Commensal Bifidobacterium promotes antitumor immunity and facilitates anti–PD-L1 efficacy

T cell infiltration of solid tumors is associated with favorable patient outcomes, yet the mechanisms underlying variable immune responses between individuals are not well understood. One possible modulator could be the intestinal microbiota. We compared melanoma growth in mice harboring distinct commensal microbiota and observed differences in spontaneous antitumor immunity, which were eliminated upon cohousing or after fecal transfer. Sequencing of the 16S ribosomal RNA identified Bifidobacterium as associated with the antitumor effects. Oral administration of Bifidobacterium alone improved tumor control to the same degree as programmed cell death protein 1 ligand 1 (PD-L1)-specific antibody therapy…

• CR
  Cancer Research Institute
• MR
  Melanoma Research Alliance
• NI
  National Institutes of Health
• NI
  National Institute of Diabetes and Digestive and Kidney Diseases