Bendamustine Versus Chlorambucil as First-Line Treatment in B Cell Chronic Lymphocytic Leukemia: An Updated Analysis from An International Phase III Study.

Introduction: Bendamustine is a purine analog/alkylator hybrid agent with a unique mechanism of action, which has shown good clinical efficacy and acceptable tolerability in various hematological malignancies, including Hodgkin’s disease, non-Hodgkin’s lymphoma, and multiple myeloma.

Patients and Methods: The efficacy and safety of bendamustine and chlorambucil have been compared in a randomized, open-label, multicenter, Phase III trial in patients with previously untreated advanced (Binet stage B/C) B cell chronic lymphocytic leukemia: an updated analysis from this trial is presented here. Patients were randomized to receive bendamustine (100 mg/m² on days 1 + 2) or chlorambucil (0.8 mg/kg on days 1 and 15) for up to 6 treatment cycles. The median cumulative dose per patient was 1820 mg and 517 mg for bendamustine and chlorambucil, respectively. The primary endpoints were overall remission rate (ORR), which was defined as complete response, nodular partial response or partial response, and progression-free survival (PFS). Secondary endpoints included overall survival (OS) and safety. The response to treatment was evaluated by a blinded Independent Response Assessment Committee.

Results: A total of 319 patients were randomized (162 bendamustine, 157 chlorambucil), of whom all were included in the efficacy analysis and 312 were evaluable for safety. The mean (± SD) number of treatment cycles was 4.8 ± 1.7 in the bendamustine group and 4.6 ± 1.7 in the chlorambucil group; the median duration of follow-up was 29.2 months (29.8 bendamustine, 27.8 chlorambucil). The ORR was significantly higher with bendamustine than with chlorambucil (67% versus 30%, P<0.0001). The median PFS was 21.5 months with bendamustine and 8.3 months with chlorambucil (P<0.0001). No difference in OS was seen between groups. Most doses were given on schedule. The mean overall relative dose intensity was 86% and 96% in the bendamustine and chlorambucil treatment groups, respectively. At least 1 grade 3/4 neutropenia occurred in 43% of bendamustine-treated patients and 21% of those receiving chlorambucil. Grade 3/4 infections were documented in 7% of bendamustine-treated patients and 4% of chlorambucil-treated patients.

Conclusion: This study has shown that bendamustine offers significantly greater efficacy than chlorambucil, with manageable toxicity, and should be considered as first-line chemotherapy for patients with advanced B-CLL.