Proprotein Convertase Subtilisin/Kexin Type 9 Inhibition: The Big Step Forward in Lipid Control

The breakthrough discovery of proprotein convertase subtilisin/kexin type 9 (PCSK9) 20 years ago revolutionised the current understanding of cholesterol homeostasis. Genetic studies have shown that gain-of-function mutations in PCSK9 lead to elevated LDL cholesterol and increased risk of atherosclerotic cardiovascular disease, while loss-of-function mutations in PCSK9 result in lifelong low levels of circulating LDL cholesterol and dramatic reduction in atherosclerotic cardiovascular disease. Therapies inhibiting PCSK9 lead to a higher density of LDL receptor on the surface of hepatocytes, resulting in greater ability to clear circulating LDL. Thus far, randomised controlled trials have shown that subcutaneous fully human monoclonal antibodies targeting PCSK9, evolocumab and alirocumab, and PCSK9 silencing with inclisiran result in drastic reductions in LDL cholesterol. Additionally, several novel strategies to target PCSK9 are in development, including oral antibody, gene silencing, DNA base editing and vaccine therapies. This review highlights the efficacy, safety and clinical use of these various approaches in PCSK9 inhibition.