Isolation and Characterisation of EpCAM‑specific scFvs using Self-Labelling Integral Membrane (SLIM) Mammalian Display
OXGENE describes a novel antibody discovery methodology based entirely on mammalian cells1. We express a library of antibodies or antibody mimetics in a cell line that displays the target polypeptide on the outer surface. Cells that secrete an scFv that binds to the target membrane protein thereby become self-labelled, enabling enrichment and isolation by magnetic sorting and FRET-based flow sorting.
This technology has the potential to target intractable membrane proteins for antibody selection in a physiological setting with their native post translational modifications intact. Library sizes of 109 variants can be screened, thus allowing campaigns of naïve scFv libraries. We demonstrate this method by screening a synthetic naïve human scFv library against CHO cells expressing the oncogenic target epithelial cell adhesion molecule (EpCAM) and identify a panel of specific novel binders; one with a dissociation constant (KD) as low as 0.8 nM. We further demonstrate that these antibodies have utility for killing EpCAM positive cells when used as a targeting domain on CAR-T cells.
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