Bendamustine and rituximab act synergistically in vitro and are effective in the treatment of relapsed or refractory indolent and mantle cell lymphomas

6565 Bendamustine combines a purine-like benzimidazol and bifunctionally alkylating nitrogen mustard group. The drug is active in a variety of lymphoproliferative disorders without crossresistance to cyclophosphamide. We investigated simultaneous combination of rituximab with bendamustine and found synergistic effects of apoptosis in vitro on lymphoma cell lines (DOHH-2, WSU-NHL) as well as on ex vivo cells of pat. with CLL. Apoptosis was determined by Annexin V and JC-1. The synergistic effects of rituximab in combination with bendamustine were evenly strong when rituximab was applied at a dose, at which half of the CD20 molecules per cell were saturated. Based on our in vitro results we initiated a phase-II study to examine efficacy and toxicity of bendamustine combined with rituximab (BR) as therapy of 1st, 2nd or 3rd relapse. Treatment schedule: 6 x Rituximab 375 mg/qm day 1 combined with 4 x Bendamustine 90 mg/qm day 2+3, every 4 weeks. Included entities: 17 immunocytomas, 16 mantle cell (MCL), 24 fo...