CTLA4 and colorectal carcinoma: The most studied immune inhibitory molecules in cancer immunotherapy are PD-L1 and cytotoxic T lymphocyte-associated antigen-4 (CTLA-4); while the therapeutic targeting of these molecules has demonstrated clinical responses in different cancers in a subset of patients including CRC, further studies are required to fully comprehend immune inhibitory mechanisms in CRC (14, 15).