Nickolas J. Serniuck, Eden Kapcan, Duane Moogk, Allyson E. Moore, Benjamin P.M. Lake, Galina Denisova, Joanne A. Hammill, Jonathan L. Bramson, Anthony F. Rullo,
Molecular Therapy: Oncology, 2024, 200842
https://doi.org/10.1016/j.omton.2024.200842
Proximity-induction of cell-cell interactions via small molecules represents an emerging field in basic and translational sciences. Covalent anchoring of these small molecules represents a useful chemical strategy to enforce proximity, however it remains largely unexplored for driving cell-cell interactions. In immunotherapeutic applications, bifunctional small molecules are attractive tools for inducing proximity between immune effector cells like T cells and tumor cells to induce tumoricidal function. We describe a two-component system comprised of electrophilic bifunctional small molecules and paired synthetic antigen receptors (SARs) that elicit T cell activation. The molecules, termed covalent immune recruiters (CIRs), were designed to affinity label and covalently engage SARs. We evaluated the utility of CIRs to direct anti-tumor function of human T cells engineered with three biologically distinct classes of SAR. Irrespective of the electrophilic chemistry, tumor targeting moiety, or SAR design, CIRs outperformed equivalent non-covalent bifunctional adapters, establishing a key role for covalency in maximizing functionality. We determined that covalent linkage enforced early T cell activation events in a manner that was dependent upon each SARs biology and signalling threshold. These results provide a platform to optimize universal SAR T cell functionality and more broadly reveal new insights into how covalent adapters modulate cell-cell proximity-induction.
