The results showed that the expression of PDCD1, CTLA4, LAG3, and TIGIT are positively correlated with TICRR in HCC (r = 0.372, r = 0.380, r = 0.347, r = 0.328, P < 0.001) (Fig. 5B, C). Here, PDCD1 is linked to hepatocellular carcinoma.