IDO1 and neoplasm: The IFN-γ signature is composed of 10 genes (IFN-γ, CCR5, CXCL11, IDO1, PRF1, GZMA, HLA-DRA, CXCL10, CXCL9 and STAT1) that play a role in the interplay of tumor cells with the tumor microenvironment and local immune response.