AGEN-2373 is a conditional agonist antibody targeting the costimulatory receptor CD137. It binds to CD137 without interfering with ligand binding. AGEN-2373 stimulates CD137 under receptor clustering conditions and can enhance T-cell activity when used with other checkpoint modulators (e.g., PD-1 antagonists and OX40 agonists). AGEN-2373 is used in human malignancy research.