CD4 and pancreatic ductal adenocarcinoma: Ablation of the tumor microbiome with antibodies reshaped the tumor microenvironment, including reducing myeloid-derived suppressor cells, increasing M1 macrophage differentiation and promoting TH1 differentiation of CD4+ T cells and CD8+ T-cell activation, and protected against the progression of preinvasive and invasive pancreatic ductal adenocarcinoma, whereas transfer of bacteria from PC patients, but not healthy control subjects, reversed this protective effect [111].