Bendamustine versus chlorambucil in treatment of chronic lymphocytic leukaemia in China: a randomized, open-label, parallel-controlled, phase III clinical trial

Abstract

Background: Chronic lymphoblastic leukemia (CLL) is the most common adult leukemia and mainly affects the elderly. Chemoimmunotherapy still has a role in the standard frontline therapy for specific population. However, the clinical activity of bendamustine has not been investigated in unfit Chinese patients with CLL. This study aimed to compare the efficacy and safety of bendamustine versus chlorambucil for untreated Chinese patients with Binet stage B/C CLL.

Methods: In this multi-center, randomized, open-label, parallel-controlled, phase III trial, patients with previously untreated CLL were enrolled and randomly assigned (1:1) to receive bendamustine or chlorambucil. The primary endpoint was the objective response rate. Secondary endpoints included progression-free survival, the duration of response, and overall survival. Adverse events were recorded to evaluate safety.

Results: Of 158 screened patients, 147 were enrolled and randomly allocated to receive bendamustine (n = 72) or chlorambucil (n = 75). After a median follow-up of 25.6 months (IQR 12.5-27.7), 69.0% (95% CI, 56.9-79.5) of bendamustine-treated patients achieved objective response and 37.0% (95% CI, 26.0-49.1) of chlorambucil with a difference of 32.0% (95%CI: 16.6-47.5), demonstrating the superiority of bendamustine to chlorambucil (p < 0.001). The median progression-free survival was longer for bendamustine (16.5 months; 95% CI, 11.3-24.7) versus chlorambucil (9.6 months; 95% CI, 8.7-11.8; p < 0.001). A longer median duration of response was seen in those receiving bendamustine (19.2 months; 95% CI, 11.8-29.1) than chlorambucil (10.7 months; 95% CI, 5.6-13.6; p = 0.0018). Median overall survival was not reached in either group. Overall survival at 18 months was 88% for bendamustine versus 85% for chlorambucil. Most common adverse events in both groups were neutropenia and thrombocytopenia.

Conclusion: In untreated Chinese patients with Binet stage B/C CLL, bendamustine induced the better objective response and resulted in longer progression-free survival than chlorambucil. Overall, these results validate the role of bendamustine as an effective and safe first-line therapy in this population.

Keywords: Bendamustine; Chlorambucil; Chronic lymphocytic leukemia; Objective response rate; Progression-free survival.