IDO1 and glioblastoma: For DSS, IDO1 was an unfavorable prognostic factor in UVM, GBM, KIRP, and LGG; IDO1 was a protective prognostic factor in OV, MESO, SARC, SKCM, HNSC, and CHCL ((Fig. 2C–D and Additional file 2: Table S4).