By David Wallace – September 1, 2026
The U.S. Food and Drug Administration approved Mimrylo™ (mim-rahy-loh), the brand name for rusfertide, on August 28, 2026, for the treatment of erythrocytosis in adults with polycythemia vera (PV). Erythrocytosis means the body is making too many red blood cells.
Mimrylo is the first FDA-approved hepcidin mimetic for PV. Protagonist Therapeutics discovered the medicine as PTG-300; Takeda commercializes it in the United States. It is given as a weekly injection under the skin. By limiting the iron available to make new red blood cells, it helps control hematocrit and can reduce the need for therapeutic phlebotomy.
For patients who have planned years of their lives around blood draws, that could be meaningful.
PV Reporter previously covered rusfertide in the VERIFY phase 3 trial while the medicine was still investigational.
Mimrylo approval at a glance
| Question | Answer |
|---|---|
| Brand and generic names | Mimrylo (rusfertide) |
| Earlier research name | PTG-300 |
| FDA approval date | August 28, 2026 |
| FDA-approved use | Treatment of erythrocytosis in adults with polycythemia vera |
| Type of medicine | Hepcidin mimetic (first approved in PV) |
| How it is given | Subcutaneous injection once weekly |
| Recommended starting dose | 19 mg once weekly |
| Labeled weekly dose range | 9.5 mg to 108 mg |
| Main approval study | Phase 3 VERIFY trial, 293 adults (NCT05210790) |
| Most common side effects | Injection-site reactions (56%) and anemia (16%) |
See the Mimrylo prescribing information for complete dosing and safety details.
Why reducing phlebotomies matters in PV
Therapeutic phlebotomy lowers hematocrit by removing blood. It remains an important and manageable part of PV care for many people.
The burden can grow when phlebotomies are needed again and again. Patients may face more appointments, missed work, difficult needle access, anxiety, and iron deficiency. Some also experience fatigue, trouble concentrating, restless legs, headaches, or other symptoms when iron remains low.
Mimrylo offers another approach. Instead of removing blood after it has been made, rusfertide limits some of the iron the bone marrow needs to produce red blood cells.
My perspective after more than 50 phlebotomies
I was diagnosed with polycythemia vera in 2009. Since then, I have undergone more than 50 therapeutic phlebotomies.
I understand why phlebotomy is used. I also know what the procedure can feel like after you have done it repeatedly. There is the physical burden, the fatigue, the appointments, and the uncertainty about whether a vein will cooperate. Will my blood be so thick they have difficulty completing the phlebotomy?
During one phlebotomy, an inexperienced staff member made two unsuccessful attempts to access a vein. I asked for someone else. The second medical professional accessed the vein on the first attempt, but the needle was not properly secured. Within about 30 seconds, the needle came out. Blood sprayed onto my jeans, t-shirt, and the treatment-room floor.
The procedure was restarted and completed, but the experience stayed with me. Afterward, I felt anxious whenever someone unfamiliar was assigned to perform my phlebotomy.
This is why reducing phlebotomies is more than a matter of convenience. For a patient, it may mean less anxiety, fewer disrupted days, and more control over daily life.
I have never received rusfertide or participated in one of its clinical trials. My view comes from living with PV since 2009 and experiencing the cumulative burden of repeated phlebotomies.
What is Mimrylo, and how does rusfertide work?
Patients may know this medicine by three names. PTG-300 was its early research name. Rusfertide is the generic name used throughout clinical development. Mimrylo is the FDA-approved brand name. All three refer to the same medicine.
PV Reporter began covering the treatment in 2020, when Dr. Srdan Verstovsek explained the early PTG-300 research.
The body needs iron to make red blood cells. Hepcidin is a natural hormone that controls how iron moves through the body. A protein called ferroportin acts like a doorway that releases iron into the blood.
Rusfertide mimics hepcidin and blocks ferroportin. That leaves less iron available for the bone marrow to make red blood cells, which helps control hematocrit. This differs from how hydroxyurea, interferon, and ruxolitinib work.
Mimrylo controls erythrocytosis. It is not a cure. It has not been shown to eliminate the abnormal PV blood-cell clone or stop PV from progressing.
VERIFY trial results for rusfertide in polycythemia vera
The phase 3 VERIFY trial (NCT05210790) included 293 adults with PV who still needed frequent phlebotomies while receiving their current care. That care could include phlebotomy alone or phlebotomy plus hydroxyurea, interferon, ruxolitinib, or another treatment used to lower blood counts. About 56% of participants were already on concurrent cytoreductive therapy.
