Peptide LibraryRusfertide
Also known as: Mimrylo, PTG-300, TAK-121
Rusfertide (also called Mimrylo or PTG-300) is an FDA-approved hepcidin mimetic (synthetic cyclic peptide). Rusfertide mimics hepcidin, the hormone that regulates iron in the body. It blocks ferroportin, the transporter that releases iron into the blood, which limits the iron available for making red blood cells and lowers hematocrit.
For research use only.
Key Facts
- CAS
- 1628323-80-7
- Molecular Weight (MW)
- 2442.0 g/mol
- Half-life
- About 28.6 hours after a single 19 mg dose in healthy adults
- FDA status
- Approved
- Evidence level
- FDA Approved
- Human dose established
- Yes
- Administration Route
- Subcutaneous
- Frequency
- Once weekly; weekly doses above 82 mg are split between day 1 and day 4 or 5
- Last updated
- Oct 30, 2026
- Reviewed
- Oct 30, 2026
- Targets
- Ferroportin
Research summary
FDA-approved hepcidin mimetic peptide (Mimrylo, August 2026) for erythrocytosis in adults with polycythemia vera. A weekly subcutaneous injection that limits the iron available for making red blood cells.
Research evidence
- Regulatory review (FDA label)1 reviewed source
- Controlled human trials2 reviewed sources
- Early or uncontrolled human studies2 reviewed sources
- Lab & animal studies1 reviewed source
How it works
Each step shows whether the sources Peptide Library has reviewed include that kind of research. Counts are reviewed sources, not every study ever published. Reviews and programme summaries that describe human use are shown as "reported", not as trials, and registered trials without published results are listed but not counted. A higher step means research has progressed further; it does not mean a compound works better or is safer. Compounds whose evidence has not been reviewed yet show "Not reviewed" instead of a guess.
Peptide Library's Rusfertide profile summarises 4 cited studies listed in the Science section, the compound's regulatory status, and research-protocol parameters reported for it. It is a research reference, not medical advice.
Rusfertide dosage evidence
Rusfertide has an FDA-approved human dosage. As Mimrylo, approved in August 2026, it starts at 19 mg by subcutaneous injection once a week and is adjusted within a labeled range of 9.5 mg to 108 mg a week to keep hematocrit below 45%, for adults with erythrocytosis in polycythemia vera. Weekly doses above 54 mg take two injections, and doses above 82 mg are split across two days.
| Human dosing established | Yes |
|---|---|
| Studied dose range | 9.5–108 mg weekly, starting at 19 mg |
| Route | Subcutaneous |
| Frequency | Once weekly; weekly doses above 82 mg are split between day 1 and day 4 or 5 |
| Duration studied | Continuous |
| Titration | Starts at 19 mg a week. After at least 2 weeks at a dose it can move up one step (9.5, 19, 28, 41, 54, 69, 82, 95, 108 mg), with at least 2 weeks between increases, to reach or hold hematocrit below 45%. Grade 2 or higher anemia or drug-related grade 3 or higher toxicity moves it down one step; at 9.5 mg, treatment stops. Blood counts are checked every 2 to 4 weeks during changes. |
| Half-life | About 28.6 hours after a single 19 mg dose in healthy adults |
| Evidence level | FDA Approved |
| Last reviewed | 2026-10-30 |
Research-reported dosing
Doses as studied, one row per regimen. Different trials used different regimens; they are listed separately rather than averaged.
| Study / context | Population | Dose | Route | Frequency | Duration | Outcome studied | Source |
|---|---|---|---|---|---|---|---|
| FDA label — MimryloFDA-approved label · FDA prescribing information | Adults with erythrocytosis due to polycythemia vera | 19 mg to start; 9.5–108 mg weekly, adjusted individually | Subcutaneous | Once weekly (split across two days above 82 mg) | Continuous | Control of erythrocytosis, keeping hematocrit below 45% | MIMRYLO (rusfertide) for injection — FDA prescribing information, DailyMed |
| Kuykendall et al., 2026 — VERIFY, phase 3Clinical trial · Randomised, double-blind, placebo-controlled phase 3 | Adults with phlebotomy-dependent polycythemia vera on standard care (147 on rusfertide, 146 on placebo) | Started at 19 mg, adjusted to hold hematocrit below 45%; 9.5 to 82 mg were given in the first 52 weeks | Subcutaneous | Once weekly | 32 weeks blinded, then open-label extension | 77% had no phlebotomy eligibility in weeks 20 to 32, versus 33% on placebo | Kuykendall AT et al. VERIFY: A Phase III Trial of Rusfertide Versus Placebo in Phlebotomy-Dependent Patients With Polycythemia Vera Receiving Standard-of-Care Therapy. J Clin Oncol. 2026. |
