TGFB1 and cancer: Immune tolerance mechanisms that protect healthy tissues are hijacked by cancer to maintain immune escape through the modulation of additional processes, such as metabolically essential amino acid (tryptophan and arginine) depletion, immunosuppressive cytokine (TGF-β and IL-10) overproduction, expansion of Tregs, MDSCs, macrophages, and expression of T cell response inhibitors and co-inhibitory ligands (e. g., PD-L1) (93).