MADCAM1 and neoplasm: colonizes the intestines of mice and down-regulates MAdCAM-1 expression in PPs and MLN through the accumulation of its metabolites lithocholic acid (LCA) and ursodeoxycholic acid (UDCA), which in turn triggers an exodus of immunosuppressive α4β7+ CD4+ Treg17 cells from the intestine to tumor-draining lymph nodes, aiding in tumor immune escape and thus diminishing the efficacy of the immune checkpoint inhibitor (ICB).