ERBB2 and neoplasm: To overcome limitations of current monoclonal antibody (mAb)-based approaches which target CD137 monospecifically, a CD137/HER2 bispecific (PRS-343) was designed to promote CD137 clustering by bridging CD137-positive T cells with HER2-positive tumor cells, thereby providing a potent costimulatory signal to tumor antigen-specific T cells.