First-In-Class Drug Approved for Polycythemia Vera: What You Need to Know About Rusfertide (Mimrylo) for PV

On August 28, 2026, the U.S. Food and Drug Administration (FDA) approved rusfertide (Mimrylo, Takeda Pharmaceuticals) to treat erythrocytosis (too many red blood cells) caused by polycythemia vera (PV).

PV is a myeloproliferative neoplasm (MPN). MPNs are a group of rare blood cancers. There are an estimated 90,000 people living with PV in the United States.  

With PV, the body produces too many red blood cells. This is called erythrocytosis. When the amount of red blood cells is not controlled, it thickens the blood. This can cause fatigue, itching, concentration problems, and night sweats. It can also cause life-threatening conditions, including: 

• Cardiovascular problems, like blood clots, stroke, and heart attack

• Progression to myelofibrosis

• Progression to acute myeloid leukemia (AML)

To manage PV, the proportion of red blood cells in the blood (hematocrit) should be below 45%. The current treatment is phlebotomy. During a therapeutic phlebotomy, blood is removed through a vein. But some people need frequent phlebotomies, which is disruptive and can cause side effects. Rusfertide is a new option for these patients whose hematocrit is not controlled by phlebotomy. 

“For patients living with PV, uncontrolled hematocrit can have serious consequences, including an elevated risk of life-threatening thrombotic events. Current treatments, such as phlebotomy, leave a significant gap for too many patients and can pose challenges to daily life and routines. The approval of Mimrylo offers clinicians and patients a novel, first-in-class therapy that targets erythrocytosis, which drives excess red blood cell production in PV,” said Dr. Andrew T. Kuykendall in a Takeda press release. Dr. Kuykendall is lead investigator on the VERIFY trial and a hematologist at Moffitt Cancer Center.

How does rusfertide treat polycythemia vera?

Rusfertide lowers iron levels. It does that by mimicking a natural hormone called hepcidin that controls iron. This lowers the amount of red blood cells the body produces. 

Rusfertide is given as an injection under the skin (subcutaneously). 

The study that led to rusfertide approval: VERIFY

The approval for rusfertide was based on the phase 3 VERIFY (NCT05210790) clinical trial. The trial included 293 adults. The participants had PV and needed frequent phlebotomies to control their hematocrit. Patients were randomized to receive either rusfertide or a placebo, plus standard of care treatment. 

Of the patients treated with rusfertide, 76.9% did not need phlebotomies during a 32-week period. In compairson, 32.9% of those treated with the placebo needed phlebotomies during the 32-week period. 

After the first part of the study, patients who were originally in the placebo group were switched to rusfertide. At 52 weeks, those patients also had their hematocrit controlled and did not need phlebotomies.

What are the common side effects of rusfertide?

The most common side effects of rusfertide for people with PV were: 

• Injection site reactions

• Anemia (too few red blood cells)

Next steps for people living with polycythemia vera

If you or a loved one has PV, ask your healthcare team about how your current treatment is working for you and if rusfertide or ongoing studies may be right for you. 

Questions to ask your care team about rusfertide

Consider asking your care team the following questions about rusfertide: 

• Is my hematocrit currently controlled with phlebotomies?

• Should I consider rusfertide for controlling high red blood cells caused by PV?

• What side effects should I watch out for if I take rusfertide?

SOURCES:

• FDA Approves First Drug of Its Kind for Polycythemia Vera, a Rare Blood Disorder

• Takeda Receives US FDA Approval of MIMRYLO (rusfertide), Marking a Potential Shift in the Treatment Paradigm for Polycythemia Vera