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Updated: Jan 16, 2026

Covalent Fragment Screening Using the Quantitative Irreversible Tethering Assay
Published on: February 28, 2025
AI-assisted delivery of novel covalent WRN inhibitors from a non-covalent fragment screen
Geoffrey M T Smith1, Laksh Aithani2, Charlotte E Barrett2
1CHARM Therapeutics Ltd., B900, Babraham Research Campus, Babraham, Cambridge, CB22 3AT, UK..
Abstract:
Werner (WRN) helicase, has emerged as a promising therapeutic target for cancers associated with microsatellite instability (MSI). This letter describes the discovery of small molecule inhibitors from a fragment screen that occupy a cryptic, allosteric site of WRN helicase. Key findings include the identification of benzimidazole and amino-indazole scaffolds, exploiting their proximity to Cys727 via covalent modification. The use of our proprietary co-folding model DragonFold assisted the identification of novel WRN helicase inhibitors. These, together with near-neighbor profiling, offer tools for furthering the understanding of WRN and BLM helicase function, and potential therapeutic avenues for MSI-associated cancers.

