Combination therapy with ruxolitinib and pegylated interferon alfa-2a in newly diagnosed patients with polycythemia vera.

We report the 2-year end-of-study results from the phase 2 COMBI II clinical trial investigating the combination treatment of ruxolitinib and low-dose pegylated interferon alfa-2a in patients with newly diagnosed polycythemia vera (PV). The primary outcome was safety and key secondary endpoints were efficacy, based on hematologic parameters, quality-of-life measurements, and JAK2V617F variant allele frequency (VAF). We used the 2013 European LeukemiaNet and International Working Group-Myeloproliferative Neoplasms Research remission criteria. The remission criteria included remissions in symptoms, splenomegaly, peripheral blood counts, and bone marrow. We included 25 patients with PV with a median age of 70 years; 5 of those had prior thromboembolic events and 3 had computed tomography-verified splenomegaly. Two patients stopped both study drugs; 1 of these due to progression to post-PV myelofibrosis, the only one with a grade 3 infection. No events of herpes zoster infections were observed. None of the patients discontinued treatment due to psychiatric symptoms. The peripheral blood cell count remission rate was 92% at 24 months. Using the 2013 European LeukemiaNet and International Working Group-Myeloproliferative Neoplasms Research remission criteria, 14 (56%) achieved remission at 24 months; 3 (12%) achieved complete remission and 11 (44%) achieved partial remission. The following items from the Myeloproliferative Neoplasm Symptom Total Symptom Score were significantly reduced: abdominal discomfort, night sweats, itching, and bone pain. The median JAK2V617F VAF decreased from 47% (95% confidence interval [CI], 35-59) to 7% (95% CI, 3-15), and 60% of patients achieved molecular remission. In conclusion, combination treatment improved cell counts; bone marrow cellularity, and fibrosis; and decreased JAK2V617F VAF; with acceptable toxicity in patients with PV. The trial was registered at www.clinicaltrialsregister.eu as #EudraCT2018-004150-13.