Obinutuzumab for chronic lymphocytic leukemia: promise of the first treatment approved with breakthrough therapy designation

Obinutuzumab (also known as GA101, afutuzumab, Gazyva) is a humanized, glycoengineered type II monoclonal antibody targeted against CD20. The US Food and Drug Administration has approved obinutuzumab for use with chlorambucil in patients with previously untreated chronic lymphocytic leukemia. The drug is the first treatment to receive approval under the agency's breakthrough therapy designation, a program intended to facilitate and expedite the review and development of therapies for serious and life-threatening conditions. In preclinical studies, obinutuzumab has showed superior efficacy, as compared with rituximab, by inducing direct cell death and increased antibody-dependent cellular cytotoxicity activity with less complement-dependent cytotoxicity. Regulatory approval of obinutuzumab is based on a phase III (CLL11) study that demonstrated improved outcomes with a combination of obinutuzumab with chlorambucil in previously untreated patients with chronic lymphocytic leukemia and comorbidities. Obinutuzumab plus chlorambucil induced deeper and longer remissions than rituximab plus chlorambucil combination as evidenced by prolongation of progression-free survival and higher complete response and molecular response rates. Marketing applications for obinutuzumab have also been submitted to other regulatory authorities including the European Medicines Agency.