To enter the study, patients had needed at least three phlebotomies during the previous 28 weeks or at least five during the previous year. VERIFY therefore focused on people with a substantial phlebotomy burden. Its results may not predict the experience of someone who rarely needs the procedure.
Participants were randomly assigned to Mimrylo or placebo in addition to existing treatment. Neither patients nor investigators knew who received Mimrylo during the first 32 weeks. Treatment started at 19 mg weekly and was titrated to keep hematocrit below 45%.
The main trial measurement was the percentage of patients who did not meet the study’s criteria for phlebotomy eligibility during weeks 20 through 32. Researchers called this a clinical response. In VERIFY, phlebotomy eligibility meant a confirmed hematocrit of 45% or higher that was also at least 3 percentage points above the patient’s baseline, or a hematocrit of 48% or higher. Those study rules are not the same as every clinic’s phlebotomy threshold. Whether Mimrylo is appropriate, and when a phlebotomy is still needed, must be discussed with your physician.
VERIFY results through week 32
| VERIFY result through week 32 | Mimrylo | Placebo |
|---|---|---|
| Clinical response, weeks 20–32 (no phlebotomy eligibility) | 76.9% | 32.9% |
| Average number of phlebotomies, weeks 0–32 | 0.5 | 1.8 |
| Maintained hematocrit below 45% | 62.6% | 14.4% |
| Fatigue (PROMIS Fatigue SF-8a) | Modest average improvement | Slight average worsening |
| Symptom burden (MFSAF) | Statistically significant improvement vs placebo | — |
Source: VERIFY 32-week results presented at ASCO 2025 and included in the FDA-approved label.
The fatigue result needs context. On average, the PROMIS Fatigue score improved modestly with Mimrylo and slightly worsened with placebo. A lower score means less fatigue. That does not mean every patient felt less tired. Fatigue in PV can have several causes, and real-life experience will show how much change patients notice.
VERIFY mainly studied Mimrylo as an addition to current care. It did not show that the medicine should replace every other PV treatment.
VERIFY results through week 52
After week 32, participants could receive Mimrylo in the open-label part of the study.
- Among patients randomized to rusfertide from the start, 61.9% (91 of 147) had a durable response with absence of phlebotomy eligibility through week 52.
- Among Mimrylo patients who had responded during weeks 20 through 32, 84.1% maintained that response in the later evaluation period.
- Of those who switched from placebo to rusfertide, 77.9% achieved a response during weeks 40 through 52.
Dr. Andrew Kuykendall, the VERIFY lead investigator at Moffitt Cancer Center, said the strength and consistency of the results gave him confidence in Mimrylo’s potential role in everyday PV care. Longer follow-up is continuing. Those week-52 findings were presented at ASH 2025.
Mimrylo side effects and monitoring
Patients should review the complete prescribing information and discuss personal risks with their healthcare team. There is no boxed warning.
Injection-site reactions and anemia
Injection-site reactions were reported in 56% of patients receiving Mimrylo and 33% receiving placebo. Reactions included redness (27%), itching (17%), pain (15%), and swelling (8%). Most were mild or moderate.
Anemia occurred in 16% of patients receiving Mimrylo and 4.1% receiving placebo. Because rusfertide limits iron availability, its effect can sometimes become too strong. A dose reduction may be needed if significant anemia develops.
Higher platelet counts
Mimrylo can cause new or worsening thrombocytosis. In VERIFY, platelet counts increased by an average of 31% within four weeks and generally leveled off by week eight. Thrombocytosis was reported in 8% of Mimrylo patients versus 0.7% on placebo. Thirty-six percent of treated patients had platelet counts above 600 × 109/L, and 6% exceeded 1,000 × 109/L.
The prescribing information calls for a complete blood count every two to four weeks after treatment begins and during dose changes, or more often when needed. Higher platelets may require a change in Mimrylo, a change in another PV medicine, or stopping Mimrylo.
Pregnancy and breastfeeding
Based on animal studies, Mimrylo may harm an unborn baby. Pregnancy testing is recommended before treatment for patients who can become pregnant. Effective birth control is advised during treatment and for at least 30 days after the final dose. Breastfeeding is not recommended during treatment or for 30 days after the last dose.
Is Mimrylo an option for people living with PV?
