IMMU-08. PRECLINICAL EVALUATION OF GAL-1-SPECIFIC CAR-T CELL FUNCTION IN AN IN VITRO AND EX VIVO MODEL OF GLIOBLASTOMA

Abstract BACKGROUND Human glioblastoma (GBM), especially those exhibiting anti-VEGF resistance, overexpress the carbohydrate-binding protein galectin-1 (Gal-1). To develop novel anti-GBM approaches, we developed Gal-1 targeted CAR-T cells to investigate potential antitumor effect with in vitro and ex vivo slice culture models. METHODS Uniform GBM brain slice cultures were collected using NICO’s Myriad resection tool and their Automated Preservation System (APS), designed to obtain fresh brain tumor samples maintaining tumor cytoarchitecture and microenvironment. To prepare Gal-1 CAR-T cells, we used creative laboratory to utilize a third-generation Gal-1-CAR construct with high binding and codon optimized scFv-Gal-1 fragment fused with CD3ζ and co-stimulatory cytoplasmic domains of CD28 and 4-1BB (Gal-1 scFv-CD28-4-1BB-CD3ζ). We then transfected into the T cells, from peripheral blood, mononuclear cells using a lentiviral system. The anti-tumor capabilities of CAR-T cells were evaluated by co-culturing with GBM cells and ex vivo APS-GBM slices. RESULTS The collected APS- GBM slices samples were clear of debris and blood product, not requiring post-surgical mechanical slices, and exhibited viability up to 12 days over traditionally prepared ex vivo cultures. With this, we found Gal-1-CAR-T cells grew exponentially in the presence of cytokines and maintained phenotypic and biological attributes such as cell viability, potency, migration, and T cell activation. Gal-1 scFv-CD28-4-1BB-CD3ζ -CAR-T cells killed more than 80% of GBM tumor cells within 24 hours in Gal-1+ve, but not Gal-1-ve GBM cells in vitro. Additionally, these CAR-T cells selectively caused significant release of IL-2, IFN-γ and TNF-α only from Gal-1+ve co-cultures and induced significant Gal-1+ve GBM cell death in an ex vivo model without any general toxicity. CONCLUSION Based on in vitro cell culture and ex vivo APS-brain slice culture results, we conclude that the novel Gal-1 scFv-CD28-4-1BB-CD3ζ CAR-T cell therapy may offer an effective therapeutic option. Further pre-clinical and clinical studies need to be performed to validate this novel approach