$PTGX Enters into Worldwide Agreement with Janssen on IBD

– Protagonist grants Janssen exclusive, worldwide rights to PTG-200, a first-in-class oral peptide IL-23 receptor antagonist currently in pre-clinical development – Protagonist to receive a $50 million upfront payment and potentially up to an additional $940 million in development and sales milestones; double-digit tiered royalties on net sales – Protagonist and Janssen to co-fund development through Phase 2; Protagonist retains option to co-detail U.S. prescribers – Protagonist to host conference call and webcast today, May 30, at 8:00 a.m. Eastern Daylight Time

NEWARK, Calif., May 30, 2017  — Protagonist Therapeutics, Inc. (Nasdaq: PTGX) today announced that the company has entered into a worldwide license and collaboration agreement with Janssen Biotech, Inc., one of the Janssen Pharmaceutical Companies of Johnson & Johnson, for the co-development and commercialization of PTG-200, Protagonist’s first-in-class, oral peptide IL-23 receptor antagonist for all indications including inflammatory bowel disease (IBD). PTG-200 is expected to enter Phase 1 clinical testing in normal healthy volunteers in the second half of 2017. The agreement builds upon a Johnson & Johnson Innovation – JJDC, Inc. Series B venture financing from 2013 in support of the discovery and development of Protagonist’s pipeline of oral peptide therapeutics.

“We are very pleased to partner with Janssen, a world-leader in the development of innovative therapies for patients suffering with chronic inflammatory and immunomodulatory diseases. As an oral IL-23 receptor antagonist, PTG-200 nicely complements Janssen’s current IBD portfolio,” said Dinesh V. Patel, Ph.D., Protagonist’s President and Chief Executive Officer. “The funding provided by this transaction enables us to advance our platform and clinical pipeline of innovative peptide drugs, including our lead oral peptide alpha-4-beta-7 integrin antagonist, PTG-100, which is currently in a Phase 2b clinical trial as a potential treatment for ulcerative colitis.”

“Our oral peptide PTG-200 works by blocking the IL-23 pathway, a mechanism which has been proven by injectable antibodies, including an approved drug and others in different stages of clinical development,” said David Y. Liu, Ph.D., Protagonist’s Chief Scientific Officer and Head of R&D. “As evidenced by PTG-200, we believe our technology platform is validated in its ability to generate potential first-in-class oral peptides as the next generation of targeted therapy drugs for IBD.”

Terms of the Collaboration

Under the terms of the license and collaboration agreement, Protagonist will receive an upfront payment of $50 million from Janssen, and will also be eligible to receive up to an additional $940 million in development, regulatory, and sales milestones. The development milestones represent significant payments that Protagonist would receive upon completion of each component of the Phase 2a/2b clinical trial in Crohn’s disease if Janssen elects to retain its license following each of those events. Janssen will receive exclusive, worldwide rights to develop and commercialize PTG-200, and Protagonist will receive double-digit tiered royalties on net product sales.

Protagonist Therapeutics and Janssen will jointly conduct the development of PTG-200 through Phase 2 clinical proof-of-concept in Crohn’s disease, after which time Janssen will be responsible for development and commercialization. Per the terms of the agreement, Protagonist will have the right to co-detail PTG-200 in the United States.

The transaction is expected to close in the third quarter of 2017, subject to customary closing conditions.

Additional details regarding the collaboration can be found in Protagonist’s Form 8-K filed today with the Securities and Exchange Commission.

Conference Call and Webcast Information

Protagonist Therapeutics will host a conference call to discuss this transaction at 8:00 a.m. EDT today, May 30, 2017. The live webcast can be accessed under “Events and Presentations” in the Investors section of the company’s website at www.protagonist-inc.com. The webcast will be available for replay for 30 days on the company website. Alternatively, investors may listen to the call by dialing toll-free 844-515-9178 from locations in the United States or via toll call +1-614-999-9313 from outside the United States. Please refer to conference ID number 30341699.

