Phase I Combination Trial of Lenalidomide and Azacitidine in Patients With Higher-Risk Myelodysplastic Syndromes

PURPOSE: Lenalidomide and azacitidine are active in patients with lower- and higher-risk myelodysplastic syndromes (MDS). These agents may complement each other by targeting both the bone marrow microenvironment and hypomethylating action on the malignant clone. PATIENTS AND METHODS: This phase I trial explored the safety of combination therapy in patients with higher-risk MDS. Response and characterization of molecular and methylation status of responders were secondary objectives. Patients were enrolled using a 3 + 3 dose escalation. Cycles lasted 28 days, and patients received a maximum of seven cycles. RESULTS: Of 18 patients enrolled, median age was 68 years (range, 52 to 78 years), interval from diagnosis was 5 weeks (range, 2 to 106 weeks), and follow-up was 7 months (range, 1 to 26 months). International Prognostic Scoring System categories were intermediate 1 (n = 2), intermediate 2 (n = 10), and high (n = 6). No dose-limiting toxicities occurred, and a maximum-tolerated dose was not reached. Grades 3 to 4 nonhematologic toxicities (> 1) included febrile neutropenia (n = 5), cardiac (n = 2), and CNS hemorrhage (n = 2). Median absolute neutrophil count decrease was 26%, and platelet decrease was 1% (mean, 24%). The overall response rate was 67%: eight patients (44%) had a complete response (CR); three patients (17%) had hematologic improvement; one patient (6%) had marrow CR. Patients achieving CR were more likely to have normal cytogenetics and lower methylation levels. CONCLUSION: The combination of lenalidomide and azacitidine is well tolerated with encouraging clinical activity. The go-forward dose is azacitidine 75 mg/m(2) on days 1 through 5 and lenalidomide 10 mg on days 1 through 21.