Abstract A020: Liposomal topotecan with low-intensity focused ultrasound utilization to improve drug penetration with brain parenchyma in pediatric brain tumors

The blood-brain barrier (BBB) remains a significant obstacle in delivering effective chemotherapeutics to treat pediatric brain tumors, limiting drug penetration and reducing therapeutic outcomes. To overcome this challenge, we investigated the use of liposomal topotecan (TPT), encapsulated in a sonosensitive formulation, designed for controlled release triggered by low-intensity focused ultrasound (LIFU). In this study, we evaluated the in vitro efficacy of a sonosensitive liposomal topotecan formulation. The liposomal topotecan was created using remote loading with an ammonium sulfate gradient. TPT was loaded at a drug-to-lipid ratio of 1:10. The liposome was composed of hydrogenated soy PC, cholesterol, and DSPE-PEG2000. IC50 assay comparing free topotecan to the liposomal topotecan indicated that the cytoxicity of free TPT is lower than liposomal TPT indicating a sustained release of drug which would decrease long term toxicity. In addition, pharmcokinetic fluorescent quantification of liposomal topotecan showed linear increase in free drug (ug/uL) as liposomal TPT concentration is increased in brain homogenates. We hypothesize that tumor growth inhibition and overall survival would be significantly improved in mice receiving LIFU-mediated liposomal topotecan delivery. Our future work includes additional pharmokinetics with survival analysis in vivo with and without low intensity focused ultrasound. These results highlight the potential of combining liposomal drug formulations with focused ultrasound to overcome the challenges of BBB permeability, offering a promising therapeutic strategy for improving drug accumulation and survival outcomes in pediatric brain tumor models.Citation Format: Avani Mangoli, Sarah Kim, Kathryn Blethen, Angela Everhart, Sasha Nikiforov, Gerry Grant, Luke Avigliano. Liposomal topotecan with low-intensity focused ultrasound utilization to improve drug penetration with brain parenchyma in pediatric brain tumors [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Optimizing Therapeutic Efficacy and Tolerability through Cancer Chemistry; 2024 Dec 9-11; Toronto, Ontario, Canada. Philadelphia (PA): AACR; Mol Cancer Ther 2024;23(12_Suppl):Abstract nr A020.