On August 28, the U.S. Food and Drug Administration (FDA) approved rusfertide (Mimrylo) for the treatment of erythrocytosis in adults with polycythemia vera (PV). Rusfertide is a first-in-class hepcidin mimetic designed to regulate iron distribution in the body and red blood cell overproduction to control hematocrit levels.
VERIFY Trial
The approval was supported by data from the global randomized phase III VERIFY study (ClinicalTrials.gov identifier NCT05210790) that included 293 patients with PV, showing that rusfertide met all efficacy endpoints and demonstrated a favorable safety profile. In the study, patients receiving rusfertide plus current standard of care demonstrated a higher response rate compared to placebo plus current standard of care. This included hematocrit control, a reduction in the need for phlebotomy, and improvement in fatigue as measured by PROMIS Fatigue Short Form 8a.
Findings from VERIFY were presented in the Plenary Session of the 2025 ASCO Annual Meeting.
Rusfertide was generally well-tolerated through 52 weeks of treatment in the VERIFY trial. The most common treatment-emergent adverse events in rusfertide-treated patients were injection site reactions and anemia.
“For patients living with PV, uncontrolled hematocrit can have serious consequences, including an elevated risk of life-threatening thrombotic events," said Andrew T. Kuykendall, MD, VERIFY lead investigator and Associate Member in the Department of Hematology at Moffitt Cancer Center. “Current treatments, such as phlebotomy, leave a significant gap for too many patients and can pose challenges to daily life and routines. The approval of rusfertide offers clinicians and patients a novel, first-in-class therapy that targets erythrocytosis, which drives excess red blood cell production in PV. The strength and consistency of the VERIFY data give me real confidence in rusfertide’s potential to advance how we treat PV in everyday practice and to maintain hematocrit control.”
Uncontrolled Hematocrit is a Challenge in the Treatment of PV
Affecting approximately 90,000 people in the United States, PV is characterized by erythrocytosis, leading to elevated hematocrit, which can increase blood viscosity. This has the potential to result in life-threatening thrombotic events, including stroke, deep vein thrombosis, and pulmonary embolism. Maintaining hematocrit levels consistently below 45% can prevent thrombotic events and alleviate burdensome symptoms, including severe fatigue, pruritus, difficulty concentrating, and night sweats. An estimated 78% of patients still experience uncontrolled hematocrit with current standard of care, including phlebotomy and cytoreductive therapies. Patients with PV experiencing uncontrolled hematocrit have a four times higher risk of cardiovascular death or major cardiovascular events.
“People living with PV often experience complex and invisible symptoms, from extreme fatigue to the emotional strain of living with a chronic blood cancer,” said Kapila Viges, Chief Executive Officer of the MPN Research Foundation. “At the same time, we know that every patient’s experience with PV is different, underscoring the need to continue to listen closely to the community to understand what matters most. There remains a need for treatments that better address these daily challenges. This meaningful approval reflects important progress and brings forward a new treatment option in a disease where patients have long needed innovation and more choices. We are encouraged by rusfertide’s potential to help patients meet their treatment goals.”
More information about the VERIFY trial can be found here.
