NK Cell-Derived Small Extracellular Vesicles Armed With CLDN4-Targeting Peptides Potentiate Radiotherapy in Gastric Cancer.

Gastric cancer (GC) persists as one of the most lethal malignancies globally, primarily due to late-stage diagnosis, limited therapeutic targeting options, and inherent resistance to conventional therapies. While molecular profiling has advanced our understanding of GC, the development of effective delivery systems capable of precise tumour targeting and enhanced treatment response remains an unmet need. In this work, we explored targeted therapeutic approaches for GC by leveraging patient-derived organoid models. Firstly, we confirmed claudin-4 (CLDN4) as an overexpressed target in malignant epithelial cells in GC through comprehensive analysis of multiple single-cell RNA sequencing datasets. Capitalising on this discovery, we developed an innovative nano-therapeutic biomaterial, designated NESC (NK-sEV-SpoVM-c-CPE(Q317I)), by engineering natural killer cell-derived small extracellular vesicles (NK-sEVs) with a CLDN4-targeting peptide and a membrane-curvature-sensing domain. Multimodal imaging further confirmed tumour-specific accumulation of NESC, underscoring its targeting precision. Proteomic profiling and functional assays revealed that NK-sEVs possessed intrinsic radiosensitising properties, which were significantly augmented upon conjugation with the targeting peptide. The resulting NESC platform demonstrated robust tumour-suppressive activity and enhanced radiosensitisation in both GC organoids and organoid-derived xenograft models. Collectively, by harnessing patient-derived organoids for functional validation, this study not only establishes a versatile framework for developing targeted sEV-based therapeutics but also provides a translational foundation for future clinical applications in GC management.