that addresses unmet medical needs and creates value in patient therapy.

In addition, our competitors may have a variety of drugs in development or awaiting market approval that could reach the market and become established before we have a product to sell. Our competitors may also develop alternative therapies that could further limit the market for any drugs that we may develop. Many of our competitors are using technologies or methods to identify and validate drug targets and to discover novel small molecule drugs. Many of our competitors and their collaborators have significantly greater experience than we do in the following:

In addition, many of our competitors and their collaborators have substantially greater advantages in the following areas:

Smaller companies also may prove to be significant competitors, particularly through proprietary research discoveries and collaborative arrangements with large pharmaceutical and established biotechnology companies. Many of our competitors have products that have been approved by the FDA or its foreign counterparts or are in advanced development. We face competition from other companies, academic institutions, governmental agencies and other public and private research organizations for collaborative arrangements with pharmaceutical and biotechnology companies, in recruiting and retaining highly qualified scientific and management personnel and for licenses to additional technologies. Developments by others may render our drug candidates or our technologies obsolete. Our failure to compete effectively could have a material adverse effect on our business.

PRS-080

Other drug candidates in development that interfere with hepcidin function or expression include ISIS/Xenon (anti-sense) and Alnylam (RNAi), which have nucleic acid based approaches aimed at reducing hepcidin

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synthesis in preclinical development. Noxxon’s RNA aptamer sequesters hepcidin and is in clinical studies in cancer and ESRD patients. A mAb against hepcidin is tested in cancer as well as chronic kidney disease patients by Eli Lilly as well as a mAb against the ferroportin transporter. Ferrumax develops a soluble form of hemojuvelin, a protein that regulates hepcidin expression and iron metabolism, that aims to suppress the production rate of hepcidin.

There are also a number of companies which are focused on treating anemia in CKD patients under alternative approaches. Fibrogen, Akebia Therapeutics, GSK, Bayer, and Japan Tobacco have hypoxia-inducible-factor prolyl hydroxylase (HIF-PH) inhibitors in clinical development that target stimulation of bone marrow activity. Acceleron is also targeting the sequestration of Activin A, a natural inhibitor of hematopoiesis, is in a Phase II clinical study. Zenerex by Keryx, which targets formulation of oral iron, is currently been tested in Phase II in CKD patients. There are also various companies conducting late-stage development of erythropoietin biosimilars.

PRS-060

Like PRS-060, new developments for the treatment of uncontrolled moderate to severe asthma patients mainly include drug candidates targeting the Th2 pathway by interfering with IL4/IL-13 or IL-5 function. Such products include dupilumab (Sanofi/Regeneron, IL-4RA), lebrikizumab (Roche/Genentech, IL-13), tralokinumab (Astra Zeneca, IL-13), mepolizumab (GSK, IL-5), reslizumab (Teva, IL-5), and benralizumab (Astra Zeneca, IL-5R). These drugs are in later clinical development (Phase II and Phase III) than PRS-060, or were submitted for approval (mepolizumab), however in contrast to PRS-060, these mAbs are given to patients through injection and distribute systemically through the blood stream. There are a number of other companies presently marketing or developing other therapies for asthmatic patients. The mAb omalizumab, directed against IgE, is approved for the treatment of uncontrolled, moderate to severe asthma patients.

300-Series

Other drug candidates which target immunomodulatory targets include ipilimumab, which is specific for the checkpoint CTLA-4 and has been marketed by Bristol-Myers Squibb for the treatment of melanoma patients since 2011. Additionally, preclinical and/or clinical testing currently focusing on additional checkpoint mechanisms and targets include PD-1 / PD-L1, LAG3, IDO, TIM3, Ox-40, CD-137, CD70, KIR and NKG2A. Bristol-Myers Squibb and Roche are most active in this area, with multiple single agent or combination therapy trials ongoing. Merck and AstraZeneca also have active trials ongoing, while Novartis is placing more of an emphasis on adoptive T cell transfer technology in its developmental efforts. In September 2014, Merck received FDA approval for its anti-PD-1 antibody, pembrolizumab, for the treatment of patients with advanced or inoperable melanoma. Similarly, Bristol-Myers Squibb recently received FDA approvals for its anti-PD-1 antibody, nivolumab, for the treatment of patients with advanced or inoperable melanoma and advanced non-small cell lung cancer with progression on or after platinum-based chemotherapy. Both companies are pursuing other indications for each of their anti-PD-1 antibodies as well.

Under the 300-Series programs, we are also developing multispecific molecules to facilitate the more effective activation of the immune system, with a strategy of employing multispecific Anticalin^® protein-based molecules that may favorably bias an immune response to the tumor microenvironment. A number of other companies, such as Amgen, Affimed, Macrogenics, F-Star and Sutro, also pursue multispecific approaches in oncology, which therapies are in clinical or preclinical development. Mono-specific antibody approaches include urelumab, a CD137-specific antibody in clinical development sponsored by Bristol-Myers Squibb, as well as PF-05082566, a mono-specific antibody specific for CD137 and which is in clinical development sponsored by Pfizer.

PRS-110

Competitor drug candidates targeting the cMet pathway include MetMab (Roche/Genentech), LY2875359 (Eli Lilly), ABT700 (Abbvie) and earlier stage candidates by other companies. MetMab is a monovalent cMet

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binder, or a one-armed antibody, and has shown efficacy in cMet-high patients (IHC 2+, 3+) in a Phase II trial in non-small-cell lung carcinoma, or NSCLC, patients. However, one Phase III study of MetMab in combination with Erlotinib in NSCLC patients was recently terminated due to lack of a survival benefit, which has led to the decision by Roche to suspend the program. LY2875359 by Eli Lilly and ABT700 by Abbvie are bivalent mAbs against cMet currently in Phase I/II clinical testing. Both mAbs have demonstrated efficacy in Phase I trials.

Several small molecule inhibitors are also undergoing clinical evaluation, including multi-targeted tyrosine kinase inhibitors from ArQule (ARQ197) and Exelixis (XL-184 & XL-880). Crizotinib by Pfizer is an FDA approved small molecule inhibitor, which targets anaplastic lymphoma kinase, or ALK, a protein implicated in certain cancers, and which also has anti-cMet activity. In 2011, Crizotinib was approved for treatment of metastatic NSCLC patients who express ALK fusion proteins. PRS-110 and other cMet-targeting drugs also compete with HGF inhibitors. The monoclonal antibody AMG102 by Amgen is the most advanced HGF- targeting molecule in clinical trials. AV299 by Aveo is another HGF-targeting antibody in clinical development.

Manufacturing

We do not own or operate, and currently have no plans to establish, any manufacturing facilities. We currently rely, and expect to continue to rely, on third-party contract manufacturers, or CMOs, for the manufacture of our drug candidates for larger scale preclinical and clinical testing, as well as for commercial quantities of any drug candidates that are approved.

We currently rely on one CMO for all of our clinical supplies, including active pharmaceutical ingredients, or APIs, drug substances and finished drug products for our preclinical research and clinical trials, including the Phase I trial for PRS-080.

We believe that we will be able to contract with another CMO to obtain API if our existing source of API was no longer available or sufficient, but there is no assurance that API would be available from another third-party manufacturer on acceptable terms, on the timeframe that our business would require, or at all. We do not have long-term supply commitments or other arrangements in place with our existing CMO. We also do not currently have arrangements in place for redundant supply of bulk drug substance.

We do not have any current contractual relationships for the manufacture of commercial supplies of any of our drug candidates if they are approved, and we intend to enter into agreements with a third-party contract manufacturer and one or more back-up manufacturers for the commercial production of our drug candidates as they near potential approval.

Any drug products to be used in clinical trials and any approved product that we may commercialize will need to be manufactured in facilities, and by processes, that comply with FDA’s current good manufacturing practice requirements and comparable requirements of the regulatory agencies of other jurisdictions in which we are seeking approval. We currently employ internal resources to manage our manufacturing contractors.

We believe that PRS-080, PRS-060, our 300-Series programs and our other Anticalin^®-branded drug candidates can be manufactured in reliable and reproducible biologic processes from readily available starting materials. PRS-080 and PRS-060 are produced using bacterial expression systems similar to those that have been used in the past for the production of other proteins and which systems are widely used in the industry. Manufacture of drug candidates originating from the 300-Series programs, including PRS-343, will include mammalian systems comparable to those known to manufacture monoclonal antibodies. We believe that the manufacturing process is amenable to scale-up and will not require unusual or expensive equipment. We expect to continue to develop, on our own or with our collaborators, drug candidates that can be produced cost-effectively at contract manufacturing facilities.

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Intellectual Property and Exclusivity

Our commercial success depends in part on our ability to obtain and maintain exclusivity of our proprietary Anticalin^®-brand technologies through intellectual property protection for our drug candidates, libraries of different protein scaffolds and consensus sequences and the fundamental Anticalin platform technology, including novel therapeutic and diagnostic discoveries, as well as other proprietary know-how, and to operate without infringing on the intellectual property rights of others.

We seek to protect our exclusive position of Anticalin^® technologies by, among other means, prosecuting our own international, U.S. and foreign patent applications related to our proprietary technology, inventions and improvements that are important to the development and implementation of our business. We established intellectual property protection in relation to our Anticalin technologies in key global markets, including Australia, Brazil, Canada, China, the European Union, Hong Kong, India, Japan, Korea, New Zealand, Russia, Singapore, South Africa and the United States. We believe we have patent exclusivity relating to drug candidates derived from lipocalin proteins that runs until at least 2020 in the U.S. We also rely on trade secrets for confidential know-how, which we generally seek to protect through contractual (e.g. confidentiality) obligations with employees and third parties.

We have protected the goodwill of our Company and our drug candidates, created through innovation and development, by putting in place trademark registrations of Pieris^® and Anticalin^® as well as several defensive registrations.

We currently, and expect that we will continue to, file patent applications and maintain granted patents directed to our key drug candidates in an effort to establish intellectual property positions relating to new compositions of matter for these drug candidates, as well as novel medical applications of these compounds in the treatment, prevention or diagnosis of various indications. We also intend to seek patent protection, if available, with respect to biomarkers that may contribute to selecting the right patient population for use of any of our drug candidates, or with respect to pharmaceutical formulations that may be useful to produce final medicinal products.

Following the effective date of our Research and Licensing Agreement with Technische Universität München, or TUM (See “—TUM License Agreement”), and as of the date of this prospectus, we own or are the exclusive licensee of a patent portfolio consisting of several issued U.S. patents, and their respective counterparts in a number of foreign jurisdictions, several pending applications under the Patent Cooperation Treaty, multiple pending U.S. patent applications and corresponding pending patent applications in a number of foreign jurisdictions as well as three pending provisional patent applications, as described in further detail below.

In applicable jurisdictions, we will seek patent term extensions for certain of our patents including the patent term adjustment period in the U.S. If we obtain marketing approval for our drug candidates in the United States or in certain jurisdictions outside of the United States, we may be eligible for regulatory protection, such as twelve years of data exclusivity for new biological entities in the United States and as mentioned below, up to five years of patent term extension potentially available in the United States under the Hatch-Waxman Act, 8 to 11 years of data and marketing exclusivity potentially available for new drugs in the European Union, up to five years of patent extension in Europe (Supplemental Protection Certificate), and eight years of data exclusivity potentially available in Japan. There can be no assurance that we will qualify for any such regulatory exclusivity, or that any such exclusivity will prevent competitors from seeking approval solely on the basis of their own studies. See “—Government Regulation.”

Among the issued patents we own are U.S. patent No. 7,250,297; U.S. patent No. 7,723,476; U.S. patent No. 8,158,753; U.S. patent No. 8,536,307; and their respective counterparts in the European Union, which patents are directed to the basic Anticalin^® protein concept and platform technology (i.e. antagonist or agonist compounds derived from a natural lipocalin protein) and are expected to expire in 2018, subject to patent term

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adjustments in the U.S. of up to 794 days. In addition, we hold issued U.S. patents Nos.: 7,001,882; 7,118,915; 7,691,970; 7,585,940; 7,893,208; and 8,313,924; and their respective counterparts in a number of foreign jurisdictions, which patents are related to libraries of different lipocalin scaffolds such as human apolipoprotein D, human neutrophil gelatinase-associated lipocalin, or hNGAL, and human tear lipocalin, and consensus sequences thereof, and are expected to expire between 2020 and 2027, subject to patent term adjustments in the U.S. of up to 685 days. We also own U.S. patent No. 7,892,827, which is directed to muteins derived from hNGAL having binding specificity for the cytotoxic T lymphocyte-associated antigen, or CTLA-4, and is expected to expire in 2025, subject to a 350-day patent term adjustments in the U.S., and U.S. patent No. 8,313,924, which is directed to a library of consensus sequences from human tear lipocalin scaffold as well as muteins of human tear lipocalin having detectable binding affinity to interleukin 4 receptor alpha chain, or IL-4 receptor alpha (IL-4RA), and is expected to expire in 2027, subject to a 424 day patent term adjustment in the U.S., as well as their counterparts in the European Union and in a number of foreign jurisdictions. In addition, we hold issued U.S. patent No. 8,986,951, as well as its counterparts in a number of foreign jurisdictions, which is directed to muteins derived from human tear lipocalin having binding specificity for IL-4RA and protects one of our lead drug candidates, PRS-060, and is expected to expire in 2031. Moreover, we hold issued U.S. patent No. 9,051,382, as well as its counterparts in a number of foreign jurisdictions, which is directed to muteins derived from hNGAL having binding specificity for hepcidin and protects one of our lead drug candidates, PRS-080, and is expected to expire in 2031, subject to a 117-day patent term adjustment in the U.S.

As a result of research efforts to date under the Research and Licensing Agreement with TUM, we hold a worldwide exclusive license to multiple patents and patent applications. In the United States, we hold an exclusive license to an issued U.S. patent No. 8,598,317 for the composition of matter of mutein of human tear lipocalin binding to the extracellular region of the T-cell co-receptor CD4 with detectable affinity, which patent will expire in 2027 (subject to a patent term adjustment period which is expected to be at least 742 days), as well as to its counterpart in the European Union. We also hold an exclusive license to an issued U.S. patent No. 8,420,051 directed to library of hNGAL scaffold of certain consensus sequence, which patent is expected to expire in 2029 (subject to a patent term adjustment period of 109 days), as well as to its counterparts in the European Union and in a number of foreign jurisdictions. Moreover, we hold an exclusive license to an issued U.S. patent No. 8,987,415 claiming isolated crystalline form of monomeric bacterial lipocalin.

As of the date of this prospectus, a significant portion of our pending U.S. patent applications and pending patent applications in foreign jurisdictions is directed to newly-discovered or improved scaffold libraries of lipocalin muteins, compounds derived therefrom, or the uses of such compounds to treat, prevent and mitigate certain diseases and conditions whose pathological development involve the targets of interest as well as to diagnose, prognose and select treatments for the diseases and conditions. We would expect that any patents that may issue from the pending U.S. patent applications would likely expire between 2029 and 2035 without taking into account possible patent term adjustments or other extensions, however, any and all of these patent applications may not result in issued patents, and not all issued patents may be maintained in force for their entire term. Specifically, granted patents and pending patent applications directed to Anticalin^® proteins for the cMet target currently have terms which could expire as late as 2029, pending patent applications directed to PEGylated versions of the lead cMet-specific Anticalin protein, when granted, could have a term expiring as late as 2030, and granted patents and pending patent applications directed to Anticalin proteins for each of hepcidin and IL-4RA currently have terms which could expire as late as 2031. We are actively pursuing intellectual property protection for our 300-Series programs in key global markets that, if granted, could expire as late as 2035. To date, we are not aware of any third party intellectual property for freedom to operate on our platforms or therapeutic programs.

In addition to patents, we hold two trademarks in the United States, for Anticalin^®, Pieris^®, and Pocket Binding™. Similarly, we hold their respective counterparts, either as registered trademarks or as pending applications, in a number of foreign jurisdictions. We expect that we will continue to look for trademark protection for the goodwill associated with our Company and our drug candidates in the countries or regions where we will have investment, research and development, sales or other activities.

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We also rely upon unpatented trade secrets and know-how and continuing technological innovation to develop and maintain our competitive advantage. We strive to protect our proprietary information, in part, by using confidentiality agreements and/or invention assignment agreements with our collaborators, scientific advisors, employees and consultants. The confidentiality agreements are designed to protect our proprietary information and, in the case of agreements requiring invention assignment, to grant us ownership of technologies that are developed through a relationship with a third-party. We also actively manage our publication and patent applications in that we only disclose information necessary to stir scientific interest or demonstrate patentability without materially compromising the secrecy of our valuable trade secrets and know-how. While we consider trade secrets and know-how to be a critical component of our intellectual property, trade secrets and know-how can be difficult to protect. In particular, with respect to our technology platform, we anticipate that these trade secrets and know-how will over the course of time be disseminated within the industry through independent development, the publication of journal articles describing the methodology and the movement of personnel skilled in the technology from academic to industry positions and vice versa. As a result, those proprietary trade secrets and know-how may lose their value to us over a period of time, and we may lose any competitive advantage afforded by them as they become public knowledge.

Strategic Partnerships

Since 2007, Pieris Operating has entered into several licensing, research and development collaborations to complement our drug discovery and early stage development capabilities. Specifically, Pieris Operating has entered into licensing, research and development agreements which are still active as of the date of this prospectus with Allergan, Inc., or Allergan, Sanofi Group (formerly Sanofi-Aventis and Sanofi-Pasteur SA) and collectively, Sanofi, and Daiichi Sankyo. Under these licensing and research and development arrangements, we have developed and conducted or will develop and conduct selection and screening of drug candidates as well as in vitro potency and efficacy testing using our Anticalin^®-brand drug discovery platform, our Anticalin-brand libraries and other proprietary methods to generate, identify and characterize drug candidates against certain biological targets associated with several diseases. These agreements have provided us with approximately €31 million ($37.5 million) in revenue to date, excluding grant revenues. In addition, we have the potential to receive several milestone payments through 2017. With respect to discontinued collaborations, we have no ongoing performance obligations, and do not expect to receive any significant additional consideration pursuant to those agreements.

Pieris Operating’s agreements with Allergan, Sanofi and Daiichi Sankyo are ongoing and, under which, our partners are obligated to use commercially reasonable efforts to develop and commercialize drug candidates identified in the course of the collaboration. We are entitled to receive from our partners’ research, development and regulatory milestone payments and, in the case of the Sanofi and Daiichi Sankyo collaborations, royalties on net sales for products developed and commercialized under these collaborations. We plan to continue to actively seek out additional collaboration partners.

In addition to Pieris Operating’s agreements with Allergan, Sanofi and Daiichi Sankyo, we are partnering with companies with expertise in clinical development, regulatory affairs and biologics manufacturing to advance our pipeline products through clinical trials and to market those products. In 2013, Pieris Operating entered into a co-development alliance with Cadila Healthcare Limited, or Zydus, with respect to the development and sale of certain proprietary products, under which Zydus will focus on developing markets and we will focus on developed markets. Pieris Operating has also entered into a joint development and license agreement with Stelis, establishing a collaboration for clinical development and commercialization of certain of our proprietary products, focusing initially on use in ophthalmological applications.

Under one of our partnership agreements, one of our partners has the potential to submit an IND covering a collaboration project as early as the fourth quarter of 2015. Further, we intend to file additional INDs covering other collaboration projects in 2016 and 2017.

Certain terms and conditions of our active agreements with Allergan, Sanofi and Daiichi Sankyo are summarized below as well as certain terms and conditions of our co-development agreements with Zydus and Stelis.

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Our agreement with Allergan

In August 2009, Pieris Operating entered into an agreement with Allergan, Inc. for the use of our proprietary Anticalin^® technologies in the discovery and development of drug candidates which inhibit a selected target. Under the terms of the agreement, we provided drug candidates for the treatment of ocular diseases, and Allergan is responsible for the further development and commercialization of products based on those candidates and bearing related costs. We have granted Allergan a worldwide and exclusive license under our patent portfolio for the use of certain drug candidates for the treatment and prevention of ocular diseases.

Upon entering into the agreement, we received a payment of $10 million. We are entitled to receive up to an aggregate of $13 million in additional payments on achieving various milestones. We are not entitled to any royalties from sales of products commercialized under our agreement with Allergan. During the term of the agreement and as long as Allergan commercializes the drug candidates designated under the agreement, we may not grant rights to any third party with respect to any drug candidates that inhibit the same target within the field licensed to Allergan.

The agreement will remain in effect until the expiration of the payment obligations of Allergan to Pieris Operating thereunder. Either party may terminate the agreement in the event of the other party’s material breach of the agreement remains uncured for a specified period or in the event the bankruptcy of the other party. Allergan has the unilateral right to terminate the agreement upon specified prior written notice to us. On termination, all rights granted to Allergan in our Anticalin^® technologies would end.

