Protagonist Therapeutics Announces Amendment of Agreement with Janssen Biotech for the Continued Development and Commercialization of IL-23 Antagonists

Protagonist Therapeutics, Inc. (Nasdaq:PTGX) ("Protagonist" or "the Company") today announced its entry into an amended collaboration agreement (the "Restated Agreement") with Janssen Biotech, Inc., one of the Janssen Pharmaceutical Companies of Johnson & Johnson, relating to research, development, manufacture and commercialization of multiple oral Interleukin (IL)-23 receptor antagonist drug candidates. The compounds currently in development are PTG-200, an oral IL-23 receptor antagonist in Phase 2 development for the treatment of Crohn's disease (CD), and PN-232 and PN-235, two second-generation oral IL-23 receptor antagonist candidates. PN-232 and PN-235 are currently in Phase 1 clinical development.

The amended agreement provides for the concurrent development of multiple oral IL-23 receptor antagonists against a broad range of indications. As such, certain development milestones have been reconfigured based on multiple drug candidates advancing in parallel. Protagonist remains eligible to potentially receive approximately $900 million in future development and sales milestones, in addition to the $80 million in payments already received under the original agreement. Royalty rates remain unchanged. Janssen will have the right to continue research on IL-23 receptor antagonists developed during the collaboration for three years from the closing of the Restated Agreement.

Under the terms of the Restated Agreement, Janssen will conduct all future studies beyond those that are currently ongoing with PTG-200, PN-232 and PN-235 and will be solely financially responsible for any such studies. Accordingly, Protagonist's development and expense obligations will be limited to its relative share of the currently ongoing studies with these candidates. With this revised agreement, Janssen will continue to deploy the breadth of its established global capabilities and proven experience toward further clinical development of these assets.

"We are very pleased with this amendment to our agreement, which reflects the successful trajectory of the collaboration to date, giving rise to the parallel development of multiple oral IL-23 receptor antagonists," said Dinesh Patel, PhD, President and Chief Executive Officer of Protagonist. "The progress from de novo discovery to development validates our innovative technology platform and its potential to develop oral peptide drugs for diverse clinical indications. We look forward to supporting our Janssen counterparts in their parallel development efforts for PTG-200, PN-232, and PN-235 in multiple indications, which may ultimately provide significant benefit to patients."

Janssen retains exclusive, worldwide rights to develop and commercialize PTG-200, PN-232, PN-235 and any other second-generation compounds derived from the research collaboration conducted under the Original Agreement, or Janssen's further research under the Restated Agreement. Protagonist will have the right to co-detail up to two licensed products in ulcerative colitis (UC) and CD in the U.S. market.

Further details related to the Restated Agreement are available on the Company's Form 8-K as submitted to the U.S. Securities and Exchange Commission.

About Protagonist Therapeutics

Protagonist Therapeutics is a biopharmaceutical company with multiple peptide-based investigational new chemical entities in different stages of development, all derived from the Company's proprietary technology platform.

Protagonist's pipeline includes rusfertide (PTG-300), an investigational, injectable hepcidin mimetic currently in a Phase 2 proof-of-concept clinical trial for polycythemia vera (PV), a Phase 2 study in PV subjects with high hematocrit levels, and a Phase 2 study for hereditary hemochromatosis. Based on the feedback provided by the FDA and EU regulatory authorities, the Company plans to initiate a single, global Phase 3 randomized, placebo-controlled trial evaluating the efficacy and safety of a once weekly, subcutaneously self-administered dose of rusfertide.

The Company is also evaluating an orally delivered, gut-restricted alpha-4-beta-7 integrin specific antagonist peptide (PN-943) currently in a Phase 2 study in adults with moderate to severe active ulcerative colitis (UC). The Company is targeting ulcerative colitis as the initial indication.

The Company has a worldwide license and collaboration agreement with Janssen Biotech, Inc., for the development of oral peptide IL-23 receptor antagonists. Compounds included in this agreement are PTG-200, PN-235 and PN-232. PTG-200 is an orally delivered interleukin-23 receptor specific antagonist peptide in a Phase 2 clinical trial for Crohn's disease. PN-235 and PN-232, both second-generation oral interleukin-23 receptor antagonist candidates, are currently in Phase 1 studies.