Pancreatic cancers are characterized by an immunosuppressive microenvironment due to the dysfunction of immune effector CD8+ T cells and Natural killer (NK) cells, which is a result of the involvement of multiple types of immune cells, including cancer-associated fibroblasts, regulatory T cells, myeloid-derived suppressor cells, tumor-associated macrophages, and tumor-infiltrating lymphocytes [99]. The gene discussed is CD8A; the disease is cancer.