CTLA4 and colorectal carcinoma: In recent years, the introduction of immune checkpoint inhibitors targeting the programmed death receptor 1 (PD-1)/programmed cell death ligand 1 (PD-L1) axis and cytotoxic T lymphocyte-associated protein 4 (CTLA-4) has broadened the spectrum of therapeutic strategies for CRC, notably for its metastatic variant (mCRC).