Mimrylo (rusfertide): FDA approval, pivotal trial and safety
Approved
Type
New molecular entity · Subcutaneous
FDA-approved use
To treat erythrocytosis in adults with polycythemia veraWording from FDA's list of novel approvals.
FDA review
Priority reviewOrphan drug
Company
Takeda
Application
NDA 220605
Specialty
Hematology
At a glance
Mimrylo (rusfertide) is a hepcidin mimetic approved by the FDA on August 28, 2026 for erythrocytosis in adults with polycythemia vera. The pivotal Phase 3 trial, VERIFY, compared it with placebo in 293 patients who needed frequent phlebotomy, but the sources provided give no efficacy numbers for the primary end point. The main safety points are rising platelet counts and frequent injection-site reactions.
What it is and how it works
Rusfertide mimics hepcidin, the body's own iron-regulating hormone, and blocks the iron transporter ferroportin. This limits the iron available for red cell production and lowers hematocrit. Phlebotomy removes red cells, and cytoreductive drugs suppress marrow production. Rusfertide instead acts on iron supply, and a review describes it as a possible noncytoreductive option.
Multicenter, randomized, double-blind, placebo-controlled Phase 3 trial. Patients were randomized 1:1 for 32 weeks. Completers could then receive open-label Mimrylo to Week 52 and long-term extension treatment to Week 156. The starting dose was titrated to control hematocrit.
Patients
293 adults with polycythemia vera and inadequate hematocrit control on standard care, defined by frequent prior phlebotomies. Mean age was 57 years, 27% were female, and 89.4% were White. At randomization, 44.7% received phlebotomy only, 38.9% phlebotomy plus hydroxyurea, 13.3% phlebotomy plus interferon, 2.4% phlebotomy plus ruxolitinib, and 0.6% phlebotomy plus combined cytoreductive therapy. 46.8% were high risk. Mean baseline hematocrit was 42.2 in the Mimrylo arm and 42.4 in the placebo arm.
Compared with
Placebo, with ongoing standard of care
Primary endpoint
The sources provided do not state the primary end point.
Result
The sources provided do not report the primary result.
Other results
The sources provided do not report secondary results.
Safety in the trial
In the 32-week controlled period, 145 patients received Mimrylo and 146 received placebo. Injection-site reactions occurred in 56% and anemia in 16% of the Mimrylo arm. One patient had serious anemia. Dose reductions for adverse reactions occurred in 11%, mostly for anemia. Permanent discontinuations were rare, for injection-site reactions, thrombocytosis, and anemia. Across the study, 285 patients were exposed to Mimrylo, with median exposure of 61 weeks.
How does Mimrylo (rusfertide) compare with the alternatives (Therapeutic phlebotomy, Hydroxyurea, Interferon) for erythrocytosis in adults with polycythemia vera? Summarize head-to-head and indirect evidence, efficacy, safety and where each fits, with citations.
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Safety signals
There is no boxed warning. The label warns of new or worsening thrombocytosis. Platelet counts rose on average within 4 weeks, and some patients exceeded 600 and 1,000 x 10^9/L. Monitor CBC after starting and after dose changes, and platelet rises may call for cytoreductive therapy or changes to rusfertide. Injection-site reactions were common, mostly Grade 1 or 2, and few led to stopping. The label also warns of embryo-fetal toxicity based on animal data, so advise effective contraception. The most common adverse reactions were injection-site reactions and anemia, and anemia was the main reason for dose reduction.
What it competes with
Polycythemia vera is managed with phlebotomy to control hematocrit, usually with low-dose aspirin. Patients at higher risk or with inadequate control add a cytoreductive drug.
Therapeutic phlebotomyStandard first-line way to keep hematocrit controlled. It does not suppress marrow production and is needed repeatedly in some patients.
HydroxyureaOral cytoreductive agent commonly added in higher-risk patients or when phlebotomy alone is not enough.
InterferonInjectable cytoreductive option that can reduce blood counts and is used in selected patients.
RuxolitinibJAK inhibitor used in patients who have an inadequate response to or cannot tolerate hydroxyurea.
Bottom line for clinicians
Mimrylo is for adults with polycythemia vera whose hematocrit stays hard to control on standard care and who need frequent phlebotomy. Weigh the platelet rise, which needs regular CBC monitoring, and the high rate of injection-site reactions. Check for anemia, and counsel patients who can become pregnant about contraception.
Dosing, contraindications and full warnings are in the prescribing information.
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Last updated October 28, 2026 by 2 Minute Medicine.
For healthcare professionals. A summary of public FDA documents and published trials, not medical advice. Check the full prescribing information before prescribing.
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