Our collaboration with Sanofi

In September 2010, Pieris Operating entered into a collaboration and license agreement with Sanofi, which was subsequently amended in February 2013. Under the terms of the agreement, we have agreed to use our proprietary Anticalin^® technologies to identify drug candidates against certain targets, with further development and commercialization activities conducted by Sanofi. The collaboration started with two targets under two separate collaboration projects and was extended by an additional multispecific Anticalin program in 2013.

When we entered the collaboration we granted Sanofi an exclusive worldwide license to develop drug candidates identified in the course of the collaboration and market products based on those drug candidates under the collaboration.

In consideration of our obligations, as a part of the collaboration we received a €3.5 million ($4.2 million) upfront payment and specified research funding. We also are entitled to receive payments on the achievement of research, development and commercial milestones for each product, with up to €26.0 million ($31.5 million) in development milestones and up to €18 million ($21.8 million) in commercial milestones for the first therapeutic application and lesser amounts on subsequent therapeutic applications. We have the ability to receive over €50 million ($60.5 million) potential milestone payments from the active collaboration project, including estimated milestone payments in connection with one or more subsequent applications. Payments due to us also include tiered mid- to mid-high single digit royalties on sales of products. We have agreed that we will not use our Anticalin^® technologies to perform, on our own behalf or for third parties, any research or development activities on the same target to which any active program relates. Unless earlier terminated, the agreement will remain in effect until the expiration of all payment and related obligations of Sanofi thereunder.

During the term of the agreement, Sanofi may terminate any or all programs thereunder for convenience by giving specified prior written notice to us. Either party may also terminate the agreement for a material breach by the other party which remains uncured after specified advance notice of such breach or for the other party’s insolvency. If a program or the agreement is terminated by Sanofi, rights in products and developed technology resulting from the terminated program (including the right to grant sublicenses) revert or are transferred to us. If a program is terminated prior to the development of the product by Sanofi, our right to commercialize that product is royalty-free. Otherwise, we would owe to Sanofi royalties in the single digits as a percentage of net

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sales on such product sold by us or our licensee, with total royalty payments capped at a certain amount, and with the royalty rate dependent on the maturity of the program at the time of termination. Sanofi has terminated two of the three programs (one program was terminated for internal strategic reasons and the other program was terminated following in vivo studies, as in vitro functionality did not fully translate into in vivo functionality for this first in class program), and we have the right to develop and commercialize drug candidates of the terminated programs on a royalty-free basis. The remaining active collaboration project was handed over to Sanofi for further development in the fourth quarter of 2014. Additionally, in January 2015, Pieris Operating transferred to Sanofi ownership of the intellectual property of the remaining active collaboration project, including the obligation for payment of expenses of obtaining patents or other registrations of such intellectual property. All other rights and obligations of the parties under the Sanofi collaboration remain unchanged.

Our collaboration with Daiichi Sankyo

In May 2011, Pieris Operating entered into a definitive collaboration research and technology licensing agreement with Daiichi Sankyo, under which we agreed to use our proprietary Anticalin^® scaffold technologies to discover novel drug candidates against two targets chosen by Daiichi Sankyo under two separate collaboration projects. Upon achievement of preclinical development milestones for lead drug candidates, Daiichi Sankyo assumes responsibility for, and to use commercially reasonable efforts in, the further development and marketing of products based on those candidates. As of the date of this prospectus, we have handed over further development responsibility for the two collaboration projects to Daiichi Sankyo in March 2013 and June 2014, respectively.

We received €7.2 million ($8.7 million) upon signing of the collaboration agreement and received research funding. We are entitled to payment on the achievement of research and development milestones of up to €35.85 million ($43.38 million) for the first prophylactic or therapeutic product, with reduced amounts for achievement of those milestones in additional indications. We are also entitled to payment of commercialization milestones of up to €45 million ($54.5 million) for a prophylactic or therapeutic product. On development and commercialization of a diagnostic product, we are entitled to development and commercialization milestones of up to €675,000 ($816,817). We have the ability to receive up to approximately €200 million ($242 million) in potential milestone payments from the two collaboration projects, including estimated milestone payments in connection with one or more additional indications. Daiichi Sankyo is further obliged to pay to us tiered, mid- to mid-high single digit royalties on sales of products for prophylactic and therapeutic uses and low single digits on sales of products for diagnostic uses. We granted Daiichi Sankyo exclusive license rights worldwide for prophylactic and therapeutic products, and nonexclusive rights for diagnostic uses. During the collaboration, we may not use our Anticalin^® technologies in research or commercial activities on the designated targets for our own account or with third parties.

Daiichi Sankyo may terminate any program under the collaboration after a certain research stage for convenience by giving specified prior written notice to us. Either party may also terminate the agreement for a material breach by the other party which remains uncured after specified advance notice of such breach or for the other party’s insolvency. If a program is terminated, rights in products and developed technology resulting from the terminated program (including the right to grant sublicenses) revert or are transferred to us. If a program is terminated by us because of a material breach by Daiichi Sankyo, our sale of products resulting from the program is royalty-free.

If a program is terminated by us because of Daiichi Sankyo’s failure to meet diligence obligations or by Daiichi Sankyo for convenience, we will be required to pay to Daiichi Sankyo royalties on sale of products resulting from the program in the low single digits as a percentage of net sales up to a specified aggregate royalty amount.

Unless earlier terminated, the agreement will remain in effect until (i) the expiration of all payment and related obligations of Daiichi Sankyo thereunder or (ii) upon the decision of Daiichi Sankyo not to develop any drug candidate under the collaboration agreement.

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Our collaboration with Zydus

In October 2013, Pieris Operating entered into a development and license agreement with Zydus. Under the terms of the agreement, we collaborate with Zydus in the development of certain Anticalin^® drug candidates, including PRS-110. Zydus takes the lead in advancing these products through preclinical and clinical proof of concept development and is responsible for its expenses relating to that advancement, which include drug manufacturing. Zydus has been granted exclusive rights to commercialize these products in India and several other developing countries. We retain the right to commercialize these products in key developed markets. We and Zydus have cross-licensed our respective rights in new inventions derived during the collaboration for these products in these territories.

Under the terms of the collaboration, we would be entitled to a payment on achievement of a certain development milestone in the Zydus territory, and a low- to mid-single digit royalty on product sales. We would also be entitled to a share of Zydus’ revenue from a sublicense of its rights in the product. We are obliged on the occurrence of a product’s achieving certain development milestones in our territory to make payments to Zydus, and to pay low-single digit royalties on product sales. We also are obliged to share with Zydus a percentage of our revenue received from out-licensing rights in the product in our territory, which percentage varies based on the stage of development of the product at the time of out-licensing, should we choose to out-license the product.

Upon completion of a certain stage of clinical development, either party may choose to discontinue development, in which case the other party would have the right to continue development and its payment obligations to the discontinuing party would be reduced. During the term of the agreement, with respect to PRS-110, we may not sell a product, or enable a third party to sell a product, that is the subject of the collaboration in the Zydus territory for use in the treatment, palliation or prevention of certain diseases in humans. Under the terms of the agreement, we could be required to pay up to an aggregate of $18.0 million in total milestone payments to Zydus, and could be entitled to a $1.0 million milestone payment from Zydus.

The agreement will remain in effect until both parties cease to have their respective payment obligations thereunder. Either party may also terminate the agreement for a material breach by the other party which remains uncured after specified advance notice of such breach, the other party’s insolvency, or where the parties conclude that clinical data do not support further development.

Our collaboration with Stelis

In November 2013, Pieris Operating entered into a joint development and license agreement with Stelis. Under the terms of the agreement, we collaborate with Stelis in the development of certain Anticalin^® drug candidates, initially for use in the treatment, palliation or prevention of ophthalmology-related diseases. Under the terms of the agreement, we contribute certain proprietary assets to the development project, and Stelis agrees to establish a production process for preclinical and clinical supplies of product at its expense and to perform and fund certain preclinical studies and a first-in-human clinical study for each product under joint development at the expense of Stelis. We agreed that upon reaching certain development stages for a product, we and Stelis would discuss the possible formation of a joint venture with approximately equal shareholding between Pieris Operating and Stelis to further develop and commercialize such product worldwide. If a party does not wish to enter into a joint venture, the other party may continue development and commercialization of a product, subject to terms and conditions to be established by a separate agreement.

Unless earlier terminated, the agreement will remain in effect on a product by product basis until the later of (i) entry by the parties into the joint venture as discussed above, (ii) upon receipt of written notice of a decision not to enter into the joint venture from the other party, the receiving party timely elects to continue development and commercialization of a product, and (iii) agreement by the parties in good faith on how to dispose of a project in the event that neither party wishes to enter into the joint venture, provided, however, that the term of any product shall automatically end no later than one year after completion of the first phase I trial

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for such product unless extended by mutual agreement of the parties. Prior to the formation of the joint venture, either party may also terminate the agreement for a material breach by the other party which remains uncured after specified advance notice of such breach, or for the other party’s insolvency.

TUM License Agreement

On July 4, 2003, Pieris Operating entered into a Research and Licensing agreement with TUM, which was subsequently renewed and, on July 26, 2007, superseded and replaced. The agreement establishes a joint research effort led by Prof. Arne Skerra, Chair of Biological Chemistry of TUM, to optimize Anticalin^® technologies for use in therapeutic, prophylactic and diagnostic applications and as research reagents, and to gain fundamental insights in lipocalin scaffolds. We provided certain funding for TUM research efforts performed under the agreement. The research phase of this collaboration ended on February 28, 2013.

Under the terms of the agreement TUM assigns to us certain materials and records resulting from the research. We retain rights to inventions made by our employees, and TUM assigns to us all inventions made under the agreement jointly by our employees and TUM personnel, provided that our employees have made a certain inventive contribution. With respect to all other inventions made in the course of the research, TUM grants to us worldwide exclusive license rights under patents and patent applications claiming such inventions. TUM retains rights to practice these inventions for research and teaching purposes.

As a result of research efforts to date under the agreement, we hold a worldwide exclusive license under our license agreement with TUM to multiple patents and patent applications. In the United States, we hold an exclusive license to an issued U.S. patent No. 8,598,317 for the composition of matter of mutein of human tear lipocalin binding to the extracellular region of the T-cell co-receptor CD4 with detectable affinity, which patent will expire in 2027 (subject to a patent term adjustment period which is expected to be at least 742 days), as well as to its counterpart in the European Union. We also hold an exclusive license to an issued U.S. patent No. 8,420,051 directed to library of hNGAL scaffold of certain consensus sequence, which patent is expected to expire in 2029 (subject to a patent term adjustment period of 109 days), as well as to its counterparts in the European Union and in a number of foreign jurisdictions. Moreover, we hold an exclusive license to an issued U.S. patent No. 8,987,415 claiming isolated crystalline form of monomeric bacterial lipocalin. We bear the costs of filing, prosecution and maintenance of patents assigned or licensed to us under the agreement.

As consideration for the assignments and licenses, we are obliged to pay to TUM milestone payments on development of our proprietary products claimed by patents assigned or licensed to us by TUM. For each of such proprietary products developed by us, we could be required to pay up to an aggregate of €175,000 ($211,768) in milestone payments to TUM under the agreement.

We also are obliged to pay low single digit royalties, including annual minimum royalties, on sales of such products. Should we grant licenses or sublicenses to those patents to third parties, we are obliged to share a percentage of resulting revenue with TUM, which percentage of resulting revenue is creditable against our annual license payments to TUM. Our payment obligations are reduced by our proportionate contribution to a joint invention. Payment obligations terminate on expiration or annulment of the last patent covered by the agreement.

We can terminate the licenses to any or all licensed patents upon specified advance notice to TUM. TUM may terminate the license provisions of the agreement only for cause. Termination of the agreement does not terminate our rights in patents assigned to us.

Upon initiation of the Phase I clinical trial of PRS-080 in November 2014, our obligation to pay TUM a milestone payment of €10,000 ($12,101) pursuant to the terms of the TUM License Agreement was triggered. We have certain reporting obligations to TUM under the TUM License Agreement and reported this trigger to TUM pursuant to the terms of the agreement. Upon issuance of such a report, we are obligated to pay to TUM

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such milestone payment, which will be paid upon receipt of an invoice from TUM. As of June 17, 2015, we have not yet received an invoice for payment. We are also currently in a dispute with TUM, which is described in more detail under “—Legal Proceedings—Arbitration Proceeding with Technische Universität München.”

Government Regulation

Government Regulation and Product Approval

Government authorities in the U.S., at the federal, state and local level, and other countries extensively regulate, among other things, the research, development, testing, manufacture, quality control, approval, labeling, packaging, storage, record-keeping, promotion, advertising, distribution, marketing and export and import of products such as those we are developing. A new drug must be approved by the FDA through the new drug application, or NDA, process and a new biologic must be approved by the FDA through the biologics license application, or BLA, process before it may be legally marketed in the U.S. The animal and other non-clinical data and the results of human clinical trials performed under an Investigational New Drug application, or IND, and under similar foreign applications will become part of the NDA or BLA.

U.S. Drug Development Process

In the U.S., the FDA regulates drugs under the Federal Food, Drug, and Cosmetic Act, or FDCA, and in the case of biologics, also under the Public Health Service Act, or PHSA, and implementing regulations. The process of obtaining regulatory approvals and the subsequent compliance with appropriate federal, state, local, and foreign statutes and regulations require the expenditure of substantial time and financial resources. Failure to comply with the applicable U.S. requirements at any time during the product development process, approval process or after approval, may subject an applicant to administrative or judicial sanctions. These sanctions could include the FDA’s refusal to approve pending applications, withdrawal of an approval, a clinical hold, warning letters, requesting product recalls, product seizures, total or partial suspension of production or distribution, injunctions, fines, refusals of government contracts, restitution, disgorgement, or civil or criminal penalties. Any agency or judicial enforcement action could have a material adverse effect on us. The process required by the FDA before a drug or biologic may be marketed in the U.S. generally involves the following:

Once a pharmaceutical candidate is identified for development it enters the preclinical testing stage. Preclinical tests include laboratory evaluations of product chemistry, toxicity and formulation, as well as animal studies. An IND sponsor must submit the results of the preclinical tests, together with manufacturing information and analytical data, to the FDA as part of the IND. The sponsor will also include a protocol detailing, among other things, the objectives of the first phase of the clinical trial, the parameters to be used in monitoring safety, and the effectiveness criteria to be evaluated, if the first phase lends itself to an efficacy evaluation. Some preclinical testing may continue even after the IND is submitted. The IND automatically becomes effective 30 days after receipt by the FDA, unless the FDA, within the 30-day time period, places the clinical trial on a

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clinical hold. In such a case, the IND sponsor and the FDA must resolve any outstanding concerns before the clinical trial can begin. Clinical holds also may be imposed by the FDA at any time before or during studies due to safety concerns or non-compliance.

All clinical trials must be conducted under the supervision of one or more qualified investigators in accordance with good clinical practice regulations. They must be conducted under protocols detailing the objectives of the trial, dosing procedures, subject selection and exclusion criteria and the safety and effectiveness criteria to be evaluated. Each protocol must be submitted to the FDA as part of the IND, and progress reports detailing the results of the clinical trials must be submitted at least annually. In addition, timely safety reports must be submitted to the FDA and the investigators for serious and unexpected adverse events. An institutional review board, or IRB, at each institution participating in the clinical trial must review and approve each protocol before a clinical trial commences at that institution and must also approve the information regarding the trial and the consent form that must be provided to each trial subject or his or her legal representative, monitor the study until completed and otherwise comply with IRB regulations.

Human clinical trials are typically conducted in three sequential phases that may overlap or be combined:

The FDA or the sponsor may suspend a clinical trial at any time on various grounds, including a finding that the research subjects or patients are being exposed to an unacceptable health risk. Similarly, an IRB can suspend or terminate approval of a clinical trial at its institution if the clinical trial is not being conducted in accordance with the IRB’s requirements or if the drug has been associated with unexpected serious harm to patients. Phase I, Phase II, and Phase III testing may not be completed successfully within any specified period, if at all.

During the development of a new drug, sponsors are given opportunities to meet with the FDA at certain points. These points may be prior to submission of an IND, at the end of Phase II, and before an NDA or BLA is submitted. Meetings at other times may be requested. These meetings can provide an opportunity for the sponsor to share information about the data gathered to date, for the FDA to provide advice, and for the sponsor and FDA to reach agreement on the next phase of development. Sponsors typically use the End of Phase II meeting to discuss their Phase II clinical results and present their plans for the pivotal Phase III clinical trial that they believe will support approval of the new drug.

Concurrent with clinical trials, companies usually complete additional animal studies and must also develop additional information about the chemistry and physical characteristics of the drug and finalize a process for manufacturing the product in commercial quantities in accordance with cGMP requirements. The manufacturing process must be capable of consistently producing quality batches of the product candidate and, among other things, the manufacturer must develop methods for testing the identity, strength, quality and purity of the final drug. Additionally, appropriate packaging must be selected and tested and stability studies must be conducted to demonstrate that the product candidate does not undergo unacceptable deterioration over its shelf life.

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U.S. Review and Approval Processes

The results of product development, preclinical studies and clinical trials, along with descriptions of the manufacturing process, analytical tests conducted on the chemistry of the drug, proposed labeling, and other relevant information are submitted to the FDA as part of an NDA or BLA requesting approval to market the product. The submission of an NDA or BLA is subject to the payment of user fees; a waiver of such fees may be obtained under certain limited circumstances. The FDA reviews all NDAs and BLAs submitted to ensure that they are sufficiently complete for substantive review before it accepts them for filing. The FDA may request additional information rather than accept a NDA or BLA for filing. In this event, the NDA or BLA must be resubmitted with the additional information. The resubmitted application also is subject to review before the FDA accepts it for filing. Once the submission is accepted for filing, the FDA begins an in-depth substantive review. FDA may refer the NDA or BLA to an advisory committee for review, evaluation and recommendation as to whether the application should be approved and under what conditions. The FDA is not bound by the recommendation of an advisory committee, but it generally follows such recommendations. The approval process is lengthy and often difficult, and the FDA may refuse to approve an NDA or BLA if the applicable regulatory criteria are not satisfied or may require additional clinical or other data and information. Even if such data and information is submitted, the FDA may ultimately decide that the NDA or BLA does not satisfy the criteria for approval. Data obtained from clinical trials are not always conclusive and the FDA may interpret data differently than we interpret the same data. The FDA may issue a complete response letter, which may require additional clinical or other data or impose other conditions that must be met in order to secure final approval of the NDA or BLA, or an approval letter following satisfactory completion of all aspects of the review process. The FDA reviews an NDA to determine, among other things, whether a product is safe and effective for its intended use and whether its manufacturing is cGMP-compliant to assure and preserve the product’s identity, strength, quality and purity. The FDA reviews a BLA to determine, among other things whether the product is safe, pure and potent and the facility in which it is manufactured, processed, packed or held meets standards designed to assure the product’s continued safety, purity and potency. Before approving an NDA or BLA, the FDA will inspect the facility or facilities where the product is manufactured.

NDAs or BLAs receive either standard or priority review. A drug representing a significant improvement in treatment, prevention or diagnosis of disease may receive priority review. Priority review for an NDA for a new molecular entity and original BLAs will be 6 months from the date that the NDA or BLA is filed. In addition, products studied for their safety and effectiveness in treating serious or life-threatening illnesses and that provide meaningful therapeutic benefit over existing treatments may receive accelerated approval and may be approved on the basis of adequate and well-controlled clinical trials establishing that the drug product has an effect on a surrogate endpoint that is reasonably likely to predict clinical benefit or on the basis of an effect on a clinical endpoint that can be measured earlier than irreversible morbidity or mortality, or IMM, that is reasonably likely to predict an effect on IMM or other clinical benefit. As a condition of approval, the FDA may require that a sponsor of a drug receiving accelerated approval perform adequate and well-controlled post-marketing clinical trials. Priority review and accelerated approval do not change the standards for approval, but may expedite the approval process.

If a product receives regulatory approval, the approval may be significantly limited to specific diseases and dosages or the indications for use may otherwise be limited, which could restrict the commercial value of the product. In addition, the FDA may require a sponsor to conduct Phase IV testing which involves clinical trials designed to further assess a drug’s safety and effectiveness after NDA or BLA approval, and may require testing and surveillance programs to monitor the safety of approved products which have been commercialized.