The FDA indication covers adults with PV who have erythrocytosis. Prior failure of hydroxyurea, interferon, or ruxolitinib is not required on the label. The strongest evidence still comes from patients who continued to need frequent phlebotomies despite their current care.
A hematologist or MPN specialist may consider your phlebotomy history, hematocrit, hemoglobin, platelet count, symptoms, iron status, current medicines, and treatment goals. Needing phlebotomies does not automatically mean Mimrylo is right for you.
Questions to ask your MPN specialist
- Am I a reasonable candidate based on my blood counts and phlebotomy history?
- Would Mimrylo be added to my current treatment?
- How often would my CBC, platelet count, and iron levels be checked?
- What would happen if I developed anemia or a higher platelet count?
- Who will teach me or my caregiver to prepare and give the injection?
- What do we know, and still not know, about long-term safety?
- Will my insurance require prior authorization, and is financial assistance available?
If you are preparing for a visit, start with these questions and the issues raised in David’s push for an MPN specialist.
Insurance coverage, prior authorization, and specialty-pharmacy rules may affect access. Patients can visit Mimrylo.com for official product information and Takeda Oncology Here2Assist (1-844-817-6468) for possible insurance and financial support. Eligibility rules apply, and assistance is not guaranteed.
Mimrylo FAQs
Is Mimrylo the same as rusfertide?
Yes. Mimrylo is the FDA-approved brand name for rusfertide. The medicine was previously studied as PTG-300.
How is Mimrylo given?
Mimrylo is injected under the skin once a week. The recommended starting dose is 19 mg. The labeled weekly dose range is 9.5 mg to 108 mg, and the dose may be adjusted based on blood counts and response. Doses above 54 mg require two injections. Doses greater than 82 mg should be given on separate days.
The medicine comes as a powder that must be mixed with the supplied liquid. After mixing, it should be used as soon as possible and within four hours. Patients or caregivers may prepare and give it after training from a healthcare professional. See the patient information in the prescribing information for preparation steps.
Does Mimrylo eliminate the need for phlebotomy?
It reduced the need for phlebotomy for many VERIFY participants, but it did not eliminate phlebotomy for everyone.
Has Mimrylo been proven to reduce blood clots?
No. Keeping hematocrit below 45% is an established PV treatment goal because it lowers the risk of clotting complications. VERIFY was not designed to prove that Mimrylo itself reduces blood clots, strokes, heart attacks, or death.
A new treatment option for erythrocytosis in PV
Mimrylo gives adults with PV another way to control erythrocytosis. VERIFY showed better hematocrit control and fewer phlebotomies compared with placebo. Important risks include injection-site reactions, anemia, and higher platelet counts.
For patients who need repeated phlebotomies, reducing that burden can matter physically and emotionally. I know that from personal experience. Patients should discuss the possible benefits, risks, monitoring, cost, and unanswered questions with an MPN specialist.
References
- U.S. Food and Drug Administration. FDA Approves First Drug of Its Kind for Polycythemia Vera, a Rare Blood Disorder. August 28, 2026.
- Mimrylo (rusfertide) Prescribing Information. Takeda Pharmaceuticals America. Revised August 2026.
- Kuykendall AT, et al. Results from VERIFY, a phase 3, double-blind, placebo-controlled study of rusfertide for treatment of polycythemia vera (PV). J Clin Oncol. 2025;43(17_suppl):LBA3.
- Kuykendall AT, et al. Rusfertide or Placebo Plus Current Standard-of-Care Therapy for Polycythemia Vera: Durability of Response and Safety Results Through Week 52 From the Randomized Controlled Phase 3 VERIFY Study. Blood. 2025;146(Supplement 1):81.
- Takeda. FDA Approves MIMRYLO (rusfertide) for Polycythemia Vera. August 28, 2026.
- VERIFY ClinicalTrials.gov record (NCT05210790).
About David Wallace
David Wallace is the founder and publisher of PV Reporter and the founder of MPN Cancer Connection. Diagnosed with polycythemia vera in 2009, he is a recognized MPN patient advocate who has spent more than 13 years translating medical research and expert insight into practical information for patients.
Read David’s PV story and remission journey.
Medical disclaimer: This article is for educational and patient-advocacy purposes and is not medical advice. It does not replace consultation with a qualified hematologist or MPN specialist. Treatment decisions should be made with your healthcare team based on your diagnosis, medical history, blood counts, current medications, and treatment goals.
