OSAKA, Japan & CAMBRIDGE, Massachusetts, August 28, 2026
Takeda 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), a chronic blood cancer characterized by excessive red blood cell production. The approval introduces a first-in-class hepcidin mimetic designed to regulate iron distribution and help control hematocrit, a key treatment target in PV.
MIMRYLO Targets Hematocrit Control in PV
Polycythemia vera affects approximately 90,000 people in the United States and can cause elevated hematocrit, increasing blood viscosity and the risk of serious thrombotic events such as stroke, deep vein thrombosis and pulmonary embolism. Maintaining hematocrit below 45% is a primary treatment goal because sustained control can help reduce thrombotic risk and alleviate symptoms including fatigue, itching, night sweats and difficulty concentrating. However, Takeda notes that an estimated 78% of patients continue to experience uncontrolled hematocrit despite existing standard-of-care approaches, including phlebotomy and cytoreductive therapies. MIMRYLO is designed to address the underlying biology of excess red blood cell production. As a hepcidin mimetic, the therapy mimics the activity of hepcidin, a natural hormone involved in iron homeostasis and erythrocytosis. By regulating iron availability, the treatment aims to reduce excessive red blood cell production and support sustained hematocrit control. MIMRYLO is administered as a once-weekly subcutaneous injection and has been generally well tolerated in clinical studies.
Phase 3 VERIFY Data Support FDA Approval
The FDA approval was supported by results from the global randomized Phase 3 VERIFY study (NCT05210790), which enrolled 293 patients with polycythemia vera. The study evaluated MIMRYLO added to current standard of care against placebo plus standard of care in patients with uncontrolled hematocrit who remained dependent on phlebotomy. The trial showed that MIMRYLO achieved its efficacy endpoints, including hematocrit control, reduced phlebotomy requirements and improvement in fatigue measured using the PROMIS Fatigue Short Form 8a. According to Takeda, 76.9% of patients achieved clinical response during Weeks 20–32, supporting the therapy’s potential to reduce the burden associated with uncontrolled erythrocytosis. The VERIFY trial evaluated patients over a planned 156-week period, with the primary endpoint assessing the proportion of patients achieving a response during Weeks 20–32 without meeting predefined phlebotomy-eligibility criteria. Secondary measures included maintaining hematocrit below 45%, reducing phlebotomy frequency and improving fatigue and overall symptom burden.
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Safety Profile and Next Regulatory Steps
MIMRYLO was generally well tolerated through 52 weeks of treatment in the VERIFY trial. The most common treatment-emergent adverse events were injection-site reactions and anemia. The prescribing information also includes warnings concerning new or worsening thrombocytosis, injection-site reactions and embryo-fetal toxicity. The most common adverse reactions occurring in more than 15% of treated patients were injection-site reactions (56%) and anemia (16%). The FDA decision marks a significant milestone for Takeda’s oncology portfolio and PV treatment development, while the company continues to work with regulators outside the United States to potentially expand access to MIMRYLO worldwide. The open-label extension of VERIFY remains ongoing, with additional findings expected from upcoming medical conferences. Takeda holds exclusive global development and commercialization rights for MIMRYLO after Protagonist discovered the therapy and led its development through Phase 3.
Source: Takeda press relese
