TGFB1 and neoplasm: Poor tumor immunogenicity can be a result of many features, including HLA class I molecule downregulation or loss (253); genetic, epigenetic, and chromosome alterations regulating presentation and processing of surface epitopes (254–256); expression and secretion of immunosuppressive factors (e.g., PD-1, TGF-β, adenosine) (257); and the inability of cancer cells to produce new surface epitopes that are different from what immune receptors have regularly experienced (258).