CCR9 and neoplasm: One study showed that B. fragilis facilitated the efficacy of CTLA-4 blockade via IL-12–induced Th1 response and dendritic cell maturation (8), and another study showed that Akkermansia muciniphila modulated the efficacy of PD-1 blockade in an IL-12–dependent manner by upregulating the recruitment of CCR9+CXCR3+CD4+ T cells to tumor beds (14).