A mechanically-engineered spray to increase brain penetration of chemotherapeutic nanoparticles in the treatment of high-grade gliomas

Design and implementation of innovative local drug delivery systems (DDS) may overcome current limitations in GBM treatment, such as the lack of therapeutic drug concentrations reaching residual GBM cells following surgery. Here we describe a novel DDS which utilises a bespoke mechanically engineered spray device, designed for safe surgical use, to deliver a mucoadhesive hydrogel containing chemotherapeutic nanoparticles (NPs) into the tumour resection margins. The overall aim is to spray a NP and polymer solution onto the resection cavity and potentially increase penetration of anti-cancer drugs within the 2 cm reoccurrence zone beyond the infiltrative margin. The mucoadhesive gel of choice, pectin, is currently used in other in vivo applications; however we have repurposed this for the brain. Pectin is biocompatible with GBM and human astrocyte cells in vitro and showed neither toxicity nor inflammation for up to 2 weeks upon orthotopic brain injection. Pectin is biodegradable in artificial CSF and is capable of being sprayed from the engineered device. A panel of polymeric, oil-based and polymer-coated NPs have been developed and optimised to maximise drug encapsulation of etoposide and olaparib as proof-of-concept for combination drug delivery. Etoposide/olaparib was chosen due to cytotoxicity from 5 GBM cell lines, including primary lines isolated from the invasive tumour margin (Mean IC50 of 1.1 µM and 8.3 µM respectively). The optimal NP/drug formulation (based on drug encapsulation, spray capability and bio-adhesiveness) will ultimately be assessed for tolerability and efficacy using orthotopic allograft and xenograft high-grade glioma models.