FDA Approves Mimrylo for Polycythemia Vera, Offering a New Treatment Approach

The U.S. Food and Drug Administration (FDA) has approved Mimrylo (rusfertide) for adults with polycythemia vera (PV), a rare blood disorder that causes the body to produce too many red blood cells.

The excess red blood cells can make the blood thicker and increase the risk of cardiovascular complications, including blood clots, stroke and heart attack.

Mimrylo is the first approved treatment for polycythemia vera that mimics hepcidin, a hormone that naturally helps regulate iron in the body. By limiting the amount of iron available to produce new red blood cells, Mimrylo is designed to reduce red blood cell overproduction and help keep hematocrit levels under control.

The FDA approval provides a new treatment option for people whose polycythemia vera has not been adequately controlled with existing therapies.

What Is Polycythemia Vera?

Polycythemia vera is a rare blood disorder in which the body produces too many red blood cells. This can increase the thickness of the blood and raise the risk of serious cardiovascular problems.

One important goal of treatment is maintaining a hematocrit — the proportion of blood made up of red blood cells — below 45%. Keeping hematocrit below this level can help reduce cardiovascular risks.

For some people with polycythemia vera, achieving adequate control can require frequent phlebotomies, a procedure that removes blood from a vein to reduce the number of red blood cells in the body.

How Does Mimrylo Work?

Mimrylo takes a different approach to treating polycythemia vera than therapies that primarily manage the consequences of excess red blood cell production.

The drug mimics hepcidin, a hormone involved in regulating iron. By limiting the iron available for the production of new red blood cells, Mimrylo helps reduce red blood cell overproduction.

This makes Mimrylo the first approved treatment for polycythemia vera to target the disease through this hepcidin-mimicking approach.

"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."

How Effective Was Mimrylo in Clinical Trials?

The safety and effectiveness of Mimrylo were evaluated in the phase 3 VERIFY trial, a multicenter, randomized, double-blind, placebo-controlled study involving 293 adults with polycythemia vera.

Participants had required frequent phlebotomies despite receiving standard-of-care treatment. They were randomly assigned to receive either Mimrylo or placebo for 32 weeks.

Mimrylo treatment began at 19 milligrams and was given as a subcutaneous injection once a week. The dose was adjusted as needed to help maintain hematocrit levels below 45%.

Researchers evaluated how many patients did not meet criteria for a phlebotomy between weeks 20 and 32.

Among patients who received Mimrylo, 76.9% did not require a phlebotomy during the 32-week period, compared with 32.9% of patients who received placebo.

These results suggest that Mimrylo may help reduce the need for frequent blood removal in people whose polycythemia vera remains difficult to control with existing treatment.

What Are the Side Effects of Mimrylo?

In the VERIFY trial, the most common adverse reactions reported with Mimrylo were injection site reactions and anemia.

Patients should talk with their health care team about the potential benefits and risks of Mimrylo and how the treatment may fit into their individual polycythemia vera treatment plan.

What Does the FDA Approval Mean for Patients With Polycythemia Vera?

For people living with polycythemia vera who continue to require frequent phlebotomies despite standard treatment, Mimrylo provides a new option for managing the disease.

The treatment's hepcidin-mimicking mechanism also represents a new approach to controlling the underlying biology involved in red blood cell production.

Mimrylo received priority review from the FDA, and the approval was granted to Takeda Pharmaceuticals America, Inc.

References

1. FDA Approves First Drug of Its Kind for Polycythemia Vera, a Rare Blood Disorder. U.S. Food and Drug Administration. August 28, 2026.
2. A Study of Rusfertide in Adults With Polycythemia Vera. ClinicalTrials.gov. VERIFY: NCT05210790.
3. Mimrylo (rusfertide) Approval Information. U.S. Food and Drug Administration. August 28, 2026.