Lung metastasis and recurrence is mitigated by CAR macrophages, in-situ-generated from mRNA delivered by small extracellular vesicles
Yuchen Xiao, Tianchuan Zhu, Zhenxing Chen, Xi Huang
Abstract
Cancer metastasis and recurrence remain the leading causes of cancer-related mortality, and lung is a major metastatic anatomical location. Chimeric antigen receptor macrophages (CAR-M) represent promising candidates for cancer therapy owing to their superior tumour-infiltrating and antigen-specific phagocytotic abilities, and to being professional antigen presenting cells. However, broader applications of CAR-Ms face challenges such as complex manufacturing processes and predominant accumulation in the liver following intravenous administration. Here we present an inhalable engineered small extracellular vesicle (sEV), which contains mesothelin-specific CAR messenger RNA (CARmRNA@aCD206 sEVs) for in situ generation of CAR-Ms. The sEVs are surface-integrated with anti-CD206 single-chain variable fragments (scFv) to target CD206-expressing, immunosuppressive (M2 phenotype) macrophages. The results in mouse models suggest that inhaled CARmRNA@aCD206 sEVs could accumulate in lung tissue and deliver CAR mRNA specifically to macrophages, facilitating in situ CAR-M production. In a lung metastasis model, inhaled CARmRNA@aCD206 sEVs effectively inhibit tumor growth and prime long-term memory immunity to prevent tumour recurrence. Collectively, our engineered sEV delivery platform demonstrates capability to selectively deliver CAR mRNA to macrophages in lung tissue, providing a promising immunotherapy strategy to effectively combat lung metastasis and recurrence via generation of CAR-Ms in situ. Chimeric antigen receptor (CAR) macrophages may represent a promising anti-cancer immune therapy strategy due to their favourable biological properties but in vitro manipulation and targeting to specific organs could be challenging. Here authors use inhalable small extracellular vesicles to deliver the CAR mRNA construct to macrophages in the lung and show that the thus in situ generated CAR macrophages successfully combat lung metastasis and cancer recurrence in a mouse model.