👤 Angela Pirillo

The causal role of LDL in atherosclerotic cardiovascular disease (ASCVD) is well established, but the contribution of HDL has proven more complex. CETP inhibitors were originally developed to increase HDL-cholesterol (HDL-C), but the failure of clinical trials and genetic evidence have changed our understanding of CETP biology. With the development of obicetrapib, a next-generation CETP inhibitor, there has been renewed interest in its therapeutic potential. This review summarizes the latest findings on CETP inhibition and highlights the evolving perspectives from lipid modulation to broader clinical applications. Clinical trials and Mendelian randomisation consistently show that increasing HDL-C alone does not reduce cardiovascular risk, while lowering apoB-containing lipoproteins is associated with benefit. Off-target effects, modest efficacy or insufficient follow-up limited previous CETP inhibitors. Obicetrapib, in contrast, achieves a significant LDL-C and apoB reduction, a marked HDL-C increase and favourable safety. Beyond ASCVD, CETP inhibition may also have an impact on diabetes risk, cognitive function and possibly other conditions, although data are still preliminary. The therapeutic focus has shifted from HDL-C elevation to apoB lowering as the determinant of cardiovascular benefit. Obicetrapib shows promise, with ongoing trials designed to define its role in ASCVD management. Show less

The availability of pharmacological approaches able to effectively reduce circulating LDL cholesterol (LDL-C) has led to a substantial reduction in the risk of atherosclerosis-related cardiovascular disease (CVD). However, a residual cardiovascular (CV) risk persists in treated individuals with optimal levels of LDL-C. Additional risk factors beyond LDL-C are involved, and among these, elevated levels of triglycerides (TGs) and TG-rich lipoproteins are causally associated with an increased CV risk. Apolipoprotein C-III (apoC-III) is a key regulator of TG metabolism and hence circulating levels through several mechanisms including the inhibition of lipoprotein lipase activity and alterations in the affinity of apoC-III-containing lipoproteins for both the hepatic receptors involved in their removal and extracellular matrix in the arterial wall. Genetic studies have clarified the role of apoC-III in humans, establishing a causal link with CVD and showing that loss-of-function mutations in the APOC3 gene are associated with reduced TG levels and reduced risk of coronary heart disease. Currently available hypolipidaemic drugs can reduce TG levels, although to a limited extent. Substantial reductions in TG levels can be obtained with new drugs that target specifically apoC-III; these include two antisense oligonucleotides, one small interfering RNA and an antibody. Show less

Low high density lipoprotein cholesterol (HDL-C) levels represent an independent risk factor for cardiovascular disease; in addition to the reduced HDL-C levels commonly observed in patients at cardiovascular risk, the presence of dysfunctional HDL, i.e. HDL with reduced atheroprotective properties, has been reported. Despite the established inverse correlation between HDL-C levels and cardiovascular risk, several clinical trials with HDL-C-increasing drugs (such as niacin, CETP inhibitors or fibrate) failed to demonstrate that a significant rise in HDL-C levels translate into a cardiovascular benefit. Statins, that are the most used lipid-lowering drugs, can also increase HDL-C levels, although this effect is highly variable among studies and statins; the most recent developed statin, pitavastatin, beside its role as LDL-C-lowering agent, increases HDL-C levels at a significantly higher extent and progressively upon treatment; such increase was observed also when patients where shifted from another statin to pitavastatin. The stratification by baseline HDL-C levels revealed that only pitavastatin significantly increased HDL-C levels in patients with baseline HDL-C ≤45 mg/dl, while no changes were observed in patients with higher baseline HDL-C levels. In the last years the hypothesis that functional properties of HDL may be more relevant than HDL-C levels has risen from several observations. The treatment with pitavastatin not only increased HDL-C levels, but also increased the phospholipid content of HDL, increased the HDL efflux capacity and their anti-oxidant properties. These observations suggest that, besides its high LDL-C-lowering effect, pitavastatin also exhibits a significantly higher ability to increase HDL-C levels and may also positively affect the quality and functionality of HDL particles. Show less

Apolipoprotein C-III (apoC-III) has a critical role in the metabolism of triglyceride (TG)-rich lipoproteins (TRLs). Animal models lacking the APOC3 gene exhibit reduced plasma TG levels, whereas the overexpression of APOC3 leads to increased TG levels. In humans, loss-of-function mutations in APOC3 are associated with reduced plasma TG levels and reduced risk for ischemic vascular disease and coronary heart disease. Several hypolipidemic agents have been shown to reduce apoC-III, including fibrates and statins, and antisense technology aimed at inhibiting APOC3 mRNA to decrease the production of apoC-III is currently in Phase III of clinical development. Here, we review the pathophysiological role of apoC-III in TG metabolism and the evidence supporting this apolipoprotein as an emerging target for hypertriglyceridemia (HTG) and associated cardiovascular disorders. Show less

A direct relationship between high plasma triglyceride (TG) levels and increased risk of cardiovascular disease has been shown in several studies. TG are present in the blood associated with different lipoprotein classes, including hepatically-derived very low density lipoproteins (VLDL) and intestinally-derived chylomicrons. Lipoprotein lipase (LPL) is a key enzyme that hydrolyzes TG, releasing free fatty acids that accumulate in peripheral tissues and remnant lipoproteins, that are then cleared by the liver. LPL activity is finely modulated by several cofactors, including apolipoprotein C-III (apoC-III) which acts as a LPL inhibitor. The key role of apoCIII has been established in several studies: animal models lacking APOC3 gene exhibit reduced plasma TG levels, whereas the overexpression of APOC3 gene led to increased TG levels. In humans, several mutations in APOC3 gene have been identified, leading to lower apoC-III levels and associated with reduced plasma TG levels. Recently, these mutations were found to be associated with a reduced risk for cardiovascular ischemia and coronary heart disease, thus confirming the negative role of apoC-III in TG metabolism and suggesting apoC-III as possible therapeutic target for the management of hypertriglyceridemia. Show less