Characterization and modulation of anti-αβTCR antibodies and their respective binding sites at the βTCR chain to enrich engineered T cells

T cell engineering strategies offer cures to patients and have entered clinical practice with chimeric antibody-based receptors; alpha beta T cell receptor (alpha beta TCR)-based strategies are, however, lagging behind. To allow a more rapid and successful translation to successful concepts also using alpha beta TCRs for engineering, incorporating a method for the purification of genetically modified T cells, as well as engineered T cell deletion after transfer into patients, could be beneficial. This would allow increased efficacy, reduced potential side effects, and improved safety of newly to-be-tested lead structures. By characterizing the antigen-binding interface of a good manufacturing process (GMP)-grade anti-alpha beta TCR antibody, usually used for depletion of abT cells from stem cell transplantation products, we developed a strategy that allows for the purification of untouched alpha beta TCR-engineered immune cells by changing 2 amino acids only in the TCR beta chain constant domain of introduced TCR chains. Alternatively, we engineered an antibody that targets an extended mutated interface of 9 amino acids in the TCR beta chain constant domain and provides the opportunity to further develop depletion strategies of engineered immune cells.