The expression of immune checkpoint genes, such as LAG3, CTLA4, CD274, PDCD1, TIGIT, IDO1, and PDCD1LG2, in MSI-H CRC was significantly higher than that in MSS/MSI-L CRC (Figure 3F; all P ≤ 0.05), while MSI-H CRC exhibited lower expression of VEGF. This evidence concerns the gene IDO1 and colorectal carcinoma.