We investigated the expression levels of a series of inhibitory checkpoint molecules across COAD and READ patients, including CD274 (PD-L1), CTLA4, TIGIT, HAVCR2 (TIM3), VISTA, PDCD1LG2 (PD-L2), IDO1, IDO2, ADORA2A (A2AR), LAG3, PDCD1 (PD-1), VISTA (C10orf54), and VTCN1 (B7-H4), among others. This evidence concerns the gene IDO1 and colon adenocarcinoma.