We then examined that relationship between common immune checkpoint inhibitors and chemotherapy and the prognostic model, which revealing that HAVCR2, the immune checkpoint marker gene, was positively associated with the high-risk group for all four digestive cancers, while other marker genes (CD274, PDCD1, CTLA4, LAG3 and TIGIT) were more significant in some single cancers such as CRC, STAD and LIHC. The gene discussed is CTLA4; the disease is cancer.