Cholesteryl Ester Transfer Protein Inhibitors and Cardiovascular Outcomes: A Systematic Review and Meta-Analysis

BACKGROUND

Atherosclerosis is a multi-factorial disease, and low-density lipoprotein cholesterol (LDL-C) is a critical risk factor in developing atherosclerotic cardiovascular disease (ASCVD). Cholesteryl-ester transfer-protein (CETP), synthesized by the liver, regulates LDL-C and high-density lipoprotein cholesterol (HDL-C) through the bidirectional transfer of lipids. The novelty of CETP inhibitors (CETPis) has granted new focus towards increasing HDL-C, besides lowering LDL-C strategies. To date, five CETPis that are projected to improve lipid profiles, torcetrapib, dalcetrapib, evacetrapib, anacetrapib, and obicetrapib, have reached late-stage clinical development for ASCVD risk reduction. Early trials failed to reduce atherosclerotic cardiovascular occurrences. Given the advent of some recent large-scale clinical trials (ACCELERATE, HPS3/TIMI55-REVEAL Collaborative Group), conducting a meta-analysis is essential to investigate CETPis' efficacy.

METHODS

We conducted a thorough search of randomized controlled trials (RCTs) that commenced between 2003 and 2023; CETPi versus placebo studies with a ≥6-month follow-up and defined outcomes were eligible.

PRIMARY OUTCOMES

major adverse cardiovascular events (MACEs), cardiovascular disease (CVD)-related mortality, all-cause mortality.

SECONDARY OUTCOMES

stroke, revascularization, hospitalization due to acute coronary syndrome, myocardial infarction (MI).

RESULTS

Nine RCTs revealed that the use of a CETPi significantly reduced CVD-related mortality (RR = 0.89; 95% CI: 0.81-0.98; p = 0.02; I2 = 0%); the same studies also reduced the risk of MI (RR = 0.92; 95% CI: 0.86-0.98; p = 0.01; I2 = 0%), which was primarily attributed to anacetrapib. The use of a CETPi did not reduce the likelihood any other outcomes.

CONCLUSIONS

Our meta-analysis shows, for the first time, that CETPis are associated with reduced CVD-related mortality and MI.

Cuban Policosanol (Raydel®) Exerts Higher Antioxidant and Anti-Glycation Activities than Chinese Policosanol (BOC Sciences) in Reconstituted High-Density Lipoproteins: In Vivo Anti-Inflammatory Activities in Zebrafish and Its Embryos

The present study compares sugarcane-wax purified policosanols sourced from Cuba (Raydel®) and China (BOC Sciences) and utilized following the synthesis of reconstituted high-density lipoproteins (rHDL). The two policosanols exhibited distinctly different ingredient ratios of long-chain aliphatic alcohols, particularly 1-octacosanol (C28) and 1-tetratriacotanol (C34). After synthesizing rHDL with apolipoprotein A-I (apoA-I), the two policosanols bound well with phospholipid and apoA-I to form the discoidal rHDL. Notably, rHDL-1, containing Cuban policosanol, displayed the largest particle diameter at approximately 78 ± 3 nm. In contrast, both control rHDL (rHDL-0) and rHDL containing Chinese policosanol (rHDL-2) exhibited smaller particles, with diameters of approximately 58 ± 3 nm and 61 ± 2 nm, respectively. Furthermore, rHDL-1 demonstrated enhanced anti-glycation activity, safeguarding apoA-I from degradation within HDL, and displayed the antioxidant ability to inhibit LDL oxidation. A microinjection of each rHDL into zebrafish embryos in the presence of carboxymethyllysine (CML) revealed rHDL-1 to have the strongest antioxidant activity with the highest embryo survivability and normal developmental morphology. Dermal application to recover the wound revealed rHDL-1 to have the highest wound-healing activity (75%) and survivability (92%) in the cutaneous wound area in the presence of CML. In adult zebrafish, injecting CML (250 μg) caused acute death and hyperinflammation, marked by heightened neutrophil infiltration and interleukin (IL)-6 production in liver. However, co-administering rHDL-1 notably increased survival (85%) and exhibited strong anti-inflammatory properties, reducing IL-6 production while improving the blood lipid profile. However, a co-injection of rHDL-2 resulted in the lowest survivability (47%) with more hepatic inflammation. In conclusion, Cuban policosanol (Raydel®) has more desirable properties for the in vitro synthesis of rHDL with stronger anti-glycation and antioxidant activities than those of Chinese policosanol (BOC Sciences). Moreover, Raydel-policosanol-integrated rHDL demonstrates a noteworthy effect on accelerated wound healing and robust anti-inflammatory properties, leading to increased survivability in zebrafish embryos and adults by effectively suppressing CML-induced hyperinflammation.

