In mouse‐glioma models with a humanized microbiome, Dees et al. uncovered increased taxa (Bacteroides cellulosilyticus, Alistipes indistinctus, Blautia hydrogenotrophica, and Eubacterium limosum), expanded CD8+ as well as CD4+ T‐cells, and higher CD8+/Treg ratio in those who responded to anti‐PD‐1 therapy, showing the potential of the microbiota as an indicator guiding immune therapy.94 The gene discussed is CD8A; the disease is central nervous system cancer.