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FDA approves Mimrylo, first-of-its-kind drug for polycythemia vera

FDA approves Mimrylo, first-of-its-kind drug for polycythemia vera

New Capabilities

A once-weekly injection that mimics the body's iron-regulating hormone offers an alternative to frequent blood draws.

Yesterday: FDA approves Mimrylo (rusfertide)

Overview

Updated Yesterday

Polycythemia vera has been treated with bloodletting for more than a century. On August 28, the FDA approved Mimrylo (rusfertide), the first drug that works instead by mimicking hepcidin, the hormone that limits iron available for new red blood cells.

The approval covers adults with polycythemia vera, a rare blood cancer affecting roughly 90,000 Americans. The disease makes the body overproduce red blood cells, thickening blood and raising the risk of clots, stroke, and heart attack.

In the Phase 3 VERIFY trial, 76.9% of patients on Mimrylo required no phlebotomy during the study period, versus 32.9% on placebo. The once-weekly injection, available within 48 hours, is designed to keep hematocrit, the proportion of red blood cells in blood, below 45%, the threshold tied to cardiovascular risk.

Why it matters

If Mimrylo works as well in the real world as in trials, polycythemia vera patients may never need another therapeutic blood draw.

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Key Indicators

76.9%
Mimrylo patients who avoided phlebotomy
During the Phase 3 VERIFY trial's 32-week primary analysis period, versus 32.9% on placebo.
90,000
Americans living with polycythemia vera
A rare, slow-growing blood cancer that thickens blood and raises clot, stroke, and heart attack risk.
293
Patients in the Phase 3 VERIFY trial
Multicenter, randomized, double-blind, placebo-controlled study of Mimrylo plus standard of care.
47.4%
Rate of injection site reactions
Most common adverse reaction in rusfertide-treated patients; events were mainly grade 1 or 2.

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People Involved

TM
Tanya Wroblewski, M.D.
Director, Division of Nonmalignant Hematology, FDA Center for Drug Evaluation and Research
Announced the Mimrylo approval
 Teresa Bitetti
Teresa Bitetti
President, Takeda's global oncology business unit
Leading Mimrylo's commercial launch

Organizations Involved

Takeda Pharmaceutical Company Limited
Takeda Pharmaceutical Company Limited
Pharmaceutical company
Markets Mimrylo in the United States

Japanese pharmaceutical company that licensed rusfertide from Protagonist Therapeutics in 2024.
Protagonist Therapeutics
Protagonist Therapeutics
Biopharmaceutical company
Discovered rusfertide; holds option to co-commercialize in the US

Biopharmaceutical company that discovered rusfertide and led its development through Phase 3.
U.S. Food and Drug Administration
U.S. Food and Drug Administration
Federal regulatory agency
Approved Mimrylo under priority review

US federal agency that approves and regulates drugs and medical devices.

Timeline

January 2024 August 2026

7 events Latest: Yesterday
Tap a bar to jump to that date

  1. FDA approves Mimrylo (rusfertide)

    Latest Regulatory

    FDA approves Mimrylo (rusfertide) for erythrocytosis in adults with polycythemia vera.

  2. FDA accepts application with priority review

    Regulatory

    FDA accepts application, grants priority review for rusfertide.

  3. New Drug Application submitted

    Regulatory

    Takeda and Protagonist submit New Drug Application to FDA.

  4. Longer-term data presented at ASH 2025

    Conference

    Longer-term efficacy and safety data presented at ASH 2025.

  5. FDA grants Breakthrough Therapy designation

    Regulatory

    FDA grants rusfertide Breakthrough Therapy designation.

  6. Phase 3 VERIFY trial succeeds

    Clinical Trial

    Phase 3 VERIFY study meets primary endpoint; positive topline results announced.

  7. Protagonist and Takeda sign license agreement

    Business

    Protagonist and Takeda sign worldwide license agreement for rusfertide.

Historical Context

3 moments from history that rhyme with this story — and how they unfolded.

2000-2001

Hepcidin discovery (2000-2001)

Two research groups independently identified hepcidin, a small peptide produced by the liver that controls iron absorption. Within a few years, it was recognized as the master regulator of iron metabolism.

Then

The discovery explained the molecular basis of hereditary hemochromatosis and anemia of inflammation.

Now

It took 25 years for the discovery to produce a drug. Rusfertide, a synthetic hepcidin mimetic, is the first approved therapy built on it.

Why this matters now

Mimrylo's mechanism, restricting iron to slow red blood cell production, is the direct clinical payoff of the hepcidin discovery, a 25-year arc from basic science to approved drug.

May 2001

Imatinib (Gleevec) for chronic myeloid leukemia (2001)

The FDA approved imatinib (Gleevec), the first drug designed to disable a specific cancer-causing protein, the BCR-ABL fusion in chronic myeloid leukemia. In the pivotal trial, 95% of patients achieved a complete hematologic response.

Then

CML shifted from a fatal diagnosis to a chronic condition managed with daily pills.

Now

Gleevec created the model for molecularly targeted cancer drugs and showed how quickly practice follows a first-in-class approval.

Why this matters now

Like Gleevec, Mimrylo is a first-in-class therapy replacing a blunt, burdensome standard approach. Gleevec shows how quickly guidelines and practice can follow such an approval.

December 2014

Ruxolitinib (Jakafi) for polycythemia vera (2014)

The FDA approved Incyte's ruxolitinib (Jakafi), a JAK inhibitor, for polycythemia vera patients who did not respond adequately to hydroxyurea. It was the first drug approved specifically for PV and the first to target the JAK2 mutation that drives the disease.

Then

Ruxolitinib gave hydroxyurea-resistant patients a new option, though many still needed phlebotomy to control hematocrit.

Now

It established the regulatory path for PV drugs and proved a commercial market existed for rare blood cancer treatments.

Why this matters now

Mimrylo follows the same regulatory path but different biology. Ruxolitinib blocks the mutated enzyme driving overproduction; Mimrylo restricts the iron supply needed to make red blood cells.

Sources

(8)
+2
U.S. Food and Drug Administration Cancer Network Reuters StockTitan Takeda via Bastille Post Takeda Drugs.com Researching Peptides