PDCD1 and hepatocellular carcinoma: While the presence of Trm and Tem cells was associated with good prognosis in HCC (30), they often express exhaustion markers such as PD-1, lymphocyte-activation gene 3 (LAG-3), and cytotoxic T-lymphocyte-associated antigen 4 (CTLA-4), which correlated negatively with their functional competency (Figure 1) (37, 53).