Fig. 2

Microbiota-oriented interventions to improve immunotherapy treatment. While stable on a global scale, the gut microbiota regularly undergoes small fluctuations and is amenable to strategies which could shape the commensal community to either help improve patient response rates to immunotherapy or prevent treatment-related toxicity such as colitis. These approaches range from complex community transfers in the form of (a) fecal microbiota transplantation (FMT) which may have many effects on the recipient, to delivery of (g) a single microbial metabolite with a specific immune-modulatory effect. Additional approaches include (b) modulating macronutrient or prebiotic intake to shift bacterial communities, (c) targeting broad classes of bacteria with antibiotics, (d) administration of a select number of known beneficial bacterial species, or (e) a single defined bacterial isolate. Bacteriophages (f) or viruses that infect and kill selected bacteria, could also be used as a means of selectively depleting a detrimental bacterial population