Evolving Concepts in LDL-Lowering Strategies: Are We There?

Abstract

High plasma levels of low density lipoproteins (LDLs) represent one of the major risk factors for cardiovascular disease, as shown by many epidemiological studies. On the other hand, randomized trials designed to address the clinical impact of lipid lowering interventions, have clearly shown that reduction in LDL plasma levels lead to a significant decrease in major cardiovascular events. Based on these observations, pharmacological modulation of LDLs has been highly investigated. Statins, alone or in combination, represent the most powerful agents to date available to reach the LDLs levels suggested by the current guidelines. However, in some patients the recommended LDL reduction is difficult to be achieved because of genetic background (familial hypercholesterolemia), side effects (statin intolerance), or simply because of a non-sufficient response. In the last few years, our understanding of the basic mechanisms involved in the lipoprotein metabolism has progressed significantly. The crucial role of proprotein convertase subtilisin/kexin type 9 (PCSK9) has emerged. The main characterized function of PCSK9 relates to the binding to LDL-C receptors (LDLR) in hepatocytes. However, PCSK9 does not interfere with the binding between LDL and its own receptor, but with the ability of the latest to return to the surface of the hepatocyte and bind new LDL molecules. Based on these observations, blocking PCSK-9 may reduce the LDLR clearance, thus increasing the ability of LDLR to remove circulating LDLs. Pharmacological inhibition of this protein has been proposed as new therapeutic approach. The clinical evidence available to date seem to fully support this hypothesis.