IDO1 and malignant colon neoplasm: So the suppressive effect of miR-448 on IDO1 expression will be aggravated in IFN-γhigh tumor microenvironment, which means that in “immune hot” (highly infiltrated T cells) tumors [50], IDO1 level will be elevated faster in these miR-448low colon cancer patients compared with miR-448high colon cancer patients, and IDO1 will substantially suppress CD8+ T cells during tumor progression.