In finding curative treatments for cancer, including HCC, the U.S. Food and Drug Administration (FDA) has approved seven immune checkpoint inhibitors (ICIs) targeting proteins such as programmed death protein-1 (PD-1), cytotoxic T lymphocyte-associated antigen 4 (CTLA-4), and programmed death-ligand 1 (PD-L1) [31,32]. The gene discussed is CTLA4; the disease is hepatocellular carcinoma.