The US Food and Drug Administration (FDA) has approved Mimrylo (rusfertide), a new treatment for adults with polycythemia vera, a rare blood disorder that causes the body to make too many Red Blood Cells (RBCs). The excess cells can thicken the blood and increase the risk of cardiovascular issues, such as blood clots, stroke and heart attack.

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 RBCs, Mimrylo helps reduce their overproduction and keep RBC levels under control. This novel approach offers a new option for patients who have not achieved adequate control with existing therapies.

Tanya Wroblewski, M.D., Director—Division of Nonmalignant Hematology, Center for Drug Evaluation and Research (CDER), FDA, said, “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 RBC overproduction. 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 RBCs in the blood (hematocrit) below 45 percent to reduce cardiovascular risks. This often requires phlebotomy, a procedure that removes blood from a vein to lower the number of RBCs 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, randomised, double-blind, placebo-controlled phase 3 study of 293 adults with polycythemia vera who required frequent phlebotomies despite ongoing Standard of Care (SoC) therapy.

Patients were randomised 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 percent.

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 percent of patients on Mimrylo required no phlebotomies during the 32-week period compared to 32.9 percent on placebo. The most common adverse reactions were injection site reactions and anemia.

Mimrylo received Priority Review (PR). The approval was granted to Takeda Pharmaceuticals America, Inc.