Obicetrapib Alone and in Combination with Ezetimibe Reduces Non-HDL-Cholesterol by Enhanced LDL-Receptor-Mediated VLDL Clearance and Increased Net Fecal Sterol Excretion in ApoE*3-Leiden.CETP Mice

Background and Aims: Obicetrapib is a selective cholesteryl ester transfer protein (CETP) inhibitor in clinical development for the treatment of hypercholesterolemia and cardiovascular risk. It reduces apolipoprotein B (ApoB) and low-density lipoprotein cholesterol (LDL-C) and increases high-density lipoprotein cholesterol (HDL-C). Ezetimibe reduces absorption of biliary and dietary cholesterol from the small intestine, also reducing LDL-C levels. The current study elucidates the mechanism for decreases in non-HDL-C by obicetrapib alone and with ezetimibe in a mouse model for hyperlipidemia and atherosclerosis.

Methods: Female ApoE*3-Leiden.CETP transgenic mice were fed a Western diet with 0.05% w/w cholesterol (equivalent to daily human intake) or this diet containing obicetrapib (2 mg/kg/day), ezetimibe (1 mg/kg/day), or obicetrapib with ezetimibe.

Results: Obicetrapib, ezetimibe, and the combination reduced total plasma cholesterol levels (-42%, -23% and -62%).Obicetrapib alone and in combination with ezetimibe nearly completely blocked CETP activity (-99% and -100%) resulting in increased HDL-C (+260% and +245%) and ApoA1 (98% and 81%). Obicetrapib, ezetimibe, and the combination enhanced clearance of VLDL-like particles (half-life: -44%, -23% and -57%) and enhanced hepatic LDL receptor expression (+63% and +74%). Increased bile acid excretion in obicetrapib-treated mice (+41%) and increased neutral sterol excretion in ezetimibe-treated mice was observed, and was more pronounced in combination with obicetrapib (+68% and +100%), resulting in a net fecal sterol loss.

Conclusions: Obicetrapib alone and with ezetimibe reduced non-HDL-C levels by increased VLDL lipolysis, increased VLDL clearance and elevated LDL receptor levels, and enhanced fecal bile acid and neutral sterol excretion.