MPN-038: PACIFICA: A Randomized, Controlled Phase 3 Study of Pacritinib Versus Physician’s Choice in Patients with Primary or Secondary Myelofibrosis and Severe Thrombocytopenia

Background: Myelofibrosis is a serious, life-threatening myeloproliferative neoplasm caused by clonal proliferation of myeloid cells. Patients with myelofibrosis and severe thrombocytopenia (platelet counts Study Design: PACIFICA is a multi-national, multi-center, randomized, controlled phase 3 trial of pacritinib versuss P/C in adults with primary or secondary myelofibrosis with DIPSS intermediate- or high-risk disease, ECOG PS 0-2, platelet counts 450 msec, or use of medications that increase risk of hemorrhage or QT prolongation. Approximately 348 patients will be randomized 2:1 to continuous pacritinib 200 mg twice daily or P/C (low-dose ruxolitinib, danazol, corticosteroids, or hydroxyurea). The primary objective is efficacy as assessed by proportion of patients achieving a ≥35% spleen volume reduction (SVR) from baseline to week 24. Secondary objectives include proportion of patients achieving a ≥50% reduction in total symptom score at week 24, Patient Global Impression of Change responses at week 24, overall survival, and safety. Tertiary endpoints include leukemia-free survival, alternative SVR analyses, hematologic improvement (transfusion independence and improvement in hemoglobin and platelet levels), fatigue improvement, and changes in biomarkers and gene expression. The primary analysis will be based on ~168 patients; secondary analyses will be based on the full sample size. PACIFICA is currently enrolling, with ~130 sites worldwide.