CD274 and hepatocellular carcinoma: The identification of the immune checkpoint mechanism has played a significant role in the development of immune checkpoint inhibitors (ICIs), including cytotoxic T lymphocyte-associated antigen 4 (CTL-4), programmed cell death 1 (PD-1), and programmed cell death ligand 1 (PD-L1) inhibitors, which provide new opportunities to treat advanced HCC [12,13,14,15,16].