The systemic immunosuppression is driven by overexpression by the glioma cells of soluble factors, such as prostaglandin E2, TGF-β, indoleamine 2,3-dioxygenase, and IL-10, all of which lead to decrease T-cell responsiveness to pro-inflammatory signals and ineffective presentation of tumor antigens by antigen-presenting cells (APCs). This evidence concerns the gene TGFB1 and neoplasm.