Identification and characterisation of novel CAR‐T cells to target IL13Rα2 positive human glioma in vitro and in vivo

Abstract

BackgroundPreviously, we discovered that human solid tumours, but not normal human tissues, preferentially overexpress interleukin‐13Receptor alpha2, a high binding receptor for IL‐13. To develop novel anti‐cancer approaches, we constructed a chimeric antigen receptor construct using a high binding and codon optimised scFv‐IL‐13Rα2 fragment fused with CD3ζ and co‐stimulatory cytoplasmic domains of CD28 and 4‐1BB.MethodsWe developed a scFv clone, designated 14‐1, by biopanning the bound scFv phages using huIL‐13Rα2Fc chimeric protein and compared its binding with our previously published clone 4‐1. We performed bioinformatic analyses for complementary determining regions (CDR) framework and residue analyses of the light and heavy chains. This construct was packaged with helper plasmids to produce CAR‐lentivirus and transduced human Jurkat T or activated T cells from peripheral blood mononuclear cells (PBMCs) to produce CAR‐T cells and tested for their quality attributes in vitro and in vivo. Serum enzymes including body weight from non‐tumour bearing mice were tested for assessing general toxicity of CAR‐T cells.ResultsThe binding of 14‐1 clone is to IL‐13Rα2Fc‐chimeric protein is ∼5 times higher than our previous clone 4‐1. The 14‐1‐CAR‐T cells grew exponentially in the presence of cytokines and maintained phenotype and biological attributes such as cell viability, potency, migration and T cell activation. Clone 14‐1 migrated to IL‐13Rα2Fc and cell free supernatants only from IL‐13Rα2+ve confluent glioma tumour cells in a chemotaxis assay. scFv‐IL‐13Rα2‐CAR‐T cells specifically killed IL‐13Rα2+ve but not IL‐13Rα2‐ve tumour cells in vitro and selectively caused significant release of IFN‐γ only from IL‐13Rα2+ve co‐cultures. These CAR‐T cells regressed IL‐13Rα2+ve glioma xenografts in vivo without any general toxicity. In contrast, the IL‐13Rα2 gene knocked‐down U251 and U87 xenografts failed to respond to the CAR‐T therapy.ConclusionTaken together, we conclude that the novel scFv‐IL‐13Rα2 CAR‐T cell therapy may offer an effective therapeutic option after designing a careful pre‐clinical and clinical study.