Abstract 2564: Selection of affinity-enhanced T-cell receptors for adoptive T-cell therapy targeting MAGE-A10

Abstract

Abstract Circulating T-cells, bearing T-cell receptors (TCRs) that have passed thymic selection, generally have low affinity for self-protein-derived cancer antigens and therefore have a limited ability to detect and eliminate tumor cells. Engineering TCRs to enhance and optimize their affinity, and therefore potency, for cancer targets is a promising strategy for adoptive immunotherapy in cancer patients. Modification of TCRs can potentially generate cross-reactivity to antigens expressed by normal tissue. Such cross reactivity might not be detected by in vivo animal studies, due to species differences in the antigenic repertoire. To mitigate the risk of such toxicities in clinical trials, we developed a comprehensive in vitro testing strategy. This strategy involves systematic substitution at each position of the antigenic peptide sequence using all natural amino acids to generate a profile of peptide specificity (“X-scan”). The likelihood of off-target reactivity was investigated by searching the human proteome for sequences matching this profile and testing against a panel of cell lines. Starting from a panel of parental TCRs with diverse sequences, we engineered several affinity-enhanced TCRs specific for the cancer-testis antigen MAGE-A10. The properties of two of these TCRs, which had the optimal balance of potency and specificity, could not be distinguished effectively with conventional biochemical and cellular assays. The X-scan method permitted us to select the most specific and potent candidate for further pre-clinical testing. This MAGE-A10c796 TCR is now being studied in clinical trials to treat HLA-A2+ patients with non-small cell lung cancer (NCT02592577), urothelial cancers, melanoma, or head and neck cancers (NCT02989064). Citation Format: Ellen Border, Joseph P. Sanderson, Thomas Weissensteiner, Natalie Hyland, Tom Holdich, Francine Brophy, Rafael Amado, Andrew Gerry, Nicholas Pumphrey. Selection of affinity-enhanced T-cell receptors for adoptive T-cell therapy targeting MAGE-A10 [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 2564.