Harnessing the gut microbiome to enhance cancer immunotherapy: Current advances and future directions in microbiota-based therapeutic strategies

Cancer immunotherapies, developed on the basis of research into tumor escape mechanisms, manipulate the immune system to reactivate an antitumor immune response to recognize and attack cancer cells. Immunotherapy has demonstrated promising and exciting outcomes in the treatment of many cancers, yet not all patients experience favorable responses. The gut microbiota plays a critical role in modulating the host immune system, influencing responses to cancer immunotherapy. Research has increasingly demonstrated that specific microbial communities can increase the efficacy of immune checkpoint inhibitors, although the mechanisms involved remain under investigation. However, a clear gap exists in the understanding of how bacterial therapies can be further optimized for cancer treatment. This review provides an in-depth analysis of current bacterial therapies used in clinical trials as adjuncts to cancer immunotherapy, summarizing common research approaches and technologies utilized to investigate gut microbiota interactions with the immune system. Additionally, advanced strategies for modifying bacteria, including genetic engineering, surface modifications, and the development of bacterial derivatives, are discussed. By synthesizing these findings, this review highlights the potential of microbiota-based therapies to improve immunotherapy outcomes and offers future directions for improving clinical applications.