With the use of the International Working Group for Myelofibrosis Treatment and

Research consensus criteria, we re-assessed the efficacy of thalidomide and lenalidomide in 125 patients with myelofi-brosis treated in 3 consecutive phase 2 trials: 44 received single-agent thalido-mide, 41 single-agent lenalidomide, and 40 a combination of lenalidomide plus prednisone. The thalidomide group in-cluded significantly more untreated pa-tients and patients with performance sta-tus of 2. The Lenalidomide-based therapy produced higher efficacy (34%-38%) than thalidomide (16%; P .06). Responses to thalidomide were seen within 3-15 weeks, whereas responses to the lenalidomide-based therapy were also seen after a prolonged course of therapy (range, 2-45 weeks). Lenalidomide plus predni-sone therapy resulted in significantly longer response duration (median, 34 months) than single-agent lenalido-mide or thalidomide (median, 7 and 13 months, respectively; P .042). Fewer patients (P .001) discontinued the lena-lidomide plus prednisone therapy (13%) because of side effects then patients on single-agents therapy (32%-39%). In con-clusion, the combination of lenalidomide plus prednisone appears to be more ef-fective and safer than single-agent tha-lidomide or lenalidomide. (Blood. 2011; 118(4):899-902