| Kremyanskaya et al., 2024 — REVIVE, phase 2Clinical trial · Phase 2 dose-finding and randomized withdrawal trial | Adults with phlebotomy-dependent polycythemia vera (n=70; 59 entered the randomized withdrawal part) | Individually adjusted in a 28-week dose-finding part; the abstract and registry give no dose range | Subcutaneous | — | 28 weeks of dose finding, then 12 weeks of randomized withdrawal | 60% responded on rusfertide versus 17% on placebo during the withdrawal part | Kremyanskaya M et al. Rusfertide, a Hepcidin Mimetic, for Control of Erythrocytosis in Polycythemia Vera. N Engl J Med. 2024. |
| Kowdley et al., 2023 — HFE hemochromatosis, phase 2 (not an approved use)Clinical trial · Open-label, proof-of-concept phase 2 | Adults with HFE-related hemochromatosis on maintenance phlebotomy (n=16) | 10 mg weekly to start; 10 to 40 mg once or twice weekly after individual adjustment | Subcutaneous | — | 24 weeks | 15 of 16 patients needed no phlebotomy during treatment | Kowdley KV et al. Rusfertide for the treatment of iron overload in HFE-related haemochromatosis: an open-label, multicentre, proof-of-concept phase 2 trial. Lancet Gastroenterol Hepatol. 2023. |
| Modi et al., 2025 — multiple-dose study in healthy adultsClinical trial · Phase 1 pharmacokinetic study | Healthy adults (n=18) | 60 mg | Subcutaneous (abdomen, thigh or upper arm) | Once weekly | 5 weeks | Pharmacokinetics and iron and blood-count effects did not differ meaningfully by injection site | Modi NB et al. Multiple-Dose Pharmacokinetics, Pharmacodynamics, Safety, and Tolerability of Subcutaneous Rusfertide, a Hepcidin Mimetic, in Healthy Subjects. Clin Pharmacol Drug Dev. 2025. |
Preclinical and analog research
Not human dosing evidence. Listed for completeness and never extrapolated to a human dose.
| Study / context | Population | Dose | Route | Frequency | Duration | Outcome studied | Source |
|---|---|---|---|---|---|---|---|
| Preclinical — animal reproduction studiesPreclinical · Animal toxicology reported in the FDA label | Pregnant rats and rabbits | 0.3 to 3 mg/kg per dose in rats and 0.03 to 1 mg/kg per dose in rabbits; not convertible to a human dose | Subcutaneous | — | — | Malformations in rats and embryo-fetal death in rabbits at exposures below the human exposure at the maximum dose | MIMRYLO (rusfertide) for injection — FDA prescribing information, section 8.1, DailyMed |
Where sources disagree
- The label allows up to 108 mg a week, but the registry shows that doses in the first 52 weeks of VERIFY stopped at 82 mg. The 95 mg and 108 mg steps were used only in the later extension.
- The label splits weekly doses above 82 mg across day 1 and day 4 or 5. The VERIFY extension split doses above 90 mg, 3 to 4 days apart.
- The label's 56% injection-site reaction rate covers the 32-week randomized part (n=145). Its 47% rate covers all 285 patients exposed in VERIFY.
- Rusfertide is approved only for polycythemia vera. Hemochromatosis is research, and phase 2 beta-thalassemia trials (NCT03802201, NCT04054921) are completed with no results posted on the registry.
- Rusfertide works by limiting iron for red cell production, so iron measures move in unexpected ways: in VERIFY, mean ferritin rose from 21 mcg/L at baseline to 174 mcg/L at week 52.
Handling & administration
- Reconstitution Guide
- Reconstitute only with the prefilled diluent syringe packed with each vial, following the Instructions for Use, and use within 4 hours.
- Injection Sites
- AbdomenFront of thighOuter upper arm (caregiver only)
Sequence & molecular data
| Amino acid sequence | S6,S16-cyclo[N-isovaleryl-Asp-Thr-His-Phe-Pro-Cys-Ile-Nε-(N-palmitoyl-γ-Glu)-Lys-Phe-Glu-Pro-Arg-Ser-Lys-Gly-Cys-Lys-NH2] |
|---|---|
| Molecular formula | C114H181N27O28S2 |
| Molecular weight | 2442.0 g/mol |
| CAS number | 1628323-80-7 |
| Half-life | About 28.6 hours after a single 19 mg dose in healthy adults |
| Appearance | White to off-white lyophilized powder in single-dose vials, packed with a prefilled diluent syringe |
| Formulation | Lyophilized Powder |
| PubChem CID | 155884410 |
| FDA UNII | XM71MYX0IQ |
| ChEMBL | CHEMBL4650507 |
Identifiers link to the public PubChem, FDA Substance Registration (UNII), ChEMBL and DrugBank records for the same entity.
Science
Mechanism of Action
Rusfertide mimics hepcidin, the hormone that regulates iron in the body. It blocks ferroportin, the transporter that releases iron into the blood, which limits the iron available for making red blood cells and lowers hematocrit. In healthy adults, serum iron was lowest 24 to 48 hours after a dose.
Origin
Synthetic cyclic peptide developed by Protagonist Therapeutics as PTG-300; the US product is from Takeda.
