The combination of ruxolitinib and low-dose pegylated interferon-α2 (PEG-IFNα2) showed positive responses for patients with polycythemia vera (PV) or myelofibrosis (MF) in the final report of a recent phase 2 study. The study results were reported in Haematologica.1

In the single-arm phase 2 COMBI study (EU Clinical Trials Registry Number: 2013-003295-12), 32 patients with PV and 18 patients with MF received ruxolitinib, dosed according to platelet count, and either PEG-IFNα2a at 45 mg/week or PEG-IFNα2b at 35 mg/week. The primary endpoint was efficacy, determined by multiple outcomes such as complete remission (CR), peripheral blood cell count remission (PBCR), quality of life, and JAK2 V617F allele burden.

The rate of remission for patients with PV was 31%, and CR was reported in 9% of patients. For patients with MF, remission occurred in 44%, with CR in 28%. PBCR occurred with a cumulative incidence of 0.85 in patients with PV and 0.75 for those with MF.

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Molecular response was demonstrated in 41% of patients overall, and the JAK2 V617F allele burden dropped from a median of 47% (95% CI, 33%-61%) to a median of 12% (95% CI, 6%-22%; P <.001).

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As a measure of quality of life, the Myeloproliferative Neoplasm Symptom Assessment Form total symptom score was reduced from a median score of 22 at the start of the study to a median of 15 at a 2-year time point.

Overall, 16% of patients dropped out of the trial, with 8% discontinuing because of adverse events.

“In this study, we showed that a novel combination treatment with ruxolitinib and low-dose PEG-IFNα2 is an effective treatment with acceptable toxicity for patients with PV or MF,” wrote the investigators.


Sørensen AL, Mikkelsen SU, Knudsen TA, et al. Ruxolitinib and interferon-α2 combination therapy for patients with polycythemia vera or myelofibrosis: a phase II study [published online December 26, 2019]. Haematologica. doi:10.3324/haematol.2019.235648