Moreover, in LIHC cohort, PHF19 was closely correlated with checkpoints including BTLA, CD27, CD274, CD276, CD28, CD40, CD70, CD80, CD86, CTLA4, HAVCR2, HHLA2, ICOS, IDO1, LAG3, PDCD1, TIGIT, TNFRSF9, and TNFSF9, indicating that PHF19 serves as a potential immune-related therapeutic target for HCC patients. The gene discussed is IDO1; the disease is hepatocellular carcinoma.