S196: ROPEGINTERFERON ALFA-2B ACHIEVES PATIENT-SPECIFIC TREATMENT GOALS IN POLYCYTHEMIA VERA: FINAL RESULTS FROM THE PROUD-PV/CONTINUATION-PV STUDIES

Background: Treatment of polycythemia vera (PV) aims to prevent thromboembolic complications, reduce the risk of progression to acute leukemia or myelofibrosis - of particular concern to patients - and ameliorate the symptom burden; specifically, to improve quality of life, therapy should address the most clinically important symptoms while reducing phlebotomies to avoid iron-deficiency symptoms. Long-term efficacy and safety of ropeginterferon alfa-2b have been demonstrated in PROUD-PV/CONTINUATION-PV; the final analysis applied a patient-focused approach. Aims: To analyze the patient-relevant benefit of ropeginterferon alfa-2b versus hydroxyurea (HU)/best available treatment (BAT) over 6 years. Methods: Patients diagnosed with PV according to WHO 2008 criteria who were cytoreduction-naïve or hydroxyurea pre-treated and gave written informed consent were randomized 1:1 to ropeginterferon alpha-2b or control treatment (HU) for one year in PROUD-PV. In CONTINUATION-PV, control arm patients could switch from HU to BAT. Patient-reported PV symptom burden was assessed based on adverse events documented in the patient diary and recorded at each visit; items defined in the Myeloproliferative Neoplasm Symptom Assessment Form Total Symptom Score (MPN-SAF TSS; fatigue, concentration problems, early satiety, inactivity, night sweats, itching, bone pain, abdominal discomfort, weight loss, and fevers) and medical synonyms were evaluated post-hoc. Efficacy assessments included Kaplan-Meier analysis of event-free survival, phlebotomy need and JAK2V617F allele burden. Analyses were conducted on the CONTINUATION-PV full analysis set over 6 years of treatment. Results: The full analysis set comprised 95 patients in the ropeginterferon alfa-2b arm and 74 in the control arm. Patient-reported symptoms defined in the MPN-SAF TSS were present in a small minority (9.5%) of patients per arm at baseline (up to Week 4 of treatment) in this early-stage PV population. Occurrence of the defined symptoms remained low over long-term treatment, reported in 15.7% of patients in the ropeginterferon alfa-2b arm and 20.7% in the control arm during the 6th year of treatment. No phlebotomies were required to maintain hematocrit <45% in the 6th year of treatment in 81.4% of patients receiving ropeginterferon alfa-2b compared with 60.0% of patients in the control arm (p=0.005). Depletion of the JAK2V617F alle burden, which may lower the risk of progression to myelofibrosis, was observed in ropeginterferon alfa-2b treated patients; JAK2V617F allele burden <1% at 6 years was achieved in 19/92 (20.7%) patients in the ropeginterferon alfa-2b arm with baseline allele burden >10%. One patient met this threshold in the control arm (1/70 [1.4%]; p=0.0001). Event-free survival (risk events: disease progression, death and thromboembolic events) over ≥6 years of treatment was significantly higher among ropeginterferon alfa-2b treated patients than the control group (risk events reported in 5/95 vs. 12/74 patients, respectively; p=0.04 [Log-Rank]; Fig 1). Image:Summary/Conclusion: Long-term ropeginterferon alfa-2b therapy fulfils treatment goals important to patients with PV: a good quality of life as indicated by a low symptom burden and phlebotomy requirement, the potential to influence myelofibrosis risk, and better event-free survival versus BAT.