CTI BioPharma Corp asserted that results from the Phase 3 PERSIST-2 clinical Trial of pacritinib which is an investigational JAK22 inhibitor that has been published online in JAMA Oncology.
The randomized, international, multicenter study compared the efficacy and safety of pacritinib at two dose levels, compared with best available therapy (BAT), which included ruxolitinib (a JAK1/JAK2 inhibitor), in patients with myelofibrosis and thrombocytopenia (defined as platelet counts ≤100 x 109/L).
In the intent-to treat patient population of the study, he combined pacritinib arms (400mg once daily and 200mg twice daily dosing, 149 patients total) demonstrated a significant improvement of 35% or more in spleen volume reduction (SVR) at 24 weeks of treatment in 27 patients (18%) compared to 2 patients (3%) out of 72 patients in the BAT arm, which included treatment with ruxolitinib (P=0.001). The combined pacritinib treatment arms also demonstrated a greater than 50% reduction in total symptom score (TSS) in 37 patients (25%), compared to 10 patients (14%) in the BAT arm (P=0.079).
Pacritinib was generally well tolerated. The most commonly reported (≥15%) nonhematologic adverse events with pacritinib were gastrointestinal events, fatigue, peripheral edema, and dizziness, and those with BAT (including 19 patients with watchful-waiting only) were abdominal pain, fatigue, diarrhea, and peripheral edema. The majority of common nonhematologic adverse events were grade 1 or 2 in severity. Diarrhea was the most frequently observed adverse event with pacritinib (53% grade 1/2; 4% grade 3) most often occurring during weeks 1 to 8.
John Mascarenhas, M.D., Adult Leukemia Program, Tisch Cancer Institute, Icahn School of Medicine at Mount Sinai said “Clinical improvements in hemoglobin levels and reduction in transfusions were also seen in patients who received pacritinib, and pacritinib had a generally manageable safety profile.”