Mimicry of molecular glues using dual covalent chimeras

A special class of proximity inducing bifunctional molecules/chimeras called molecular glues leverage positive co-operativity to stabilize ternary complex formation and induce a biological response. Despite their utility, molecular glues remain challenging to rationally design. This is particularly true in the context of inducing cell-cell proximity which involve ternary complexes that comprise non- or negatively interacting proteins. In this work, we develop a dual proximity labeling strategy enabling a chimera to covalently crosslink a non-interacting serum antibody to a tumor surface protein, within a ternary complex. The resultant resistance to dissociation, including in the presence of competitor binding ligands, mimics molecular glue stabilization. We demonstrate these covalent glue mimics (CGMs) can induce cell-cell proximity in three distinct model systems of tumor-immune recognition, leading to significant functional enhancements. Collectively, this work underscores the utility of dual proximal covalent labeling as a potential general strategy to stabilize ternary complexes comprising non-interacting proteins and enforce cell-cell interactions. The authors report the development of dual covalent proximity inducing molecules capable of selectively cross-linking two non-interacting proteins. Through the selective proximity-based activation of two SuFEx electrophiles, a functional ternary complex of interest can be trapped kinetically which mimics the thermodynamic stabilization associated with molecular glues. This work further demonstrates that "covalent glue mimics" can efficiently and selectively crosslink tumor immunotherapeutically relevant proteins to stabilize and promote cell-cell interactions enacting tumor cell clearance.