EXTH-14. MRNA-LOADED EXOSOMES FOR TARGETED GLIOBLASTOMA IMMUNOTHERAPY

Abstract Recent successes of mRNA therapeutics against pathogenic infections have increased interest in their investigations for other human diseases including cancer. However, precisely delivering the genetic cargo to cells and tissues of interest remains challenging. Extracellular vesicles such as exosomes have gained increased interest recently as potential nucleic acid and drug carriers given their favorable immunogenic profile, long circulatory half-life, and ability to cross biological barriers such as blood-brain barrier. Here, we show an adaptive strategy that enables the docking of different targeting ligands onto the surface of mRNA-loaded exosomes. This was achieved using a microfluidic electroporation approach where a combination of nano- and milli-second pulse electroporations produced a large quantity of IFN-γ mRNA-loaded exosomes with CD64 overexpressed on their surface. The CD64 molecule serves as an adaptor to dock targeting ligands, such as anti-CD71 and anti-programmed cell death-ligand 1 (PD-L1) antibodies. The resulting immunogenic exosomes (imExo) selectively targeted glioblastoma cells and generated potent antitumor activities in vivo, including against tumors intrinsically resistant to immunotherapy. Together, these results provide a new adaptive approach to engineering mRNA-loaded exosomes with targeting functionality and pave the way for their adoption in cancer immunotherapy applications.