Current Immunotherapeutic Approaches in Pancreatic Cancer

Figure 3

Pancreatic cancers induce an immunosuppressive tumor microenvironment. Pancreatic cancer cells secrete various immunosuppressive factors such as VEGF, IL-6, IL-10, TGF-β, Fas-L, IDO, PD-L1, and microvesicles, all of which promote the accumulation of TAM, MDSC, or tolerogenic DC. These immunosuppressive cells inhibit antitumor immunity by various mechanisms, including depletion of arginine and elaboration of ROS and NO. An immunosuppressive tumor microenvironment induced by pancreatic cancers suppresses CD8+ CTL function through secretion of IL-10 and TGF-β from Treg cells. All contribute to pancreatic cancer-induced immune suppression.