Harnessing exosomes: From tumor immune escape to therapeutic innovation in gastric cancer immunotherapy.

Gastric cancer ranks fifth among the most prevalent cancers globally, with a dismal prognosis. In recent years, immunotherapy, particularly immune checkpoint inhibitors, has emerged as a glimmer of hope for advanced gastric cancer patients. However, not all patients can benefit from this treatment modality, as the tumor microenvironment significantly influences treatment efficacy. Exosomes, pivotal mediators of intercellular communication, exert intricate and diverse effects in shaping and regulating the tumor microenvironment. This review provides a comprehensive overview of the functional mechanisms of exosomes within the gastric cancer tumor microenvironment. It delves into their biogenesis, functions, and impact on innate and adaptive immune cells (such as dendritic cells, myeloid-derived suppressor cells, and T cells) and cancer-associated fibroblasts. Additionally, the potential applications of exosomes in gastric cancer immunotherapy are explored, including their use as biomarkers to predict responses to immune checkpoint inhibitors, and drug delivery vectors, and in the development of exosome-based vaccines and gene therapy. Notably, this review emphasizes the dual nature of exosomes: they can facilitate tumor immune escape, yet they also serve as promising targets for innovative therapeutic strategies. It also compares potential exosome-based strategies with existing immunotherapies like ICIs and emerging CAR-T cell therapies. Finally, insights into the future of exosomes in precision immunotherapy for gastric cancer are offered, presenting a forward-looking perspective on this emerging field.