ASCO: PERSIST-1 – pacritinib tops best available therapy in myelofibrosis

The proportion of patients having at least a one-half reduction in Total Symptom Score was 24.5% with pacritinib and 6.5% with best available therapy (P < .0001).

“We did not see any significant drug-emergent thrombocytopenia,” Dr. Mesa reported. In fact, among patients who entered the trial with a platelet count of less than 50,000 per microliter, those in the pacritinib arm had a significant, steady improvement in platelet count. “This could be multifactorial, from reduced splenic sequestration amongst other beneficial features,” he proposed

Among patients who were red cell transfusion dependent at baseline, 25.7% in the pacritinib arm achieved transfusion independence, compared with none in the control arm (P = .04).

The most common nonhematologic grade 3 or 4 adverse event with pacritinib was diarrhea (5% vs. 0%), while the most common hematologic grade 3 or 4 adverse event was anemia (16.8% vs. 15.1%).

Dr. Mesa noted that an ongoing sister trial, PERSIST-2, is still open to accrual. “This is a trial exclusively for patients with thrombocytopenia and allows individuals who have previously received JAK inhibitor therapy, with patients being randomized to the dose tested in the PERSIST-1 study or a b.i.d. dosing with similar goals and endpoints,” he elaborated.