CTI BioPharma Corp. (CTI BioPharma) (NASDAQ and MTA: CTIC) today announced that results of a Phase 2 study of pacritinib, in patients with myelofibrosis were published in the journal Blood. Pacritinib is a next-generation oral JAK2/FLT3 multikinase inhibitor currently in Phase 3 development in the PERSIST program. Dr. Rami S. Komrokji, Associate Professor of Oncologic Sciences at the University of South Florida College of Medicine and Clinical Director of the Department of Malignant Hematology at Moffitt Cancer Center in Tampa, Fla., was the lead author.
Results of the Phase 2 study demonstrated that pacritinib is active in patients with myelofibrosis, resulting in spleen volume reduction, while producing substantial and prolonged improvement in disease-related symptoms without causing clinically significant myelosuppression. We believe pacritinib was well tolerated, including in patients with disease-related anemia and thrombocytopenia, with the predominant side effect being manageable gastrointestinal toxicity.
"The results of this Phase 2 study are consistent with our recently reported top-line results from the PERSIST-1 randomized Phase 3 trial with a comparable reduction in spleen volume of up to Week 24 in addition to the observation that patients on pacritinib continued to respond over time," said James A. Bianco, M.D., President and CEO of CTI BioPharma. "Based on the results of this study and the recently announced PERSIST-1 top-line data, we believe pacritinib may provide an important therapeutic option for a broader spectrum of patients suffering from this challenging disease. We look forward to presenting additional data from PERSIST-1 at a scientific conference this year."
"The publication of the Phase 2 results in the Blood journal was timely as we recently learned about the positive results from PERSIST-1 randomized Phase 3 study. Currently, myelofibrosis patients with anemia and thrombocytopenia have limited treatment options for splenomegaly and constitutional symptoms and these data show that pacritinib has potential to help patients that are sub-optimally managed on currently available treatments," said Dr. Komrokji.
Phase 2 Study Design and Results
The multicenter, single-arm, open-label Phase 2 study evaluated the safety and efficacy of pacritinib in the treatment of patients with myelofibrosis who had clinical splenomegaly poorly controlled with standard therapies or were newly diagnosed with intermediate- or high-risk disease and not considered candidates for standard therapy. Patients were allowed to enroll irrespective of their degree of thrombocytopenia, anemia or neutropenia. A total of 35 patients were enrolled and treated with pacritinib 400 mg administered once daily in 28-day cycles. The median age of the patients was 69 years. The endpoint of the study was assessment of the spleen response rate, defined as the proportion of subjects achieving 35 percent or greater reduction in spleen volume from baseline up to Week 24 as measured by magnetic resonance imaging (MRI). Other endpoints included the proportion of patients with 50 percent or greater reduction in spleen size as determined by physical exam and the proportion of patients with 50 percent or greater reduction in total symptom score (TSS), including symptoms of abdominal pain, bone pain, early satiety, fatigue, inactivity, night sweats and pruritus, from baseline up to Week 24.
Results showed that up to Week 24:
- 30.8 percent of evaluable patients (8/26) had 35 percent or greater reduction in spleen volume by computerized tomography (CT) or MRI scan with 42 percent of patients reaching 35 percent or greater reduction by end of treatment
- 42.4 percent of evaluable patients (14/33) achieved 50 percent or greater reduction in spleen size by physical exam
- 48.4 percent of evaluable patients (15/31) achieved 50 percent or greater reduction in TSS
The most common treatment-emergent adverse events were Grade 1-2 diarrhea (69%) and nausea (49%), which caused one patient to discontinue treatment. The study drug was discontinued in nine patients (26%) due to adverse events, of which three were deemed unrelated to study drug. There were five deaths, three of which were due to serious adverse events. Of those, one (subdural hematoma) was considered possibly related to study drug. Anemia and thrombocytopenia adverse events were reported in 12 (34.3%) and eight (22.9%) patients, respectively.
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