The resilient microbiome: how baseline gut microbial composition influences response to cancer treatment

The human gut microbiome is increasingly recognized as a key modulator of health and disease, with growing evidence supporting its influence on responses to cancer therapy. An important aspect of this relationship is gut microbial resilience, defined as the ability of the microbiome to recover its ecological equilibrium following disruption. Individual variations in microbial composition significantly influence resilience and, consequently, personalized responses to cancer treatments. However, the underlying functional characteristics of a resilient microbiome remain incompletely understood. Identifying specific microbial profiles with greater resilience to cancer therapies could improve the ability to predict treatment responses and mitigate adverse events. However, despite growing interest, a lack of longitudinal and mechanistic studies currently limits their clinical translation. This review examines current literature on gut microbiome compositions and individual treatment response to cancer therapy, with a focus on microbial features linked to resilience which could enable prediction of adverse response. While the use of microbial metabolites as predictive biomarkers (e.g. short-chain fatty acids and bile acids) is promising, further longitudinal and interventional studies are essential to support clinical application. Establishing specific microbial and metabolite profiles that promote resilience is essential to advance this emerging field of personalized gut-microbiome therapy.