In recent years, progress has been made in immune checkpoint inhibitor (ICI) for HCC, including cytotoxic T lymphocyte-associated protein 4 (CTLA-4) inhibitors (for example, Ipilimumab), programmed cell death protein 1 (PD-1) inhibitors (for example, Nivolumab, pembrolizumab), and programmed death ligand 1 (PD-L1) inhibitors (for example, atezolizumab) (15–17). The gene discussed is PDCD1; the disease is hepatocellular carcinoma.