Multicenter phase II study of bendamustine for relapsed or refractory indolent B‐cell non‐Hodgkin lymphoma and mantle cell lymphoma

Bendamustine is a unique cytotoxic agent that has demonstrated efficacy in the treatment of indolent B‐cell non‐Hodgkin lymphomas (B‐NHLs). In this multicenter phase II trial, the efficacy and safety of bendamustine were evaluated in Japanese patients with relapsed or refractory indolent B‐NHL or mantle‐cell lymphoma (MCL). Patients received bendamustine (120 mg/m2) on days 1–2 of a 21‐day cycle, for up to six cycles. The primary endpoint was the overall response rate (ORR) as assessed by an extramural committee according to International Workshop Response Criteria (IWRC). Secondary endpoints included complete response (CR) rate, ORR according to Revised Response Criteria (revised RC), progression‐free survival (PFS), and safety. Fifty‐eight patients with indolent B‐NHL and 11 with MCL were enrolled. By IWRC, bendamustine produced an ORR of 91% (95% confidence interval [CI], 82–97%; 90% and 100% in patients with indolent B‐NHL and MCL, respectively), with a CR rate of 67% (95% CI, 54–78%). ORR and CR rates according to revised RC were 93% (95% CI, 84–98%) and 57% (95% CI, 44–68%), respectively. After a median follow‐up of 12.6 months, median PFS had not been reached. Estimated PFS rates at 1 year were 70% and 90% among indolent B‐NHL and MCL patients, respectively. Bendamustine was generally well tolerated. Reversible myelosuppression, including grade 3/4 leukopenia (65%) and neutropenia (72%), was the most clinically significant toxicity observed. Common non‐hematologic toxicities included mild gastrointestinal events and fatigue. These results demonstrate the high efficacy and tolerability of single‐agent bendamustine in relapsed patients with indolent B‐NHL or MCL histologies. (ClinicalTrials.gov ID: NCT00612183). (Cancer Sci 2010;)