CD8A and hepatocellular carcinoma: TIGIT is expressed on human tumor-infiltrating CD8+ T cells, NK cells, Th and Treg cells in melanoma (54, 55), NSCLC (56, 57), colon cancer (52), HCC (31, 58), gastric cancer (59), glioblastoma (60) and hematological malignancies (42, 61, 62).