About PTG-200

PTG-200 is a first-in-class oral Interleukin-23 receptor (IL-23R) antagonist being co-developed with Janssen initially for the treatment of Crohn’s disease. PTG-200 is currently in pre-clinical development studies, and is expected to enter Phase 1 clinical testing in the second half of 2017.

PTG-200 may have the potential to transform the existing IBD treatment paradigm because it is designed to offer significant advantages over injectable antibody drugs, including improved convenience, patient compliance, and the potential for improved safety and tolerability compared to currently approved injectable antibody drugs.

About Protagonist Therapeutics

Protagonist Therapeutics is a clinical-stage biopharmaceutical company with a proprietary technology platform which is utilized to discover and develop novel peptide-based drugs to address significant unmet medical needs. Its primary focus is on developing potential first-in-class oral targeted therapy-based peptide drugs that work by blocking biological pathways that are currently targeted by marketed injectable antibody drugs. Protagonist’s initial lead peptide product candidates, PTG-100 and PTG-200, are based on this approach, and the company believes these candidates have the potential to transform the existing treatment paradigm for inflammatory bowel disease (IBD), chronic gastrointestinal diseases consisting primarily of ulcerative colitis and Crohn’s disease.

PTG-100, a potential first-in-class oral peptide alpha-4-beta-7 integrin antagonist, is currently in a global Phase 2b clinical trial for treatment of moderate-to-severe ulcerative colitis.  PTG-200, a first-in-class oral Interleukin-23 receptor antagonist for potential treatment of IBD, initially Crohn’s disease, is currently in pre-clinical development and is expected to enter a Phase 1 clinical study in the second half of 2017.

In addition to PTG-100 and PTG-200, the company is developing an injectable hepcidin mimetic PTG-300 as a potential orphan drug for the treatment of rare diseases such as beta-thalassemia.  PTG-300 is currently being studied in a Phase 1 clinical trial.

Protagonist is headquartered in Newark, California with its pre-clinical and clinical staff in California, and discovery operations both in California and in Brisbane, Queensland, Australia. For further information, please visit http://www.protagonist-inc.com.

Forward Looking Statements

This press release contains forward-looking statements for purposes of the safe harbor provisions of the Private Securities Litigation Reform Act of 1995. Forward-looking statements include statements regarding our intentions or current expectations concerning, among other things, the potential for our programs, the timing of our clinical trials, the potential for eventual regulatory approval and commercialization of our product candidates and our potential receipt of milestone payments and royalties under our collaboration agreement with Janssen. In some cases you can identify these statements by forward-looking words such as “may,” “will,” “continue,” “expect,” “potential,” or the negative or plural of these words or similar expressions.  Forward-looking statements are not guarantees of future performance and are subject to risks and uncertainties that could cause actual results and events to differ materially from those anticipated, including, but not limited to, our history of net operating losses, our reliance on third parties and uncertainty regarding our ability to achieve profitability, our ability to develop and commercialize our product candidates, our ability to use and expand our programs to build a pipeline of product candidates, our ability to obtain and maintain regulatory approval of our product candidates, our ability to operate in a competitive industry and compete successfully against competitors that have greater resources than we do,  and our ability to obtain and adequately protect intellectual property rights for our product candidates.  We discuss many of these risks in greater detail under the heading “Risk Factors” contained in our Quarterly Report on Form 10-Q for the quarter ended March 31, 2017, filed with the Securities and Exchange Commission on May 10, 2017. Forward-looking statements are not guarantees of future performance, and our actual results of operations, financial condition and liquidity, and the development of the industry in which we operate, may differ materially from the forward-looking statements contained in this press release. Any forward-looking statements that we make in this press release speak only as of the date of this press release. We assume no obligation to update our forward-looking statements whether as a result of new information, future events or otherwise, after the date of this press release.