The Food and Drug Administration Safety and Innovation Act, or FDASIA, which was enacted in 2012, made permanent the Pediatric Research Equity Act, or PREA, which requires a sponsor to conduct pediatric studies for most drugs and biologics, for a new active ingredient, new indication, new dosage form, new dosing regimen or new route of administration. Under PREA, original NDAs, BLAs and supplements thereto, must contain a pediatric assessment unless the sponsor has received a deferral or waiver. The required assessment must assess the safety and effectiveness of the product for the claimed indications in all relevant pediatric

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subpopulations and support dosing and administration for each pediatric subpopulation for which the product is safe and effective. The sponsor or FDA may request a deferral of pediatric studies for some or all of the pediatric subpopulations. A deferral may be granted for several reasons, including a finding that the drug or biologic is ready for approval for use in adults before pediatric studies are complete or that additional safety or effectiveness data needs to be collected before the pediatric studies begin. After April 2013, the FDA must send a non-compliance letter to any sponsor that fails to submit the required assessment, keep a deferral current or fails to submit a request for approval of a pediatric formulation.

Patent Term Restoration and Marketing Exclusivity

Depending upon the timing, duration and specifics of FDA approval of our drugs, some of our U.S. patents may be eligible for limited patent term extension under the Drug Price Competition and Patent Term Restoration Act of 1984, referred to as the Hatch-Waxman Amendments. The Hatch-Waxman Amendments permit a patent restoration term of up to five years as compensation for patent term lost during product development and the FDA regulatory review process. However, patent term restoration cannot extend the remaining term of a patent beyond a total of 14 years from the product’s approval date. The patent term restoration period is generally one- half the time between the effective date of an IND, and the submission date of an NDA or BLA, plus the time between the submission date of an NDA or BLA and the approval of that application, except that the period is reduced by any time during which the applicant failed to exercise due diligence. Only one patent applicable to an approved drug is eligible for the extension, and the extension must be applied for prior to expiration of the patent. The United States Patent and Trademark Office, in consultation with the FDA, reviews and approves the application for any patent term extension or restoration.

Pediatric exclusivity is another type of marketing exclusivity available in the U.S. The FDASIA made permanent the Best Pharmaceuticals for Children Act, or BPCA, which provides for an additional six months of marketing exclusivity if a sponsor conducts clinical trials in children in response to a written request from the FDA, or a Written Request. If the Written Request does not include studies in neonates, the FDA is required to include its rationale for not requesting those studies. The FDA may request studies on approved or unapproved indications in separate Written Requests. The issuance of a Written Request does not require the sponsor to undertake the described studies.

Biologics Price Competition and Innovation Act of 2009

On March 23, 2010, President Obama signed into law the Patient Protection and Affordable Care Act which included the Biologics Price Competition and Innovation Act of 2009, or BPCIA. The BPCIA amended the PHSA to create an abbreviated approval pathway for two types of “generic” biologics—biosimilars and interchangeable biologic products, and provides for a twelve-year exclusivity period for the first approved biological product, or reference product, against which a biosimilar or interchangeable application is evaluated; however if pediatric studies are performed and accepted by the FDA, the twelve-year exclusivity period will be extended for an additional six months A biosimilar product is defined as one that is highly similar to a reference product notwithstanding minor differences in clinically inactive components and for which there are no clinically meaningful differences between the biological product and the reference product in terms of the safety, purity and potency of the product. An interchangeable product is a biosimilar product that may be substituted for the reference product without the intervention of the health care provider who prescribed the reference product.

The biosimilar applicant must demonstrate that the product is biosimilar based on data from (1) analytical studies showing that the biosimilar product is highly similar to the reference product; (2) animal studies (including toxicity); and (3) one or more clinical studies to demonstrate safety, purity and potency in one or more appropriate conditions of use for which the reference product is approved. In addition, the applicant must show that the biosimilar and reference products have the same mechanism of action for the conditions of use on the label, route of administration, dosage and strength, and the production facility must meet standards designed to assure product safety, purity and potency.

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An application for a biosimilar product may not be submitted until four years after the date on which the reference product was first approved. The first approved interchangeable biologic product will be granted an exclusivity period of up to one year after it is first commercially marketed, but the exclusivity period may be shortened under certain circumstances.

The FDA has issued a number of final and draft guidances in order to implement the law. On April 28, 2015, the FDA issued the following three final guidances: “Scientific Considerations in Demonstrating Biosimilarity to a Reference Product,” “Quality Considerations in Demonstrating Biosimilarity of a Therapeutic Protein Product to a Reference Product,” and “Biosimilars: Questions and Answers Regarding Implimentation of the Biologics Price Competition and Innovation Act of 2009 Guidance for Industry.” The draft guidances include “Formal Meetings between the FDA and Biosimilar Biological Product Sponsors or Applicants” issued March 29, 2013, “Clinical Pharmacology Data to Support a Demonstration of Biosimilarity to a Reference Product” issued May 13, 2014, “Reference Product Exclusivity for Biological Products Filed Under Section 351(a) of the PHS Act” issued August 4, 2014, and “Biosimilars: Additional Questions and Answers Regarding Implementation of the Price Competition and Innovation Act of 2009,” issued May 12, 2015. The guidance documents provide FDA’s current thinking on approaches to demonstrating that a proposed biological product is biosimilar to a reference product. The FDA intends to issue additional guidance documents in the future. Nevertheless, the absence of final guidance documents covering all biosimilars issues does not prevent a sponsor for seeking licensure of a biosimilar under the BPCIA, and the FDA recently approved the first biosimilar application in the United States.

Orphan Drug Designation

Under the Orphan Drug Act, the FDA may grant orphan drug designation to a drug intended to treat a rare disease or condition, which is generally a disease or condition that affects fewer than 200,000 individuals in the U.S., or more than 200,000 individuals in the U.S. and for which there is no reasonable expectation that the cost of developing and making available in the U.S. a drug for this type of disease or condition will be recovered from sales in the U.S. for that drug. Orphan drug designation must be requested before submitting an NDA or BLA. After the FDA grants orphan drug designation, the identity of the therapeutic agent and its potential orphan use are disclosed publicly by the FDA. Orphan drug designation does not convey any advantage in or shorten the duration of the regulatory review and approval process. If a product that has orphan drug designation subsequently receives the first FDA approval for the disease for which it has such designation, the product is entitled to orphan product exclusivity, which means that the FDA may not approve any other applications to market the same drug for the same indication, except in very limited circumstances, for seven years. Orphan drug exclusivity, however, also could block the approval of one of our products for seven years if a competitor obtains approval of the same drug as defined by the FDA or if our product candidate is determined to be contained within the competitor’s product for the same indication or disease.

The FDA also administers a clinical research grants program, whereby researchers may compete for funding to conduct clinical trials to support the approval of drugs, biologics, medical devices, and medical foods for rare diseases and conditions. A product does not have to be designated as an orphan drug to be eligible for the grant program. An application for an orphan grant should propose one discrete clinical study to facilitate FDA approval of the product for a rare disease or condition. The study may address an unapproved new product or an unapproved new use for a product already on the market.

Fast Track Designation and Accelerated Approval

FDA is required to facilitate the development, and expedite the review, of drugs that are intended for the treatment of a serious or life-threatening disease or condition for which there is no effective treatment and which demonstrate the potential to address unmet medical needs for the condition. Under the fast track program, the sponsor of a new drug candidate may request that FDA designate the drug candidate for a specific indication as a fast track drug concurrent with, or after, the filing of the IND for the drug candidate. FDA must

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determine if the drug candidate qualifies for fast track designation within 60 days of receipt of the sponsor’s request.

Under the fast track program, FDA may designate a drug for fast-track status if it is intended to treat a serious or life-threatening illness and nonclinical or clinical data demonstrate the potential to address an unmet medical need. Similarly, the agency may designate a drug for accelerated approval if it treats a serious condition and generally provides meaningful therapeutic benefit to patients over existing treatments based upon a surrogate endpoint that is reasonably likely to predict clinical benefit, or on a clinical endpoint that can be measured earlier than irreversible morbidity or mortality, that is reasonably likely to predict an effect on irreversible morbidity or mortality or other clinical benefit, taking into account the severity, rarity, or prevalence of the condition and the availability or lack of alternative treatments.

In clinical trials, a surrogate endpoint is a measurement of laboratory or clinical signs of a disease or condition that substitutes for a direct measurement of how a patient feels, functions, or survives. Surrogate endpoints can often be measured more easily or more rapidly than clinical endpoints. A drug candidate approved on this basis is subject to rigorous post-marketing compliance requirements, including the completion of Phase 4 or post- approval clinical trials to confirm the effect on the clinical endpoint. Failure to conduct required post-approval studies, or confirm a clinical benefit during post-marketing studies, will allow FDA to withdraw the drug from the market on an expedited basis. All promotional materials for drug candidates approved under accelerated regulations are subject to prior review by FDA.

In addition to other benefits such as the ability to use surrogate endpoints and engage in more frequent interactions with FDA, FDA may initiate review of sections of a fast track drug’s BLA before the application is complete. This rolling review is available if the applicant provides, and FDA approves, a schedule for the submission of the remaining information and the applicant pays applicable user fees. However, FDA’s time period goal for reviewing an application does not begin until the last section of the BLA is submitted. Additionally, the fast track designation may be withdrawn by FDA if FDA believes that the designation is no longer supported by data emerging in the clinical trial process.

In FDASIA, Congress encouraged the FDA to utilize innovative and flexible approaches to the assessment of products under accelerated approval. The law required the FDA to issue related draft guidance within a year after the law’s enactment and also promulgate confirming regulatory changes. In May 2014, the FDA published a Guidance for Industry entitled, “Expedited Programs for Serious Conditions-Drugs and Biologics” which provides guidance on FDA programs that are intended to facilitate and expedite development and review of new drugs as well as threshold criteria generally applicable to concluding that a drug is a candidate for these expedited development and review programs. In addition to the Fast Track, accelerated approval and priority review programs discussed above, the FDA also provided guidance on a new program for Breakthrough Therapy designation. A request for Breakthrough Therapy designation should be submitted concurrently with, or as an amendment to an IND. FDA has already granted this designation to over 30 new drugs and has approved several.

Post-Approval Requirements

Once an approval is granted, the FDA may withdraw the approval if compliance with regulatory standards is not maintained or if problems occur after the product reaches the market. Later discovery of previously unknown problems with a product may result in restrictions on the product or even complete withdrawal of the product from the market. After approval, some types of changes to the approved product, such as adding new indications, manufacturing changes and additional labeling claims, are subject to further FDA review and approval. Drug manufacturers and other entities involved in the manufacture and distribution of approved drugs are required to register their establishments with the FDA and certain state agencies, and are subject to periodic unannounced inspections by the FDA and certain state agencies for compliance with cGMP and other laws and regulations. We rely, and expect to continue to rely, on third parties for the production of clinical and commercial quantities of our products. Future inspections by the FDA and other regulatory agencies may

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identify compliance issues at the facilities of our contract manufacturers that may disrupt production or distribution, or require substantial resources to correct.

Any drug products manufactured or distributed by us pursuant to FDA approvals are subject to continuing regulation by the FDA, including, among other things, record-keeping requirements, reporting of adverse experiences with the drug, providing the FDA with updated safety and efficacy information, drug sampling and distribution requirements, complying with certain electronic records and signature requirements, and complying with FDA promotion and advertising requirements. FDA strictly regulates labeling, advertising, promotion and other types of information on products that are placed on the market. Drugs may be promoted only for the approved indications and in accordance with the provisions of the approved label.

From time to time, legislation is drafted, introduced and passed in Congress that could significantly change the statutory provisions governing the approval, manufacturing and marketing of products regulated by the FDA. It is impossible to predict whether further legislative changes will be enacted, or FDA regulations, guidance or interpretations changed or what the impact of such changes, if any, may be.

Foreign Regulation

In addition to regulations in the United States, we will be subject to a variety of foreign regulations governing clinical trials and commercial sales and distribution of our products. Whether or not we obtain FDA approval for a product, we must obtain approval by the comparable regulatory authorities of foreign countries or economic areas, such as the 28-member European Union, before we may commence clinical trials or market products in those countries or areas. The approval process and requirements governing the conduct of clinical trials, product licensing, pricing and reimbursement vary greatly from place to place, and the time may be longer or shorter than that required for FDA approval.

Under European Union regulatory systems, a company may submit marketing authorization applications either under a centralized or decentralized procedure. The centralized procedure, which is compulsory for medicinal products produced by biotechnology or those medicinal products containing new active substances for specific indications such as the treatment of AIDS, cancer, neurodegenerative disorders, diabetes, viral diseases and designated orphan medicines, and optional for other medicines which are highly innovative. Under the centralized procedure, a marketing application is submitted to the European Medicines Agency where it will be evaluated by the Committee for Medicinal Products for Human Use and a favorable opinion typically results in the grant by the European Commission of a single marketing authorization that is valid for all European Union member states within 67 days of receipt of the opinion. The initial marketing authorization is valid for five years, but once renewed is usually valid for an unlimited period. The decentralized procedure provides for approval by one or more “concerned” member states based on an assessment of an application performed by one member state, known as the “reference” member state. Under the decentralized approval procedure, an applicant submits an application, or dossier, and related materials to the reference member state and concerned member states. The reference member state prepares a draft assessment and drafts of the related materials within 120 days after receipt of a valid application. Within 90 days of receiving the reference member state’s assessment report, each concerned member state must decide whether to approve the assessment report and related materials. If a member state does not recognize the marketing authorization, the disputed points are eventually referred to the European Commission, whose decision is binding on all member states.

When conducting clinical trials in the EU, we must adhere to the provisions of the EU Clinical Trials Directive and the laws and regulations of the EU Member States implementing them. These provisions require, among other things, that the prior authorization of an Ethics Committee and the submission and approval of a clinical trial authorization application be obtained in each Member State be obtained before commencing a clinical trial in that Member State.

As in the United States, it may be possible in foreign countries to obtain a period of market and/or data exclusivity that would have the effect of postponing the entry into the marketplace of a competitor’s generic

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product. For example, in the EU, if any of our products receive marketing approval in the European Economic Area, or EEA which is comprised of the 28 member states of the EU plus Norway, Iceland and Liechtenstein, we expect they will benefit from 8 years of data exclusivity and an additional 2 years of marketing exclusivity. An additional one-year extension of marketing exclusivity is possible if during the data exclusivity period, we obtain an authorization for one or more new therapeutic indications that is deemed to bring a significant clinical benefit compared to existing therapies. The data exclusivity period begins on the date of the product’s first marketing authorization in the EU and prevents biosimilars from relying on the holder of the marketing authorization for the reference biological medicine’s pharmacological, toxicological and clinical data for a period of 8 years. After 8 years, a biosimilar product application may be submitted and the sponsoring companies may rely on the marketing authorization holder’s data. However, a biosimilar medicine cannot launch until 2 years later (or a total of 10 years after the first marketing authorization in the EU of the innovator product), or 3 years later (or a total of 11 years after the first marketing authorization in the EU of the innovator product) if the marketing authorization holder obtains marketing authorization for a new indication with significant clinical benefit within the 8 year data exclusivity period.

As in the United States, a sponsor may apply for designation of a product as an orphan drug for the treatment of a specific indication in the EU before the application for marketing authorization is made. Orphan drugs in Europe enjoy economic and marketing benefits, including up to 10 years of market exclusivity for the approved indication unless another applicant can show that its product is safer, more effective or otherwise clinically superior to the orphan-designated product.

Reimbursement

Sales of pharmaceutical products depend in significant part on the availability of third-party reimbursement. Third-party payors include government healthcare programs, managed care providers, private health insurers and other organizations. These third-party payors are increasingly challenging the price and examining the cost- effectiveness of medical products and services. In addition, significant uncertainty exists as to the reimbursement status of newly approved healthcare products. We may need to conduct expensive pharmacoeconomic studies in order to demonstrate the cost-effectiveness of our products. Our drug candidates may not be considered cost-effective. It is time consuming and expensive to seek reimbursement from third-party payors. Reimbursement may not be available or sufficient to allow us to sell our products on a competitive and profitable basis.

In addition, in some foreign countries, the proposed pricing for a drug must be approved before it may be lawfully marketed. The requirements governing drug pricing vary widely from country to country. For example, the European Union provides options for its member states to restrict the range of medicinal products for which their national health insurance systems provide reimbursement and to control the prices of medicinal products for human use. A member state may approve a specific price for the medicinal product or it may instead adopt a system of direct or indirect controls on the profitability of the company placing the medicinal product on the market. There can be no assurance that any country that has price controls or reimbursement limitations for pharmaceutical products will allow favorable reimbursement and pricing arrangements for any of our products. Historically, products launched in the European Union do not follow price structures of the United States and generally tend to by significantly lower.

Employees

As of June 17, 2015, we have 29 full-time employees and five part-time employees, including 10 employees with Ph.D. degrees. Of these 34 employees, 28 are engaged in research and development activities and six work in general support and administration. None of our employees is represented by a labor union or covered by a collective bargaining agreement. We consider our relationship with our employees to be good. To successfully develop our drug candidates, we must be able to attract and retain highly skilled personnel. We anticipate hiring additional employees for research and development, clinical and regulatory affairs and general and administrative activities over the next few years. We also utilize the services of consultants, clinical research organizations and other third parties on a regular basis.

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Legal Proceedings

Arbitration Proceeding with Technische Universität München

On March 20, 2014, Pieris Operating instituted arbitration proceedings, or the TUM Arbitration, against Technische Universität München, or Munich Technical University and hereafter TUM, to address issues regarding the calculation of payments due from Pieris Operating to TUM under Pieris Operating’s Research and Licensing Agreement with TUM, as amended, or the TUM License Agreement. Pursuant to the terms of the TUM License Agreement, the arbitration is proceeding in Munich, Germany and governed by German law, in accordance with the arbitration rules of the Deutsche Institution für Schiedsgerichtsbarkeit.

On July 4, 2003, or the Effective Date, Pieris Operating and TUM entered into the TUM License Agreement, as superseded and replaced on July 26, 2007, under which TUM has exclusively licensed, or in some cases assigned, to Pieris Operating certain intellectual property and know-how that has become part of the Anticalin^® proprietary technologies. In return, Pieris Operating agreed to pay to TUM certain undisclosed annual license fees, milestones and royalties for its own proprietary drug development and sales, as well as an undisclosed variable fee as a function of out-licensing revenues, or the Out-License Fee, where such Out-License Fees are creditable against annual license payments to TUM.

As required by the TUM License Agreement, Pieris Operating provided to TUM its calculation of the Out- License Fee owed by Pieris Operating to TUM for the period beginning on the Effective Date and ending on December 31, 2012, the Dispute Period, in the amount of $0.4 million excluding value-added tax. TUM has asserted that, under the TUM License Agreement, the Out-License Fee due to TUM for the Dispute Period amounts to $3.4 million excluding value-added tax in the aggregate and has threatened to terminate the TUM License Agreement if the Out-License Fee is not paid. We believe that if TUM sought to terminate the license agreement for cause as a result of this dispute, it would potentially face wrongful termination claims for substantial damages if the arbitral tribunal in the TUM Arbitration sides with Pieris in its final decision regarding the proper amount of the Out-License Fee, but we can provide no assurance regarding the timing, nature or consequences of such decision. Pieris Operating instituted the TUM Arbitration to request the arbitration tribunal to hold that Pieris Operating’s calculation of the payments owed to TUM is accurate and shall govern all current and future payments due in respect of the Out-License Fee under the TUM License Agreement. Pieris Operating has reserved a liability on its balance sheet in respect of such payment in the amount of €271,000 ($327,937). An adverse ruling in the TUM Arbitration could have a material adverse effect on Pieris Operating’s results of operations and financial condition.

In April 2014, TUM argued to the arbitrators that it is not the proper party to be sued under the action for a declaratory arbitration decision brought by Pieris Operating in relation to the Research and Licensing Agreement, and that instead, it is the Free State of Bavaria that is the proper respondent to the action. Pieris Operating has responded that TUM has capacity to be sued in relation to any disputes arising from and regarding contractual provisions of the Research and Licensing Agreement and is thus also the proper respondent in the action. In accordance with the arbitration rules of the Deutsche Institution für Schiedsgerichtsbarkeit, each party to the arbitration proceeding has appointed one arbitrator and the party-named arbitrators collectively selected the third arbitrator as the chairman of the arbitration panel.

On December 1, 2014, TUM filed its statement of defense, maintaining its earlier calculation of the Out-License Fee. On December 23, 2014, TUM filed a counterclaim in the amount of €2.5 million ($3.1 million) to suspend the statute of limitations on its claims. On January 12, 2015, Pieris Operating filed a reply brief in response to TUM’s defense.

