IDO1 and hepatocellular carcinoma: The results showed that the FRlncRNAs signature was positively related to PD −1 (R = 0.17, P = 0.0019), CTLA-4 (R = 0.19, P = <0.001), and TIM-3 (R = 0.16, P < 0.001; except for IDO1, PD-L1, and PD-L2), revealing that the FRlncRNAs signature might play vital roles in assessment of response to ICB immunotherapy in the patients with HCC (Figs. 8G–8I and Fig. S1).