Identification of the targets of T cell receptor therapeutic agents and cells by use of a high throughput genetic platform.

T cell receptor (TCR)-based therapeutic cells and agents have emerged as a new class of effective cancer therapies. These therapies work on cells that express intracellular cancer-associated proteins by targeting peptides displayed on major histocompatibility complex receptors. However, cross-reactivities of these agents to off-target cells and tissues have resulted in serious, sometimes fatal, adverse events. We have developed a high throughput genetic platform (termed "PresentER") that encodes MHC-I peptide minigenes for functional immunological assays and determines the reactivities of TCR-like therapeutic agents against large libraries of MHC-I ligands. In this report, we demonstrated that PresentER could be used to identify the on-and-off targets of T cells and TCR mimic antibodies using in vitro co-culture assays or binding assays. We found dozens of MHC-I ligands that were cross-reactive with two TCR mimic antibodies and two native TCRs and that were not easily predictable by other methods.