5 Ongoing Clinical Trials in Myeloproliferative Neoplasms

Myeloproliferative neoplasms are a type of blood disorder in which blood cell production goes haywire due to mutated bone marrow stem cells, leading to an overabundance of platelets (PLT), red blood cells (RBCs), or white blood cells (WBCs) that your body cannot use.^1-3 They are considered a rare disease with complications that include anemia, infection, stroke, and leukemias. Many medications are approved to treat this group of hematologic disorders,⁴ but there are also many ongoing clinical trials. Here are 5 phase 3 clinical trials currently evaluating outcomes among patients living with polycythemia vera (PV), myelofibrosis (MF), and essential thrombocythemia (ET).

Efficacy, Safety, and Tolerability of P1101⁵

In this interventional trial (NCT05481151) taking place at 23 locations in the US and Canada, with an estimated completion date of July 31, 2027, patients receive 1 of 2 doses of the pegylated, long-acting type 1 interferon ropeginterferon alfa-2b-njft (P1101) in a prefilled syringe to be administered via subcutaneous (SC) injection every 2 weeks: they will start at either 250, 350, or 500 mcg or at 100 up to 500 mcg (in 50-mcg increases). The primary outcome of interest in this interventional trial is complete hematologic response at 24 weeks, defined as hematocrit below 45%, WBC below 10 x 10⁹/L, and PLT count at or below 400 x 10⁹/L. The total patient population is 111 adult individuals with PV according to 2008 or 2016 World Health Organization (WHO) criteria, and they must have hemoglobin of at least 10 g/dL for female patients and at least 11 g/dL for male patients, a neutrophil count of at least 1.5 × 10⁹/L at screening, and creatinine clearance of at least 40 mL/min at screening.

The THRIVE Trial⁶

Another interventional trial also for PV, THRIVE (NCT06033586), has a patient population of 46 adults in whom the first-in-class hepcidin mimetic peptide rusfertide is being administered subcutaneously, with no masking. The primary outcomes of interest are median hematocrit below 45% and reduced need for phlebotomies, both from 0 to 2 years. Patients are eligible to participate if they have completed at least 12 months of treatment with rusfertide in a phase 2 analysis, are willing and able to adhere to all study requirements, and agree to use medically acceptable contraception for 30 (women) or 90 (men) days after the last dose of the study drug. Pregnant or lactating women are ineligible. The study location is the Pontchartrain Cancer Center in Louisiana.

The INDEPENDENCE Trial⁷

Luspatercept is an erythroid maturation agent, and in this double-blind, randomized study (NCT04717414), it is being evaluated for its efficacy and safety vs placebo for patients diagnosed with MPN-associated MF and anemia on a Janus kinase 2 inhibitor who have to undergo regular RBC transfusions. After an assessment period of 169 days, participants will be allowed to unblind if they do not demonstrate a clinical benefit. The total study population is 313 adults, at 185 locations in the US and around the world, who must have a confirmed diagnosis of primary MF via 2016 WHO criteria or post-ET or post-PV MF via International Working Group for Myelofibrosis Research and Treatment 2007 criteria. Also known as ACE-536, luspatercept is administered via SC injection on day 1 of each 21-day treatment cycle. For those receiving placebo, an equivalent-dose placebo is also administered on day 1 of each 21-day treatment cycle.

The SURPASS-ET Trial⁸

SURPASS-ET (NCT04285086) is an open-label, multicenter, randomized, active-controlled interventional analysis among 174 adult patients comparing the efficacy and safety of the experimental biologic drug ropeginterferon alfa-2b against the platelet-reducing agent anagrelide for ET demonstrating hydroxyurea resistance or intolerance. The 174 adult patients are from the US, Canada, China, Hong Kong, Japan, Singapore, South Korea, and Taiwan. Ropeginterferon alfa-2b is given via SC injection every 2 weeks, in doses that range from 250 mcg to 500 mcg, and anagrelide is given orally at 0.5 mg/capsule per labeling instructions and physician judgment. There are 4 primary outcomes of interest, each measured at month 9 and month 12: peripheral blood count remission, improvement or nonprogression in disease-related signs, large symptom improvement or maintain nonprogression, and absence of hemorrhagic or thrombotic events. Again, 2016 WHO criteria are used to determine diagnosis of ET, this time in high-risk patients.

The PACIFICA Trial⁹

Pacritinib is a kinase inhibitor, and in this randomized, controlled investigation (NCT03165734), a twice-daily 200-mg dose (n = 266) is being compared with physician’s choice of therapy (n = 133) in patients who have MF and severe thrombocytopenia, as indicated by a platelet count below 50,000/μL at study screening. The originally predicted patient enrollment was 399 adult patients, but total enrollment now stands at 407. There are 207 locations spread across the US and internationally. To be eligible to participate, patients must have a confirmed diagnosis of primary MF, post-PV MF, or post-ET per Tefferi and Vardiman 2008 criteria; adequate liver and renal function; Eastern Cooperative Oncology Group performance status of 0 to 2; an absolute neutrophil count of at least 500/µL; and left ventricular ejection fraction of at least 50%. The original primary outcome of interest was spleen volume at 24 weeks, but now there are 2 primary outcomes of interest, both from baseline to 24 weeks: spleen volume and total symptom score.

References

1. Myeloproliferative neoplasms. Cleveland Clinic. Updated September 1, 2022. Accessed June 19, 2026. https://my.clevelandclinic.org/health/diseases/24144-myeloproliferative-neoplasms
2. Myeloproliferative disorders (MPDs) causes, symptoms, and treatment options. UPMC Hillman Cancer Center. Accessed June 19, 2026. https://hillman.upmc.com/cancer-care/blood/types/mpd
3. Myeloproliferative neoplasm. National Cancer Institute. Accessed June 19, 2026. https://www.cancer.gov/publications/dictionaries/cancer-terms/def/myeloproliferative-neoplasm
4. Drugs approved for myeloproliferative neoplasms or myelodysplastic syndromes. National Cancer Institute. Updated March 14, 2025. Accessed June 19, 2026. https://www.cancer.gov/about-cancer/treatment/drugs/myeloproliferative-neoplasms
5. A study to assess efficacy, safety, and tolerability of P1101 in adult patients with PV. ClinicalTrials.gov. Updated June 30, 2025. Accessed June 19, 2026. https://clinicaltrials.gov/study/NCT05481151
6. Study to evaluate the long-term safety of rusfertide (ptg-300) in subjects with polycythemia vera (THRIVE). ClinicalTrials.gov. Updated August 6, 2025. Accessed June 19, 2026. https://clinicaltrials.gov/study/NCT06033586
7. An efficacy and safety study of luspatercept (ACE-536) versus placebo in subjects with myeloproliferative neoplasm-associated myelofibrosis on concomitant JAK2 inhibitor therapy and who require red blood cell transfusions (INDEPENDENCE). ClinicalTrials.gov. Updated July 10, 2025. Accessed June 19, 2026. https://clinicaltrials.gov/study/NCT04717414
8. Ropeginterferon alfa-2b (P1101) vs anagrelide in essential thrombocythemia patients with hydroxyurea resistance or intolerance (SURPASS ET). ClinicalTrials.gov. Updated August 13, 2025. Accessed June 19, 2026. https://clinicaltrials.gov/study/NCT04285086
9. A phase 3 study of pacritinib in patients with primary myelofibrosis, post polycythemia vera myelofibrosis, or post-essential thrombocythemia myelofibrosis (PACIFICA). ClinicalTrials.gov. Updated April 30, 2026. Accessed June 19, 2026. https://clinicaltrials.gov/study/NCT03165734