A humanized agonistic monoclonal antibody directed against human tumor necrosis factor-related apoptosis-inducing ligand receptor 2 (TRAIL-R2) with potential antitumor activity. Mimicking the natural receptor ligand TRAIL, CS-1008 binds to TRAIL-R2, activating signal transduction pathways that may result in tumor cell apoptosis and a reduction in tumor growth. A member of the tumor necrosis factor (TNF) receptor family, TRAIL-R2, also known as DR5 (death receptor 5), is expressed on the surfaces of many types of malignant cells.