CTLA4 and colorectal carcinoma: Immunotherapies, such as programmed death-1 (PD-1) and cytotoxic T-lymphocyte antigen 4 (CTLA-4) inhibitors, have transformed the treatment landscape for CRC patients and become important treatments, especially for advanced CRC patients with microsatellite instability-high (MSI-H) disease, which is highly infiltrated with immune cells and carries a high neoantigen load15.