Project Title

A Phase 3 Study of Pacritinib in Patients With Primary Myelofibrosis, Post Polycythemia Vera Myelofibrosis, or Post-Essential Thrombocythemia Myelofibrosis

Official Title

A Randomized, Controlled Phase 3 Study of Pacritinib Versus Physician’s Choice in Patients with Primary Myelofibrosis, Post Polycythemia Vera Myelofibrosis, or Post Essential Thrombocythemia Myelofibrosis with Severe Thrombocytopenia (Platelet Counts <50,000/μL)

Project Summary

The study is a randomized, controlled phase 3 study comparing the efficacy of pacritinib with P/C therapy in patients with PMF, PPV-MF, or PET-MF (Dynamic International Prognostic Scoring System [DIPSS] risk score of Intermediate-1 to High-Risk), who have had had no or limited exposure to any JAK2 inhibitor or are JAK2 inhibitor-naive, and who have severe thrombocytopenia (platelet count <50,000/µL). This study was designed to use the pacritinib 200 mg BID dose, which was determined to be the optimal dose based on dose- and exposure-response analyses conducted using all available data, including the dosing data from the previous portion of this study. Patients will be randomized 2:1 to receive pacritinib 200 mg BID or the P/C therapy (limited to single drugs from the following list: corticosteroids, hydroxyurea, danazol, or low-dose ruxolitinib). The proposed P/C regimen for a patient must be selected prior to randomization. Randomization will be stratified by prior JAK2 inhibitor therapy (yes/no) and P/C therapy selected prior to randomization. Prior JAK2 inhibitor therapy will be defined as any duration of treatment with a JAK2 inhibitor, such as ruxolitinib, fedratinib, or momelotinib. To be eligible, patients are not allowed to have been treated with more than one JAK2 inhibitor. Assigned treatment will continue until the patient experiences progressive disease or intolerable AEs, withdraws consent, or initiates new MF-directed therapy. No study treatment crossover will be allowed at any time. All patients should complete all visit procedures through Week 24, including patients who stop treatment or have protocol-defined progressive disease prior to Week 24, unless the patient withdraws consent for study procedures, dies, undergoes splenic irradiation or splenectomy, initiates any non-protocol-directed anti-MF treatment, or the study is terminated. In addition to the above, patients will be considered to have discontinued treatment if pacritinib or P/C therapy is held for >28 consecutive days due to treatment toxicity, or if treatment is discontinued for lack of efficacy, or at the request of the principal investigator or the patient. Following the Week 24 assessment, patients who are benefiting from therapy will be allowed to continue receiving the assigned treatment (pacritinib or P/C) until the patient experiences progressive disease, intolerable AEs, withdraws consent, or initiates new MF-directed therapy. All randomized patients will be followed for survival for 2.5 years from the date of randomization unless consent for follow-up is withdrawn. 

Blood Disorder

• Primary Myelofibrosis

• Post-Polycythemia Vera Myelofibrosis

• Post-essential Thrombocythemia Myelofibrosis

Patient Recruitment Details

Patient recruitment status: Open

Number of Patients (Globally)

Undetermined.