Abstract
<title>Abstract</title> <p> Osimertinib (Osi) resistance remains a major challenge in EGFR-mutant NSCLC. To uncover the underlying mechanisms, we performed integrated transcriptomic, metabolomic, genomic, structural (including advanced 3D imaging of mitochondrial networks), and functional analyses in matched H1975 parental (Par) and Osi-resistant (OsiR) cells. OsiR cells display mitochondrial dysfunction characterized by impaired oxidative phosphorylation (OXPHOS), altered mitochondrial gene expression, and accumulation of mutations in both mitochondrial DNA and nuclear-encoded mitochondrial genes. A K45Q mutation in MT-ATP8 may contribute to mitochondrial remodeling associated with this resistant phenotype. Genetic ablation of <italic>Aldh2</italic> significantly restores osimertinib sensitivity, identifying aldehyde dehydrogenase-dependent metabolism as a functional contributor to resistance. We introduce <italic>mitochondriomics</italic> to describe this multilayered remodeling, integrating genomic, transcriptomic, structural, and functional changes. Metabolomic profiling revealed extracellular accumulation of pyruvate, lactate, acetaldehyde, and acetate, reflecting enhanced glycolysis and activation of an alternative pyruvate-acetaldehyde-acetate (PAA) adaptive pathway. Stable-isotope tracing revealed increased extracellular accumulation of glucose-derived acetate in resistant cells. Together with ALDH2 loss-of-function studies, these findings support a role for PAA-associated metabolism in maintaining metabolic homeostasis during drug resistance, while the non-oxidative pentose phosphate pathway (non-oxPPP) contributes to biosynthetic demands. Single-cell analyses of genetically paired transgenic mice revealed that resistant tumors are enriched in pulmonary epithelial AT2-like subpopulations, which recapitulate the mitochondrial remodeling and bioenergetic signatures observed <italic>in vitro</italic> . These findings uncover a mitochondria-centered adaptive program in Osi-resistant EGFR-mutant NSCLC, where mitochondrial remodeling and the PAA-associated metabolic adaptation converge to promote survival and drug tolerance. The work highlights metabolic vulnerabilities with potential therapeutic relevance to overcome osimertinib resistance. </p>