Efficacy and safety of pegylated interferon alfa-2b in myeloproliferative neoplasms: A multicenter retrospective study of 210 patients

Abstract Background： Pegylated interferon alfa-2b (Peg-IFN-α-2b) may induce molecular remission in myeloproliferative neoplasms (MPN) through JAK-STAT pathway modulation, but real-world evidence regarding its long-term efficacy and safety profile requires further validation. Objective： To evaluate hematologic overall response rate (ORR), molecular response rate (MRR), and treatment-emergent adverse events (AEs) incidence of Peg-IFN-α-2b in Chinese MPN patients. Methods： This retrospective study enrolled 210 MPN patients (183 essential thrombocythemia [ET], 20 polycythemia vera [PV], 7 primary myelofibrosis [PMF]) treated with Peg-IFN-α-2b across 10 centers (2016-2025). Primary endpoints included ORR (complete response [CR] and partial response [PR]) at 6 and 12 months, and MRR (complete molecular response [CMR] and partial molecular response [PMR]) at 12 months. Secondary endpoints covered MPN-SAF TSS improvement and AEs incidence (CTCAE v5.0). Results： Median age was 55 years (range 18-80), with 78.1% harboring JAK2 V617F mutation. At 6 months (n=177), ORR was 97.74% (CR rate 75.14%); at 12 months (n=113), ORR increased to 99.12% (CR rate 83.04%). Among 41 molecularly-evaluated patients, 97.6% showed variant allele frequency (VAF) reduction, with MRR of 63.41% (all PMR). MPN-SAF TSS assessment (n=166) demonstrated symptom improvement in 74.1% (65.85% with ≥10-point reduction), with median scores decreasing from 11.0/18.5 to 1.0/2.0 in ET/PV patients. AEs occurred in 53.33% of patients, including hepatic dysfunction (15.24%), hematologic toxicity (14.29%), and neurologic symptoms (6.67%). Grade ≥3 AEs incidence was 3.8%, with AE-related discontinuation rate of 3.8%. Conclusion： Peg-IFN-α-2b demonstrates sustained high hematologic and molecular response rates, significant symptom improvement, and manageable safety in Chinese MPN patients, particularly those with ET/PV. Keywords： Myeloproliferative neoplasms; Pegylated interferon alfa-2b; Molecular response; Real-world evidence