Obicetrapib: Reversing the Tide of CETP Inhibitor Disappointments

PURPOSE OF REVIEW

To discuss the history of cardiovascular outcomes trials of cholesteryl ester transfer protein (CETP) inhibitors and to describe obicetrapib, a next-generation, oral, once-daily, low-dose CETP inhibitor in late-stage development for dyslipidemia and atherosclerotic cardiovascular disease (ASCVD).

RECENT FINDINGS

Phase 1 and 2 trials have evaluated the safety and lipid/lipoprotein effects of obicetrapib as monotherapy, in conjunction with statins, on top of high-intensity statins (HIS), and with ezetimibe on top of HIS. In ROSE2, 10 mg obicetrapib monotherapy and combined with 10 mg ezetimibe, each on top of HIS, significantly reduced low-density lipoprotein cholesterol (LDL-C), non-high-density lipoprotein cholesterol (non-HDL-C), apolipoprotein B, total LDL particles, small LDL particles, small, dense LDL-C, and lipoprotein (a), and increased HDL-C. Phase 3 pivotal registration trials including a cardiovascular outcomes trial are underway. Obicetrapib has an excellent safety and tolerability profile and robustly lowers atherogenic lipoproteins and raises HDL-C. As such, obicetrapib may be a promising agent for the treatment of ASCVD.

Novel and future lipid-modulating therapies for the prevention of cardiovascular disease

Lowering the levels of LDL cholesterol in the plasma has been shown to reduce the risk of atherosclerotic cardiovascular disease (ASCVD). Several other lipoproteins, such as triglyceride-rich lipoproteins, HDL and lipoprotein(a) are associated with atherosclerosis and ASCVD, with strong evidence supporting causality for some. In this Review, we discuss novel and upcoming therapeutic strategies targeting different pathways in lipid metabolism to potentially attenuate the risk of cardiovascular events. Key proteins involved in lipoprotein metabolism, such as PCSK9, angiopoietin-related protein 3, cholesteryl ester transfer protein and apolipoprotein(a), have been identified as viable targets for therapeutic intervention through observational and genetic studies. These proteins can be targeted using a variety of approaches, such as protein inhibition or interference, inhibition of translation at the mRNA level (with the use of antisense oligonucleotides or small interfering RNA), and the introduction of loss-of-function mutations through base editing. These novel and upcoming strategies are complementary to and could work synergistically with existing therapies, or in some cases could potentially replace therapies, offering unprecedented opportunities to prevent ASCVD. Moreover, a major challenge in the prevention and treatment of non-communicable diseases is how to achieve safe, long-lasting reductions in causal exposures. This challenge might be overcome with approaches such as small interfering RNAs or genome editing, which shows how far the field has advanced from when the burden of achieving this goal was placed upon patients through rigorous adherence to daily small-molecule drug regimens.

Familial Hypercholesterolemia: JACC Focus Seminar 4/4

Detecting familial hypercholesterolemia (FH) early and "normalizing" low-density lipoprotein (LDL) cholesterol values are the 2 pillars for effective cardiovascular disease prevention in FH. Combining lipid-lowering therapies targeting synergistic/complementary metabolic pathways makes this feasible, even among severe phenotypes. For LDL receptor-dependent treatments, PCSK9 remains the main target for adjunctive therapy to statins and ezetimibe through a variety of approaches. These include protein inhibition (adnectins), inhibition of translation at mRNA level (antisense oligonucleotides or small interfering RNA), and creation of loss-of-function mutations through base-pair editing. For patients with little LDL receptor function, LDL receptor-independent treatment targeting ANGPTL3 through monoclonal therapies are now available, or in the future, antisense/small interfering RNA-based approaches offer alternative approaches. Finally, first-in-human studies are ongoing, testing adenovirus-mediated gene therapy transducing healthy LDLR DNA in patients with HoFH. Further development of the CRISPR cas technology, which has shown promising results in vivo on introducing PCSK9 loss-of-function mutations, will move a single-dose, curative treatment for FH closer.

