The U.S. Food and Drug Administration (FDA) has approved Takeda’s Mimrylo (rusfertide) for the treatment of erythrocytosis in adults with polycythemia vera (PV), introducing the first-in-class hepcidin mimetic for the chronic blood cancer.
The approval is supported by results from the Phase 3 VERIFY trial, in which Mimrylo demonstrated improved hematocrit control, reduced the need for phlebotomy, and improved fatigue when added to current standard-of-care treatment.
A First-in-Class Approach to Polycythemia Vera
Polycythemia vera is a chronic myeloproliferative blood cancer characterized by excessive red blood cell production, or erythrocytosis. This increases hematocrit and blood viscosity and can raise the risk of serious thrombotic complications, including stroke, deep vein thrombosis, and pulmonary embolism.
Maintaining hematocrit below 45% is a central treatment goal in PV.
Mimrylo is a hepcidin mimetic that regulates iron distribution and limits the iron available for excessive red blood cell production. The treatment is administered as a once-weekly subcutaneous injection.
According to Takeda, approximately 90,000 people in the United States are affected by PV, while a substantial proportion of patients continue to experience inadequately controlled hematocrit despite existing treatments, including phlebotomy and cytoreductive therapy.
VERIFY Phase 3 Trial Supports Approval
The approval was supported by the global, randomized, placebo-controlled Phase 3 VERIFY trial (NCT05210790), which enrolled 293 patients with PV whose hematocrit remained uncontrolled and who were dependent on phlebotomy despite current standard-of-care treatment.
Patients received once-weekly subcutaneous Mimrylo or placebo alongside existing therapy, which could include phlebotomy, hydroxyurea, interferon and/or ruxolitinib.
The study’s primary endpoint was clinical response during Weeks 20–32, defined by the absence of eligibility for phlebotomy. 76.9% of patients receiving Mimrylo achieved the primary endpoint, compared with 32.9% receiving placebo.
The trial also evaluated phlebotomy requirements, maintenance of hematocrit below 45%, fatigue, and overall symptom burden. Takeda reported that Mimrylo met all efficacy endpoints and improved fatigue as measured by the PROMIS Fatigue Short Form 8a.
The most common adverse reactions associated with Mimrylo were injection-site reactions and anemia. Takeda reported that the treatment was generally well tolerated through 52 weeks in VERIFY.
Long-Term Follow-Up Continues
VERIFY is an ongoing, three-part study designed to evaluate Mimrylo for up to 156 weeks, with an additional treatment extension available to patients continuing to derive benefit.
All participants have now completed the randomized, placebo-controlled portion of the study and entered the open-label phases. Takeda said additional findings will be presented at upcoming medical conferences.
Julie Kim, President and Chief Executive Officer of Takeda, said:
“The approval of MIMRYLO underscores the strength of Takeda’s late-stage pipeline and our focus on developing genuinely differentiated therapies for patients who are urgently waiting for new options.”
From Protagonist to Takeda
Mimrylo was originally discovered by Protagonist Therapeutics, which led the drug’s development through Phase 3. Takeda now holds exclusive global development and commercialization rights for the therapy.
With its FDA approval, Mimrylo introduces a new mechanism-based treatment option for adults with PV, directly targeting erythrocytosis while potentially reducing dependence on repeated therapeutic phlebotomy.
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