CAT-2003: A Novel Sterol Regulatory Element-Binding Protein Inhibitor That Reduces Steatohepatitis, Plasma Lipids, and Atherosclerosis in Apolipoprotein E*3-Leiden Mice

CAT-2003 is a novel conjugate of eicosapentaenoic acid (EPA) and niacin designed to be hydrolyzed by fatty acid amide hydrolase to release EPA inside cells at the endoplasmic reticulum. In cultured liver cells, CAT-2003 blocked the maturation of sterol regulatory element-binding protein (SREBP)-1 and SREBP-2 proteins and decreased the expression of multiple SREBP target genes, including HMGCR and PCSK9. Consistent with proprotein convertase subtilisin/kexin type 9 (PCSK9) reduction, both low-density lipoprotein receptor protein at the cell surface and low-density lipoprotein particle uptake were increased. In apolipoprotein E*3-Leiden mice fed a cholesterol-containing western diet, CAT-2003 decreased hepatic inflammation and steatosis as evidenced by fewer inflammatory cell aggregates in histopathologic sections, decreased nuclear factor kappa B activity in liver lysates, reduced inflammatory gene expression, reduced intrahepatic cholesteryl ester and triglyceride levels, and decreased liver mass. Plasma PCSK9 was reduced and hepatic low-density lipoprotein receptor protein expression was increased; plasma cholesterol and triglyceride levels were lowered. Aortic root segments showed reduction of several atherosclerotic markers, including lesion size, number, and severity. CAT-2003, when dosed in combination with atorvastatin, further lowered plasma cholesterol levels and decreased hepatic expression of SREBP target genes. Conclusion: SREBP inhibition is a promising new strategy for the prevention and treatment of diseases associated with abnormal lipid metabolism, such as atherosclerosis and nonalcoholic steatohepatitis.