Multiple species within the genera Bifidobacterium and Collinsella increased in responders to anti-PD-1 therapy for melanoma32, resulting in depleted peripherally derived colonic regulatory T cells, increased Batf3-lineage dendritic cells (DC), and augmented T-helper 1 cell (Th1) responses and thus better immune-mediated tumor control33. Here, PDCD1 is linked to neoplasm.