Microbiota-targeted nanoplatforms for colorectal cancer immunotherapy

Colorectal cancer (CRC) remains a major global health burden, and immunotherapy efficacy is often restricted by an immunosuppressive tumor microenvironment (TME). Emerging evidence highlights the pivotal role of the gut microbiota in shaping tumor progression and therapeutic responses. This review first summarizes the bidirectional crosstalk between gut microbiota and the CRC immune microenvironment, detailing how specific microbial species and metabolites regulate key immune cells (MDSCs, Tregs, TAMs, DCs, CD8⁺ T cells, and CD4⁺ T cells) through pathways such as NF-κB, RIG-I lactylation, AhR, and cGAS-STING. Based on these insights, we then examine microbiota-targeted nanoplatforms (lipid/protein-based, polymer-based, and inorganic systems) that enable precise modulation of microbial composition and function. These nanoplatforms synergize with immune checkpoint inhibitors, cancer vaccines, CAR-T cells, and oncolytic viruses by reshaping the microbiota and reprogramming the TME. Despite promising preclinical outcomes, challenges remain, including microbiome heterogeneity, biosafety concerns, slow clinical translation, and pharmacokinetic hurdles. Overall, microbiota-targeted nanoplatforms represent a novel and integrative strategy to improve CRC immunotherapy.