Immune checkpoint inhibitors (ICIs) are known to potentiate the body’s own adaptive immunity against cancer cells through inhibition of the interaction between positive programmed death-ligand 1 (PD-L1) and its receptor PD-1, or between cytotoxic T lymphocyte-associated antigen-4 (CTLA-4) and its receptors on antigen-presenting cells [57]. Here, CTLA4 is linked to cancer.