FDA Approves First-of-Its-Kind Drug for Rare Blood Disorder Polycythemia Vera
Takeda's Mimrylo, a once-weekly injection, cut the need for routine blood draws in a 293-patient trial and becomes the first hepcidin-mimicking drug ever approved.
Meridians Life Desk
Published 2 September 2026 · Updated 2 September 2026 · 4 min read
HealthThe short answer
- The FDA approved Mimrylo (rusfertide) on August 28, 2026, for adults with polycythemia vera, a rare bone marrow disorder.
- In the 293-patient VERIFY trial, 76.9% of patients on Mimrylo needed no therapeutic blood draws between weeks 20 and 32, versus 32.9% on placebo.
- It is a once-weekly injection; the most common side effects were injection-site reactions (56%) and anemia (16%).
- Takeda has not disclosed pricing. Roughly 90,000 people in the U.S. live with polycythemia vera.
The FDA approved Mimrylo (rusfertide) on August 28, 2026, for adults with polycythemia vera, a rare bone marrow disorder that causes the body to overproduce red blood cells. It is the first hepcidin-mimicking drug ever approved for any condition.
Why treatment options were limited
Polycythemia vera thickens the blood and raises the risk of clots, strokes and heart attacks. Standard care combines phlebotomy — therapeutic blood removal — with cytoreductive drugs, but Takeda estimates about 78% of the roughly 90,000 people in the U.S. with the condition still have uncontrolled hematocrit despite that treatment.
How the drug works
Mimrylo mimics hepcidin, a hormone that restricts how much iron is available in the body. Less available iron limits the bone marrow's ability to keep overproducing red blood cells. It is given as a once-weekly subcutaneous injection, starting at 19 mg and adjusted to keep hematocrit below 45%.
The trial data
- The VERIFY trial enrolled 293 adults with polycythemia vera who still needed frequent phlebotomies despite standard treatment.
- It was a 32-week, randomized, double-blind, placebo-controlled study.
- Primary endpoint — no phlebotomy eligibility during weeks 20–32 — was met by 76.9% of Mimrylo patients versus 32.9% on placebo.
- Secondary measures included hematocrit control and fatigue improvement on the PROMIS fatigue scale.
“Today's approval of Mimrylo offers a new, first-in-class option that has the potential to meaningfully reduce patient burden.”
Side effects
The most common adverse reactions were injection-site reactions, affecting 56% of patients including some Grade 3 cases, and anemia, affecting 16%. The label also flags a risk of thrombocytosis (high platelet count) and warns of embryo-fetal toxicity.
Takeda President and CEO Julie Kim called the approval evidence of "our late-stage pipeline strength and commitment to differentiated therapies for waiting patients." Kapila Viges, CEO of the MPN Research Foundation, a patient advocacy group, said the approval "reflects progress and brings a treatment option where patients need innovation and more choices."
Sources
Every factual claim above is traceable to these documents. Check them — that is why they are here.
- FDA Approves First Drug of Its Kind for Polycythemia Vera, a Rare Blood DisorderU.S. Food and Drug Administration
- Takeda Receives U.S. FDA Approval of MIMRYLO (rusfertide)Takeda Pharmaceutical Company
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