New Drug Offers Hope for Polycythemia Vera Patients, Reducing Need for Bloodletting

The U.S. Food and Drug Administration (FDA) has approved Mimrylo (rusfertide), a novel drug for treating polycythemia vera, a chronic blood disorder characterized by the overproduction of red blood cells and an increased risk of life-threatening blood clots. For years, patients have relied on frequent bloodletting to manage the condition, a process that can lead to severe iron deficiency and impact quality of life. The approval follows a Phase 3 study involving nearly 300 patients, where approximately 77% of those receiving Mimrylo maintained balanced hematocrit levels without needing bloodletting, compared to only 33% in the control group.

Polycythemia vera is a chronic blood disorder stemming from an abnormal proliferation of blood-producing cells in the bone marrow, often due to a mutation in the JAK2 gene. While not typically aggressive like some cancers, it causes elevated blood counts, leading to symptoms such as fatigue, blurred vision, headaches, and itching. The primary danger, however, is the heightened risk of blood clots, which can result in heart attacks, strokes, and deep vein thrombosis. In rare cases, the disease can progress to more severe blood conditions like myelofibrosis or acute myeloid leukemia, as exemplified by the case of Olympic windsurfer Lee Korzits.

Traditional treatment for polycythemia vera involves aspirin to reduce clotting risk, managing other risk factors, and therapeutic phlebotomy (bloodletting) to lower red blood cell counts. This phlebotomy, while effective, often leads to significant iron deficiency, impacting patients' well-being. Mimrylo works by mimicking the action of hepcidin, a hormone that regulates iron absorption and release, thereby reducing the body's ability to produce red blood cells without depleting iron stores or requiring bloodletting.

Clinical trials demonstrated Mimrylo's efficacy, with patients requiring significantly fewer bloodletting procedures and experiencing improved iron levels, reduced fatigue, and enhanced overall quality of life. Side effects were generally mild, including injection site irritation and temporary, minor increases in platelet counts. Eight Israeli patients participated in the trials, with significant benefits reported by Dr. Eran Zimran of Hadassah Medical Center, who noted life-changing improvements for some.

Mimrylo is currently available in the U.S., and the manufacturer is seeking inclusion in Israel's national health basket for 2027. Researchers are also exploring other drugs with similar mechanisms, signaling a new era in treating this chronic condition.