Abstract LB195: Beyond hydrolase: Lactylation converts ABHD6 into a mitochondrial regulator of lenvatinib resistance in HCC

Abstract Hepatocellular carcinoma (HCC) frequently develops resistance to lenvatinib, a frontline tyrosine kinase inhibitor, via poorly understood metabolic adaptations. Here we report that α/β Hydrolase Domain Containing 6 (ABHD6) is a critical driver of lenvatinib resistance, acting as a molecular switch between canonical enzymatic and non-canonical scaffolding functions. This switch is allosterically controlled by ligand-binding at the S148 catalytic site. Its pro-resistance role is independent of catalysis but requires an unoccupied catalytic site. In resistant HCC, the Warburg effect elevates lactate, leading to K245 lactylation of ABHD6. This modification triggers the mitochondrial translocation of ABHD6, which functions as a scaffold, competitively binding the fission regulator FIS1 and displacing DRP1. This disruption of fission machinery stabilizes hyperfused mitochondria, thereby conferring resistance by suppressing drug-induced apoptosis and ROS generation. Crucially, this resistance is reversible. Both inhibiting lactate production and enforcing occupancy of the S148 site with substrates or a specific inhibitor allosterically disrupted the ABHD6-FIS1 complex, reactivate mitochondrial fission, and restored the sensitivity to lenvatinib. This study identified a lactate-driven functional switch in ABHD6 and established that targeting this allosteric mechanism is an effective therapeutic strategy for overcome lenvatinib resistance. Citation Format: Zhiyuan Tang, Yuening Sun, Chengju Luo. Beyond hydrolase: Lactylation converts ABHD6 into a mitochondrial regulator of lenvatinib resistance in HCC abstract. In: Proceedings of the American Association for Cancer Research Annual Meeting 2026; Part 2 (Late-Breaking, Clinical Trial, and Invited Abstracts) ; 2026 Apr 17-22; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2026;86 (8Suppl): Abstract nr LB195.