KRAS and pancreatic neoplasm: Most patients with pancreatic cancer carry mutations in KRAS and TP53, and the production of these mutations creates a highly immunosuppressive tumor microenvironment specific to pancreatic cancer, including a large infiltration of the regulatory T cells (Treg) and myeloid derived suppressor cells (MDSCs), so current immune checkpoint blockade therapies have very limited efficacy [52, 53].