In clinical trials
Heart & blood
Rusfertide
Also called PTG-300
Rusfertide is an FDA-approved hepcidin-mimetic peptide for polycythemia vera. Learn how it limits iron for red blood cells and what the trials showed.
- Reviewed by
- William Maish, MD MBA MPH, Clinical Product Lead
- Published
- October 5, 2026
- Last updated
- October 5, 2026
Key takeaway
Rusfertide is a hepcidin-mimetic peptide that limits the body's iron supply for red-blood-cell production, developed by Protagonist Therapeutics and Takeda for polycythemia vera, a blood disorder of overproduced red cells. In Phase 2 and Phase 3 trials it controlled hematocrit and reduced the need for therapeutic blood draws. It was approved by the FDA in 2026 under the brand name Mimrylo.
At a glance
| What it is | A hepcidin-mimetic peptide, sold as Mimrylo |
| Approved for | Polycythemia vera in adults, as a first-in-class treatment |
| Key fact | In trials it controlled hematocrit and reduced the need for phlebotomy |
| Route | Subcutaneous injection |
| Evidence strength | FDA approved |
What is rusfertide?
Rusfertide is a peptide that imitates hepcidin, the body's master hormone for iron regulation. It is used to treat polycythemia vera, a myeloproliferative disorder in which the bone marrow makes too many red blood cells, thickening the blood and raising the risk of clots. It is developed by Protagonist Therapeutics and Takeda and is given by subcutaneous injection under the brand name Mimrylo.
How does rusfertide work?
Rusfertide mimics hepcidin by binding ferroportin1, the channel that exports iron from gut cells and from the body's iron stores. By limiting that export, it reduces the iron available for the bone marrow to build new red blood cells. Because red-cell production depends on a steady iron supply, restricting iron slows that production and helps keep hematocrit, the proportion of blood made up of red cells, under control, reducing the need for repeated therapeutic blood draws (phlebotomy).
Is it FDA-approved?
Yes. The FDA approved2 rusfertide on August 28, 2026, as Mimrylo for adults with polycythemia vera, a first-in-class approval for a hepcidin-mimetic peptide, based on the Phase 3 VERIFY trial.
What is rusfertide prescribed for?
Rusfertide is prescribed for adults with polycythemia vera to help control hematocrit and reduce reliance on phlebotomy, the standard approach of removing blood to lower red-cell counts. It is used under the direction of a hematologist as part of managing the disease and its clotting risk.
What are the side effects?
According to the prescribing information, the most common side effects are:
- Injection-site reactions
- Anemia
More serious considerations include:
- New or worsening thrombocytosis (a high platelet count)
- Harm to an unborn baby
More for heart & blood
Sources: the REVIVE Phase 2 trial (Kremyanskaya et al., New England Journal of Medicine, 2024, DOI: 10.1056/NEJMoa23088091) and an open-label Phase 2 study (Chew et al., Leukemia Research, 2025, DOI: 10.1016/j.leukres.2025.1081323), both indexed on PubMed; and FDA prescribing information for Mimrylo. This document is educational and does not constitute medical advice.