Specifically, in GBM, TDO was positively correlated with the expression of immunosuppressive molecules related with the evasion of innate immunity, checkpoint inhibitors, the angiogenic expression of VEGF, and the protease migration-related protein matrix metalloproteinase 9 (MMP9); TDO was negatively correlated with EGFR. The gene discussed is MMP9; the disease is glioblastoma.