The FDA has approved Takeda’s Mimrylo (rusfertide) for polycythemia vera, introducing a new mechanism of action to the nonmalignant rare blood cancer and handing CEO Julie Kim another major regulatory win since taking the helm.
A form of myeloproliferative neoplasm, polycythemia vera (PV) causes the bone marrow to make too many red blood cells, which can result in life-threatening cardiovascular events, such as stroke and heart attack.
Mimrylo offers a new approach to curtailing the overproduction of red blood cells; it’s the first drug for PV that mimics hepcidin, a hormone that naturally regulates iron in the body. By limiting the iron being released into the bloodstream, Mimrylo essentially starves excess production of new red blood cells.
To keep the hematocrit level—the percentage of red blood cells in one’s blood—below the safe threshold of 45%, existing first-line treatment for PV includes withdrawing blood (known as phlebotomy), hydroxyurea and interferons, and Incyte’s JAK inhibitor, Jakafi, is also available as a second-line option.
“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,” Tanya Wroblewski, M.D., director of the division of nonmalignant hematology within the FDA’s Center for Drug Evaluation and Research, said in an Aug. 28 statement. “Today’s approval of Mimrylo offers a new, first-in-class option that has the potential to meaningfully reduce patient burden.”
PV affects approximately 90,000 people in the U.S., and roughly 78% of patients don’t have hematocrit level under control with existing standard treatment, according to Takeda.
Mimrylo proved its worth in the phase 3 Verify study. The double-blind trial enrolled 293 patients with uncontrolled hematocrit and randomized them to receive either a once-weekly subcutaneous injection of Mimrylo or placebo over 32 weeks. Between weeks 20 and 32 of the study, significantly more patients in the Mimrylo group improved to become not eligible for phlebotomy compared with those who took placebo. The percentages were 76.9% and 32.9%, respectively.
Besides hematocrit control, Mimrylo patients also saw a reduction in the number of phlebotomy sessions and statistically significant improvement in fatigue compared with placebo.
The drug was generally well-tolerated, as the most common treatment-emergent adverse events for the drug were injection site reactions and anemia. The trial is continuing into an open-label portion, which covers weeks 32 to 52 of treatment.
Mimrylo marks the second FDA new drug approval that Takeda has secured since CEO Julie Kim officially took the reins in June 2026. In another first-in-class nod, the company’s orexin type 2 receptor agonist Orzeyful earned an FDA green light for narcolepsy type 1 earlier this month.
“The approval of Mimrylo underscores the strength of Takeda’s late-stage pipeline and our focus on developing genuinely differentiated therapies for patients who are urgently waiting for new options,” Kim said in an Aug. 28 statement. “We are at an important inflection point as we prepare to deliver three new medicines, which have the potential to drive our future growth and are a reflection of our commitment to advancing innovation that doesn’t just add to the treatment landscape, but reshapes it.”
The third new product Kim mentioned is the oral TYK 2 inhibitor zasocitinib, a potential competitor to Bristol Myers Squibb’s Sotyktu. Takeda is aiming to launch the drug in the U.S. for psoriasis in the first half of 2027. The Japanese pharma hopes the three new drugs could help it shake off some generic erosion to its top line.
With Mimrylo’s launch, Takeda plans to draw on its existing expertise in hematology. The company already boasts a strong portfolio in blood disorders, including multiple myeloma drugs Velcade and Ninlaro, leukemia med Iclusig and Pfizer-partnered antibody-drug conjugate Adcetris.
During Takeda’s recent earnings call in July, Kim flagged “a sense of inertia” among doctors in their treatment of PV, as they view the patients as “good cancer patients.”
“So it’s a lot of education we need to do to help shine a light on the burden that PV patients have,” she said.
Mimrylo was originally developed by Protagonist Therapeutics. Takeda paid the biotech $300 million upfront in 2024 to gain certain rights to the drug before buying its partner out earlier this year. The Japanese pharma now holds sole responsibility for commercializing Mimrylo globally.
Before Friday’s approval, Jefferies analysts projected Mimrylo peak sales at roughly $2 billion.