Long-term results of a phase II trial of lenalidomide plus prednisone therapy for patients with myelofibrosis.

Lenalidomide, with or without prednisone, is an active therapy for patients with myelofibrosis (MF). We provide an update of a phase II study of lenalidomide plus prednisone in patients with MF, after median follow up of 9 years. Forty patients were enrolled in the study and all patients were evaluable for response. Response to the treatment was reevaluated using IWG response criteria published in 2013: quality of response improved over time and overall response rate was 35%. Response in splenomegaly was seen in 39% of patients and anemia response in 32%. The median time to treatment failure (TTF) in all patients was 8.2 months and the median duration of response was 34.6 months. Response was highly durable in some patients: six patients (15%) had TTF for more than 60 months (5 years) and three patients are still on the treatment beyond 109 months (9 years). Complete and partial responses were seen in one and five patients, respectively, but achieving deeper response was not necessary for the response to be durable. New clinical studies are needed to explore safe and well tolerated lenalidomide-based combination strategies for patients with MF.