DDEL-13. Enhanced CNS delivery of therapeutic nanoparticles with focused ultrasound improves treatment efficacy in glioblastoma

Abstract BACKGROUND Glioblastoma (GBM) is an aggressive primary malignant brain tumor with limited treatment options. Immunotherapy is a promising treatment modality. One such therapy in development is our novel multilamellar RNA lipid nanoparticle (RNA-LNP) carrying total tumor mRNA. These have been shown to successfully stimulate immune pathways and improve survival in animal models. Blood-brain barrier (BBB) penetrance is an obstacle to delivering effective doses of RNA-LNP. Low-intensity focused ultrasound (LIFU) is capable of disrupting the BBB by oscillating microbubbles in vasculature, which could be used to deliver RNA-LNP directly to the GBM site non-invasively. HYPOTHESIS Utilizing LIFU to disrupt the BBB will increase the amount of RNA-LNP delivered to GBM, resulting in improved transduction, immune response, and survival. METHODS LIFU was administered to mice at various pressures followed with Evans Blue dye to determine the focality and an optimal pressure for disruption. Fluorescently labeled RNA-LNPs were delivered to track permeance of RNA-LNP aggregates with LIFU. RNA-LNP carrying mRNA for Cre recombinase were delivered with LIFU to tumor-bearing TdTomato reporter mice to measure transduction via whole-brain immunofluorescence and to characterize cellular targets via single cell RNA sequencing. The therapeutic effect of RNA-LNP with LIFU was assessed through murine glioma survival studies. RESULTS LIFU delivered controlled and focal disruption, and enhanced uptake of RNA-LNP. Detection of TdTomato signal indicated improved local transduction. In murine glioma models, RNA-LNP delivered in combination with LIFU significantly increased survival when compared to RNA-LNP alone. DISCUSSION LIFU has been shown to overcome the obstacle of the BBB and improve the uptake of RNA-LNP to confer a survival benefit. By being transient, focal, and non-invasive, LIFU may serve as an efficacious tool in enhancing not only RNA-LNP therapy for patients with GBM but a wide array of therapeutic strategies that would benefit from enhanced delivery into the brain.