CHICAGO–Daratumumab at 16 mg/kg demonstrated profound durable single agent activity with meaningful responses and a favorable safety profile in patients with heavily pretreated multiple myeloma, a study presented at the 2015 American Society of Clinical Oncology (ASCO) annual meeting has shown.

“Daratumumab is a human monoclonal antibody that binds to CD38-expressing malignant cells, inducing cell death through multiple pathways,” said Sagar Lonial, MD, principal investigator and Chief Medical Officer at the Winship Cancer Institute of Emory University in Atlanta, GA.

For the two-part, open-label, international, ongoing phase 2 trial, researchers randomly assigned 34 patients with heavily pretreated multiple myeloma to receive daratumumab 8 mg/kg every 4 weeks or 16 mg/kg every week for 8 weeks, every 2 weeks for 16 weeks, then every 4 weeks. Ninety additional patients were subsequently enrolled in the 16 mg/kg treatment arm.

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Results showed that among 106 patients treated with daratumumab 16 mg/kg, the IRC-assessed-overall response rate was 29% (95% CI: 21, 39) in the 16 mg/kg arm with a median time to progression of 3.7 months (95% CI: 2.8, 4.6). The estimated 1-year overall survival rate was 65% and median overall survival has not yet been reached.

Of the 31 responders, 29 were still alive at the time of data cutoff.

Subgroup analyses showed that there was a consistent overall response rate across all subgroups assessed.

In regard to safety, the most common adverse events were fatigue, anemia, nausea, thrombocytopenia, back pain, neutropenia, and cough, all occurring in more than 20% of patients. “No patients developed febrile neutropenia,” Dr. Lonial added.

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Infusion-related reactions, which occurred in 42.5% of patients and were typically grade 1 to 2 during the first infusion of daratumumab. A total of five patients discontinued treatment due to adverse events, but none due to infusion-related reactions.

Dr. Lonial concluded, “Daratumumab is a fully human monoclonal antibody with remarkable single-agent activity in heavily pretreated and refractory multiple myeloma patients who have exhausted other therapeutic options…Based on this data, daratumumab represents a new standard of care for patients in the relapsed/refractory myeloma setting.”