HHLA2 and hepatocellular carcinoma: 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.