In the GBM microenvironment, the antitumor immune response is further suppressed by high levels of circulating immunosuppressive cytokines such as IL-10, TGF-β, and PGE2 as well as membrane-bound proteins such as FasL and B7-H1 (PD-L1) [36, 37]. This evidence concerns the gene CD274 and glioblastoma.