The arbitration panel held its first hearing in Munich, Germany on January 20, 2015, however the arbitration panel did not come to a conclusion on whether TUM is the proper respondent in the action or on the merits of the case. The panel had previously indicated that it will first decide the issue of whether TUM is the proper respondent in this action. The panel resolved that the value in dispute for both parties’ claims and counterclaims

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would be fixed at €3.5 million ($4.2 million), as the calculation of the outstanding Out-Licensing Fee also impacts future payments. On March 3, 2015, Pieris Operating submitted a reply brief responding to TUM’s statement of defense and counterclaim. On March 31, 2015, TUM submitted a rebuttal brief. The panel requested that both Pieris Operating and TUM indicate to the panel by April 27, 2015 whether proceedings should be stayed as a result of settlement negotiations. On April 27, 2015, Pieris Operating submitted a reply brief requesting proceedings to continue without disruption and moving for leave to comment on TUM’s latest submission. Following an approved extension by the panel for TUM’s submission, TUM submitted its proposal on May 4, 2015, requesting that the panel conduct a mediation hearing and assist the parties in negotiating a settlement. On May 8, 2015, the arbitration tribunal set June 1, 2015 as the deadline for final briefs and offered to schedule another oral hearing in mid-June for the purpose of supporting further settlement negotiations if both parties are in favor of holding a hearing. Pieris Operating submitted its final brief on June 1, 2015 and TUM refrained from submitting an additional brief. On June 8, 2015, the arbitration tribunal issued a procedural order indicating they will proceed with the arbitration without another oral hearing.

As of the date of this prospectus, other than the arbitration proceeding against TUM, we are not currently involved in any material legal proceedings. However, from time to time, we could be subject to various legal proceedings and claims that arise in the ordinary course of our business activities. Regardless of the outcome, legal proceedings can have an adverse impact on us because of defense and settlement costs, diversion of management resources and other factors.

Properties

We rent approximately 1,414 square meters of office and laboratory space in Freising, Germany under a lease that provides for a monthly rent payment of €18,200 ($22,024), or €218,400 ($264,286) annually. This lease may be terminated by either party subject to an 8-month notice period, provided, however, that such period must finish at the end of a quarter and, if not, the notice period will be extended to the following quarter-end. We believe that our facilities are sufficient to meet our current needs and we will look for suitable additional space as and when needed.

Available Information

Historically, we have filed periodic reports under the Securities Exchange Act of 1934, as amended, and file annual, quarterly and current reports and other information with the SEC. You may read and copy these reports and other information at the public reference facilities of the SEC at 100 F Street, NE., Washington, DC 20549, on official business days during the hours of 10 a.m. to 3 p.m. You may also obtain information on the operation of the Public Reference Room by calling the Commission at 1-800-SEC-0330. The Commission maintains an Internet site that contains reports, proxy and information statements, and other information regarding issuers that file electronically with the Commission at http://www.sec.gov.

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MANAGEMENT

Directors, Executive Officers and Other Non-Executive Officers

The table below sets forth information about our directors and executive officers:

Business Experience

The following is a brief account of the education and business experience of our current directors and executive officers:

Stephen S. Yoder. Stephen S. Yoder joined Pieris Operating as Chief Executive Officer in January 2010. Upon the effectiveness of the Acquisition, he joined the Board of Directors of Pieris and was appointed as Chief Executive Officer and President. Prior to joining Pieris Operating, from July 2003 to December 2010 he led the intellectual property and legal departments at MorphoSys AG, a biotechnology company involved in the development and research of antibodies, as General Counsel. Prior to MorphoSys AG, from September 1999 to June 2003 he worked in several Washington, D.C. law firms, specializing in a life sciences intellectual property practice. Mr. Yoder holds degrees in molecular biology and Spanish from Grove City College and a Juris Doctorate, with honors, from The George Washington University Law School. As an attorney, he is licensed to practice before the United States Patent and Trademark Office, and in the jurisdictions of Maryland and Washington, D.C. We believe that Mr. Yoder adds value to our Board of Directors based on his intimate knowledge of our business plans and strategies of our business and his years of experience in the biotechnology and life sciences industry.

Darlene Deptula-Hicks. Darlene Deptula-Hicks is our Acting Chief Financial Officer. Ms. Deptula-Hicks was engaged as a financial consultant to Pieris Operating on November 19, 2014, providing financial services relating to the Acquisition pursuant to a consulting agreement with the financial advisory firm of Danforth Advisors, LLC, or Danforth. Upon the effectiveness of the Acquisition, she was appointed as Acting Chief Financial Officer, Secretary and Treasurer of Pieris and she will continue to provide her services through Danforth. Prior to that time and since June 2012, Ms. Deptula-Hicks served as the Executive Vice President and Chief Financial Officer of Microline Surgical, Inc., a surgical instruments and medical devices company. From 2006 to May 2011 Ms. Deptula-Hicks served as Executive Vice President and Chief Financial Officer of iCAD, Inc., a publicly traded medical device company. From 2002 to 2006 Ms. Deptula-Hicks served as Executive Vice President and Chief Financial Officer of ONI Medical Systems, Inc., a venture capital-backed designer and manufacturer of high-field diagnostic imaging systems for orthopedic applications, and from 1998

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to 2001 Ms. Deptula-Hicks was Executive Vice President and Chief Financial Officer of Implant Sciences Corporation, an early stage medical device company that had its initial public offering in June of 1999. Prior to 1998, Ms. Deptula-Hicks also held various senior financial and accounting positions at Abiomed, Inc., GCA Corporation, Edwards High Vacuum International and Puritan Bennett Corporation. Ms. Deptula-Hicks also serves on the Board of Directors and as Chair of the Audit Committee of Xenetic Biosciences, Inc. and between 2006 and October 2014 served on the Board of Directors of IMCOR Pharmaceutical Company, Technest Holdings, Inc., and USfalcon. Ms. Deptula-Hicks received her B.S. in accounting from Southern NH University and her MBA from Rivier College.

Chau Khuong. Mr. Khuong joined the Board of Directors of Pieris effective upon the closing of the Acquisition and has served on the supervisory board of Pieris Operating since May 2014. Mr. Khuong has worked at OrbiMed Advisors LLC since 2003 and is currently a Private Equity Partner. Mr. Khuong gained experience in start-up operations and business development at Veritas Medicine, Inc. and in basic science research at the Yale School of Medicine and at Massachusetts General Hospital. He currently serves as a director of several public and private companies, including Aerpio Therapeutics, Inc., Inspire Medical Systems, Nabriva Therapeutics, AG, Otonomy, Inc., Rempex Pharmaceuticals and Cerapedics Inc. Mr. Khuong holds a B.S. in molecular, cellular and developmental biology with concentration in biotechnology and an MPH with concentration in infectious diseases, both from Yale University. We believe that Mr. Khuong adds value to our Board of Directors due to his experience as an investor, particularly with respect to healthcare companies, and his broad life sciences industry knowledge. He also has extensive experience overseeing the operations and research and development of biotechnology companies.

Christina Takke, Ph.D. Dr. Takke joined the Board of Directors of Pieris effective upon the closing of the Acquisition and has served on the supervisory board of Pieris Operating since 2005. On April 7, 2015, the Company decided not to nominate Dr. Christina Takke for re-election at the 2015 Annual Meeting. Dr. Takke will no longer serve as a member of the Board of Directors effective on June 30, 2015. Until June 1, 2015, Dr. Takke served as a Partner at Forbion Capital Partners in the Netherlands, where she served in such capacity since 2010, and previously worked as a Partner at ABN AMRO Capital Life Sciences from September 2000 to January 2007. At Forbion, Dr. Takke was responsible for scouting and the analysis of new investment opportunities as well as general deal execution, in particular the financing of several Forbion portfolio companies including arGEN-X. Prior to that time, Dr. Takke served as a consultant at Bio-Gen-Tec-NRW, a regional development organization for the biotechnology industry. Dr. Takke currently serves on the supervisory board of arGEN-X N.V., Amakem N.V. and Ophtakem N.V. Dr. Takke also previously served on the supervisory board of Bioceros B.V. and Simibio B.V. and as a board observer of GlycArt, which was sold to Roche in 2005. Dr. Takke received her Ph.D. in developmental biology from the Institute of Development Biology at the University of Cologne and a master’s degree in molecular biology and biochemistry from the Technical University of Darmstadt. We believe that Dr. Takke adds value to our Board of Directors based on her intimate knowledge of our business plans and strategies of our business, her years of experience in the biotechnology and life sciences industry, and her experience with financing and other aspects of company-building for enterprises in our industry.

Michael Richman. Mr. Richman joined the Board of Directors of Pieris effective upon the closing of the Acquisition and has served on the supervisory board of Pieris Operating since October 2014. He is the President and Chief Executive Officer of Amplimmune, Inc., a privately held biologics company focused on cancer and autoimmune diseases which was acquired by Astra Zeneca in 2013, and has held this position since July 2008. From May 2007 through June 2008, he served as President and Chief Operating Officer of Amplimmune, Inc. Prior to such time, Mr. Richman has gained years of experience working in research, intellectual property and business development capacities in companies such as Chiron Corporation (now Novartis), MedImmune, Inc. (now Astra Zeneca) and MacroGenics. He is a member of the board of directors of GenVec, Inc., a public company, Opexa Therapeutics, Inc., a public company, Madison Vaccines, Inc., a private company, and was previously director of Cougar Biotechnology until its acquisition by Johnson & Johnson. Mr. Richman obtained his B.S. in genetics/molecular biology at the University of California at Davis and his M.S.B.A. in international

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business at San Francisco State University. We believe that Mr. Richman adds value to our Board of Directors due to his extensive experience in mergers and acquisitions, business development and strategic planning for life science companies, as well as executive leadership and management experience.

Steven Prelack. Mr. Prelack joined the Board of Directors of Pieris effective upon the closing of the Acquisition. Mr. Prelack is the Senior Vice President and Chief Operating Officer of VetCor, which owns and operates veterinary hospitals across the United States, and has served in this position since June 2012. Prior to that time and since May 2010, Mr. Prelack served at VetCor as Senior Vice President of Operations and as Chief Financial Officer. From 2001 until May 2010, he was the Senior Vice President, Chief Financial Officer and Treasurer of VelQuest Corporation, a provider of automated compliance software solutions for the pharmaceutical industry. He is currently a director and audit committee chair of Galectin Therapeutics, Inc., a publicly traded clinical-stage biotechnology company engaged in drug research and development to create new therapies for fibrotic disease and cancer. Mr. Prelack also previously served as director and audit committee chair for BioVex Group, Inc., a clinical-stage biotechnology company focused on the development and future commercialization of targeted treatments for cancer and the prevention of infectious disease, which was sold to Amgen in 2011, and as a director of VelQuest Corporation, OPCAT, Inc. and Foodsafe Solutions, Inc. Mr. Prelack is a Certified Public Accountant, received a B.B.A. degree from the University of Massachusetts at Amherst in 1979 and is a member of the National Association of Corporate Directors. We believe that Mr. Prelack adds value to our Board of Directors due to his extensive executive leadership experience, director experience within the biotechnology sector and his many years serving in senior financial and operational management roles.

Jean-Pierre Bizzari, M.D. Dr. Bizzari joined the Board of Directors of Pieris on May 12, 2015. Dr. Bizzari served as Executive Vice-President, Group Head, Clinical Oncology Development at Celgene Corporation, a role he held from October 2008 until his retirement. In this position, Dr. Bizzari was responsible for Celgene’s clinical development and operations-statistics teams across the U.S., Europe and Asia/Japan, and has overseen the development and approval of a number of leading oncology products including REVLIMID^® (lenalidomide), VIDAZA^® (azacitidine), ISTODAX^® (romidepsin) and ABRAXANE^® (nab-paclitaxel). In addition, he was Chairman of Celgene’s hematology oncology development committee and a member of the company’s management committee. Prior to his role at Celgene and from 2004 to 2008, Dr. Bizzari was the Vice President, Clinical Oncology Development for Sanofi-Aventis where he oversaw the approval of Eloxatin^® (oxaliplatin), Taxotere^® (docetaxel) and Elitek^® (rasburicase). From 2002 to 2004, he was Vice President, Clinical Development Oncology for Sanofi-Synthelabo and from 1993 to 2002 served in the same role for Rhône-Poulenc Rorer (Aventis). Dr. Bizzari is a member of the Scientific Advisory Board of France’s National Cancer Institute and Netrix Pharma, is currently a member of the board of directors of Halozyme Therapeutics, Inc., Celator Pharmaceuticals, Inc., and Transgene SA, and previously served as a board member of Synapse Technology and Oncalis AG. Dr. Bizzari received his medical degree from the University of Nice (France) and is an oncologist, having trained at La Pitié-Salpêtrière hospital in Paris, followed by training at the Ontario Cancer Institute and McGill Cancer Center. We believe that Dr. Bizzari adds value to our Board of Directors based on his considerable experience in the pharmaceutical industry and his insight on clinical, regulatory and commercial aspects of drug development, particularly in oncology and global drug approval strategy.

Term of Office of Directors

We currently have authorized six directors. In accordance with our Amended and Restated Articles of Incorporation and Amended and Restated Bylaws, our board of directors is divided into three classes with staggered three-year terms. At each annual meeting of stockholders commencing with the meeting in 2015, the successors to the directors whose terms then expire will be elected to serve until the third annual meeting following the election. Our directors are divided among the three classes as follows:

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Any additional directorships resulting from an increase in the number of directors will be distributed among the three classes so that each class will consist of approximately one-third of the directors.

Family Relationships

There are no family relationships among any of our current or former directors or executive officers.

Involvement in Certain Legal Proceedings

None of our directors, executive officers, significant employees, promoters or control persons has been involved in any legal proceeding in the past 10 years that would require disclosure under Item 401(f) of Regulation S-K promulgated under the Securities Act.

Nominations to the Board of Directors

Director candidates are considered based upon various criteria, including without limitation their broad-based business and professional skills and experiences, expertise in or knowledge of the life sciences industry and ability to add perspectives relating to that industry, concern for the long-term interests of our stockholders, diversity, and personal integrity and judgment. Our Board of Directors has a critical role in guiding our strategic direction and overseeing the strategy of our business, and accordingly, we seek to attract and retain highly qualified directors who have sufficient time to engage in the activities of our Board of Directors and to understand and enhance their knowledge of our industry and business plans.

Committees of the Board of Directors

Our board has established three standing committees—audit, compensation, and nominating and corporate governance—each of which operates under a charter that has been approved by our board.

Our board has determined that all of the members of each of the board’s three standing committees are independent as defined under the rules of the NASDAQ Capital Market. In addition, all members of the audit committee meet the independence requirements contemplated by Rule 10A-3 under the Exchange Act.

Audit Committee

The audit committee’s main function is to oversee our accounting and financial reporting processes and the audits of our financial statements. This committee’s responsibilities include, among other things:

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The members of our audit committee are Steven Prelack, Chau Khuong, Dr. Christina Takke and Dr. Jean-Pierre Bizzari. Steven Prelack serves as the chairperson of the committee. All members of our audit committee meet the requirements for financial literacy under the applicable rules and regulations of the SEC and the NASDAQ Capital Market. Our board of directors has determined that Steven Prelack is an “audit committee financial expert” as defined by applicable SEC rules and has the requisite financial sophistication as defined under the applicable NASDAQ rules and regulations.

Compensation Committee

Our compensation committee reviews and approves policies relating to compensation of our directors, officers and employees. The compensation committee reviews and approves corporate goals and objectives relevant to the compensation of our Chief Executive Officer and other executive officers, evaluates the performance of these officers in light of those goals and objectives and approves the compensation of these officers based on such evaluations. The compensation committee also reviews and approves the issuance of stock options and other awards under our equity plan. The compensation committee will review and evaluate, at least annually, the performance of the compensation committee and its members, including compliance by the compensation committee with its charter.

The members of our compensation committee are Michael Richman and Chau Khuong. Michael Richman serves as the chairperson of the committee.

Nominating and Corporate Governance Committee

The nominating and corporate governance committee is responsible for assisting our board of directors in discharging the board’s responsibilities regarding the identification of qualified candidates to become board members, the selection of nominees for election as directors at our annual meetings of stockholders (or special meetings of stockholders at which directors are to be elected), and the selection of candidates to fill any vacancies on our board of directors and any committees thereof. In addition, the nominating and corporate governance committee is responsible for overseeing our corporate governance policies, reporting and making recommendations to our board of directors concerning governance matters and oversight of the evaluation of our board of directors.

The members of our nominating and corporate governance committee are Dr. Christina Takke, Mr. Chau Khuong, Michael Richman and Dr. Jean-Pierre Bizzari. Dr. Christina Takke serves as the chairperson of the committee.

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EXECUTIVE COMPENSATION

The following table summarizes the compensation earned in each of our fiscal years ended December 31, 2014 and 2013 by our named executive officers, which consisted solely of our principal executive officer as our other executive officer, Darlene Deptula-Hicks, did not earn more than $100,000. The following table includes compensation earned by the parties named therein for services performed for Pieris Operating prior to that entity becoming our wholly owned subsidiary upon the completion of the Acquisition on December 17, 2014, as well as compensation earned following the closing of the Acquisition. The following table does not include compensation information for the individuals who served as Pieris’ executive officers prior to the completion of the Acquisition, as all such individuals tendered their resignations from all such positions with us in connection with and effective as of the closing of the Acquisition and no compensation was earned by or paid to any such individuals for their services as officers of Pieris. We refer to the executive officers listed below as the Named Executive Officers.

Summary Compensation Table

Narrative Disclosure to Summary Compensation Table Employment Agreements with our Chief Executive Officer

Pieris Operating

Stephen S. Yoder serves as the Chief Executive Officer of Pieris Operating pursuant to a management agreement with Pieris Operating dated August 30, 2009, as amended on March 12, 2012, or the Yoder AG Agreement. On December 17, 2014 in connection with the Acquisition, the Yoder AG Agreement was amended and restated to have Mr. Yoder continue as the Chief Executive Officer of Pieris Operating and to provide him with the compensation and benefits set forth in his employment agreement with Pieris, as described below. The Yoder AG Agreement provided for a term of 18 months with the term automatically extending for additional one-year periods. Under the terms of the Yoder AG Agreement, Mr. Yoder received an annual base salary of $254,121 (€210,000), and on January 1, 2013 we increased Mr. Yoder’s annual base salary to $266,222 (€220,000). In addition, Mr. Yoder was eligible to receive a bonus for each calendar year during the term in an amount up to $60,505 (€50,000) based upon achievement of certain objectives, each as approved by the supervisory board of Pieris Operating in consultation with Mr. Yoder. Pursuant to the terms of the Yoder AG Agreement Mr. Yoder was also provided with a car allowance of $1,331 (€1,100) plus value added tax (VAT) per month.

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Pieris Pharmaceuticals, Inc.

Stephen S. Yoder serves as our President and Chief Executive Officer pursuant to an employment agreement dated December 17, 2014, or the Yoder Employment Agreement. The Yoder Employment Agreement provides for a continuous term and may be terminated by either party at any time, provided that if Mr. Yoder resigns he shall provide us with at least 90 days’ prior written notice. Pursuant to this agreement, Mr. Yoder’s annual base salary was increased to $375,000, effective as of the closing of the Acquisition. In addition, Mr. Yoder is eligible to receive an annual discretionary bonus of up to 40% of Mr. Yoder’s then-effective annual base salary, based upon achievement of individual and corporate performance objectives as determined by the Board of Directors or a committee thereof.

Mr. Yoder is entitled to participate in any employee benefit programs, plans and practices on the same terms as other salaried employees on a basis consistent with the participation of other senior executives, provided, however, that while Mr. Yoder remains employed outside the United States we shall only be responsible for 50% of the total cost of health insurance for Mr. Yoder’s spouse and children. Mr. Yoder will also be provided with a monthly automobile allowance while he is employed outside of the United States and up to $25,000 of relocation expenses in the event Mr. Yoder relocates to the United States. On the effective date of the Acquisition, Mr. Yoder was granted a stock option to purchase 1,280,000 shares of our common stock with the exercise price being the fair market value at the time of grant. The option is subject to and governed by the terms of the Pieris Plan and a stock option agreement, which stock option agreement provides for a ten year term, and that (i) 25% of the option vested immediately upon grant and (ii) 75% of the option shall vest ratably over three years in equal installments on a quarterly basis beginning on the last day of the next calendar quarter after the date of grant, subject to Mr. Yoder’s continued employment.

Under the Yoder Employment Agreement, Mr. Yoder is prohibited during the term of the agreement, subject to certain exceptions, from (i) accepting any other employment or consultancy, (ii) serving on the board of directors or similar body of any other entity, unless approved by the Chairman of the Board of Directors, and (iii) acquiring, assuming or participating in, directly or indirectly, any financial position, investment or interest known by Mr. Yoder to be adverse or antagonistic to Pieris, its business or prospects, financial or otherwise, or in any competing business.

