T-Switch: A specificity-based engineering platform for developing safe and effective Tcell therapeutics.

Abstract

Many promising targets for adoptive Tcell therapy (ACT) are self-antigens, but self-reactive Tcells are generally eliminated during thymic selection or diverted to regulatory phenotypes. To bypass Tcell tolerance and obtain potent and safe Tcell therapeutics, we developed T-Switch, an invitro Tcell receptor (TCR) engineering platform for the creation, modification, and comprehensive profiling of TCRs that can target self-antigens. T-Switch first expands Tcells that recognize a "foreign" peptide closely related to a self-antigen. The fine specificity of the TCR is then modified by directed evolution of the peptide binding region to switch its specificity to the self-antigen of interest. We applied T-Switch to engineer synthetic TCRs reactive to a tumor-associated self-antigen, validated the safety and efficacy of this approach, and detected no off-target recognition as measured against the human proteome. Thus, T-Switch represents a resource for the creation of collections of highly sensitive synthetic TCRs for Tcell-based immunotherapies.