Durable long-term responses in patients with myelodysplastic syndromes treated with lenalidomide.

Lenalidomide has proven efficacy and safety and has been shown to reduce transfusion requirements and reverse cytogenetic abnormalities in lower-risk myelodysplastic syndromes (MDS). However, long-term follow-up data have not yet been reported. Here, we describe 6 patients with International Prognostic Scoring System low- or intermediate-1-risk MDS who began lenalidomide therapy between April 2002 and June 2003 as part of the MDS-001 study and who have maintained long-term therapy. Five of these patients had an ongoing requirement for red blood cell transfusions despite previous treatment with recombinant erythropoietin. One patient began lenalidomide therapy because of progressive and symptomatic anemia. To date, all patients maintained long-term transfusion independence (over 4.5 years) while receiving oral lenalidomide therapy, including 5 patients who remain on therapy. Sustained erythroid response was reported despite persistence of the deletion 5q [del(5q)] abnormality in 3 of the 4 patients with del(5q) at study entry. Side effects were largely predictable and manageable. The favorable outcomes presented here show that lenalidomide can induce durable erythroid responses with sustained transfusion independence that can exceed 6 years in patients with lower-risk MDS.