The agreement contains (i) customary confidentiality obligations which are not limited by the term of the agreement, (ii) certain non-compete provisions extending during the term of the agreement and one year thereafter and (iii) certain non-solicitation provisions during the term of the agreement and for one year thereafter. Mr. Yoder also agreed to assign certain intellectual property rights to Pieris.

All compensation and benefits to be paid to Mr. Yoder pursuant to the Yoder Employment Agreement other than the equity awards shall be paid to Mr. Yoder through the terms and conditions of the Yoder AG Agreement with Pieris Operating, as amended and restated, for so long as Mr. Yoder remains employed at Pieris Operating. Upon termination of the Yoder AG Agreement provided that the Yoder Employment Agreement is still in effect, all compensation shall be paid by Pieris.

Termination for Any Reason

Upon termination of Mr. Yoder for any reason, Mr. Yoder will receive all earned but unpaid salary, any accrued vacation time, any vested benefits he may have under any employee benefit plan and any unpaid expense reimbursement accrued through the date of termination, or the Accrued Obligations.

Termination by us for Without Cause or by Executive for Good Reason

If Mr. Yoder’s employment is terminated (i) by us without cause or (ii) by him for good reason, then we must pay Mr. Yoder (i) the Accrued Obligations earned through the date of termination, (ii) a lump-sum payment

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comprised of (a) an amount equal to 12 months of his base salary at the time of his termination, and (b) a pro rata portion of the bonus for the year in which the termination occurs, based on year-to-date performance as determined by the Board of Directors, or a committee thereof, in its sole discretion, and (iii) an amount equal to his health insurance premium, paid directly or as a reimbursement to Mr. Yoder, for up to a maximum of 12 months. Payments under items (i)—(iii) above are sometimes referred to in this section as Severance. All unvested equity awards held by Mr. Yoder will immediately vest in full and become exercisable following termination and any forfeiture restrictions will immediately lapse. The Severance and acceleration of any unvested options is expressly conditioned on Mr. Yoder executing and delivering to Pieris a release of claims.

Acting Chief Financial Officer

From November 19, 2014 to December 17, 2014, Darlene Deptula-Hicks was engaged pursuant to a consulting agreement with the financial advisory firm Danforth Advisors, LLC, or Danforth, as a financial consultant to Pieris Operating, providing financial services relating to the Acquisition. As of the effectiveness of the Acquisition, she was appointed as the Acting Chief Financial Officer, Secretary and Treasurer of Pieris and will continue to provide financial services through the Danforth consulting agreement. Pursuant to the Danforth consulting agreement, Pieris will pay Danforth $280 per hour for her services. The current term of the Danforth consulting agreement expires on November 19, 2015, which term may be extended for an additional period by mutual written consent of Pieris and Danforth. The agreement may be terminated by either Pieris or Danforth for cause upon 30 days’ prior written notice or without cause upon 60 days’ prior written notice. “Cause” shall include (i) a breach of the terms of the consulting agreement which is not cured within 30 days of written notice of such default or (ii) the commission of any act of fraud, embezzlement or deliberate disregard of a rule or policy of Pieris. The Danforth consulting agreement contains customary confidentiality obligations which apply to both Danforth and Ms. Deptula-Hicks and extend for a period of five years. In addition, we may not solicit employees or contractors of Danforth for so long as such individuals are contractual agents of Danforth and for a period of one year thereafter. Should Danforth refer an employee or consultant to Pieris, Danforth is entitled to a fee of 10% of such employee’s starting base salary. Further, we shall indemnify and hold harmless Danforth and Ms. Deptula-Hicks against any claims, losses, damages, or liabilities (or actions in respect thereof) that arise out of or are based on the services performed by Danforth or Ms. Deptula-Hicks for us, except for any such claims, losses, damages or liabilities arising out of the gross negligence or willful misconduct of Danforth or Ms. Deptula-Hicks.

Potential Payments upon Termination or Change in Control

Chief Executive Officer

Under the Yoder Employment Agreement, if Mr. Yoder’s employment is terminated (i) by us without cause or (ii) by Mr. Yoder for good reason within 12 months following a change in control, and Mr. Yoder executes and delivers to Pieris a release of claims, then Mr. Yoder shall receive (i) the Accrued Obligations earned through the date of termination, (ii) a lump-sum payment comprised of (a) an amount equal to 12 months of his base salary at the time of his termination, and (b) the target bonus for the year in which the termination occurs, and (iii) an amount equal to his health insurance premium, paid directly or as a reimbursement to Mr. Yoder, for up to a maximum of 12 months. All unvested equity awards will immediately vest in full and become exercisable following termination and any forfeiture restrictions will immediately lapse.

For purposes of the Yoder Employment Agreement, “cause” shall mean the occurrence of any of the following events, as determined by the Board of Directors or a committee designated by the Board of Directors, in its sole discretion: (i) Mr. Yoder’s commission of any felony or any crime involving fraud, dishonesty, or moral turpitude under the laws of Germany, the United States or any state thereof; (ii) Mr. Yoder’s attempted commission of, or participation in, a fraud against Pieris; (iii) Mr. Yoder’s intentional, material violation of any contract or agreement between Mr. Yoder and Pieris or of any statutory duty owed to Pieris; (iv) Mr. Yoder’s unauthorized use or disclosure of Pieris’ confidential information or trade secrets; or (v) Mr. Yoder’s gross misconduct.

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For purposes of the Yoder Employment Agreement, “good reason” means Mr. Yoder’s resignation from all positions he then holds with Pieris if (i) (a) there is a material diminution in Mr. Yoder’s duties and responsibilities with Pieris; (b) there is a material reduction of Mr. Yoder’s base salary; provided, however, that a material reduction in Mr. Yoder’s base salary pursuant to a salary reduction program affecting all or substantially all of the employees of Pieris and that does not adversely affect Mr. Yoder to a greater extent than other similarly situated employees shall not constitute good reason; or (c) Mr. Yoder is required to relocate Mr. Yoder’s primary work location to a facility or location that would increase Mr. Yoder’s one-way commute distance by more than 50 miles from Mr. Yoder’s primary work location as of immediately prior to such change, (ii) Mr. Yoder provides written notice outlining such conditions, acts or omissions to Pieris within 30 days immediately following such material change or reduction, (iii) such material change or reduction is not remedied by Pieris within 30 days following Pieris’ receipt of such written notice and (iv) Mr. Yoder’s resignation is effective not later than 30 days after the expiration of such 30 day cure period.

For purposes of the Yoder Employment Agreement, a “change in control” shall be deemed to occur (i) when any “person” (as such term is used in Sections 13(d) and 14(d) of the Exchange Act) becomes the “Beneficial Owner” (as defined in Rule 13d-3 under the Exchange Act), directly or indirectly, of securities of Pieris representing 50% or more of the total voting power represented by Pieris’ then outstanding voting securities (excluding for this purpose any such voting securities held by the Pieris or its affiliates or by any employee benefit plan of Pieris) pursuant to a transaction or a series of related transactions which the Board of Directors does not approve; or (ii) a merger or consolidation of Pieris whether or not approved by the Board of Directors, other than a merger or consolidation which would result in the voting securities of Pieris outstanding immediately prior thereto continuing to represent (either by remaining outstanding or by being converted into voting securities of the surviving entity or the parent of such corporation) more than 50% of the total voting power represented by the voting securities of Pieris or such surviving entity or parent of such corporation, as the case may be, outstanding immediately after such merger or consolidation; or (iii) the sale or disposition by Pieris of all or substantially all of its assets in a transaction requiring stockholder approval.

Outstanding Equity Awards at Fiscal Year-End

The table below summarizes the aggregate stock and option awards held by our named executive officers as of December 31, 2014.

Description of Pieris Plan

In December 2014, our Board of Directors and stockholders adopted the 2014 Employee, Director and Consultant Equity Incentive Plan, or the Pieris Plan, which became effective upon closing of the Acquisition. The Pieris Plan is intended to encourage ownership of common stock by our employees and directors and certain of our consultants, including employees of Pieris Operating, in order to attract and retain such people, to induce them to work for the benefit of us and to provide additional incentive for them to promote our success. The Pieris Plan reserves for issuance 3,200,000 shares of our common stock. In addition the Pieris Plan

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provides for an “evergreen” provision whereby the number of shares of our common stock reserved for issuance under the Pieris Plan shall be automatically increased on January 1 of each of year commencing in fiscal 2016 by the lesser of (i) 1,000,000 shares, (ii) 4% of the number of shares of our common stock outstanding on such date, and (iii) such other amount determined by the administrator. As of June 17, 2015, options to purchase 1,470,235 shares of our common stock have been issued under the Pieris Plan to our executive officers and directors, and options to purchase 1,146,500 shares have been issued under the Pieris Plan to other employees and consultants. For additional information, see “Executive Compensation—Director Compensation” and “Executive Compensation—Employment Agreements with our Chief Executive Officer.” As a result of such grants, 583,265 shares of our common stock remain available for future issuances under the Pieris Plan.

Types of Awards. The Pieris Plan provides for the granting of incentive stock options, non-qualified stock options, stock grants and other stock-based awards, including restricted stock units.

Plan Administration. Our compensation committee is the administrator of the Pieris Plan, except to the extent it delegates its authority to a committee, in which case the committee shall be the administrator. The administrator has the authority to determine the recipients of the awards, the terms of awards, including exercise and purchase price, the number of shares subject to awards, the vesting schedule applicable to awards, the form of consideration, if any, payable upon exercise or settlement of an award and the terms of award agreements for use under the Pieris Plan. In addition, the administrator may amend any term or condition of any outstanding award including, without limitation, to reduce or increase the exercise price or purchase price, accelerate the vesting schedule or extend the expiration date, provided that no such amendment shall impair the rights of a participant without such participant’s consent.

Eligibility. The administrator will determine the participants in the Pieris Plan from among our employees, directors and consultants. A grant may be approved in advance with the effectiveness of the grant contingent and effective upon such person’s commencement of service within a specified period. No participant may receive awards for more than 1,500,000 shares of our common stock in any fiscal year.

Termination of Service. Unless otherwise provided by the administrator or in an award agreement, upon a termination of a participant’s service, all unvested options then held by the participant will terminate and all other unvested awards will be forfeited.

Transferability. Awards under the Pieris Plan may not be transferred except by will or by the laws of descent and distribution, unless otherwise provided by our board in its discretion and set forth in the applicable agreement, provided that no award may be transferred for value.

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Adjustment. In the event of a stock dividend, stock split, recapitalization or reorganization or other change in change in capital structure, the administrator will make appropriate adjustments to the number and kind of shares of stock or securities subject to awards.

Corporate Transaction. Upon a merger, consolidation or sale of all or substantially all of our assets, the administrator, or the board of directors of any corporation assuming our obligations, may, in its sole discretion, take any one or more of the following actions pursuant to our plan, as to some or all outstanding awards:

Amendment and Termination. The Pieris Plan will terminate on December 17, 2024 or at an earlier date by vote of the stockholders or our Board of Directors; provided, however, that any such earlier termination shall not affect any awards granted under the Pieris Plan prior to the date of such termination. The Pieris Plan may be amended by our Board of Directors, except that our Board of Directors may not alter the terms of the Pieris Plan if it would adversely affect a participant’s rights under an outstanding stock right without the participant’s consent. Stockholder approval will be required for any amendment to the Pieris Plan to the extent such approval is required by law, include the Internal Revenue Code or applicable stock exchange requirements.

Upon the closing of the Acquisition, Pieris granted a stock option to Mr. Yoder under the Pieris Plan to purchase 1,280,000 shares of our common stock with the exercise price being the fair market value of our common stock on the date of grant. 25% of the option vested immediately upon grant and 75% of the option shall vest ratably over three years in equal installments on a quarterly basis beginning on the last day of the next calendar quarter after the date of grant, subject to Mr. Yoder’s continued employment.

Director Compensation

Effective upon the closing of the Acquisition on December 17, 2014, Pieris’ former sole director resigned as a director and appointed Stephen S. Yoder, Chau Khuong, Dr. Christina Takke, Michael Richman and Steven Prelack as our directors. Following the closing of the Acquisition, our newly appointed directors appointed Chau Khuong as the Chairman of the Board. As is described in more detail elsewhere in this prospectus, Chau Khuong, Dr. Christina Takke, Michael Richman, Steven Prelack and Dr. Jean-Pierre Bizzari are independent non-employee members of our Board of Directors.

Mr. Yoder was the President and Chief Executive Officer of Pieris and Chief Executive Officer of Pieris Operating during our 2014 fiscal year.

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The table below summarizes all compensation earned by each of our non-employee directors for services performed during our fiscal year ended December 31, 2014. Pieris’ sole director before completion of the Acquisition is not in the table below because he received no compensation for his services as a director of our company. Mr. Yoder is not in the table below because he receives no separate compensation for his services as a director of our company, and all of the compensation earned by Mr. Yoder during our 2014 fiscal year as an executive officer of our company is reflected in the Summary Compensation Table above.

Upon the closing of the Acquisition, Pieris granted a stock option to Michael Richman to purchase 60,000 shares of our common stock and granted stock options to purchase 30,000 shares of our common stock to each of our other non-employee directors under the Pieris Plan, each with the exercise price equal to the fair market value of our common stock on the date of grant. Each of the options are subject to and governed by the terms of the Pieris Plan and a stock option agreement, which stock option agreement provides for a ten year term and that the option shall vest ratably over three years in equal installments on a quarterly basis beginning on the last day of the next calendar quarter after the date of grant, subject to the non-employee director’s continued service.

On January 11, 2015, our Board of Directors approved a director compensation policy applicable to our non- employee directors. This policy provides for annual cash compensation of $25,000 for each non-employee member of our Board of Directors. In addition, the chair of our audit committee will receive additional annual cash compensation of $15,000, the chair of our compensation committee will receive additional annual cash compensation of $10,000 and the chair of our nominating and corporate governance committee will receive additional annual cash compensation of $7,500. The policy also provides for annual cash compensation of $7,500 for each of the members of our audit committee, $5,000 for each of the members of our compensation committee and $3,750 for each of the members of our nominating and corporate governance committee. Our non-employee directors may elect to receive their annual fees for board and committee service from January 1 to December 31 of a given year in either cash or fully vested shares of our common stock. This election must be made on an annual basis at the beginning of each fiscal year.

In addition, the policy provides that each of our non-employee directors will be eligible to receive annual equity awards of 15,000 options to purchase our common stock, and that upon appointment, new non-employee directors will be eligible to receive an inducement equity award of 30,000 options to purchase our common stock. It is anticipated that all such equity awards will be granted under the Pieris Plan or any other equity compensation plan our Board of Directors and stockholders may approve and adopt in the future. The type of

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any such award, the amount of shares subject to the award, the vesting schedule and all other terms thereof will be subject to the discretion and approval of our Board of Directors on an annual basis. In connection with his appointment to the Board of Directors on May 12, 2015, Dr. Jean-Pierre Bizzari received an option to purchase 30,000 shares of common stock at an exercise price of $2.80, which vests over a one year period in equal installments on a quarterly basis beginning on September 30, 2015, subject to Dr. Bizzari’s continued service.

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CERTAIN RELATIONSHIPS AND RELATED TRANSACTIONS, AND DIRECTOR INDEPENDENCE

Related Party Transactions

Pieris (Pieris Pharmaceuticals, Inc., formerly known as Marika Inc.)

Except as described below, since our inception in May 2013, there has not been, nor is there currently proposed, any transaction to which Pieris is or was a party in which the amount involved exceeds the lesser of $120,000 and 1% of the average of its total assets at year-end for the last two completed fiscal years, and in which any of our current directors, executive officers, holders of more than 5% of any class of our voting securities or any of their respective affiliates or immediate family members, had, or will have, a direct or indirect material interest.

We were incorporated in Nevada in May 2013 as Marika Inc. In connection with our incorporation, Aleksandrs Sviks was appointed the sole director of Marika Inc., and in such capacity Mr. Sviks appointed himself as President, Chief Executive Officer, Chief Financial Officer, Treasurer and Secretary. On June 26, 2013, Marika Inc. issued 5,000,000 shares of common stock to Mr. Sviks, in exchange for an aggregate payment of $5,000 (or $0.001 per share).

Upon the closing of the Acquisition, Pieris and its former majority stockholder, Aleksandrs Sviks, entered into a Split-Off Agreement and General Release Agreement pursuant to which Pieris transferred all of its pre-Acquisition operating assets and liabilities to a wholly-owned special purpose subsidiary, or the Split-Off Subsidiary. Pursuant to such agreements, Pieris transferred all of the outstanding shares of capital stock of the Split-Off Subsidiary to Mr. Sviks in consideration of and in exchange for (i) the surrender and cancellation of an aggregate of 11,363,635 shares of Pieris common stock held by Mr. Sviks (which were cancelled and will resume the status of authorized but unissued shares of Pieris common stock) and (ii) certain representations, covenants and indemnities. Under the terms of a General Release Agreement, dated December 17, 2014, among Pieris, Split-Off Subsidiary and Aleksandrs Sviks, Split-Off Subsidiary and Mr. Sviks agreed to a general release of all claims and liabilities of Pieris and Pieris Operating, as well as certain other customary covenants. The descriptions of the Split-Off Agreement and the General Release Agreement set forth in this prospectus are qualified in their entirety by reference to the full text of those documents, which are filed as exhibits to the registration statement of which this prospectus forms a part and incorporated herein by reference.

We have entered into indemnification agreements with each of our directors and executive officers. Each of those indemnification agreements is in the form approved by our Board of Directors. Those indemnification agreements require that, under the circumstances and to the extent provided for therein, we indemnify such persons to the fullest extent permitted by applicable law against certain expenses and other amounts incurred by any such person as a result of such person being made a party to certain actions, suits and proceedings by reason of the fact that such person is or was a director, officer, employee or agent of our company, any entity that was a predecessor corporation of our company or any of our affiliates. The rights of each person who is a party to such an indemnification agreement are in addition to any other rights such person may have under applicable Nevada law, our Amended and Restated Articles of Incorporation, our Amended and Restated Bylaws, any other agreement, a vote of our stockholders, a resolution adopted by our Board of Directors or otherwise. The foregoing is only a brief description of the form of indemnification agreement and does not purport to be a complete description of the rights and obligations of the parties thereunder, and is qualified in its entirety by reference to the form of indemnification agreement filed as an exhibit to the registration statement of which this prospectus forms a part and incorporated herein by reference.

On December 17, 2014, we entered into a securities purchase agreement, or the Securities Purchase Agreement, with certain accredited investors providing for the issuance and sale to such investors of an aggregate of 6,779,510 shares of the our common stock in a private placement offering conducted through a series of closings occurring

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on December 17, 18 and 23, 2014, at a purchase price per share of $2.00 and for aggregate gross proceeds to us of $13.56 million, or the Private Placement. After deducting for placement agent and other fees and expenses, the aggregate net proceeds from the Private Placement were $12.04 million. In connection with the Private Placement we received funding from the holders of more than 5% of our common stock as follows: (i) of $495,282 from OrbiMed Private Investments III, LP, or OPI III, (ii) $4,718 from OrbiMed Associates III, LP, an affiliate of OPI III, or Associates III, (iii) $1,250,000 from Mark N. Tompkins and, and (iv) approximately $3.0 million from 1798 Fundamental Strategies Master Fund Ltd., or Fundamental Strategies. After giving effect to the Private Placement and as of June 17, 2015, each of OPI III, Mark N. Tompkins and Fundamental Strategies is a holder of more than 5% of the outstanding capital stock of Pieris.

See “Description of Capital Stock—Registration Rights Agreement” for a description of registration rights granted to the holders of the shares of common stock and “Description of Capital Stock—Placement Warrants” for a description of common stock purchase warrants issued in connection with the Acquisition and the Private Placement, which descriptions are incorporated herein by reference.

Pieris Operating

Except as described below and except for employment compensation, since January 1, 2012, there has not been, nor is there currently proposed, any transaction to which it was or is a party in which the amount involved exceeds the lesser of $120,000 and 1% of the average of Pieris Operating’s total assets at year-end for the last two completed fiscal years, and in which any of its directors, executive officers, holders of more than 5% of any class of its voting securities or any of their respective affiliates or immediate family members, had, or will have, a direct or indirect material interest.

In 2001, Pieris Operating entered into a consulting agreement with Dr. Arne Skerra, who was a member of the Pieris Operating supervisory board, pursuant to which Dr. Skerra provides advice regarding the use of new proteins for the purpose of research and development. For each of the years ended December 31, 2012, December 31, 2013 and December 31, 2014, Pieris Operating paid Dr. Skerra €20,000 ($24,202) under the consulting agreement.

