However, in cases of advanced liver disease, especially in HCC patients, dysfunctional T cell phenotypes are well described, and immune checkpoint molecules such as cytotoxic T-lymphocyte-associated protein 4 (CTLA-4) and programmed cell death protein 1 (PD-1) are upregulated in HCC-infiltrating T lymphocytes [2,3]. Here, PDCD1 is linked to hepatocellular carcinoma.