Takeda: FDA approves MIMRYLO (rusfertide) for erythrocytosis in polycythemia vera

What was approved

The U.S. FDA approved MIMRYLO (rusfertide) for the treatment of erythrocytosis in adults with polycythemia vera (PV). MIMRYLO is described as a first-in-class hepcidin mimetic that regulates iron distribution and red blood cell production to control hematocrit, where maintaining levels below 45% is the primary treatment goal in PV.

Key clinical data

Approval was supported by the global randomized Phase 3 VERIFY study (NCT05210790) of 293 patients, which met all efficacy endpoints. VERIFY showed 76.9% of patients achieved clinical response during weeks 20–32. Outcomes reported included hematocrit control, a reduction in the need for phlebotomy and improvement in fatigue measured by the PROMIS Fatigue Short Form 8a.

Clinical need and patient impact

PV affects an estimated 90,000 people in the U.S. and is driven by erythrocytosis that raises hematocrit and blood viscosity, increasing risk of thrombotic events. The release notes that about 78% of patients still experience uncontrolled hematocrit with current standard of care and that uncontrolled hematocrit is associated with a fourfold higher risk of cardiovascular death or major cardiovascular events. Symptoms cited include severe fatigue, pruritus, concentration difficulties and night sweats.

Safety and next steps

MIMRYLO was generally well tolerated through 52 weeks; the most common treatment-emergent adverse events were injection-site reactions and anemia. The VERIFY open-label extension is ongoing, further data will be presented at medical conferences, and Takeda is pursuing regulatory reviews outside the U.S.