Fig. 1.

First proof-of-concept of the curative potential of FMT combined to reintroduction of anti-PD-1 Ab in cancer patients resistant to immunotherapy in two independent study. Nine different donors diagnosed with metastatic melanoma in partial or complete remission donated their stools for FMT (via oral or colonoscopic delivery) into 26 metastatic melanoma patients refractory to PD-1 blockade. The fecal product of distinct donors successfully engrafted in recipients who benefited the FMT and reprogrammed the local mucosae, reinstated tumor immunosurveillance, and induced changes in the metabolic, immune, and inflammatory tonus in nine patients who experienced long-term responses to this combinatorial regimen. Abbreviations: BA: biliary acids; CTL: cytotoxic T lymphocyte; FMT: fecal microbial transplantation; Gzm: granzymes; IFNγ: interferon gamma; MAIT: mucosal-associated invariant T cells; MHC: major histocompatibility complex; NKR: killer activating receptors; Pfr: perforin; TME: tumor microenvironment