A phase II study of bendamustine plus rituximab in Japanese patients with relapsed or refractory indolent B-cell non-Hodgkin lymphoma and mantle cell lymphoma previously treated with rituximab: BRB study.

To evaluate the efficacy and safety of a combined regimen of bendamustine (B) and rituximab (R) in Japanese patients with relapsed/refractory (r/r) indolent B-cell non-Hodgkin lymphomas (B-NHLs) and mantle cell lymphoma (MCL). Patients aged 20-79 years with pathologically confirmed B-NHLs or MCL, which were r/r after 1-2 R-containing regimens, were included in this study. The BR regimen consisted of B (90 mg/m(2)) for two consecutive days and R (375 mg/m(2)) on day 1, 2, or 3. The course was repeated every 4 weeks for up to four cycles. Fifty-three patients were enrolled in this study and analyzed. The diagnosis included follicular lymphoma (FL) (77 %), mucosa-associated lymphoid tissue lymphoma (13 %) and others (10 %). Forty-seven (90 %) patients completed four cycles of treatment as per schedule. Best overall response rate (ORR) and complete response rate (CRR) was 94 and 71 %, respectively (for FL, ORR 95 % and CRR 80 %). The treatment was well tolerated and the primary toxicity was myelosuppression; the incidence of grade 3/4 leukopenia and neutropenia were 42 and 40 %, respectively. There were no grade 5 toxicities. The BR regimen is safe in Japanese patients with r/r indolent B-NHLs and MCL, and is effective for those with r/r indolent B-NHLs. For the evaluation of late toxicity, especially infection, longer follow-up of this cohort is needed.