Targets
Studies
- VERIFY: A Phase III Trial of Rusfertide Versus Placebo in Phlebotomy-Dependent Patients With Polycythemia Vera Receiving Standard-of-Care Therapy
- Rusfertide, a Hepcidin Mimetic, for Control of Erythrocytosis in Polycythemia Vera
- Rusfertide for the treatment of iron overload in HFE-related haemochromatosis: an open-label, multicentre, proof-of-concept phase 2 trial
- Multiple-Dose Pharmacokinetics, Pharmacodynamics, Safety, and Tolerability of Subcutaneous Rusfertide, a Hepcidin Mimetic, in Healthy Subjects
Research statistics
15 PubMed publications · 53.3% human clinical research · 10 registered trials
Counts of published research through 2026-11-01, not evidence that it works. Publications by year, study types and trials · How publications are counted
Regulatory & research status
Rusfertide is an FDA-approved product for specific labelled indications. Approval does not extend to the research contexts described on this page, and approved products are prescription medicines.
| FDA status | Approved |
|---|---|
| Research status | Approved product (see FDA status) |
| Availability | Prescription-Only |
| WADA (sport) | Unknown / Not Listed |
| Library classification | FDA-Approved |
How FDA approval, compounding and research-only status differ
Benefits
Rusfertide side effects
The effects below are drawn from Rusfertide's prescribing information, which lists the full adverse-reaction data.
Side Effects
- Injection site reactions (56% versus 33% on placebo)
- Anemia (16% versus 4.1%)
- Thrombocytosis (8% versus 0.7%)
- Shortness of breath (8% versus 1.4%)
Storage & stability
This compound is not supplied as a powder to be mixed, so the freeze-dried powder and reconstitution handling described for research peptides does not apply. Storage conditions are product-specific: follow the label or packaging of the product itself.
Rusfertide: frequently asked questions
What is rusfertide?
Rusfertide is a weekly injectable medicine sold as Mimrylo for people with polycythemia vera, a blood cancer in which the bone marrow makes too many red blood cells. It is a synthetic cyclic peptide that copies the action of hepcidin, the hormone that controls iron.
How does rusfertide work?
Rusfertide blocks ferroportin, the transporter that moves iron into the blood. With less iron reaching the bone marrow, fewer red blood cells are made and hematocrit falls. It treats too many red cells by limiting a raw material, not by removing blood.
Is rusfertide FDA approved?
Yes. FDA approved rusfertide as Mimrylo on 28 August 2026 (NDA 220605, Takeda) for erythrocytosis in adults with polycythemia vera. Other uses studied, such as hemochromatosis, are not on the label.
What is the labeled dose of rusfertide?
The FDA label starts at 19 mg by subcutaneous injection once a week and adjusts within 9.5 mg to 108 mg a week, in set steps at least 2 weeks apart, to keep hematocrit below 45%. Doses above 54 mg take two injections, and doses above 82 mg are split across two days. This is reference information, not medical advice.
What are the side effects of rusfertide?
In the randomized part of VERIFY, the most common were injection site reactions (56% versus 33% on placebo) and anemia (16% versus 4.1%), followed by thrombocytosis and shortness of breath. The label also warns about rising platelet counts and harm to a developing fetus. This is reference information, not medical advice.
What is the half-life of rusfertide?
After a single 19 mg dose in healthy adults, the mean plasma half-life was 28.6 hours, with peak levels at a median of 24 hours. Steady state took about 3 weekly doses in healthy participants.
Does rusfertide replace phlebotomy?
For many patients in the phase 3 VERIFY trial it did for the period studied: 77% had no need for phlebotomy in weeks 20 to 32, versus 33% on placebo. Patients stayed on their usual care in that trial, and hematocrit still has to be monitored.
What compounds are similar to rusfertide?
This library has no other hepcidin mimetic. Pegcetacoplan and motixafortide are listed alongside it as peptides used in blood disorders, but they act on different targets and are not substitutes.
References
- MIMRYLO (rusfertide) for injection — FDA prescribing information, DailyMedExternal reference
- NDA 220605 approval letter — FDA, August 2026External reference
- VERIFY: A Phase III Trial of Rusfertide Versus Placebo in Phlebotomy-Dependent Patients With Polycythemia Vera — J Clin Oncol, 2026External reference
- Rusfertide, a Hepcidin Mimetic, for Control of Erythrocytosis in Polycythemia Vera — N Engl J Med, 2024External reference
- Rusfertide for the treatment of iron overload in HFE-related haemochromatosis — Lancet Gastroenterol Hepatol, 2023External reference
- Multiple-Dose Pharmacokinetics, Pharmacodynamics, Safety, and Tolerability of Subcutaneous Rusfertide — Clin Pharmacol Drug Dev, 2025External reference
- NCT05210790 — VERIFY phase 3 trial of rusfertideExternal reference
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Compiled by Peptide Library Editorial · Reviewed Oct 30, 2026 · Updated Oct 30, 2026 · Version 1
This Rusfertide profile is compiled from published literature (4 cited studies linked above), public regulatory records and chemical registries. It describes what research reports; it is not medical advice, and nothing here is a dosing recommendation for humans. Peptide Library does not sell peptides. Editorial policy · How profiles are compiled · Report an error
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