Bispecific T-Cell Engager -Armored Chimeric Antigen Receptor T Cells Overcome Antigen Escape From EGFRvIII-Targeted Therapy For Glioblastoma. (1st September 2019)

• Record Type: Journal Article
• Authors: Choi, Bryan D; Yu, Xiaoling; Castano, Ana P; Bouffard, Amanda A; Schmidts, Andrea; Larson, Rebecca C; Bailey, Stefanie R; Boroughs, Angela C; Frigault, Matthew J; Leick, Mark B; Scarfo, Irene; Cetrulo, Curtis L; Demehri, Shadmehr; Nahed, Brian V; Cahill, Daniel P; Wakimoto, Hiroaki; Curry, William T; Carter, Bob S; Maus, Marcela V
• Is Part Of: Neurosurgery. Volume 66(2010)Supplement 1
• Publication Date: 2019-09-01
• Subjects: Nervous system -- Surgery -- Periodicals; 617.48005
• DOI: 10.1093/neuros/nyz310_154
• Languages: English
• ISSNs: 0148-396X

Abstract

Abstract: INTRODUCTION: Immune therapy with T cells engineered to express chimeric antigen receptors (CARs) represents a promising therapy for patients with glioblastoma (GBM). However, clinical responses have been limited due to heterogeneous target antigen expression and outgrowth of tumors lacking the antigen targeted by CAR T cells directed against a single target. In clinical studies with CART-EGFRvIII, EGFRvIII-targeted T cells successfully localized to the brain tumor microenvironment, but ultimately failed to prevent disease progression with post-treatment specimens demonstrating high levels of wild-type EGFR despite reduced expression of EGFRvIII. METHODS: We developed a novel bicistronic CAR construct engineered for local delivery of bispecific T-cell engagers (BiTEs) that target residual tumor. Specifically, EGFRvIII-targeted CAR T cells were engineered to secrete BiTEs against wild-type EGFR, which is frequently amplified and overexpressed in GBM. RESULTS: Human T cells were efficiently transduced with the dual CART.BiTE transgene. These modified cells secreted biologically active EGFR-specific BiTEs that not only redirected CAR T cells but also recruited and activated untransduced bystander T cells against wild-type EGFR. Recapitulating clinical data, EGFRvIII CAR T cells were unable to completely treat tumors with heterogenous EGFRvIII expression, leading to outgrowth of EGFRvIII-negative, EGFR-positive GBM. Conversely, CART.BiTE cells cured mice even in the setting of antigen-loss, against heterogeneous and well-established intracerebral tumors in mice. Unlike CAR T cells directly targeting EGFR, which caused toxicity in human skin grafts in vivo, secreted BiTE-EGFR was both locally effective and did not result in toxicity against grafted human skin. CONCLUSION: This is the first instance in which CARs and BiTEs have been combined into a single platform of immune therapy. Our results demonstrate that CARs and BiTEs can be combined strategically to mitigate antigen heterogeneity in GBM and also provide a unique T-cell-based delivery method for BiTEs to tumors in the brain.