Obinutuzumab plus bendamustine for relapsed/refractory chronic lymphocytic leukemia and predictive and prognostic impact of genetic alterations: the phase II GABRIELL study

GABRIELL was a phase II single-arm study to evaluate the efficacy and safety of obinutuzumab plus bendamustine for relapsed/refractory (R/R) chronic lymphocytic leukemia (CLL). Seventy-two patients with active disease received treatment for up to six 28-day cycles. Overall response rate was 78.6% with a median progression-free survival (PFS) of 26 months, and overall survival (OS) not reached at the end of follow-up (36 months). Undetectable measurable residual disease (<= 0.01%; 36.4% in bone marrow and 53.4% in peripheral blood) correlated with a significantly longer PFS and OS (vs. >0.01). Common grade >= 3 adverse events (76.4%) were neutropenia (58.3%), thrombocytopenia (26.4%) and febrile neutropenia (11.1%). TP53 disruption was the only independent predictive factor for response (Hazard ratio; HR: 0.228). Unmutated immunoglobulin heavy chain variable region (HR: 16.061) was a negative prognostic factor for PFS. In conclusion, the combination of obinutuzumab plus bendamustine is an active and generally adequately-tolerated treatment for R/R CLL.