ICIs are monoclonal antibodies that interfere with immune regulators, including cytotoxic T-lymphocyte-associated antigen-4 (CTLA-4) (such as Ipilimumab and Tremelimumab), programmed death-1 (PD-1) (such as Nivolumab, Cemiplimab, and Pembrolizumab), and programmed death-ligand 1 (PD-L1) (such as Atezolizumab, Avelumab, and Durvalumab), found in cancer cells. Here, CTLA4 is linked to cancer.