Although hydroxyurea is considered first-line therapy for essential thrombocythemia (ET) or polycythemia vera (PV) patients with a higher risk of vascular complications, some MPN patients can be resistant or intolerant to this kind of therapy. According to a study published in Blood, Pegylated interferon proved to be effective for patients with high-risk ET and PV who had previously discontinued treatment with hydroxyurea.
At 12 months, complete (CR) and partial response (PR) rates were observed in 43.1% and 26.2%, respectively, of the intention-to-treat (ITT) population of patients with ET. In the ITT population of patients with PV, the corresponding response rates were 22% and 38%. Patients with CALR-mutated ET had significantly higher CR rates compared with those with disease characterized by CALR wild-type ET (56.5% vs 28.0%; P =.01).
Notably, no major bleeding events occurred over the course of the study. Disease transformation to myelofibrosis occurred in 1 patient with PV, and 1 patient with ET with a baseline biopsy consistent with prefibrotic myelofibrosis had disease progression to acute myeloid leukemia.