An agonist mouse monoclonal antibody directed against TRAIL death receptor type 5 (DR5) with potential antineoplastic activity. Anti-DR5 agonist monoclonal antibody TRA-8 binds DR5, which may induce apoptosis in DR5-expressing tumor cells. DR5 is a tumor cell surface ligand that crosslinks with death receptor type 4 (DR4) when bound by TRAIL [Tumor necrosis (TNF)-related apoptosis-inducing ligand], triggering apoptosis via a death receptor signaling pathway. The apoptotic activity of this antibody may not require DR4/DR5 crosslinking.