A Phase 3 Study of Pacritinib in Patients With Primary Myelofibrosis, Post Polycythemia Vera Myelofibrosis, or Post-Essential Thrombocythemia Myelofibrosis
Key claim: A Phase 3 randomized trial is evaluating pacritinib 200 mg BID versus physician’s choice therapy in approximately 399 myelofibrosis patients with severe thrombocytopenia (platelets <50,000/μL) to establish efficacy and safety in this high-risk subpopulation.
Abstract
This study (study ID PAC203 North America; PAC303 ex-North America) is evaluating 200 mg BID of pacritinib compared to physician’s choice (P/C) therapy in patients with MF and severe thrombocytopenia (platelet count <50,000/μL). Approximately 399 patients in total will be enrolled, randomized 2:1 to either pacritinib (approximately 266 patients) or to P/C therapy (approximately 133 patients)
Condition or disease: Primary Myelofibrosis/Post-Polycythemia Vera Myelofibrosis/ Post-essential Thrombocythemia Myelofibrosis
Intervention/treatment: Drug-Pacritinib
Why this matters
Severe thrombocytopenia (platelets <50,000/μL) defines a high-mortality MF subpopulation across PMF, post-PV MF, and post-ET MF where ruxolitinib is poorly tolerated and prognosis is worse than platelet-replete MF. A confirmatory Phase 3 of pacritinib in this exact subgroup directly informs subtype-specific natural history and treatment selection for the cytopenic transformation arms of all three upstream MPNs, and complements parallel cytopenic-MF strategies (selinexor+pacritinib, DISC-0974) already tracked in this area.