PDCD1 and neoplasm: In recent years, numerous BsAbs targeting the costimulatory (e.g., OX40, CD40, 4-1BB etc.), coinhibitory pathways (PD-1, CTLA-4, TIM-3, TIGIT etc.)or tumor antigens (MUC1, MUC16) have been developed and are in preclinical and clinical investigations.