GBM exhibits reduced numbers of effective tumor-infiltrating CD8+ T lymphocytes and the presence of multiple immunosuppressive cell populations, such as tumor-associated macrophages (TAMs) [61, 62], regulatory T cells (Tregs) [63], and myeloid-derived suppressor cells (MDSCs) [64, 65] in the TME. This evidence concerns the gene CD8A and glioblastoma.