PDCD1 and neoplasm: Potential TME targets have already been identified, such as tumor-associated macrophage (combination with granulocyte colony-stimulating factor or with a colony-stimulating factor 1 receptor antagonist monoclonal antibody), 4-1BB, a transmembrane glycoprotein presents on activated effector T cells (combination with a 4-1BB agonist monoclonal antibodies) and TGF-β (combination with a monoclonal antibody targeting TGF-β or with a bispecific antibodies targeting both PD-1 and TGF-β) (90).