PCSK9 Inhibitors: Mechanism of Action, Efficacy, and Safety

Low-density lipoprotein (LDL) receptors on the surface of liver hepatocytes are the primary way that humans regulate serum LDL cholesterol levels. Proprotein convertase subtilisin/kexin type 9 (PCSK9) is a proteolytic enzyme that indirectly regulates serum LDL cholesterol (LDL-C) by causing the destruction of LDL receptors. Less LDL receptors result in increased LDL-C in the bloodstream but inhibiting or binding the circulating PCSK9 results in increased LDL receptors with the resultant decrease in serum LDL-C. Two PCSK9 inhibitors are currently approved for use: alirocumab and evolocumab. Both are fully human monoclonal antibodies that bind free PCSK9. Herein we discuss the mechanism of action, efficacy, and safety of PCSK9 inhibitors.