A humanized agonistic monoclonal antibody targeting the CD137 receptor with potential immunostimulatory and antineoplastic activities. Urelumab specifically binds to and activates CD137-expressing immune cells, stimulating an immune response, in particular a cytotoxic T cell response, against tumor cells. CD137 is a member of the tumor necrosis factor (TNF)/nerve growth factor (NGF) family of receptors and is expressed by activated T- and B-lymphocytes and monocytes; its ligand has been found to play an important role in the regulation of immune responses.