PDCD1 and hepatocellular carcinoma: Recently, some immune checkpoint inhibitors (ICIs), such as anti-cytotoxic T-lymphocyte-associated protein 4 (anti-CTLA-4), anti-PD1 ligand (anti-PD-L1), and anti-programmed death-1 (anti-PD1) monoclonal antibodies (mAbs) (Hu et al., 2019), have demonstrated good prognosis among some advanced HCC patients.