Within the GBM TME, PD-1/PD-L1 signaling contributes to CD8+ T cell dysfunction and apoptosis, CD4+ T cell exhaustion and cytokine dysregulation, expansion of Tregs and Bregs, M1-to-M2 macrophage polarization, and MDSC-mediated immunosuppression. Here, CD8A is linked to glioblastoma.