Complete Hematological Response Coupled with Molecular Response in Polycythemia Vera Treatment with Ropeginterferon Alfa-2b.

Background: Polycythemia vera (PV) is characterized by mutation JAK2 V617F, elevated blood counts, and risk of thrombosis. Ropeginterferon alfa-2b (ropeg) approved for PV at a low-starting dose and slow-titration schema with efficacy at 12 months with assessment visits every three months. This period might be at thrombotic risk resulting from inadequate control of hematological parameters and JAK2. The study was aimed at assessing its efficacy at less than 12 months with assessment visits every two weeks. Methods: Thirteen patients with Hydroxyurea (HU)/Intolerance (HU/I) high-risk PV and pruritus were treated with ropeg at a low-starting dose and slow-titration schema with assessment visits every two weeks. The primary endpoint was the complete hematological response (CHR) at less than 12 months. The secondary endpoints were the CHR rates, CHR dose, durable CHR, and reduction in JAK2V617F variant allele frequency (VAF). Results: The CHR of patients was 8 weeks in 30.7% (4/13), 16 weeks in 30.7% (4/13), and 24 weeks in 38.4% (5/13), respectively, with a mean time of 4.15 months. Durable CHR was at 20, 28, and 36 weeks, respectively, with a mean time of 6.55 months. JAK2 VAF continuously declined from 43.38% at baseline to 12.96% at durable CHR. Eleven patients (85%) achieved partial molecular response (PMR) and two (15.38%) complete molecular responses (CMRs) and all patients resolved the pruritus. No adverse event (AE) or thrombosis occurred. Conclusions: We report that ropeg is efficacious under the low-starting dose and slow-titration regimen in obtaining CHR and molecular response (MR) at less than 12 months.