Clinical efficacy of lenalidomide in patients with relapsed or refractory chronic lymphocytic leukemia: Results of a phase II study

Purpose: Patients with relapsed or refractory chronic lymphocytic leukemia (CLL) have profound immune defects and limited treatment options. Given the dramatic activity of lenalidomide in other B-cell malignancies and its pleotropic immunomodulatory effects, we conducted a phase II trial of this agent in CLL. Patients and Methods: Patients with relapsed or refractory B-cell CLL (B-CLL) were eligible if they required treatment as per the National Cancer Institute Working Group 1996 guidelines. Lenalidomide was administered orally at 25 mg on days 1 through 21 of a 28-day cycle. Response was assessed after each cycle. Patients were to continue treatment until disease progression, unacceptable toxicity, or complete remission. Rituximab was added to lenalidomide on disease progression. Results: Forty-five patients were enrolled, with a median age of 64 years. Sixty-four percent of the patients had Rai stage III or IV disease, and 51% were refractory to fludarabine. The overall response rate was 47%, with 9% of the patients attaining a complete remission. Fatigue, thrombocytopenia, and neutropenia were the most common adverse effects noted in 83%, 78%, and 78% of the patients, respectively. Conclusion: Lenalidomide is clinically active in patients with relapsed or refractory B-CLL. These findings are encouraging and warrant further investigation of this agent in the treatment of this disorder.