Discovery of Highly Selective AKR1C3 Inhibitors to Overcome EGFR C797S-Mediated Osimertinib Resistance in Non-Small Cell Lung Cancer

Osimertinib resistance driven by the cis-C797S/T790M EGFR triplet mutation remains clinically intractable. We identify aldo-keto reductase 1C3 (AKR1C3) as a metabolic vulnerability that sustains glutathione-reactive oxygen species (GSH-ROS) homeostasis in resistant non-small cell lung Cancer (NSCLC). Starting from the selective inhibitor S07-2001, six rounds of structure-guided optimization delivered 55 analogues. The most advanced, SG-55, is a noncompetitive AKR1C3 inhibitor with nanomolar potency, exhibiting a half-maximal inhibitory concentration (IC₅₀) of 5 ± 1 nM, whereas the IC₅₀ values against AKR1C1, AKR1C2, and AKR1C4 are >10 μM. In 19Del/T790M/C797S mutant cells, SG-55 elevated the reduced/oxidized nicotinamide adenine dinucleotide phosphate (NADPH/NADP⁺) ratio, decreased the reduced/oxidized glutathione (GSH/GSSG) ratio, induced DNA double-strand breaks, and synergized with Osimertinib to suppress proliferation, clonogenicity, and survival. This combination therapy demonstrated efficacy in xenograft models and exhibited favorable pharmacokinetics in mice, thereby validating AKR1C3 blockade as a "metabolism-targeted" strategy to overcome resistance mediated by the EGFR C797S mutation.