Findings of a phase III clinical trial in patients with relapsed or refractory multiple myeloma reveal that addition of elotuzumab, an immunostimulatory monoclonal antibody, to a treatment regimen of lenalidomide and dexamethasone results in a 30% reduction in the risk of disease progression or death. Few adverse events overall were detected in either treatment group, although 10% of patients in the elotuzumab group experienced grade 3 or 4 adverse events. These findings indicate that elotuzumab can be included in existing treatment regimens, and improves the outcomes of patients with relapsed or refractory multiple myeloma.