FDA Approves Mimrylo (Rusfertide), the First-in-Class Hepcidin Mimetic Peptide, for Erythrocytosis in Polycythemia Vera
Takeda (NYSE: TAK) and Protagonist Therapeutics (NASDAQ: PTGX) announced Friday August 28, 2026 FDA approval of Mimrylo (rusfertide, a first-in-class subcutaneous synthetic hepcidin mimetic peptide) for the treatment of erythrocytosis in adults with polycythemia vera (PV), a rare BCR-ABL-negative myeloproliferative neoplasm in which uncontrolled red blood cell production drives increased thrombotic risk. Approval was based on the Phase 3 VERIFY trial (n=293) in which 76.9% of patients on rusfertide plus standard of care were phlebotomy-free through Week 32 versus 32.9% on placebo plus standard of care, with statistically significant improvements in hematocrit control and patient-reported fatigue and symptom burden. Adverse events were generally low-grade and included localized injection-site reactions (55.9%), anemia (15.9%), and fatigue (15.2%). Mimrylo will be commercialized by Takeda under the 2024 worldwide license and collaboration agreement with Protagonist and will ship within 48 hours. Jefferies analysts project peak sales potential of $2 billion. The mechanism (mimicking the natural iron-regulator hepcidin to constrain iron availability for erythropoiesis) is the first commercial validation of the hepcidin mimetic peptide class after more than a decade of academic development.