Microbiota and cancer immunotherapy: Mechanisms, clinical implications, and precision therapeutics

The microbiota has emerged as a pivotal modulator of cancer immunotherapy, offering novel insights into the efficacy and toxicity of immune checkpoint inhibitors (ICIs). Recent evidence highlights that microbial communities and their metabolites dynamically regulate host immunity by priming dendritic cells, enhancing T-cell infiltration, and reprogramming the tumor microenvironment. Microbiome dysbiosis is implicated in immune-related adverse events (irAEs), underscoring its dual role in therapeutic outcomes. Leveraging these findings, precision microbiome interventions, including fecal microbiota transplantation, engineered probiotics, and dietary modulation, which demonstrate potential to enhance ICIs responsiveness and mitigate irAEs in preclinical and early-phase clinical studies. However, translating these strategies into clinical practice requires rigorous validation through multicenter trials to establish safety, efficacy, and standardized protocols. This review synthesizes current knowledge on the microbiome-immune-oncology axis, with a focus on mechanistic underpinnings, translational challenges, and innovative therapeutic strategies. By integrating microbiome profiling with patient-specific factors, proposing a roadmap for personalized immunotherapy, aligning with the emerging paradigm of precision oncology.