Synergistic SuFEx‐Driven Covalent Cancer Therapy Using a HER2/EGFR Bivalent Affinity Protein Drug

Abstract The integration of sulfur fluoride exchange (SuFEx) chemistry into proteins is significantly advancing their applications in biological fields. However, its suboptimal reaction rates in proteins limit the effectiveness of covalent crosslinking. In this study, we develop a bivalent affinity protein drug by chemically coupling maleimide‐substituted aryl fluorosulfate (MFS) linkers to a dual‐targeting affinity protein drug that can covalently target both HER2 and EGFR. Benefiting from the HER2/EGFR ligand‐assisted multivalent interactions, the obtained bivalent affinity protein drug with two MFS warheads exhibits an enhancement of covalent cross‐link performance, which is 440% and 630% higher than that of monovalent ones. Generally, the bivalent affinity protein drug achieves over 80% covalent binding efficiency to its targets within 12 h and ultimately achieves 290% to 340% higher intracellular uptake and 360% to 460% longer tumor retention compared with that of monovalent or non‐covalent control. Consequently, this bivalent affinity protein drug showed extraordinary antitumor efficacy in HER2/EGFR‐positive pancreatic tumor models with a tumor inhibition rate (TIR) of 90.4%, which was significantly higher than that of monovalent or non‐covalent ones (28.4% to 66.9%). In brief, this SuFEx‐engineered, bivalent targeted strategy provides a promising platform for the design of covalent protein drugs in the future.