CD8A and neoplasm: Oral administration of Bifidobacterium alone improved tumor control to the same degree as anti-PD-L1 therapy, and combination treatment nearly abolished tumor outgrowth. Augmented dendritic cell function leading to enhanced CD8+ T-cell priming and accumulation in the tumor microenvironment mediated the effect. Commensal Bifidobacterium-derived signals modulate the activation of DCs in the steady state, which in turn supports improved effector function of tumor-specific CD8+ T cells