The Gastrointestinal Microbiome and Immune Checkpoint Inhibitors: A Review of Human Interventional Studies Among Melanoma Patients.

Immune checkpoint inhibitors (ICI) are widely utilized for the treatment of malignant melanoma. Interestingly, gastrointestinal microbiome composition has emerged as a predictive biomarker of immunotherapy outcomes. This review seeks to assess the effect of microbiota-modulatory interventions on the clinical and immunological response of metastatic melanoma treated with ICIs. A systematic search was performed to retrieve studies and cases involving any microbiota-modulating intervention. Three studies assessed the effect of fecal microbiota transplantation (FMT) on ICI efficacy, and one case report assessed its effect on clearance of ICI-associated colitis. Overall, 37.5% of melanoma patients who had been previously refractory to ICI immunotherapy demonstrated complete or partial response following FMT and subsequent immunotherapy. 65% of immunotherapy-naïve melanoma patients demonstrated an objective response. No severe FMT-associated adverse events were reported, and FMT depicted efficacy in the remission of ICI-associated colitis. The results suggest that FMT may be a safe and moderately effective microbiota-modulating intervention to improve the efficacy of therapy in ICI-treated melanoma patients. Large, randomized, controlled trials are needed to determine optimal FMT donors and assess other microbiota-modulating interventions, such as pre- and probiotics, in melanoma patients.  J Drugs Dermatol. 2024;23(2):78-84.     doi:10.36849/JDD.7674.