Nanotechnology - Microbiota synergy in cancer immunotherapy.

The global burden of cancer continues to escalate, yet the efficacy of current targeted therapies and immune checkpoint inhibitors (ICIs) is often hampered by drug resistance and immune escape. The gut microbiota orchestrates tumor progression and ICI efficacy bidirectionally via the "microbiota-immune-tumor" axis. However, traditional interventions, including fecal microbiota transplantation and antibiotics, are limited by inherent drawbacks such as poor targeting. Nanotechnology can overcome this limitation: it not only enables precise targeting of the gut microbiota and reshapes the tumor immune microenvironment to synergistically enhance ICI efficacy but also reverses drug resistance in tumor chemotherapy, radiotherapy, and targeted therapy through multiple strategies. Additionally, it can synergize with probiotics, extracellular vesicles, and other agents to achieve tumor therapy. This review synthesizes current understanding of gut microbiota-immune crosstalk, the microbiota's role in regulating ICI efficacy, and the central applications of nanotechnology, thereby proposing novel synergistic strategies for cancer treatment.