IDO1 and hepatocellular carcinoma: TIMER results adjusted by tumor purity showed PRKDC was positively correlated to CD274 (r = 0.433; p = 3.47e−17), CTLA4 (r = 0.214; p = 5.98e−05), HAVCR2 (r = 0.407; p = 3.43e−15), IDO1 (r = 0.181; p = 7.41e−04), PDCD1LG2 (r = 0.264; p = 6.34e−07) and PDCD1 (r = 0.209; p = 9.32e−05), suggesting PRKDC may exert a vital role in ICB treatment of HCC (Fig. 12C-H).