FDA Approves Rusfertide for Polycythemia Vera

The U.S. FDA has approved Mimrylo (rusfertide) for adults with polycythemia vera (PV), a rare blood disorder characterized by excessive production of red blood cells. The resulting increase in blood viscosity can raise the risk of serious cardiovascular complications, including blood clots, stroke and heart attack. Rusfertide provides a new treatment option for adults with this chronic condition.

Mimrylo offers a new treatment approach for patients whose disease has not been adequately controlled with existing therapies. It is the first approved treatment for polycythemia vera 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. This novel approach offers a new option for patients who have not achieved adequate control with existing therapies.

“People living with polycythemia vera have long faced the challenge of managing a chronic blood disorder with frequent blood draws to help address the consequences of the red blood cell overproduction,” said Tanya Wroblewski, M.D., Director of the Division of Nonmalignant Hematology within the FDA’s Center for Drug Evaluation and Research. “Today's approval of Mimrylo offers a new, first-in-class option that has the potential to meaningfully reduce patient burden."

A key goal of treatment for polycythemia vera is keeping the proportion of red blood cells in the blood (hematocrit) below 45% to reduce cardiovascular risks. This often requires phlebotomy, a procedure that removes blood from a vein to lower the number of red blood cells in the body. However, some patients continue to need frequent phlebotomies despite treatment, creating an ongoing burden.

The safety and efficacy of Mimrylo were evaluated in the VERIFY trial, a multicenter, randomized, double-blind, placebo-controlled phase 3 study of 293 adults with polycythemia vera who required frequent phlebotomies despite ongoing standard-of-care therapy. Patients were randomized 1:1 to receive either Mimrylo or placebo over 32 weeks. Mimrylo treatment started at 19 mg, administered subcutaneously (under the skin) once weekly, and was titrated to maintain hematocrit levels below 45%.

Efficacy was measured by the proportion of patients who did not meet criteria for phlebotomy between weeks 20 and 32 of the study. Overall, 76.9% of patients on Mimrylo required no phlebotomies during the 32-week period compared to 32.9% on placebo. The most common adverse reactions were injection site reactions and anemia.

Mimrylo received priority review. The approval was granted to Takeda Pharmaceuticals America, Inc.