Protagonist Therapeutics, Newark, California, August 28, 2026
Protagonist Therapeutics announced that the U.S. Food and Drug Administration (FDA) has approved MIMRYLO™ (rusfertide) for the treatment of erythrocytosis in adults with polycythemia vera (PV), marking the company’s second FDA approval in 2026. Developed as a first-in-class hepcidin mimetic peptide, MIMRYLO is designed to regulate iron availability and reduce excessive red blood cell production associated with PV. The approval represents a significant milestone for Protagonist’s peptide-based drug discovery and development platform and expands the company’s portfolio of partnered medicines. Takeda Pharmaceutical Company Limited, which holds worldwide commercialization rights under its collaboration with Protagonist, will commercialize MIMRYLO following the regulatory approval. The company said the approval establishes a new therapeutic approach for managing erythrocytosis in adults with PV.
MIMRYLO Introduces Novel Hepcidin-Based Approach
MIMRYLO is the first and only hepcidin mimetic peptide approved for PV, providing a mechanism designed to address iron dysregulation underlying excessive red blood cell production. Rusfertide mimics the activity of naturally occurring hepcidin, a key regulator of iron availability in the body. By reducing iron availability to erythroid progenitor cells, MIMRYLO is designed to help control hematocrit levels while potentially reducing the need for repeated phlebotomy. The therapy is administered through a weekly subcutaneous injection and is approved specifically for adults with PV experiencing erythrocytosis. According to Protagonist, the approved product label also reflects improvement in fatigue, an important symptom burden for people living with PV. The approval therefore strengthens the company’s position in developing therapies that target underlying disease biology rather than relying solely on conventional approaches to hematocrit management.
FDA Approval Activates Major Takeda Milestones
The FDA decision also has a substantial financial impact for Protagonist Therapeutics through its global collaboration with Takeda. The approval triggers $275 million in payments to Protagonist, consisting of a $200 million opt-out fee and a separate $75 million approval milestone. Protagonist remains eligible for up to $875 million in additional potential milestone payments, together with tiered royalties ranging from 14% to 29% of worldwide net sales. The company previously discovered rusfertide and led its development through Phase 3 before Takeda assumed responsibility for regulatory submission and commercialization following Protagonist’s opt-out election in April 2026. The partnership provides Protagonist with a potentially significant long-term revenue stream while allowing Takeda to lead the commercial launch of the newly approved therapy. The company said the MIMRYLO approval further validates its peptide-centric discovery and development capabilities and provides additional financial support for advancing its wholly owned pipeline.
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Protagonist Advances Pipeline Following Second Approval
The approval of MIMRYLO follows Protagonist’s earlier FDA approval of ICOTYDE™ (icotrokinra) in 2026, giving the company two approved medicines generated from its peptide technology platform. Protagonist said its strategic focus is now shifting toward advancing the next generation of wholly owned candidates in areas including IL-17, obesity and other unmet medical needs. MIMRYLO’s regulatory success was supported by the Phase 3 VERIFY study, in which treatment demonstrated significant benefits across key measures of hematocrit control, phlebotomy burden and fatigue compared with placebo plus standard of care. The company reported that 76.9% of patients receiving MIMRYLO achieved a clinical response during Weeks 20-32, compared with 32.9% for placebo plus standard of care. Protagonist and Takeda will now move toward commercialization of MIMRYLO in the United States, positioning the therapy as a new treatment option for adults with PV and strengthening Protagonist’s growing presence in innovative peptide therapeutics.
Source:Protagonist Therapeutics,,press relese
