CD8A and neoplasm: Researchers have also found that the removal of bacteria resident in pancreatic cancer was related to the immune response to PDAC, and altering the tumour microenvironment by inhibiting the infiltration of myeloid-derived suppressor cells (MDSCs) could enhance the differentiation of M1 macrophages, which stimulated the differentiation of Th1 cells and increased the number of activated CD4+ T cells and CD8+ T cells [7].