Cholesteryl ester transfer protein (CETP) as a drug target for cardiovascular disease

Development of cholesteryl ester transfer protein (CETP) inhibitors for coronary heart disease (CHD) has yet to deliver licensed medicines. To distinguish compound from drug target failure, we compared evidence from clinical trials and drug target Mendelian randomization of CETP protein concentration, comparing this to Mendelian randomization of proprotein convertase subtilisin/kexin type 9 (PCSK9). We show that previous failures of CETP inhibitors are likely compound related, as illustrated by significant degrees of between-compound heterogeneity in effects on lipids, blood pressure, and clinical outcomes observed in trials. On-target CETP inhibition, assessed through Mendelian randomization, is expected to reduce the risk of CHD, heart failure, diabetes, and chronic kidney disease, while increasing the risk of age-related macular degeneration. In contrast, lower PCSK9 concentration is anticipated to decrease the risk of CHD, heart failure, atrial fibrillation, chronic kidney disease, multiple sclerosis, and stroke, while potentially increasing the risk of Alzheimer's disease and asthma. Due to distinct effects on lipoprotein metabolite profiles, joint inhibition of CETP and PCSK9 may provide added benefit. In conclusion, we provide genetic evidence that CETP is an effective target for CHD prevention but with a potential on-target adverse effect on age-related macular degeneration.

Invention of MK-8262, a Cholesteryl Ester Transfer Protein (CETP) Inhibitor Backup to Anacetrapib with Best-in-Class Properties

Cholesteryl ester transfer protein (CETP) represents one of the key regulators of the homeostasis of lipid particles, including high-density lipoprotein (HDL) and low-density lipoprotein (LDL) particles. Epidemiological evidence correlates increased HDL and decreased LDL to coronary heart disease (CHD) risk reduction. This relationship is consistent with a clinical outcomes trial of a CETP inhibitor (anacetrapib) combined with standard of care (statin), which led to a 9% additional risk reduction compared to standard of care alone. We discuss here the discovery of MK-8262, a CETP inhibitor with the potential for being the best-in-class molecule. Novel in vitro and in vivo paradigms were integrated to drug discovery to guide optimization informed by a critical understanding of key clinical adverse effect profiles. We present preclinical and clinical evidence of MK-8262 safety and efficacy by means of HDL increase and LDL reduction as biomarkers for reduced CHD risk.

Cholesteryl ester transfer protein inhibitors in precision medicine

Dyslipidemia is associated with atherosclerosis and cardiovascular disease development, posing serious risks to human health. Cholesteryl ester transfer protein (CETP) is responsible for exchange of neutral lipids, such as cholesteryl ester and TG, between plasma high density lipoprotein (HDL) particles and Apolipoprotein B-100 (ApoB-100) containing lipoprotein particles. Genetic studies suggest that single-nucleotide polymorphism (SNPs) with loss of activity CETP is associated with increased HDL-C, reduced LDL-C, and cardiovascular risk. In animal studies, mostly in rabbits, which have similar CETP activity to humans, inhibition of CETP through antisense oligonucleotides reduced aortic arch atherosclerosis. Concerning this notion, inhibiting the CETP is considered as a promise approach to reduce cardiovascular events, and several CETP inhibitors have been recently studied as a cholesterol modifying agent to reduce cardiovascular mortality in high risk cardiovascular disease patients. However, in Phase III cardiovascular outcome trials, three CETP inhibitors, named Torcetrapib, Dalcetrapib, and Evacetrapib, did not provide expected cardiovascular benefits and failed to improve outcomes of patient with cardiovascular diseases (CVD). Although REVEAL trail has recently shown that Anacetrapib could reduce major coronary events, it was also shown to induce excessive lipid accumulation in adipose tissue; thereby, the further regulatory approval will not be sought. On the other hand, growing evidence indicated that the function of CETP inhibitors on modulating the cardiovascular events are determined by correlated single nucleotide polymorphism (SNP) in the ADCY9 gene. However, the underlying mechanisms whereby CETP inhibitors interact with the genotype are not yet elucidated, which could potentially be related to the genotype-dependent cholesterol efflux capacity of HDL particles. In the present review, we summarize the current understanding of the functions of CETP and the outcomes of the phase III randomized controlled trials of CETP inhibitors. In addition, we also put forward the implications from results of the trials which potentially suggest that the CETP inhibitors could be a promising precise therapeutic medicine for CVD based on genetic background.

