FDA clears Mimrylo, a first-in-class therapy for polycythemia vera

The FDA has approved Mimrylo (rusfertide) to treat adults with polycythemia vera (PV), a blood cancer that causes the overproduction of red blood cells. The excess cells thicken the blood, slowing blood flow and increasing the chance of blood clots.

There are an estimated 88,943 patients living with PV in the United States in 2025, and that is predicted to grow to 97,011 by 2030, according to an analysis presented this year at the 2026 ASCO annual meeting and published in June 2026 in the Journal of Clinical Oncology.

Current treatment for polycythemia vera focuses on keeping the hematocrit level below 45% to reduce the risk of blood clots, strokes and cardiovascular events. The hematocrit level is the ratio of red blood cells to the total amount of blood in the body.

“For patients living with PV, uncontrolled hematocrit can have serious consequences, including an elevated risk of life-threatening thrombotic events," Andrew T. Kuykendall, M.D., lead investigator and associate member in the Department of Hematology at Moffitt Cancer Center, said in a news release. “Current treatments, such as phlebotomy, leave a significant gap for too many patients and can pose challenges to daily life and routines.”

Developed by Takeda, Mimrylo is a first-in-class therapy that mimics hepcidin, a hormone that naturally regulates iron in the body. By limiting the iron available to make new red blood cells, Mimrylo helps reduce their overproduction and keep red blood cell levels under control.

Mimrylo is available now and has a list price of $4,200 per vial. A spokesperson said the company believes this price reflects the value Mimrylo provides to patients, especially for patients who are not adequately controlled with existing therapies. “We are working with stakeholders across the healthcare system, including commercial and government payers, to support broad and timely access and help ensure cost is not a barrier for appropriate patients,” the spokesperson said.

Takeda offers patient support through Here2Assist. Commercially insured patients may be eligible for a $0 copay. Takeda also offers a bridge program for up to two months of therapy at no cost, as well as a patient assistance program for those who are uninsured.

The safety and efficacy of Mimrylo were evaluated in the VERIFY trial, a placebo-controlled phase 3 study of 293 adults with polycythemia vera. Patients were randomized to either Mimrylo or placebo over 32 weeks as an add-on to their current treatment. Mimrylo treatment started at 19 mg, administered subcutaneously once weekly, and was titrated to maintain hematocrit levels below 45%.

In the study, patients receiving Mimrylo plus the current standard of care demonstrated a higher response rate compared with placebo plus the current standard of care. This included hematocrit control, a reduction in the need for phlebotomy and improvement in fatigue.

In the study, 61.9% of patients treated with Mimrylo plus the current standard of care throughout Parts 1a (the first 32 weeks) and 1b (week 32 to week 52) of the study experienced a durable clinical response. 84.1% of patients treated with rusfertide who experienced a clinical response in the Part 1a assessment window (weeks 20-32)

Mimrylo was generally well-tolerated through 52 weeks of treatment. The most common treatment-emergent adverse events in Mimrylo-treated patients were injection site reactions and anemia. Serious adverse events occurred in 8.1% of overall Mimrylo-treated patients.