In July 2007, Pieris Operating entered into a Research and Licensing Agreement with Technische Universität München, or TUM and the TUM License Agreement. The TUM License Agreement granted certain licenses and protective rights to Pieris Operating related to Anticalin^®-brand drug and lipocalin research and Anticalin technology developed by a research team led by Dr. Arne Skerra, who is employed by TUM as Chair of Biological Chemistry. For these licenses and rights, Pieris Operating paid TUM €15,000 ($18,152) in 2012 and €50,000 ($60,505) in 2013, as well as additional payments of €102,000 ($123,430) in 2012 and €25,500 ($30,858) in 2013 for the research conducted in subsequent project stages. No payments were made for such licenses and rights or any other payments in 2014.

Pieris Operating is the project coordinator and a participant of the European Consortium for Anticalin^® proteins as next generation high-affinity protein therapeutics, or EUROCALIN, collaborative research project, a drug development collaboration among ten distinct companies and academic institutions across Europe funded in large part by the European Commission under its FP7 HEALTH program pursuant to a Consortium Agreement dated November 21, 2011, or the Consortium Agreement, and the Grant Agreement No. 278408 dated November 21, 2011, or the FP7 Grant Agreement. EUROCALIN received a €6.0 million ($7.3 million) grant from the European Union in 2011. TUM is also a member of the EUROCALIN consortium and is entitled to payments under the FP7 Grant Agreement. Pursuant to the FP7 Grant Agreement, in 2012 and 2013, Pieris Operating, as project coordinator, paid TUM €62,900 ($76,115) and €65,400 ($79,141), respectively, out of the grant funds. No grant funds were dispensed to TUM in 2014.

In November 2012, Pieris Operating entered into the 2012 Bridge Loan. In connection with the financing, Pieris Operating received (i) €492,113 ($595,506) from OPI III, (ii) €4,687 ($5,672) from Associates III, (iii) €421,015 ($509,470) from Gilde Europe Food & Agribusiness Fund B.V., or Gilde, (iv) €219,225

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($265,284) from Coöperatieve AAC LS U.A. (Forbion), or Forbion, (v) €252,173 ($305,154) from The Global Life Science Ventures Funds II GmbH & Co. KG i.L., or Global Life KG, (vi) €196,145 ($237,355) from The Global Life Science Ventures Fund II LP, an affiliate of Global Life KG, or Global Life LP, (vii) €199,606 ($241,543) from Novo Nordisk A/S, or Novo, and (viii) €164,751 ($199,365) from BioM AG, or BioM. The 2012 Bridge Loan accrued interest at a rate of 12% per year and had a maturity date of December 31, 2013, after which the loan amounts began to accrue interest at a rate of 18% per year. In 2012, Pieris Operating accrued interest in the amounts of €3,445 ($4,169), €33 ($40), €3,368 ($4,076), €1,461 ($1,768), €1,008 ($1,220), €0 ($0), €1,397 ($1,691) and €1,373 ($1,661) under the loans to OPI III, Associates III, Gilde, Forbion, Global Life KG, Global Life LP, Novo and BioM, respectively. In 2013, Pieris Operating accrued interest in the amounts of €59,054 ($71,461), €562 ($680), €50,522 ($61,137), €26,307 ($31,834), €30,261 ($36,619), €23,537 ($28,482), €23,953 ($28,986) and €19,770 ($23,924) to OPI III, Associates III, Gilde, Forbion, Global Life KG, Global Life LP, Novo and BioM, respectively. BioM Venture Capital GmbH & Co. KG, or BioM Venture, who, as of the date of execution of the 2012 Bridge Loan was a holder of more than 5% of the outstanding capital stock of Pieris Operating, is an affiliate of BioM. As of the date of execution of the 2012 Bridge Loan, Forbion was a holder of more than 5% of the outstanding capital stock of Pieris Operating.

In March 2014, the 2012 Bridge Loan was amended. Pursuant to the terms of the amendment, (i) the outstanding amount under the 2012 Bridge Loan was reduced by a $400,000 payment to the holders under the 2012 Bridge Loan and (ii) the maturity date was extended to December 31, 2015. Due to the extension, interest under the amended facility accrued at a rate of 12% per year. In connection with the amended financing, Pieris Operating had total repayment amounts owed by Pieris Operating of (i) $98,423 from OPI III, (ii) $937 from Associates III, (iii) $84,203 from Gilde, (iv) $43,845 from Forbion, (v) $50,435 from Global Life KG, (vi) $39,229 from Global Life LP, (vii) $39,921 from Novo, and (viii) $32,950 from BioM. BioM Venture and Forbion, as of the date of execution of the amendment, were holders of more than 5% of the outstanding capital stock of Pieris Operating. Immediately prior to the 2014 Series C Financing, as defined below, there was €2,000,000 ($2,420,200) outstanding under the 2012 Bridge Loan, as amended. As of December 17, 2014 and pursuant to the terms of the 2014 Series C Financing under which the outstanding indebtedness was converted to equity, there were no amounts outstanding under the 2012 Bridge Loan, as amended.

In April 2014, Pieris Operating entered into a second bridge loan agreement, or the 2014 Bridge Loan, with certain of its stockholders pursuant to which Pieris Operating received a commitment for financing in the aggregate amount of €2,000,000 ($2,420,200), which loan amounts, if called by Pieris Operating, would be convertible into shares of Pieris Operating after the maturity date or upon the occurrence of certain events. The 2014 Bridge Loan included two tranches of available financing: (i) Tranche A of €1,500,000 ($1,815,150) and (ii) Tranche B of €500,000 ($605,050). The Tranche A financing commitment consisted of commitments of (i) €598,400 ($724,124) from OPI III, (ii) €3,751 ($4,539) from Associates III, (iii) €149,705 ($181,158) from Novo, (iv) €126,560 ($153,150) from Global Life KG, (v) €98,440 ($119,122) from Global Life LP, (vi) €225,000 ($272,273) from Gilde, (vii) €97,500 ($117,985) from Forbion, (viii) €150,000 ($181,515) from Baytech Venture Capital GmbH & Co. KG, or Baytech, and (ix) €10,310 ($12,476) from BioM. The Tranche B financing commitment consisted of (i) €199,497 ($241,411) from OPI III, (ii) €1,250 ($1,513) from Associates III, (iii) €49,902 ($60,386) from Novo, (iv) €42,197 ($51,063) from Global Life KG, (v) €32,813 ($39,707) from Global Life LP, (vi) €75,000 ($90,758) from Gilde, (vii) €32,500 ($39,328) from Forbion, (viii) €50,000 ($60,505) from Baytech and (ix) €10,310 ($12,476) from BioM. Forbion, BioM Venture and Baytech, as of the date of execution of the 2014 Bridge Loan, were holders of more than 5% of the outstanding capital stock of Pieris Operating. In June 2014, Pieris Operating borrowed 67% of Tranche A, which equals €1,000,000 ($1,210,100). The amount borrowed consisted of funds of (i) €398,993 ($482,821) from OPI III, (ii) €2,501 ($3,026) from Associates III, (iii) €99,803 ($120,772) from Novo, (iv) €84,373 ($102,100) from Global Life KG, (v) €65,627 ($79,415) from Global Life LP, (vi) €150,000 ($181,515) from Gilde, (vii) €65,000 ($78,657) from Forbion, (viii) €100,000 ($121,010) from Baytech, and (ix) €6,873 ($8,317) from BioM. Loan amounts outstanding under the 2014 Bridge Loan accrued interest at a rate of 12% per year and had a maturity date of December 31, 2015, after which the loan amounts would accrue interest at a rate of 18% per year. Immediately prior to the 2014 Series C Financing, as defined below, there was €1,000,000 ($1,210,100) outstanding under

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the 2014 Bridge Loan. In September 2014 and in connection with the 2014 Series C Financing, the stockholder parties to the 2014 Bridge Loan invested the remaining €1,000,000 ($1,210,100) commitment under the bridge loan in cash directly in the 2014 Series C Financing, including funds of (i) €398,994 ($482,823) from OPI III, (ii) €2,500 ($3,025) from Associates III, (iii) €99,803 ($120,772) from Novo, (iv) €84,373 ($102,100) from Global Life KG, (v) €65,627 ($79,415) from Global Life LP, (vi) €150,000 ($181,515) from Gilde, (vii) €65,000 ($78,657) from Forbion, (viii) €100,000 ($121,010) from Baytech, and (ix) €6,874 ($8,318) from BioM, which was treated as new investment under the 2014 Series C Financing, or the Convertible Cash Investment. As of December 17, 2014 and pursuant to the 2014 Series C Financing under which the outstanding indebtedness was converted to equity, there were no amounts outstanding under the 2014 Bridge Loan.

On October 10, 2014, Pieris Operating entered into an investment agreement and consolidated shareholders’ agreement, each dated October 10, 2014, pursuant to which (i) the aggregate outstanding amounts under the 2012 Bridge Loan, as amended, and 2014 Bridge Loan of €3,000,000 ($3,630,300) were converted into shares of Series C Preferred Stock of Pieris Operating and (ii) Pieris Operating received a cash investment, including the Convertible Cash Investment, in the aggregate amount of €5,970,149 ($7,224,477) in consideration for shares of Pieris Operating’s Series C Preferred Stock, or the 2014 Series C Financing.

The converted bridge loan portion of the 2014 Series C Financing included (a) €2,000,000 ($2,420,200) outstanding under the 2012 Bridge Loan, as amended, including funds of (i) €492,113 ($595,506) from OPI III, (ii) €4,687 ($5,672) from Associates III, (iii) €421,015 ($509,470) from Gilde, (iv) €219,225 ($265,284) from Forbion, (v) €252,173 ($305,155) from Global Life KG, (vi) €196,145 ($237,355) from Global Life LP, (vii) €199,606 ($241,543) from Novo and (viii) €164,751 ($199,365) from BioM and (b) €1,000,000 ($1,210,100) outstanding under the 2014 Bridge Loan including funds of (i) €398,994 ($482,823) from OPI III, (ii) €2,500 ($3,025) from Associates III, (iii) €99,803 ($120,772) from Novo, (iv) €84,373 ($102,100) from Global Life KG, (v) €65,627 ($79,415) from Global Life LP, (vi) €150,000 ($181,515) from Gilde, (vii) €65,000 ($78,657) from Forbion, (viii) €100,000 ($121,010) from Baytech, and (ix) €6,874 ($8,318) from BioM.

The cash investment portion of the 2014 Series C Financing provided for two tranches of available financing.

The first tranche consisted of a cash investment of €3,552,646 ($4,299,057) and the second tranche consisted of a cash investment of €1,417,503 ($1,715,320). In addition, the cash investment portion of the 2014 Series C Financing included €1,000,000 ($1,210,100) from the Convertible Cash Investment as described above. In October to November 2014, the first tranche of the 2014 Series C Financing was consummated, consisting of an issuance of an aggregate of 1,629,469 shares of Series C Preferred Stock, including funds of (i) €2,218,972 ($2,685,178) from OPI III, (ii) €19,843 ($24,012) from Associates III, (iii) €150,000 ($181,515) from Gilde, (iv) €65,000 ($79,657) from Forbion, (v) €84,373 ($102,100) from Global Life KG, (vi) €65,627 ($79,415) from Global Life LP, (vii) €99,803 ($120,772) from Novo, (viii) €6,874 ($8,318) from BioM, (ix) €275,000 ($332,778) from Baytech and (x) €1,492,537 ($1,806,119) from Cadila Healthcare Limited, or Zydus. In November to December 2014, the second tranche of the 2014 Series C Financing was consummated, consisting of the issuance of an aggregate of 234,877 shares of Series C preferred stock including funds of €579,861 ($701,690) from Mark N. Tompkins. Forbion, BioM Venture, Baytech and Zydus, as of the date of execution of the 2014 Series C Financing, were holders of more than 5% of the outstanding capital stock of Pieris Operating.

In the aggregate, as of June 17, 2015, Pieris Operating has received approximately €51.7 million ($62.6 million) in equity investments from its stockholders as follows: (i) in 2001, seed round financing of €0.6 million ($.7 million); (ii) in 2002, two tranches of Series A financing in an aggregate amount of approximately €12.2 million ($14.8 million); (iii) in 2006, Series A-1 financing of approximately €4.9 million ($5.9 million), (iv) in 2008, two tranches of Series B financing in an aggregate of approximately €25.0 million ($30.3 million) and (v) the 2014 Series C Financing of approximately €9.0 million ($10.9 million). Our stockholders have invested in these activities in the following aggregate amounts: (i) approximately €13.1 million ($15.9 million) from OPI III and Associates III; (ii) approximately €8.0 million ($9.7 million) from Global Life KG and Global

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Life LP; (iii) approximately €7.9 million ($9.6 million) from Gilde; (iv) approximately €5.4 million ($6.5 million) from Novo; (v) approximately €4.8 million ($5.8 million) from Forbion; (vi) approximately €3.4 million ($4.1 million) from Baytech; (vii) an aggregate of approximately €2.7 million ($3.3 million) from Bio M and BioM Venture, an affiliate of BioM, (viii) approximately €1.5 million ($1.8 million) from Zydus, and (ix) approximately €0.6 million ($0.7 million) from Mark N. Tompkins. Other stockholders invested in aggregate approximately €4.4 million ($5.3 million).

Each of OPI III, Gilde, Forbion, Global Life KG, Global Life LP, Novo, Baytech and Zydus was a holder of more than 5% of the outstanding capital stock of Pieris Operating prior to the closing of the Acquisition, and each of OPI III, Gilde, Forbion, Global Life KG, Novo, Zydus and Mark N. Tompkins was a holder of more than 5% of the outstanding capital stock of Pieris as of December 17, 2014 giving effect to the Acquisition. After giving effect to the Private Placement and as of June 17, 2015, each of OPI III, Gilde, Global Life KG, Novo, Mark N. Tompkins and Fundamental Strategies is a holder of more than 5% of the outstanding capital stock of Pieris. Former members of the supervisory board of Pieris Operating are associated with these 5% stockholders as follows: Dr. Michael Sheffery is a Partner Emeritus at OrbiMed Advisors LLC, which is the general partner of Associates III and the sole managing member of OPI III, Dr. Hans A. Küpper is a managing director of The Global Life Sciences Ventures GmbH, which is the general partner of Global Life KG and advisor to Global Life LP, and Edwin de Graaf is the managing director of Glide Healthcare Holding B.V., the parent company of Gilde Agribusiness Management B.V., the manager of Gilde. Further, Chau Khuong, a current member of our Board of Directors and a member of the supervisory board of Pieris Operating, is also an employee of OrbiMed Advisors LLC and Dr. Christina Takke, a current member of our Board of Directors and a member of the supervisory board of Pieris Operating, was until June 1, 2015 a proxy holder of Forbion I Management B.V., the director of Forbion. Last, in October 2013, Pieris Operating entered into a development and license agreement with Zydus for the preclinical development of PRS-110, pursuant to which Pieris Operating shares certain commercial rights to PRS-110 with Zydus. For more information about the Zydus agreement, see “Business—Strategic Partnerships”.

Review, Approval or Ratification of Transactions with Related Persons

Pursuant to the written charter of our audit committee, the audit committee is responsible for reviewing and approving all transactions in which we are a participant and in which any parties related to us, including our executive officers, our directors, beneficial owners of more than 5% of our securities, immediate family members of the foregoing persons and any other persons whom our Board of Directors determines may be considered related parties under Item 404 of Regulation S-K, has or will have a direct or indirect material interest. All of the transactions described in this section occurred prior to the adoption of the audit committee charter.

Director Independence

In connection with the closing of the Acquisition, our Board of Directors undertook a review of the composition of our Board of Directors and independence of each director. Based upon information requested from and provided by each director concerning his or her background, employment and affiliations, including family relationships, our Board of Directors has determined that Chau Khuong, Dr. Christina Takke, Michael Richman, Steven Prelack and Dr. Jean-Pierre Bizzari would qualify as “independent” as that term is defined by NASDAQ Listing Rule 5605(a)(2). Stephen S. Yoder would not qualify as “independent” under applicable NASDAQ Listing Rules applicable to the Board of Directors generally or to separately designated board committees because he currently serves as our Chief Executive Officer. In making such determinations, our Board of Directors considered the relationships that each of our non-employee directors has with our company and all other facts and circumstances deemed relevant in determining independence, including the beneficial ownership of our capital stock by each non-employee director.

Subject to some exceptions, NASDAQ Listing Rule 5605(a)(2) provides that a director will only qualify as an “independent director” if, in the opinion of our Board of Directors, that person does not have a relationship that

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would interfere with the exercise of independent judgment in carrying out the responsibilities of a director, and that a director cannot be an “independent director” if (a) the director is, or in the past three years has been, an employee of ours; (b) a member of the director’s immediate family is, or in the past three years has been, an executive officer of ours; (c) the director or a member of the director’s immediate family has received more than $120,000 per year in direct compensation from us within the preceding three years, other than for service as a director or benefits under a tax-qualified retirement plan or non-discretionary compensation (or, for a family member, as a non-executive employee); (d) the director or a member of the director’s immediate family is a current partner of our independent public accounting firm, or has worked for such firm in any capacity on our audit at any time during the past three years; (e) the director or a member of the director’s immediate family is, or in the past three years has been, employed as an executive officer of a company where one of our executive officers serves on the compensation committee; or (f) the director or a member of the director’s immediate family is an executive officer, partner or controlling stockholder of a company that makes payments to, or receives payments from, us in an amount which, in any twelve-month period during our past three fiscal years, exceeds the greater of 5% of the recipient’s consolidated gross revenues for that year or $200,000 (except for payments arising solely from investments in our securities or payments under non-discretionary charitable contribution matching programs). Additionally, in order to be considered an independent member of an audit committee under Rule 10A-3 of the Exchange Act, a member of an audit committee may not, other than in his or her capacity as a member of the audit committee, the Board of Directors, or any other committee of the Board of Directors, accept, directly or indirectly, any consulting, advisory, or other compensatory fee from the applicable company or any of its subsidiaries or otherwise be an affiliated person of the applicable company or any of its subsidiaries.

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SECURITY OWNERSHIP OF CERTAIN BENEFICIAL OWNERS AND MANAGEMENT

The following table sets forth the number of shares of our common stock beneficially owned as of June 15, 2015, by (i) each of our current directors and named executive officers, (ii) all executive officers and directors as a group, and (iii) each person known by us to be the beneficial owner of more than 5% of the outstanding shares of our common stock. We have determined beneficial ownership in accordance with applicable rules of the SEC, which generally provide that beneficial ownership includes voting or investment power with respect to securities. Except as indicated by the footnotes to the table below, we believe, based on the information furnished to us, that the persons named in the table have sole voting and investment power with respect to all shares of common stock that they beneficially own, subject to applicable community property laws.

The information set forth in the table below is based on 29,429,522 shares of our common stock issued and outstanding on of June 15, 2015. In computing the number of shares of common stock beneficially owned by a person and the percentage ownership of that person, we deemed to be outstanding all shares of common stock subject to options, warrants or other convertible securities held by that person that are currently exercisable or will be exercisable within 60 days after June 15, 2015. We did not deem these shares outstanding, however, for the purpose of computing the percentage ownership of any other person. Except as otherwise noted in the footnotes below, the address for each person listed in the table below, solely for purposes of filings with the SEC, is c/o Pieris AG, Lise-Meitner-Strasse 30, 85354 Freising-Weihenstephan, Germany.

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DESCRIPTION OF CAPITAL STOCK

The following describes the material terms of the capital stock of Pieris. The following description does not purport to be complete and is subject to, and qualified in its entirety by reference to, Pieris’ Amended and Restated Articles of Incorporation and Amended and Restated Bylaws, which are filed as exhibits to the registration statement of which this prospectus forms a part. All of our stockholders are urged to read our Amended and Restated Articles of Incorporation and Amended and Restated Bylaws carefully and in their entirety.

Authorized Capital Stock; Issued and Outstanding Capital Stock

We currently have authorized capital stock of 310,000,000 shares, of which 300,000,000 are designated as common stock, par value $0.001 per share, and 10,000,000 shares are designated as preferred stock, par value $0.001 per share. The following is a summary of the rights of our common and preferred stock and some of the provisions of our Amended and Restated Articles of Incorporation and Amended and Restated Bylaws, and the Nevada Revised Statutes, or the NRS. Because it is only a summary, it does not contain all the information that may be important to you. For a complete description you should refer to our Amended and Restated Articles of Incorporation and Amended and Restated Bylaws, copies of which have been filed as exhibits to the registration statement of which this prospectus forms a part, as well as the relevant provisions of the NRS.

As of June 17, 2015, there were 29,429,522 shares of common stock outstanding and no shares of preferred stock issued and outstanding. In addition, there are warrants to purchase 542,360 shares of our common stock outstanding and, as of June 17, 2015, we granted options to purchase 2,616,735 shares of our common stock under the Pieris Plan, and there were 583,265 shares of common stock reserved for future issuance under the Pieris Plan.

