Furthermore, glioma tumor microenvironment (TME) abundantly constitutes immunosuppressive players such as TGF-ß, IFN-γ, cytotoxic T-lymphocytes [CTLs]) (59–61), regulatory T-cells (Treg), and dysfunctional NK cells (overexpressed ~12 times more in tumor cells than in the normal cells) etc. Moreover, the recruitment and prolongs survival of these immunosuppressive players supported via activation of high concentration of cytokines and tryptophan catabolic enzyme like indolamine 2,3-dioxygenase-1 (IDO1) thereby aid to sustained the immunosuppression (62–65). This evidence concerns the gene IDO1 and neoplasm.