Vaccines Targeting PCSK9: A Promising Alternative to Passive Immunization with Monoclonal Antibodies in the Management of Hyperlipidaemia?

Hypercholesterolaemia is frequently observed in patients with cardiovascular diseases (CVD) and is associated with increased mortality. Statin treatment has been the standard of care for reducing low-density lipoprotein cholesterol (LDL-C) to improve cardiovascular outcomes. However, statins have limited effects in some patients and may be discontinued due to adverse effects resulting in LDL-C above target levels. The proprotein convertase subtilisin kexin type 9 (PCSK9) is a pivotal regulator in the LDL-C metabolism by degrading the LDL-C receptor on hepatocytes. Inhibition of PCSK9 by monoclonal antibodies (mAb) significantly lowers LDL-C levels and is considered to reduce the likelihood of adverse cardiac events. However, such treatment regimens are not cost-effective, and require frequent administrations at high doses that may be associated with side effects and poor drug adherence. Furthermore, it has been shown that these PCSK9 medicines may trigger the formation of antidrug antibodies followed by a significant attenuation of the LDL-C-lowering effect. Active vaccination inducing high-affinity antibodies against PCSK9 with less frequent administration intervals may be a novel promising therapeutic approach to overcome the drawback of passive immunization with PCSK9 mAb. However there is a paucity of available clinical safety and efficacy data. This article discusses challenges in the development of PCSK9 vaccines and their potential therapeutic benefits by reviewing clinical studies that evaluated the safety and efficacy of PCSK9 mAb.