CD274 and neoplasm: Inhibitors targeting immune checkpoint molecules such as programmed death receptor 1 (PD-1), programed death ligand 1 (PD-L1) and cytotoxic T lymphocyte-associated protein 4 (CTLA-4) block the co-inhibitory signals in immune-reactive T cells [26,27], thereby reversing the immunosuppressive TIME and enhancing immune-mediated clearance of tumor cells [28].