Abstract A062: Selective USP10 inhibition by GL-458 re-sensitizes platinum-resistant non-small cell lung cancer through DNA damage response disruption
Platinum-based chemotherapy remains one of the standard treatments for advanced non-small cell lung cancer (NSCLC); however, most patients eventually relapse because of acquired resistance. A major driver of therapeutic resistance is hyperactivation of the DNA damage response (DDR), which allows tumor cells to repair chemotherapy-induced DNA lesions and evade cytotoxic stress. The deubiquitinating enzyme USP10 stabilizes multiple DDR and pro-survival proteins, making it an attractive therapeutic target for re-sensitizing resistant tumors. Inhibition of USP10 may impair DNA repair signaling and enhance anti-tumor activity in resistant NSCLC models. We developed selective and potent USP10 inhibitors through medicinal chemistry optimization. GL-458 was identified as the lead USP10 inhibitor and demonstrated improved selectivity in deubiquitinase (DUB) assays compared with previously reported USP10 inhibitors, including Wu-5 and P22077. P22077 functions as a covalent, non-specific inhibitor, whereas Wu-5 is a non-covalent, non-selective inhibitor. In cellular viability MTT assays, GL-458 demonstrated greater potency, with approximately 3-fold lower IC50 values than Wu-5 and approximately 1.7-fold lower IC50 values than P22077. GL-458 target selectivity and target-dependent cytotoxicity were further evaluated using mouse KRAS/TP53-driven (KP) and USP10-knockout KPU NSCLC models. MTT and colony formation assays demonstrated robust, dose-dependent suppression of proliferation and clonogenic survival. Combination treatment studies using CellTiter-Glo showed that GL-458 effectively re-sensitized cisplatin-resistant cells. Flow cytometric analysis using the Click-iT EdU assay demonstrated early G0/G1 cell-cycle arrest accompanied by ATM/ATR activation, increased gamma-H2AX, and elevated cleaved PARP-1 expression. Immunofluorescence analyses revealed accumulation of gamma-H2AX, 53BP1, and Chk1 foci, consistent with impaired DNA repair capacity. Co-treatment with ATM inhibitors further validated the involvement of DDR signaling in mediating the anti-tumor effects of USP10 inhibition. Generative AI tools were used solely for language editing and improvement of abstract clarity; all scientific content, data interpretation, and conclusions were generated and verified by the authors. Sadaf Dorandish, Komal Bhayekar, Amirreza Samarbakhsh, Babita Kushwaha. Dorandish, Yubin Ge, Navnath S Gavande. Selective USP10 inhibition by GL-458 re-sensitizes platinum-resistant non-small cell lung cancer through DNA damage response disruption [abstract]. In: Proceedings of AACR Drug Discovery and Development (AACR D3) Conference; 2026 Jul 21-24; Boston, MA. Philadelphia (PA): AACR; Clin Cancer Res 2026;32(14_Suppl):Abstract nr A062.