First-in-Class Small Molecules Inhibit c-MET Activity Through Self-Regulatory Elements in Its Extracellular Domain
Aberrant HGF-c-MET signaling is a major driver of hepatocellular carcinoma (HCC) progression and a clinically validated therapeutic axis, but current inhibitors predominantly target the intracellular kinase domain and remain vulnerable due to limited selectivity and resistance development. We therefore pursued an upstream strategy based on small molecules that target the extracellular HGF-c-MET interaction interface. We combined large-scale virtual screening of more than one million compounds from the ChemDiv and Enamine libraries with molecular dynamics (MD) simulations, steered MD, MM/GBSA profiling, and iterative lead optimization to identify candidate c-MET inhibitors targeting its extracellular (EC) domain. In HGF-stimulated HuH7 cells, selected compounds suppressed c-MET autophosphorylation, reduced cell viability, and inhibited long-term colony formation. Surface plasmon resonance (SPR) further confirmed direct binding of L083-1287 and 8008-3424 to the recombinant c-MET ectodomain. Mechanistic analyses identified previously unrecognized hotspot residues on the c-MET EC domain and a novel inhibitory network spanning multiple c-MET ectodomain interfaces. L083-0077 displayed the most consistent interaction pattern within this framework, including stabilization of key hotspot residues and preserved binding under acidic conditions relevant to the tumor microenvironment. Zebrafish xenograft assays with selected early hit compounds revealed compound-dependent developmental liabilities supporting the use of this model as an early in vivo prioritization step during lead optimization. These findings establish EC interface-directed c-MET inhibition as a promising therapeutic strategy in HCC and provide a mechanism-guided platform for the development of selective, upstream c-MET inhibitors with the potential to complement or overcome limitations of kinase-directed therapies.