Genetically platform presenting CD24 ScFv enhance antitumor immunity by restoring macrophage phagocytosis and modulating the immune environment

Immunotherapy has achieved remarkable progress in treating cancers that evade immune surveillance. Among the components of the tumor microenvironment, macrophages play important roles in maintaining homeostasis, preventing pathogen invasion, engulfing and promoting the adaptive immune response. It is acknowledged that blocking the CD24-Siglec-10 interaction significantly enhances the macrophage phagocytosis ability. In this study, we identified CD24 as an over-expressed molecule in ovarian and breast cancer using data from the GEO database and clinical samples. We then developed genetically programmable extracellular vesicles displaying CD24 single-chain variable fragment (CD24 scFv-EVs) and evaluated their ability to restore macrophage phagocytic activity and eliminate CD24-overexpressing cancer cells. Our findings demonstrate that CD24 scFv-EVs effectively block CD24 on ovarian cancer cells as well as breast cancer cells, thereby inhibiting the CD24-Siglec-10 pathway and enhancing macrophage-mediated clearance of cancer cells. Furthermore, CD24 scFv-EVs promote the polarization of tumor-infiltrated macrophages toward an M1-like phenotype. These results highlight CD24 blockade as a novel therapeutic strategy to target ovarian and breast cancer cells and enhance macrophage-driven tumor cell clearance.