Lenalidomide following fludarabine and rituximab in previously untreated CLL

Abstract

Fludarabine-based regimens have overall response rates (ORR) of 90-95% in untreated chronic lymphocytic leukemia (CLL), but almost all patients inevitably relapse. Given the promising activity of lenalidomide in relapsed/refractory CLL, we studied the combination of fludarabine and rituximab (FR) followed by lenalidomide in untreated disease (n=22). Patients received three cycles (C) of FR (F 25 mg/m 2 days (D) 1-5, R 375 mg/m 2 D1). Those who responded received three more cycles of FR followed by three cycles of lenalidomide; whereas patients with stable or progressive disease switched to lenalidomide (5 mg C1D1-21, 10 mg in subsequent cycles). After three cycles of lenalidomide, patients with a response or stable disease received another three cycles, whereas those who progressed were removed. The ORR with FR was 77% (complete response (CR) 23%). With lenalidomide (n=15), three converted from a partial response to CR, increasing the CR rate to 36%. The most common >grade 3 toxicity was neutropenia (59%). The median progression-free survival was 38.5 months (95% CI: 32.0, 53.9) and the median overall survival had not yet been reached at the time of analysis. The study demonstrated the feasibility of FR-L when administered in a sequential manner.