PDCD1 and hepatocellular carcinoma: Subsequently, we compared the mRNA expression levels of immune checkpoint–related genes commonly used in HCC treatment, including PD-L1, PDCD1LG2, PDCD1, TIGIT, TIM-3, and CTLA4, which we found to be overexpressed in the high-risk group, implying that the high-risk group may respond to immunotherapy (Fig. 6B–G).