CD8A and neoplasm: For instance, gut microbiota enriched with Akkermansia muciniphila and Bifidobacterium longum promotes CD8+T cell infiltration into the tumor microenvironment, thereby potentiating the anti-tumor effects of PD-1/PD-L1 inhibitors (Zhu et al., 2024; Yan et al., 2023; Nan et al., 2025).