Ropeginterferon Versus Standard Therapy for Low-Risk Patients with Polycythemia Vera

BACKGROUND: Whether phlebotomy alone can adequately maintain target hematocrit in patients with low-risk polycythemia vera (PV) remains elusive. METHODS: In a phase 2 open-label randomized trial, we compared ropeginterferon alfa-2b (ropeg; 100 μg every 2 weeks) with phlebotomy only regarding maintenance of a median hematocrit level (≤45%) over 12 months in the absence of progressive disease (primary end point). In follow-up, crossover to the alternative treatment group was allowed if the primary end point was not met. RESULTS: In total, 127 patients were enrolled (ropeg: n=64; standard group: n=63). The primary end point was met in 81% and 51% in the ropeg and standard groups, respectively. Responders continued the assigned treatment until month 24 and maintained response in 83% and 59%, respectively (P=0.02). Ropeg responders less frequently experienced moderate/severe symptoms (33% vs. 67% in the standard group) and palpable splenomegaly (14% vs. 37%) and showed normalization of ferritin levels and blood counts. Nonresponders at 12 months crossed over to the standard (n=9) or ropeg (n=23) group; in patients switched to ropeg only, 7 of 23 met the response criteria in 12 months, and phlebotomy need was high (4.7 per patient per year). Discontinuation because of adverse events occurred in seven patients treated with ropeg. CONCLUSIONS: In this 24-month trial, ropeg was superior to phlebotomy alone in maintaining hematocrit on target. No dose-limiting side effects or toxicities were noted; 9.2% of patients on ropeg and no patients on standard treatment developed neutropenia. (Funded by AOP Health and others; ClinicalTrials.gov number, NCT03003325.)