Apabetalone Drives a Metabolic Shift Towards Ketogenesis and Reduces Liver Steatosis in Diet-Induced Obesity Mice

Background/Objectives: Obesity can cause metabolic disorders and hepatic steatosis. Continuous hepatic influx of dietary lipids leads to adaptive metabolic changes, including increased fatty acid oxidation (FAO) and ketogenesis. However, these adaptations are not enough to counter the detrimental accumulation of lipids, resulting in hepatic steatosis. Apabetalone is a clinical-stage Bromodomain and Extra-Terminal domain inhibitor (BETi) that attenuated the increase in hepatic fibrosis score (FS) and reduced the rate of ischemic major adverse cardiovascular events and hospitalizations for heart failure in a subgroup of patients having a high likelihood of Metabolic Dysfunction-Associated Steatotic Liver Disease (MASLD) in the phase 3 clinical trial, BETonMACE. Methods: To analyze apabetalone's effects on lipid and ketone metabolism, RNA seq, Oil Red staining and triglyceride quantification were performed in livers from a mouse model of diabetes-induced obesity and ketones were measured in plasma. Results: Mice fed a high-fat diet (HFD) were obese and demonstrated liver steatosis. Apabetalone treatment maintained the beneficial metabolic adaptation induced by HFD (increased FAO) and decreased hepatic triglycerides and lipid droplets. This inhibition of lipid anabolism redirected substrates to FAO and ketogenesis, resulting in increased plasma ketones, showing for the first time the role of BETi in ketogenesis. In the heart, apabetalone treatment reduced cardiac oxidative stress and plasma NT-proBNP levels. Conclusions: Apabetalone improves hepatic lipid handling, favoring ketogenesis. As ketones have demonstrated beneficial effects on cardiac function, increased ketones induced by apabetalone may not only contribute to the observed attenuation of FS in patients, but also a reduction in cardiac events among patients with high likelihood of MASLD, as well as in the overall trial population.