GBM has been characterized as an immunosuppressive tumor [9, 29] that is able to alter the immune system by secreting immunosuppressive cytokines such as TGF-β, expressing immunosuppressive cell-surface factors such as CD95 and PD-1 ligands, and recruiting of immunosuppressive cells to the tumor microenvironment [29]. This evidence concerns the gene PDCD1 and glioblastoma.