Obinutuzumab for the treatment of chronic lymphocytic leukemia

Obinutuzumab is a novel therapeutic anti-CD20 monoclonal antibody recently approved by the United States Food and Drug Administration (FDA) for use in combination with chlorambucil as first-line treatment of chronic lymphocytic leukemia (CLL). It is distinguished from other anti-B-lymphocyte antigen CD20 (anti-CD20) therapeutic antibodies in current clinical use by its type II properties and glycoengineered Fc region. In vitro these unique properties translate into higher rates of antibody-dependent cytotoxicity and direct cell death compared to rituximab, and obinutuzumab demonstrates improved efficacy in human lymphoma xenograft models and whole blood lymphocyte depletion assays. FDA approval was based upon results from a randomized phase III trial comparing treatment with single-agent chlorambucil to the combination of chlorambucil and either rituximab or obinutuzu-mab. The obinutuzumab arm resulted in higher rates of complete remission and significant improvements in progression-free survival versus either comparator regimen. The majority of patients in the obinutuzumab and chlorambucil arm finished all six planned treatment cycles, and therapy was well tolerated. Toxicities of obinutuzumab are similar to those of other anti-CD20 antibodies, although infusion-related reactions and neutropenia appear to be more common. This trial establishes chemoimmunotherapy with obinutuzumab and chlorambucil as an attractive treatment option for CLL patients, particularly those with comorbid medical illnesses or advanced age. Obinutuzumab remains under study in combination with both chemotherapy and novel agents for CLL and non-Hodgkin's lymphoma, where it is expected to find additional clinical applications.