Rituximab plus bendamustine or chlorambucil for chronic lymphocytic leukemia: primary analysis of the randomized, open-label MABLE study.
Michallet A-S., Aktan M., Hiddemann W., Ilhan O., Johansson P., Laribi K., Meddeb B., Moreno C., Raposo J., Schuh A., Ünal A., Widenius T., Bernhardt A., Kellershohn K., Messeri D., Osborne S., Leblond V.
MABLE investigated the efficacy and safety of rituximab plus bendamustine or rituximab plus chlorambucil in fludarabine-ineligible patients with chronic lymphocytic leukemia. Patients received rituximab plus bendamustine or rituximab plus chlorambucil every four weeks for six cycles. Rituximab plus chlorambucil-treated patients without a complete response after Cycle 6 received chlorambucil monotherapy for at least six additional cycles or until complete response. The primary endpoint was complete response rate (confirmed by bone marrow biopsy) after Cycle 6 in first-line patients. Secondary endpoints included progression-free survival, overall survival, minimal residual disease, and safety. Overall, 357 patients were randomized (rituximab plus bendamustine, n=178; rituximab plus chlorambucil, n=179; intent-to-treat population), including 241 first-line patients (n=121 and n=120, respectively); 355 patients received treatment (n=177 and n=178, respectively; safety population). In first-line patients, complete response rate after Cycle 6 (rituximab plus bendamustine, 24%; rituximab plus chlorambucil, 9%; P=0.002) and median progression-free survival (rituximab plus bendamustine, 40 months; rituximab plus chlorambucil, 30 months; P=0.003) were higher with rituximab plus bendamustine than rituximab plus chlorambucil. Overall response rate and overall survival were not different. In first-line patients with a complete response, minimal residual disease-negativity was higher with rituximab plus bendamustine than rituximab plus chlorambucil (66% vs 36%). Overall adverse event incidence was similar (rituximab plus bendamustine, 98%; rituximab plus chlorambucil, 97%). Rituximab plus bendamustine may be a valuable first-line option for fludarabine-ineligible patients with chronic lymphocytic leukemia.