Overcoming T cell tolerance to tumor self-antigens through catch-bond engineering.

Abstract

T cells are often weakly responsive to tumor self-antigens because of central tolerance, constraining their ability to eliminate tumors. We exploited mechanical force to engineer a weakly reactive T cell receptor (TCR) specific for a nonmutated tumor-associated antigen (TAA), prostatic acid phosphatase (PAP). We identified a catch-bonding "hotspot" whose mutation enhanced T cell activity by increasing TCR-pMHC (peptide-major histocompatibility complex) bond lifetime while preserving physiological affinities and antigen fine specificities. T cells expressing these engineered TCRs showed vastly superior expansion in the tumor, effector phenotypes, and tumor elimination. Crystal structures and molecular dynamics simulations revealed a single amino acid mutation at the catch-bond hotspot primes the TCR for peptide interaction through water reorganization at the TCR-pMHC interface. Catch-bond engineering is a viable biophysically based strategy for transforming tolerized antitumor T cells into potent TCR-T cell therapy killers.