As the expression of immune checkpoint genes significantly influences immunotherapy efficacy, we utilized the TCGA database to investigate the expression correlation between GGT5 and immune checkpoint-associated genes: SIGLEC15, IDO1, CD274, HAVCR2, PDCD1, CTLA4, LAG3, and PDCD1LG2 across various cancers. The gene discussed is PDCD1; the disease is cancer.