Common Stock

All of the securities being offered pursuant to the registration statement of which this prospectus is a part are shares of our common stock. The holders of our common stock are entitled to one vote per share on matters on which our stockholders vote. Holders of our common stock have no cumulative voting rights. Subject to any preferential dividend rights of any outstanding shares of preferred stock, holders of our common stock are entitled to receive dividends, if declared by our Board of Directors, out of funds that we may legally use to pay dividends. If we liquidate or dissolve, holders of our common stock are entitled to share ratably in our assets once our debts and any liquidation preference owed to any then-outstanding preferred stockholders are paid. Our Amended and Restated Articles of Incorporation do not provide our common stock with any redemption, conversion or preemptive rights. All of the issued and outstanding shares of our common stock are duly authorized, validly issued, fully paid and non-assessable.

Preferred Stock

If we issue preferred stock in the future, such preferred stock may have priority over common stock with respect to dividends and other distributions, including the distribution of assets upon liquidation. Our Board of Directors has the authority, without further stockholder authorization, to issue from time to time up to 10,000,000 shares of preferred stock in one or more series and to fix the terms, limitations, voting rights, relative rights and preferences and variations of each series. Although we have no present plans to issue any shares of preferred stock, the issuance of shares of preferred stock, or the issuance of rights to purchase such shares, could decrease the amount of earnings and assets available for distribution to the holders of common stock, could adversely affect the rights and powers, including voting rights, of the common stock, and could have the effect of delaying, deterring or preventing a change of control of us or an unsolicited acquisition proposal. As of June 17, 2015, no shares of preferred stock were outstanding.

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Placement Warrants

Upon the closings of the December 2014 private placement, the Company issued to the investors and their designees, warrants, or the Placement Warrants, to acquire up to 542,360 shares of its common stock. Each of the Placement Warrants is exercisable at any time at the option of the holder until the five-year anniversary of its date of issuance. Each Placement Warrant entitles the registered holder to purchase one share of our common stock at a price of $2.00 per share. The number of shares issuable upon exercise of each Placement Warrant is adjustable in the event of stock splits, stock dividends, combinations of shares and similar transactions. Furthermore, if we engage in a merger, sale of substantially all of our assets or similar transaction the holders of more than 50% of the outstanding shares of common stock accept a tender offer, each holder of a Placement Warrant that is outstanding shall have the right to receive the number of shares of the surviving corporation and any additional consideration receivable by a holder of the same number of shares of common stock for which such Placement Warrant is exercisable.

See “—Registration Rights Agreement” below for a description of the registration rights granted to the holders of the shares of common stock and common stock purchase warrants issued in connection with the Acquisition and the Private Placement.

No fractional shares of common stock will be issued upon exercise of the warrants. If, upon exercise of the warrants, a holder would be entitled to receive a fractional interest in a share, we will, upon exercise, either pay a cash adjustment in respect of such final fraction in an amount equal to such fraction multiplied by the exercise price or round up to the next whole share.

Registration Rights Agreement

On December 17, 2014, we entered into a registration rights agreements with the investors that participated in the private placement of our common stock. Pursuant to the terms of the registration rights agreement, on February 17, 2015, we filed with the SEC a registration statement to register for resale all of the 6,779,510 shares of our common stock issued in such private placement, as well as an additional 20,000,000 shares of our common stock which we issued to former stockholders of Pieris Operating in connection with the closing of the Acquisition, and an additional 542,360 shares of common stock issuable to holders of the Placement Warrants, which registration statement, as amended, was subsequently declared effective by the SEC on May 11, 2015.

Under the registration rights agreement, subject to exception in certain circumstances or pursuant to the Acquisition, as applicable, we have agreed to keep such registration statement effective until the later of December 17, 2016 and such time as all of the securities registered thereunder have been sold under such registration statement or pursuant to Rule 144 or may be sold without restriction pursuant to Rule 144. If there is not an effective registration statement covering the resale of the securities to be registered thereunder at any time prior to December 17, 2015, then the selling stockholders will have “piggyback” registration rights with respect to any such securities that are not eligible for resale pursuant to Rule 144 without volume or manner of sale restrictions in connection with any other registration statement we determine to file that would permit the inclusion of those shares.

If the registration statement ceases to be effective during the required effectiveness period, except as permitted under the registration rights agreement, we will be obligated pay to each selling stockholder an amount in cash equal to 1.0% of the value of such selling stockholder’s shares of outstanding common stock on every monthly anniversary of such failure and prorated for any portion of a month, until it is cured or all of such selling stockholder’s securities to be registered hereunder have been or may be sold without restriction pursuant to Rule 144. Furthermore, if we fail to timely file reports required to be filed by us pursuant to Section 13(a) or 15(d) under the Exchange Act, we will be obligated pay to each selling stockholder an amount in cash equal to 1.0% of the value of such selling stockholder’s shares of outstanding common stock. Notwithstanding the foregoing, we will not be obligated to make any such payments with respect to any of the securities to be registered hereunder that we are unable to register due to limits imposed by the SEC’s interpretation of Rule 415 promulgated under the Securities Act.

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The foregoing description of the registration rights agreement does not purport to be complete, and is qualified in its entirety by the complete text of that agreement, which is attached as an exhibit to the registration statement of which this prospectus forms a part and is incorporated herein by reference.

Dividends and Other Distributions

Under NRS 78.288, the directors of a Nevada corporation may authorize, and the corporation may make, distributions (including cash dividends) to stockholders, but no such distribution may be made if, after giving it effect:

The NRS prescribes the timing of the determinations above depending on the nature and timing of payment of the distribution. For cash dividends paid within 120 days after the date of authorization, the determinations above must be made as of the date the dividend is authorized. When making their determination that a distribution is not prohibited by NRS 78.288, directors may consider:

Declaration and payment of any dividend will be subject to the discretion of our Board of Directors. The payment of any future dividends will be at the discretion of our Board of Directors; however, the time and amount of such dividends, if any, will be dependent upon our financial condition, operations, compliance with applicable law, cash requirements and availability, debt repayment obligations, capital expenditure needs and restrictions in our debt instruments, contractual restrictions, business prospects, industry trends, the provisions of Nevada law affecting the payment of distributions and any other factors our Board of Directors may consider relevant. Our ability to pay dividends on our common stock may depend in part on our receipt of cash dividends from our operating subsidiaries, which may be restricted from paying us dividends as a result of the laws of their jurisdiction of organization, agreements of our subsidiaries or covenants under any existing and future outstanding indebtedness we or our subsidiaries incur.

Anti-Takeover Effects of Our Amended and Restated Articles of Incorporation and Amended and Restated Bylaws and Certain Provisions of Nevada Law

Our Amended and Restated Articles of Incorporation, Amended and Restated Bylaws and the NRS contain provisions that may have the effect of maintaining continuity and stability in the composition of our Board of Directors. These provisions may help us avoid costly takeover battles, reduce our vulnerability to a hostile change of control and enhance the ability of our Board of Directors to effectively evaluate and negotiate in connection with any unsolicited offer to acquire us. However, these provisions may have an anti-takeover effect and may delay, deter or prevent a merger or acquisition of our company by means of a tender offer, a proxy contest or other takeover attempt that a stockholder might consider to be in its best interest, including attempts that might result in a premium over the prevailing market price for the shares of common stock held by stockholders.

Business Combinations and Acquisition of Control Shares

Nevada’s “combinations with interested stockholders” statutes (NRS 78.411 through 78.444, inclusive) prohibit specified types of business “combinations” between certain Nevada corporations and any person deemed to be an “interested stockholder” for two years after such person first becomes an “interested stockholder” unless the

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corporation’s board of directors approves the combination (or the transaction by which such person becomes an “interested stockholder”) in advance, or unless the combination is approved by the board of directors and sixty percent of the corporation’s voting power not beneficially owned by the interested stockholder, its affiliates and associates. Furthermore, in the absence of prior approval certain restrictions may apply even after such two-year period. An amendment to the NRS, effective October 1, 2015, however, provides that these statutes do not apply to any combination of a corporation and an interested stockholder after the expiration of four years after the person first became an interested stockholder. NRS 78.439 has also been amended, effective October 1, 2015, to eliminate the prohibition on stockholder approval by written consent with respect to combinations undertaken after the two-year period prescribed under the statutes. For purposes of these statutes, an “interested stockholder” is any person who is (1) the beneficial owner, directly or indirectly, of ten percent or more of the voting power of the outstanding voting shares of the corporation, or (2) an affiliate or associate of the corporation and at any time within the two previous years was the beneficial owner, directly or indirectly, of ten percent or more of the voting power of the then-outstanding shares of the corporation. The definition of the term “combination” is sufficiently broad to cover most significant transactions between a corporation and an “interested stockholder.” These laws generally apply to Nevada corporations with 200 or more stockholders of record, but a Nevada corporation may elect in its articles of incorporation not to be governed by these particular laws. We have not made such an election in our Amended and Restated Articles of Incorporation.

Nevada’s “acquisition of controlling interest” statutes (NRS 78.378 through 78.3793, inclusive) contain provisions governing the acquisition of a controlling interest in certain Nevada corporations. These “control share” laws provide generally that any person that acquires a “controlling interest” in certain Nevada corporations may be denied voting rights, unless a majority of the disinterested stockholders of the corporation elects to restore such voting rights. Our Amended and Restated Articles of Incorporation, include our election to provide that these statutory provisions shall not apply to us or to any acquisition of our common stock. If our Amended and Restated Articles of Incorporation are amended to remove such elective provision, and absent a similar provision included in an amendment to our Amended and Restated Bylaws, these laws would then apply to us if we were to have 200 or more stockholders of record (at least 100 of whom have addresses in Nevada appearing on our stock ledger) and do business in the State of Nevada directly or through an affiliated corporation, unless our articles of incorporation or bylaws in effect on the tenth day after the acquisition of a controlling interest provide otherwise. These laws provide that a person acquires a “controlling interest” whenever a person acquires shares of a subject corporation that, but for the application of these provisions of the NRS, would enable that person to exercise (i) one-fifth or more, but less than one-third, (ii) one-third or more, but less than a majority or (iii) a majority or more, of all of the voting power of the corporation in the election of directors. Once an acquirer crosses one of these thresholds, shares which it acquired in the transaction taking it over the threshold and within the 90 days immediately preceding the date when the acquiring person acquired or offered to acquire a controlling interest become “control shares” to which the voting restrictions described above apply.

In addition, NRS 78.139 also provides that directors may resist a change or potential change in control if the directors, by majority vote of a quorum, determine that the change is opposed to, or not in, the best interest of the corporation.

Classified Board of Directors; Removal of Directors Only for Cause

Pursuant to our Amended and Restated Articles of Incorporation and Amended and Restated Bylaws, our Board of Directors is divided into three classes, with the term of office of the first class to expire at the first annual meeting of stockholders following the initial classification of directors and until their successors are duly elected and qualified, the term of office of the second class to expire at the second annual meeting of stockholders following the initial classification of directors and until their successors are duly elected and qualified, and the term of office of the third class to expire at the third annual meeting of stockholders following the initial classification of directors and until their successors are duly elected and qualified. At each annual meeting of stockholders, directors elected to succeed those directors whose terms expire, other than directors elected by the holders of any series of preferred stock under specified circumstances, will be elected for a three-year term of office. All directors elected to our classified Board of Directors will serve until the election and

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qualification of their respective successors or their earlier resignation or removal. Members of the Board of Directors may only be removed for cause and only by the affirmative vote of at least 80% of our outstanding voting stock. These provisions are likely to increase the time required for stockholders to change the composition of the Board of Directors. For example, at least two annual meetings will be necessary for stockholders to effect a change in a majority of the members of the Board of Directors.

Advance Notice Provisions for Stockholder Proposals and Stockholder Nominations of Directors

Our Amended and Restated Bylaws provide that, for nominations to the Board of Directors or for other business to be properly brought by a stockholder before a meeting of stockholders, the stockholder must first have given timely notice of the proposal in writing to our Secretary. For an annual meeting, a stockholder’s notice generally must be delivered not less than 90 days nor more than 120 days prior to the first anniversary of the previous year’s annual meeting date. For a special meeting, the notice must generally be delivered not earlier than the 90th day prior to the meeting and not later than the later of (i) the 60th day prior to the meeting or (ii) the 10th day following the day on which public announcement of the meeting is first made. Detailed requirements as to the form of the notice and information required in the notice are specified in the Amended and Restated Bylaws. If it is determined that business was not properly brought before a meeting in accordance with our bylaw provisions, such business will not be conducted at the meeting.

Special Meetings of Stockholders

Special meetings of the stockholders may be called only by our Board of Directors pursuant to a resolution adopted by a majority of the total number of directors.

No Stockholder Action by Written Consent

Any action to be effected by our stockholders must be effected at a duly called annual or special meeting of the stockholders and not by written consent.

Super Majority Stockholder Vote Required for Certain Actions

Our Amended and Restated Articles of Incorporation and Amended and Restated Bylaws provide that the Board of Directors is expressly authorized to make, alter, amend, change, add to, rescind or repeal, in whole or in part, our bylaws without a stockholder vote in any manner not inconsistent with Nevada law and our Amended and Restated Articles of Incorporation. Our Amended and Restated Articles of Incorporation require the affirmative vote of the holders of at least 80% of our outstanding voting stock to amend or repeal any of the provisions discussed in this section under the heading “Anti-Takeover Effects of Our Amended and Restated Articles of Incorporation and Amended and Restated Bylaws and Certain Provisions of Nevada Law,” as well as certain other provisions of our Amended and Restated Articles of Incorporation. This 80% stockholder vote would be in addition to any separate class vote that might in the future be required pursuant to the terms of any preferred stock that might then be outstanding. An 80% vote is also required for any amendment to, or repeal of, our Amended and Restated Bylaws by the stockholders and for the removal of any member of or our entire Board of Directors. Our Amended and Restated Bylaws may be amended or repealed by a majority vote of the Board of Directors.

Deemed Notice and Consent

Our Amended and Restated Articles of Incorporation provide that any person purchasing or otherwise acquiring any interest in shares of our capital stock shall be deemed, to the fullest extent permitted by law, to have notice of and consented to all of the provisions of our Amended and Restated Articles of Incorporation, our Amended and Restated Bylaws and any amendment to our articles of incorporation or bylaws enacted in accordance therewith and applicable law.

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Transfer Agent and Registrar

Our transfer agent and registrar is Globex Transfer, LLC, 780 Deltona Blvd., Suite 202, Deltona, Florida. Its telephone number is (813) 344-4490.

Exchange Listing

Our common stock has been quoted for trading on the OTCQB under the symbol “PIRS.” In connection with this offering, our common stock has been approved for listing on the NASDAQ Capital Market under the symbol “PIRS,” beginning on June 30, 2015.

Liability and Indemnification of Directors and Officers

The Nevada Revised Statutes empower us to indemnify our directors and officers against expenses relating to certain actions, suits or proceedings as provided for therein. In order for such indemnification to be available, the applicable director or officer must not have acted in a manner that constituted a breach of his or her fiduciary duties and involved intentional misconduct, fraud or a knowing violation of law and was material to the action, or must have acted in good faith and reasonably believed that his or her conduct was in, or not opposed to, our best interests. In the event of a criminal action, the applicable director or officer must not have had reasonable cause to believe his or her conduct was unlawful.

Under applicable provisions of the Nevada Revised Statutes, our Amended and Restated Articles of Incorporation, Amended and Restated Bylaws or any separate agreement may provide for our payment of expenses incurred by any such director or officer in advance of the final disposition of the applicable action, suit or proceeding, upon delivery by such director or officer of an undertaking to repay all amounts so advanced if it is ultimately determined that the director or officer is not entitled to be indemnified by us.

Our Amended and Restated Articles of Incorporation provide for indemnification of our directors and officers substantially identical in scope to that permitted under applicable Nevada law. Our Amended and Restated Articles of Incorporation also provide that the expenses of our directors and officers incurred in defending any applicable action, suit or proceeding must be paid by us as they are incurred and in advance of the final disposition of the action, suit or proceeding, provided that the required undertaking by the director or officer is delivered to us.

We have also entered into separate indemnification agreements with each of our current directors and executive officers consistent with Nevada law and in the form approved by our Board of Directors and our stockholders, and we contemplate entering into such indemnification agreements with directors and certain executive officers that may be elected or appointed in the future. Those indemnification agreements require that under the circumstances and to the extent provided for therein, we indemnify such persons to the fullest extent permitted by applicable law against certain expenses incurred by any such person as a result of such person being made a party to certain actions, suits and proceedings by reason of the fact that such person is or was a director, officer, employee or agent of our company, any entity that was a predecessor corporation of our company or any of our affiliates. The rights of each person who is a party to such an indemnification agreement are in addition to any other rights such person may have under applicable Nevada law, our Amended and Restated Articles of Incorporation, our Amended and Restated Bylaws, any other agreement, a vote of our stockholders, a resolution adopted by our Board of Directors or otherwise. The foregoing is only a brief description of the form of indemnification agreement, does not purport to be a complete description of the rights and obligations of the parties thereunder and is qualified in its entirety by reference to the form of indemnification agreement filed as an exhibit to the registration statement of which this prospectus forms a part and incorporated herein by reference.

We also maintain a customary insurance policy that indemnifies our directors and officers against various liabilities, including liabilities arising under the Securities Act that may be incurred by any director or officer in his or her capacity as such.

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At present, there is no pending litigation or proceeding involving any of our directors or officers for which indemnification is sought, nor are we aware of any threatened litigation that is likely to result in claims for indemnification.

Insofar as indemnification for liabilities arising under the Securities Act may be permitted for our directors, officers and controlling persons pursuant to the foregoing provisions, or otherwise, we have been informed that in the opinion of the SEC such indemnification is against public policy as expressed in the Securities Act and is, therefore, unenforceable. In the event a claim for indemnification against such liabilities (other than payment by us for expenses incurred or paid by a director, officer or controlling person of ours in successful defense of any action, suit, or proceeding) is asserted by a director, officer or controlling person in connection with the securities being registered, we will, unless in the opinion of our counsel the matter has been settled by controlling precedent, submit to a court of appropriate jurisdiction, the question of whether such indemnification by it is against public policy in the Securities Act and will be governed by the final adjudication of such issue.

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SHARES ELIGIBLE FOR FUTURE SALE

There is not now, nor has there been since our inception, any significant volume of trading activity in our common stock or an active market for shares of our common stock, and an active trading market for our shares may never develop or be sustained after this offering. Future sales of substantial amounts of our common stock in the public market, including shares issued upon exercise of outstanding options and warrants, or the anticipation of these sales, could adversely affect prevailing market prices from time to time and could impair our ability to raise equity capital in the future.

As of June 17, 2015, there were 29,429,522 shares of our common stock issued and outstanding, of which 29,279,522 have been registered under the Securities Act and are freely tradable without restriction. As of June 17, 2015, there were (i) outstanding options to purchase up to 2,616,735 shares of our common stock, and (ii) outstanding warrants to purchase up to 542,360 shares of our common stock. 515,235 of our common stock are beneficially owned by our directors and executive officers (which includes shares our directors and executive officers have the right to acquire within 60 days after June 15, 2015).

Upon completion of this offering, we will have 38,520,431 shares of common stock outstanding, after giving effect to the issuance of 9,090,909 shares of our common stock in the offering, based on the number of shares outstanding as of March 31, 2015 and assuming (i) no exercise of any options or warrants outstanding as of March 31, 2015 and (ii) no exercise of the underwriters’ option to purchase additional shares from us.

Rule 144

Rule 144 promulgated under the Securities Act will generally permit the public sale of outstanding shares of our common stock that have been issued as restricted securities by the following persons and under the following circumstances commencing one year following the filing of our “Form 10 information” on our Current Report on Form 8-K, filed on December 18, 2014:

Regulation S

Regulation S under the Securities Act provides that shares owned by any person may be sold without registration in the U.S., provided that the sale is effected in an offshore transaction and no directed selling efforts are made in the U.S. (as these terms are defined in Regulation S), subject to certain other conditions. In general, this means that our shares of common stock may be sold in some other manner outside the U.S. without requiring registration in the U.S.

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Lock-up Agreements

We and each of our executive officers and directors and certain stockholders have agreed that, subject to certain exceptions that are described in more detail in the section in this prospectus entitled “Underwriting,” without the prior written consent of Oppenheimer & Co. Inc. and JMP Securities LLC, we and such officers, directors and certain stockholders will not, during the period ending 90 days after the date of this prospectus:

whether any such transaction described above is to be settled by delivery of common stock or such other securities, in cash or otherwise, or publicly announce an intention to do any of the foregoing. In addition, during such 90-day restricted period, we have agreed not make any demand for or exercise any right with respect to, the registration of any shares of common stock or any security convertible into or exercisable or exchangeable for common stock. Upon the expiration of the lock-up period, all of the shares subject to such lock-up restrictions will become eligible for sale, subject to the limitations discussed above.

