Abstract

Targeting the gut microbiota is a promising strategy to enhance the efficiency of cancer immunotherapy; however, success has been limited. Here we combined metagenomic analysis and in silico prediction to identify bacterial species associated with immunotherapy response in patients with non-small-cell lung cancer. We constructed a defined consortium (RCom) of 15 bacterial species, most of which were isolated from responder patient faeces, associated with improved clinical response to anti-programmed cell death protein 1 (PD-1) treatment. Metabolic models and in vitro experiments revealed that RCom is a stable and cooperative community, and in vivo experiments showed that RCom engrafts and produces immunomodulatory metabolites. Oral administration of RCom improved the anti-tumour activity of anti-PD-1 by increasing the intratumoural infiltration and cytotoxic function of CD8 + T cells in syngeneic tumour models and across mice with heterogeneity in baseline gut microbiota composition. RCom supplementation also limited anti-PD-1 resistance in mice conferred by faecal microbiota transplantation from individual non-responsive patients. These findings suggest that RCom is a potential adjuvant to improve responsiveness to anti-PD-1 therapy in cancer.