Abstract 2501: A glioblastoma and blood-brain barrier in vitro model to assess the tumor microenvironment and temozolomide resistance

Abstract Glioblastoma multiforme (GBM) is the most common primary brain tumor in adults with a dismal prognosis. Currently, Temozolomide (TMZ) and Bevacizumab are the main approved agents for primary and recurrent GBM, respectively. However, TMZ resistance is frequent and Bevacizumab does not improve overall survival. The heterogeneity of GBM and the presence of a highly selectively permeable blood-brain barrier (BBB) preclude the use of chemotherapeutics approved for other malignancies. Meanwhile, new therapy development is limited in part because most pre-clinical models do not recapitulate the key features of GBM that are relevant to therapy resistance and drug delivery. This is particularly important when validating immunotherapies such as engineered T cell therapy, which has shown some promise in the clinics. We therefore developed an in vitro 3D model that recapitulates the major features of the GBM tumor microenvironment (TME) that are involved in therapy resistance, including the dense tumor core and infiltrating invasive front observed in clinical tumors, surrounded by a perfusable BBB with a physiological permeability. With this model, we investigate the angiogenic nature of GBM, and the role of tumor organization and the TME in TMZ resistance and immunosuppression. We find that TMZ sensitivity decreases as complexity of tumor cell 3D organization increases, and identify pathways potentially associated with TMZ resistance and immunosuppression using proteomics and genomics approaches. Additionally, we find that tumor-associated vasculature has a higher permeability due to VEGFA from GBM tumors, which leads to the downregulation of endothelial junction proteins. Using an IL13Ra2-targetting chimeric antigen receptor (CAR) T cell as a model for engineered T cell therapy, we find that tumor-associated vasculature acts as a physical barrier to CAR-T cell extravasation, significantly impeding CAR-T cell efficacy. We then use the model to screen a CAR library to identify novel CAR combinations that can improve CAR-T cell extravasation and cytotoxicity in GBM. Citation Format: Maxine S. Lam, Joey Aw, Damien Tan, Ragavi Vijayakumar, Khloe S. Gordon, Michael E. Birnbaum, Radoslaw M. Sobota, Giulia Adriani, Andrea Pavesi. A glioblastoma and blood-brain barrier in vitro model to assess the tumor microenvironment and temozolomide resistance [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 2501.