HAVCR2 and hepatocellular carcinoma: In addition to the well-known PD-1/PD-L1 and CTLA-4, a series of inhibitory immune checkpoint molecules involved in the immune tolerance of HCC have been reported, including lymphocyte activation gene 3 (LAG-3) [114], T cell immunoglobulin mucin-3 (TIM-3)/galectin-9 (GLA-9) [115], T cell immunoglobulin and ITIM domain (TIGHT) [116], and adenosine A2a receptor.