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 mg 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: n564; standard group: n563). The primary end point was met in 81% and 51% in the ropeg and standard groups, respec- tively. Responders continued the assigned treatment until month 24 and maintained response in 83% and 59%, respectively (P50.02). Ropeg responders less frequently expe- rienced 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 (n59) or ropeg (n523) 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 main- taining 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.