Faecalibaterium prausnitzii strain EXL01 boosts efficacy of Immune Checkpoint Inhibitors

Gut microbiota impacts responses to immune checkpoint inhibitors (ICI). High level of Faecalibacterium prausnitzii has been associated with a positive response to ICI in multiple cancer types. Here, we show in two independent cohorts of patients with non-small cell lung cancer and advanced melanoma that high level of F. prausnitzii at baseline is positively associated with a better clinical response to ICI. In a mouse preclinical model, we show that the F. prausnitzii strain EXL01, already in clinical development for Inflammatory Bowel Disease, restores the anti-tumor response to ICI in the context of antibiotic-induced microbiota perturbation at clinical and tumor transcriptomics level. In vitro, EXL01 strain enhances T cell activation in the presence of ICI. Interestingly, oral administration of EXL01 strain is not associated with a change in fecal microbiota diversity or composition suggesting a direct effect on immune cells in the small intestine.