A phase II study of lenalidomide alone in relapsed/refractory acute myeloid leukemia or high-risk myelodysplastic syndromes with chromosome 5 abnormalities

Background: Lenalidomide is effective in low-risk myelodysplastic syndromes (MDS) with deletion 5q. We conducted a phase II study to evaluate the safety and efficacy of lenalidomide in patients with relapsed/refractory acute myeloid leukemia (AML) and high-risk MDS with any chromosome 5 abnormality. Patients and Methods: Eighteen adults with AML and 9 with high-risk MDS were enrolled. Lenalidomide was given orally at doses 5 to 25 mg daily for 21 days of a 28-day cycle until disease progression or unacceptable adverse event. Results: Median age for all 27 patients was 64 years (range, 39-88 years) with a median of 2 previous therapies (range, 1-6 lines). Two patients (7%) with AML and 5q deletion and +8 cytogenetic abnormality in 2 separate clones achieved complete remission (CR) or CR without platelet recovery (CRp). Response durations were 4 and 6 months, respectively. No responses were seen in patients with chromosome 5 abnormality in a complex cytogenetic background. Twenty patients (74%) developed neutropenic fever or infection requiring hospitalization. Conclusions: Clinical activity of lenalidomide as single agent in AML and high-risk MDS with chromosome 5 abnormalities appears to be limited to patients with noncomplex cytogenetics.