Rusfertide Receives Breakthrough Therapy Designation for Treatment of Erythrocytosis in Patients with Polycythemia Vera

Breakthrough Therapy designation complements Rusfertide's Orphan Drug and Fast Track designations, which together confer multiple benefits to the development program

U.S. New Drug Application filing for Rusfertide in polycythemia vera on track for Q4

NEWARK, CA / ACCESS Newswire / August 25, 2025 / Protagonist Therapeutics, Inc. ("Protagonist" or "the Company") announced today that rusfertide, a potential first-in-class hepcidin-mimetic peptide, has been granted Breakthrough Therapy Designation by the U.S. Food and Drug Administration (FDA) for the treatment of erythrocytosis in patients with polycythemia vera (PV). In 2020, rusfertide received Orphan Drug status and Fast Track designation. Breakthrough Therapy Designation is a process designed to expedite the development and review of drugs that are intended to treat a serious condition and preliminary clinical evidence indicates that the drug may demonstrate substantial improvement over available therapies.¹ Breakthrough Therapy Designation also conveys eligibility for priority NDA review¹ and Orphan Drug Designation qualifies sponsors for various incentives including a potential for extended market exclusivity.²

Breakthrough designation for rusfertide was supported by positive 32-week data from the Phase 3 VERIFY study, which was presented as a late breaking abstract highlighting its practice-changing potential during the plenary session at the 2025 American Society of Clinical Oncology (ASCO) Annual Meeting.

"We are very pleased with the FDA's decision to grant Breakthrough Therapy Designation to rusfertide, which underscores its potential to demonstrate substantial improvement over available PV therapies," said Dinesh V. Patel, Ph.D., President and Chief Executive Officer at Protagonist. We remain on track for NDA submission of rusfertide in polycythemia vera by the end of this year."

"In the VERIFY Phase 3 trial, rusfertide demonstrated positive results across all primary and key secondary endpoints including hematocrit control, decreased phlebotomy dependence, and patient reported outcomes including improvement in fatigue," said Arturo Molina, M.D., M.S., Chief Medical Officer at Protagonist. "The comprehensive data provide compelling evidence of the potential for rusfertide to address unmet medical needs in patients with PV who are unable to achieve adequate hematocrit control with standard of care or currently available treatments."

Rusfertide is being co-developed with Takeda Pharmaceuticals pursuant to a worldwide collaboration and license agreement entered in 2024, under which Protagonist remains primarily responsible for development through NDA filing.

About VERIFY
The Phase 3 VERIFY study (NCT05210790) is an ongoing, three-part, global, randomized, placebo-controlled study evaluating rusfertide in 293 patients with polycythemia vera over a 156-week period. The study is evaluating the efficacy and safety of once-weekly, subcutaneously self-administered rusfertide in patients with uncontrolled hematocrit who are phlebotomy dependent despite current standard of care treatment, which could include hydroxyurea, interferon and/or ruxolitinib. The primary endpoint of the study was the proportion of patients achieving a response during weeks 20-32, which was defined as the absence of "phlebotomy eligibility." To meet phlebotomy eligibility, patients in the study were required to have: confirmed hematocrit ≥45% that was ≥3% higher than their baseline hematocrit value, or hematocrit ≥48%.

All patients have completed their participation in the randomized, placebo-controlled portion of the study evaluating the efficacy and safety of rusfertide plus current treatment versus placebo plus current treatment and are now in the open-label portion of the study.

About Protagonist
Protagonist Therapeutics is a discovery through late-stage development biopharmaceutical company. Two novel peptides derived from Protagonist's proprietary discovery platform are currently in advanced Phase 3 clinical development, with New Drug Application (NDA) for icotrokinra submitted to the FDA in July and the NDA submission for rusfertide expected by end of 2025. Icotrokinra (formerly, JNJ-2113), a first-in-class investigational targeted oral peptide that selectively blocks the Interleukin-23 receptor ("IL-23R") is licensed to J&J Innovative Medicines ("JNJ"), formerly Janssen Biotech, Inc.. Following icotrokinra's joint discovery by Protagonist and JNJ scientists pursuant to the companies' IL-23R collaboration, Protagonist was primarily responsible for development of icotrokinra through Phase 1, with JNJ assuming responsibility for development in Phase 2 and beyond. Rusfertide, a mimetic of the natural hormone hepcidin, is currently in Phase 3 development for the rare blood disorder polycythemia vera (PV). Rusfertide is being co-developed and will be co-commercialized with Takeda Pharmaceuticals pursuant to a worldwide collaboration and license agreement entered in 2024 under which the Company remains primarily responsible for development through NDA filing. The Company also has a number of pre-clinical stage drug discovery programs addressing clinically and commercially validated targets, including IL-17 oral peptide antagonist PN-881, an obesity triple agonist peptide PN-477, and the oral hepcidin program.

More information on Protagonist, its pipeline drug candidates and clinical studies can be found on the Company's website at https://www.protagonist-inc.com/.

Cautionary Note on 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 the potential benefits of rusfertide and the timing of rusfertide regulatory submissions. In some cases, you can identify these statements by forward-looking words such as "anticipate," "believe," "may," "will," "expect," 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 ability to develop and commercialize our product candidates, our ability to earn milestone payments under our collaboration agreements with Janssen and Takeda, 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. Additional information concerning these and other risk factors affecting our business can be found in our periodic filings with the Securities and Exchange Commission, including under the heading "Risk Factors" contained in our most recently filed periodic reports on Form 10-K and Form 10-Q filed with the Securities and Exchange Commission. 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.

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Endnotes