Another feature of the pancreatic cancer tumour environment is immune evasion or restriction of immune surveillance, whereby the PDAC microenvironment is composed of T regulatory cells (Treg), tumour-associated macrophages (TAMs), and myeloid-derived suppressive cells (MDSCs), which block CD8+ T-cell roles in tumour recognition and clearance [9]. This evidence concerns the gene CD8A and neoplasm.