Securities Authorized for Issuance under Equity Compensation Plans

Equity Compensation Plan Information

On December 17, 2014, Pieris’ Board of Directors and the holders of at least a majority of its then-outstanding capital stock adopted the Pieris Plan, which authorized the issuance of 3,200,000 shares of our common stock.

For a description of the terms of the Pieris Plan, please see “Executive Compensation—Description of Pieris Plan.” As of the date hereof, options to purchase 2,616,735 shares of our common stock have been issued under the Pieris Plan to our executive officers, directors, employees and consultants. As a result of such grants, 583,265 shares of our common stock are available for future issuances under the Pieris Plan. For additional information, see “Executive Compensation—Director Compensation” and “Executive Compensation—Description of Pieris Plan.”

We have filed a registration statement on Form S-8 under the Securities Act covering all of the shares of common stock subject to equity grants outstanding and reserved for issuance under our Pieris Plan. Accordingly, shares of our common stock issued under the Pieris Plan are eligible for sale in the public market, subject to vesting restrictions. However, resales of certain shares held by our affiliates registered on the Form S-8 will be subject to volume limitations, manner of sale, notice and public information requirements of Rule 144.

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MATERIAL U.S. FEDERAL TAX CONSIDERATIONS TO NON-U.S. HOLDERS

The following is a general discussion of the material U.S. federal income and estate tax considerations relating to ownership and disposition of our common stock by a non-U.S. holder. For purposes of this discussion, the term “non-U.S. holder” means a beneficial owner of our common stock that is not, for U.S. federal income tax purposes:

This discussion is based on current provisions of the Internal Revenue Code of 1986, as amended, or the Code, existing and proposed U.S. Treasury Regulations promulgated thereunder, current administrative rulings and judicial decisions, all as in effect as of the date of this prospectus and all of which are subject to change or to differing interpretation, possibly with retroactive effect. Any change could alter the tax consequences to non-U.S. holders described in this prospectus. In addition, the Internal Revenue Service, or the IRS, could challenge one or more of the tax consequences described in this prospectus.

We assume in this discussion that each non-U.S. holder holds shares of our common stock as a capital asset (generally, property held for investment). This discussion does not address all aspects of U.S. federal income and estate taxation that may be relevant to a particular non-U.S. holder in light of that non-U.S. holder’s individual circumstances nor does it address any aspects of state, local or non-U.S. taxes, the Medicare Contributions tax imposed under Section 1411 of the Code, or U.S. federal taxes other than income and estate taxes. This discussion does not represent a detailed description of the U.S. federal income tax consequences applicable to a non-U.S. holder subject to special treatment under the U.S. federal income tax laws (including if the non-U.S. holder is a United States expatriate, “controlled foreign corporation,” or “passive foreign investment company”).

In addition, this discussion does not address the tax treatment of partnerships or persons who hold their common stock through partnerships or other entities that are transparent for U.S. federal income tax purposes. A partner in a partnership or other transparent entity that will hold our common stock should consult his, her or its own tax advisor regarding the tax consequences of the ownership and disposition of our common stock through a partnership or other transparent entity, as applicable.

Prospective investors should consult their own tax advisors regarding the U.S. federal, state, local and non-U.S. income and other tax considerations of acquiring, holding and disposing of our common stock.

Dividends

If we pay distributions on our common stock, those distributions generally will constitute dividends for U.S. federal income tax purposes to the extent paid from our current or accumulated earnings and profits, as determined under U.S. federal income tax principles. If a distribution exceeds our current and accumulated earnings and profits, the excess will be treated as a tax-free return of the non-U.S. holder’s investment, up to such holder’s tax basis in the common stock. Any remaining excess will be treated as capital gain, subject to the tax treatment described below under the heading “—Gain on Disposition of Common Stock.”

Dividends paid to a non-U.S. holder generally will be subject to withholding of U.S. federal income tax at a 30% rate or such lower rate as may be specified by an applicable income tax treaty between the United States

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and such holder’s country of residence. If we determine, at a time reasonably close to the date of payment of a distribution on our common stock, that the distribution will not constitute a dividend because we do not anticipate having current or accumulated earnings and profits, we intend not to withhold any U.S. federal income tax on the distribution as permitted by U.S. Treasury Regulations.

Dividends that are treated as effectively connected with a trade or business conducted by a non-U.S. holder within the United States, and, if an applicable income tax treaty so provides, that are attributable to a permanent establishment or a fixed base maintained by the non-U.S. holder within the United States, are generally exempt from the 30% withholding tax if the non-U.S. holder satisfies applicable certification and disclosure requirements. To obtain this exemption, a non-U.S. holder must provide us or the applicable withholding agent with a properly executed original and unexpired IRS Form W-8ECI properly certifying such exemption. However, such U.S. effectively connected income, net of specified deductions and credits, is taxed at the same graduated U.S. federal income tax rates applicable to United States (as defined in the Code). Any U.S. effectively connected income received by a non-U.S. holder that is a corporation may also, under certain circumstances, be subject to an additional “branch profits tax” at a 30% rate or such lower rate as may be specified by an applicable income tax treaty between the United States and such holder’s country of residence.

A non-U.S. holder of our common stock who claims the benefit of an applicable income tax treaty between the United States and such holder’s country of residence providing for a reduced withholding tax rate on dividends generally will be required to provide a properly executed IRS Form W-8BEN (or successor form) and satisfy applicable certification and other requirements. Non-U.S. holders are urged to consult their own tax advisors regarding their entitlement to benefits under a relevant income tax treaty.

A non-U.S. holder that is eligible for a reduced rate of U.S. withholding tax under an income tax treaty may obtain a refund or credit of any excess amounts withheld by timely filing an appropriate claim with the IRS.

Gain on Disposition of Common Stock

Any gain realized on the disposition of our common stock generally will not be subject to United States federal income tax unless:

An individual non-U.S. holder described in the first bullet point immediately above will be subject to tax on the net gain derived from the sale under regular graduated U.S. federal income tax rates. An individual non-U.S. holder described in the second bullet point immediately above will be subject to a flat 30% tax on the gain derived from the sale, which may be offset by U.S. source capital losses, even though the individual is not considered a resident of the United States. If a non-U.S. holder that is a foreign corporation falls under the first bullet point immediately above, it will be subject to tax on its net gain in the same manner as if it were a United States person as defined under the Code and, in addition, may be subject to the branch profits tax equal to 30% of its effectively connected earnings and profits or at such lower rate as may be specified by an applicable income tax treaty.

We believe we are not and do not anticipate becoming a “United States real property holding corporation” for U.S. federal income tax purposes.

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Information Reporting and Backup Withholding Tax

We must report annually to the IRS and to each non-U.S. holder the gross amount of the distributions on our common stock paid to such holder and the tax withheld, if any, with respect to such distributions. Non-U.S. holders may have to comply with specific certification procedures to establish that the holder is not a U.S. person (as defined in the Code) in order to avoid backup withholding at the applicable rate (currently 28%) with respect to dividends on our common stock. Generally, a holder will comply with such procedures if it provides a properly executed IRS Form W-8BEN or otherwise meets documentary evidence requirements for establishing that it is a non-U.S. holder, or otherwise establishes an exemption.

Information reporting and, depending on the circumstances, backup withholding will apply to the proceeds of a sale of our common stock within the United States or conducted through certain United States-related financial intermediaries, unless the beneficial owner certifies under penalty of perjury that it is a non-U.S. holder (and the payor does not have actual knowledge or reason to know that the beneficial owner is a United States person as defined under the Code), or such owner otherwise establishes an exemption.

Copies of information returns may be made available to the tax authorities of the country in which the non-U.S. holder resides or is incorporated under the provisions of a specific treaty or agreement.

Backup withholding is not an additional tax. Any amounts withheld under the backup withholding rules from a payment to a non-U.S. holder can be refunded or credited against the non-U.S. holder’s U.S. federal income tax liability, if any, provided the required information is timely furnished to the IRS.

Additional Withholding Requirements

Under legislation enacted in 2010 and administrative guidance, a 30% U.S. federal withholding tax may apply to any dividends and the gross proceeds from a disposition of our common stock occurring after December 31, 2016, in each case paid to (i) a “foreign financial institution” (as specifically defined in the legislation), whether such foreign financial institution is the beneficial owner or an intermediary, unless such foreign financial institution agrees to verify, report and disclose its United States “account” holders (as specifically defined in the legislation) and meets certain other specified requirements or (ii) a non-financial foreign entity, whether such non-financial foreign entity is the beneficial owner or an intermediary, unless such entity provides a certification that the beneficial owner of the payment does not have any substantial United States owners or provides the name, address and taxpayer identification number of each such substantial United States owner and certain other specified requirements are met. In certain cases, the relevant foreign financial institution or non-financial foreign entity may qualify for an exemption from, or be deemed to be in compliance with, these rules. Non-U.S. holders should consult their own tax advisors regarding this legislation and whether it may be relevant to their ownership and disposition of our common stock.

Federal Estate Tax

Common stock owned or treated as owned by an individual who is a non-U.S. holder (as specially defined for U.S. federal estate tax purposes) at the time of death will be included in the individual’s gross estate for U.S. federal estate tax purposes and, therefore, may be subject to U.S. federal estate tax, unless an applicable estate tax or other treaty provides otherwise.

The preceding discussion of material U.S. federal tax considerations is for general information only. It is not tax advice. Prospective investors should consult their own tax advisors regarding the particular U.S. federal, state, local and non-U.S. tax consequences of purchasing, holding and disposing of our common stock, including the consequences of any proposed changes in applicable laws.

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UNDERWRITING

We have entered into an underwriting agreement with the underwriters named below. Oppenheimer & Co. Inc. and JMP Securities LLC are acting as the representatives of the underwriters.

The underwriting agreement provides for the purchase of a specific number of shares of common stock by each of the underwriters. The underwriters’ obligations are several, which means that each underwriter is required to purchase a specified number of shares, but is not responsible for the commitment of any other underwriter to purchase shares. Subject to the terms and conditions of the underwriting agreement, each underwriter has severally agreed to purchase the number of shares of common stock set forth opposite its name below:

The underwriters have agreed to purchase all of the shares offered by this prospectus (other than those covered by the over-allotment option described below) if any are purchased. Under the underwriting agreement, if an underwriter defaults in its commitment to purchase shares, the commitments of non-defaulting underwriters may be increased or the underwriting agreement may be terminated, depending on the circumstances.

The shares should be ready for delivery on or about July 6, 2015 against payment in immediately available funds. The underwriters are offering the shares subject to various conditions and may reject all or part of any order. The representatives have advised us that the underwriters propose to offer the shares directly to the public at the public offering price that appears on the cover page of this prospectus. In addition, the representatives may offer some of the shares to other securities dealers at such price less a concession of $0.1155 per share. After the shares are released for sale to the public, the representatives may change the offering price and other selling terms at various times.

We have granted the underwriters an over-allotment option. This option, which is exercisable for up to 30 days after the date of this prospectus, permits the underwriters to purchase a maximum of 1,363,636 additional shares from us to cover over-allotments. If the underwriters exercise all or part of this option, they will purchase shares covered by the option at the initial public offering price that appears on the cover page of this prospectus, less the underwriting discount. If this option is exercised in full, the total price to public will be approximately $28.8 million and the total proceeds to us, after deducting underwriting discounts and commissions and before expenses, will be approximately $26.7 million. The underwriters have severally agreed that, to the extent the over-allotment option is exercised, they will each purchase a number of additional shares proportionate to the underwriter’s initial amount reflected in the foregoing table.

We have agreed to indemnify the underwriters against certain liabilities, including liabilities under the Securities Act of 1933.

Commission and Expenses

The following table shows the per share and total underwriting discounts and commissions to be paid to the underwriters assuming both no exercise and full exercise of the underwriters’ option to purchase additional shares.

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We have also agreed to reimburse the underwriters for certain of their expenses, in an amount of up to $20,000, incurred in connection with review by the Financial Industry Regulatory Authority, Inc. of the terms of this offering, as set forth in the underwriting agreement.

We estimate that our total expenses of the offering, excluding the underwriting discounts and commissions, will be approximately $550,000.

No Sales of Similar Securities

We, each of our executive officers and directors and certain of our stockholders have agreed to a 90-day “lock up” with respect to shares of common stock that they beneficially own, including securities that are convertible into shares of common stock and securities that are exchangeable or exercisable for shares of common stock. This means that, subject to certain exceptions, for a period of 90 days following the date of this prospectus, we and such persons may not offer, sell, pledge or otherwise dispose of these securities without the prior written consent of the representatives.

Listing

Our common stock has been quoted for trading on the OTCQB under the symbol “PIRS.” In connection with this offering, our common stock has been approved for listing on the NASDAQ Capital Market under the symbol “PIRS,” beginning on June 30, 2015.

Stabilization

Rules of the Securities and Exchange Commission may limit the ability of the underwriters to bid for or purchase shares before the distribution of the shares is completed. However, the underwriters may engage in the following activities in accordance with the rules:

Similar to other purchase transactions, the underwriters’ purchases to cover the syndicate short sales or to stabilize the market price of our common stock may have the effect of raising or maintaining the market price

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of our common stock or preventing or mitigating a decline in the market price of our common stock. As a result, the price of the shares of our common stock may be higher than the price that might otherwise exist in the open market. The imposition of a penalty bid might also have an effect on the price of the shares if it discourages resales of the shares.

Neither we nor the underwriters makes any representation or prediction as to the effect that the transactions described above may have on the price of the shares. If such transactions are commenced, they may be discontinued without notice at any time.

Passive Market Making

In connection with the offering, the underwriters may engage in passive market-making transactions in the common stock on the NASDAQ Capital Market in accordance with Rule 103 of Regulation M under the Exchange Act through the completion and distribution of the common stock sold in this offering. A passive market-maker must display its bids at a price not in excess of the highest independent bid of the security. However, if all independent bids are lowered below the passive market-maker’s bid, that bid must be lowered when specified purchase limits are exceeded.

Electronic Delivery of Prospectus

A prospectus in electronic format may be delivered to potential investors by one or more of the underwriters participating in this offering. The prospectus in electronic format will be identical to the paper version of such prospectus. Other than the prospectus in electronic format, the information on any underwriter’s web site and any information contained in any other web site maintained by an underwriter is not part of this prospectus or the registration statement of which this prospectus forms a part.

Other Activities and Relationships

The underwriters and certain of their affiliates are full service financial institutions engaged in various activities, which may include securities trading, commercial and investment banking, financial advisory, investment management, investment research, principal investment, hedging, financing and brokerage activities. The underwriters and certain of their affiliates have, from time to time, performed, and may in the future perform, various commercial and investment banking and financial advisory services for us and our affiliates, for which they received or will receive customary fees and expenses. As consideration for services provided as a sub-placement agent in connection with our issuance and sale of an aggregate of 6,779,510 shares of our common stock in a private placement offering conducted through a series of closings occurring on December 17, 18 and 23, 2014, we issued to Trout Capital, LLC warrants to purchase an aggregate of 80,000 shares of our common stock at an exercise price of $2.00 per share. Such securities are deemed by the Financial Industry Regulatory Authority, Inc. to be underwriter compensation and are therefore subject to a 180-day lock-up. Pursuant to FINRA Rule 5110(g)(1), these securities will not be sold, transferred, assigned, pledged or hypothecated, or be subject to any hedging, short sale, derivative, put, or call transaction that would result in the effective economic disposition of such securities for a period of 180 days immediately following the date of this prospectus.

In the ordinary course of their various business activities, the underwriters and certain of their affiliates may make or hold a broad array of investments and actively trade debt and equity securities (or related derivative securities) and financial instruments (including bank loans) for their own account and for the accounts of their customers, and such investment and securities activities may involve securities and/or instruments issued by us and our affiliates. If the underwriters or their respective affiliates have a lending relationship with us, they routinely hedge their credit exposure to us consistent with their customary risk management policies. The underwriters and their respective affiliates may hedge such exposure by entering into transactions which consist of either the purchase of credit default swaps or the creation of short positions in our securities or the securities

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of our affiliates, including potentially the common shares offered hereby. Any such short positions could adversely affect future trading prices of the common shares offered hereby. The underwriters and certain of their respective affiliates may also communicate independent investment recommendations, market color or trading ideas and/or publish or express independent research views in respect of such securities or instruments and may at any time hold, or recommend to clients that they acquire, long and/or short positions in such securities and instruments.

International Selling Restrictions

Other than in the United States, no action has been taken by us or the underwriters that would permit a public offering of the securities offered by this prospectus in any jurisdiction where action for that purpose is required. The securities offered by this prospectus may not be offered or sold, directly or indirectly, nor may this prospectus or any other offering material or advertisements in connection with the offer and sale of any such securities be distributed or published in any jurisdiction, except under circumstances that will result in compliance with the applicable rules and regulations of that jurisdiction. Persons into whose possession this prospectus comes are advised to inform themselves about and to observe any restrictions relating to the offering and the distribution of this prospectus. This prospectus does not constitute an offer to sell or a solicitation of an offer to buy any securities offered by this prospectus in any jurisdiction in which such an offer or a solicitation is unlawful.

Belgium

The offering is exclusively conducted under applicable private placement exemptions and therefore it has not been and will not be notified to, and this document or any other offering material relating to the securities has not been and will not be approved by, the Belgian Banking, Finance and Insurance Commission (“Commission bancaire, financière et des assurances/Commissie voor het Bank-, Financie-en Assurantiewezen”). Any representation to the contrary is unlawful.

Each underwriter has undertaken not to offer sell, resell, transfer or deliver directly or indirectly, any securities, or to take any steps relating/ancillary thereto, and not to distribute or publish this document or any other material relating to the securities or to the offering in a manner which would be construed as: (a) a public offering under the Belgian Royal Decree of 7 July 1999 on the public character of financial transactions; or (b) an offering of securities to the public under Directive 2003/71/EC which triggers an obligation to publish a prospectus in Belgium. Any action contrary to these restrictions will cause the recipient and us to be in violation of the Belgian securities laws.

France

Neither this prospectus nor any other offering material relating to the securities has been submitted to the clearance procedures of the Autorité des marchés financiers in France. The securities have not been offered or sold and will not be offered or sold, directly or indirectly, to the public in France. Neither this prospectus nor any other offering material relating to the securities has been or will be: (a) released, issued, distributed or caused to be released, issued or distributed to the public in France; or (b) used in connection with any offer for subscription or sale of the securities to the public in France. Such offers, sales and distributions will be made in France only: (i) to qualified investors (investisseurs qualifiés) and/or to a restricted circle of investors (cercle restreint d’investisseurs), in each case investing for their own account, all as defined in and in accordance with Articles L.411-2, D.411-1, D.411-2, D.734-1, D.744-1, D.754-1 and D.764-1 of the French Code monétaire et financier; (ii) to investment services providers authorised to engage in portfolio management on behalf of third parties; or (iii) in a transaction that, in accordance with article L.411-2-II-1° or -2° or -3° of the French Code monétaire et financier and article 211-2 of the General Regulations (Règlement Général) of the Autorité des marchés financiers, does not constitute a public offer (appel public à l’épargne). Such securities may be resold only in compliance with Articles L.411-1, L.411-2, L.412-1 and L.621-8 through L.621-8-3 of the French Code monétaire et financier.

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United Kingdom/Germany/Norway/The Netherlands

In relation to each Member State of the European Economic Area which has implemented the Prospectus Directive (each, a “Relevant Member State”) an offer to the public of any securities which are the subject of the offering contemplated by this prospectus may not be made in that Relevant Member State other than any offer where a prospectus has been or will be made to the public in that Relevant Member State or, where appropriate, approved in another Relevant Member State and notified to the relevant competent authority in that Relevant Member State in accordance with the Prospectus Directive except that an offer to the public in that Relevant Member State of any securities may be made at any time under the following exemptions under the Prospectus Directive, if they have been implemented in that Relevant Member State:

For the purposes of this provision, the expression an “offer to the public” in relation to any securities in any Relevant Member State means the communication in any form and by any means of sufficient information on the terms of the offer and any securities to be offered so as to enable an investor to decide to purchase any securities, as the same may be varied in that Member State by any measure implementing the Prospectus Directive in that Member State and the expression “Prospectus Directive” means Directive 2003/71/EC and includes any relevant implementing measure in each Relevant Member State.

Each underwriter has represented, warranted and agreed that:

Israel

In the State of Israel, the securities offered hereby may not be offered to any person or entity other than the following:

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