Characterisation of antibodies for chimeric antigen receptor applications
Leonard Leong1, Simeon Cua1, Tan Heng Liang1, Andre Choo1, 2*
1Bioprocessing Technology Institute; 2Department of Bioengineering, National University of Singapore, Singapore
Chimeric antigen receptors (CARs) have recently shown clinical potential for the purposes of tumour clearance. As genetic constructs, T cells can be reprogramed and redirected by CARs to target cell surface tumour antigens, thereby allowing T cells to home in on cancer targets, mediating antigen-specific tumour clearance. As CARs are based on single-chain variable fragments (scFvs), they are capable of targeting antigens that have not undergone major histocompatibility (MHC) processing, thereby countering MHC downregulation, which is a key mechanism of tumour immune evasion.
While CARs targeting haematological malignancies have shown promising clinically efficacy, the dearth of antigen targets prevents the utilisation of CAR T cells into a broader span of therapies. Here, we explore the conversion of novel anti-glycan antibodies generated by our group into the CAR format, with the aim of expanding the target space of CAR T cell therapy. TAG-2, a monoclonal antibody (mAb) (previously reported at Keystone Symposia 2016: Antibodies as Drugs (X2)), was found to specifically bind and kill via ADCC/ADC a number of ovarian and breast cancer cell lines, with minimal reactivity to non-malignant normal tissue.
We have hence isolated the variable genes from this mAb and constructed the scFv derived create TAG-2-CAR. When transduced into T cells via the Sleeping Beauty transposon system, cell surface expression of TAG-2-CAR expression was proven. We are currently in the process of optimising the transduction protocols and construct variants. The cytotoxicity and cytokine release of the TAG-2-CAR construct, in response to target antigen, will also be examined in an in vitro setting in the future.
This project was funded by the Agency for Science, Technology, and Research (A*STAR), Singapore and the A*STAR Graduate Academy (A*GA).
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