Session Item

The cancer-immune dialogue subject to immuno-oncological intervention is profoundly influenced by micro-environmental factors. Indeed, the mucosal microbiota - and more specifically the intestinal ecosystem - influences systemic immunity, metabolism, the inflammatory tone and the fitness of the epithelial barrier, culminating in keep in in check cancer immunosurveillance and the clinical benefit of immunotherapy. Several pro-and retro-spective studies and meta-analyses, indicated that antibiotics blunt the efficacy of immune checkpoint inhibitors. Importantly, pioneering studies brought up the proof-of-principle that fecal microbial transplantation can possibly restore responsiveness of ICI-resistant melanoma. This talk will review the yin and yang of intestinal bacteria at the crossroads between the intestinal barrier, metabolism, and local or systemic immune responses during anticancer therapies. I will discuss diagnostic tools to identify gut dysbiosis and the future prospects of microbiota-based therapeutic interventions. The results of the impact of the taxonomic composition of intestinal commensals from the SABR study conducted at Gustave Roussy will be unveiled.