Bendamustine plus rituximab for previously untreated patients with indolent B-cell non-Hodgkin lymphoma or mantle cell lymphoma: a multicenter Phase II clinical trial in Japan

A Phase II, multicenter clinical trial of bendamustine plus rituximab (BR) regimen was conducted in previously untreated patients with high-tumor-burden indolent B-cell non-Hodgkin lymphoma (B-NHL) and previously untreated elderly patients with mantle cell lymphoma (MCL) in Japan. Bendamustine 90 mg/m²/day on days 1 and 2, as well as rituximab 375 mg/m² on day 1 were administered intravenously up to six cycles. The primary endpoint was the complete response (CR) rate as assessed by the International Workshop Response Criteria (1999). Sixty-nine patients (59 with indolent B-NHL and 10 with MCL) were treated. The median number of delivered cycles was six (range 1–6). The CR rates were 67.8% [95% confidence interval (CI) 54.4–79.4%] and 70.0% (95% CI 34.8–93.3%) for indolent B-NHL and MCL, respectively. Estimated progression-free survival at 30 months was 72.1% (95% CI 58.5–82.0%) in indolent B-NHL and was 67.5% (95% CI 29.1–88.2%) in MCL. Major grade 3/4 toxicities were hematologic and included lymphopenia (97%), CD4 lymphopenia (91%), neutropenia (86%), and leukopenia (83%). No treatment-related death was found. The BR regimen showed high efficacy as evidenced by the expected CR rate and durable response, as well as an acceptable safety profile for the study populations.