Studies have shown that the binding of PD-1 to PD-L1 triggers a pathway that prevents T cells from activating.18,40,41 In HCC cells, PD-L1 was expressed at a rate of 23.9–81.1%.42 PD-L1 overexpression on the HCC cell surface is significantly associated with poorer OS and DFS.43,44 The molecular mechanisms by which PD-L1 promotes HCC progression include the following:Inhibition of T-cell function: PD-L1 binds to PD-1 and transmits inhibitory signals that reduce T-cell receptor and CD28 activity. Here, CD28 is linked to hepatocellular carcinoma.