PDCD1 and hepatocellular carcinoma: A promising approach for HCC patients is immunotherapy which includes immune checkpoint blockers/monoclonal antibodies against the programmed cell death protein 1 (PD-1), PD-1 ligand (PD-L1), and cytotoxic T lymphocyte antigen-4 (CTLA-4) such as nivolumab, pembrolizumab, MED14736, ipilimumab, and tremelimumab [147].