Impact of drug distribution into adipose on tissue function: The cholesteryl ester transfer protein (CETP) inhibitor anacetrapib as a test case

Anacetrapib is an inhibitor of cholesteryl ester transfer protein (CETP) previously under development as a lipid-modifying agent that reduces LDL-cholesterol and increases HDL-cholesterol in hypercholesterolemic patients. Anacetrapib demonstrates a long terminal half-life and accumulates in adipose tissue, which contributes to a long residence time of anacetrapib. Given our previous report that anacetrapib distributes into the lipid droplet of adipose tissue, we sought to understand whether anacetrapib affected adipose function, using a diet-induced obese (DIO) mouse model. Following 20 weeks of treatment with anacetrapib (100 mg/kg/day), levels of the drug increased to approximately 0.6 mmol/L in white adipose tissue. This level of anacetrapib was not associated with any impairment in adipose functionality as evidenced by a lack of any reduction in biomarkers of adipose functionality (plasma adiponectin, leptin, insulin; adipose adiponectin, leptin mRNA). In DIO wild-type (WT) mice treated with anacetrapib for 2 weeks and then subjected to 30% food restriction during washout to induce weight loss (18%) and fat mass loss (7%), levels of anacetrapib in adipose and plasma were not different between food restricted and ad lib-fed mice. These data indicate that despite deposition and long-term residence of ~0.6 mmol/L levels of anacetrapib in adipose tissue, adipose tissue function appears to be unaffected in mice. In addition, these data also indicate that even with severe caloric restriction and acute loss of fat mass, anacetrapib does not appear to be mobilized from the fat depot, thereby solidifying the role of adipose as a long-term storage site of anacetrapib.

Association of CETP Gene Variants With Risk for Vascular and Nonvascular Diseases Among Chinese Adults

Question

What is the association of genetic variants in the CETP gene that lower cholesteryl ester transfer protein activity with risk for cardiovascular and other diseases?

Findings

In this biobank study of 151 217 Chinese adults, CETP gene variants were associated with higher levels of high-density lipoprotein cholesterol but not with lower levels of low-density lipoprotein cholesterol and were not associated with risk for cardiovascular disease.

Meaning

Increasing levels of high-density lipoprotein cholesterol by cholesteryl ester transfer protein inhibition in the absence of lower levels of low-density lipoprotein cholesterol may not confer significant benefits for cardiovascular disease.

Importance

Increasing levels of high-density lipoprotein (HDL) cholesterol through pharmacologic inhibition of cholesteryl ester transfer protein (CETP) is a potentially important strategy for prevention and treatment of cardiovascular disease (CVD).

Objective

To use genetic variants in the CETP gene to assess potential risks and benefits of lifelong lower CETP activity on CVD and other outcomes.

Design, Setting, and Participants

This prospective biobank study included 151 217 individuals aged 30 to 79 years who were enrolled from 5 urban and 5 rural areas of China from June 25, 2004, through July 15, 2008. All participants had baseline genotype data, 17 854 of whom had lipid measurements and 4657 of whom had lipoprotein particle measurements. Median follow-up of 9.2 years (interquartile range, 8.2-10.1 years) was completed January 1, 2016, through linkage to health insurance records and death and disease registries.

Exposures

Five CETP variants, including an East Asian loss-of-function variant (rs2303790), combined in a genetic score weighted to associations with HDL cholesterol levels.

Main Outcomes and Measures

Baseline levels of lipids and lipoprotein particles, cardiovascular risk factors, incidence of carotid plaque and predefined major vascular and nonvascular diseases, and a phenome-wide range of diseases.

Results

Among the 151 217 individuals included in this study (58.4% women and 41.6% men), the mean (SD) age was 52.3 (10.9) years. Overall, the mean (SD) low-density lipoprotein (LDL) cholesterol level was 91 (27) mg/dL; HDL cholesterol level, 48 (12) mg/dL. CETP variants were strongly associated with higher concentrations of HDL cholesterol (eg, 6.1 [SE, 0.4] mg/dL per rs2303790-G allele; P = 9.4 × 10⁻⁴⁷) but were not associated with lower LDL cholesterol levels. Within HDL particles, cholesterol esters were increased and triglycerides reduced, whereas within very low-density lipoprotein particles, cholesterol esters were reduced and triglycerides increased. When scaled to 10-mg/dL higher levels of HDL cholesterol, the CETP genetic score was not associated with occlusive CVD (18 550 events; odds ratio [OR], 0.98; 95% CI, 0.91-1.06), major coronary events (5767 events; OR, 1.08; 95% CI, 0.95-1.22), myocardial infarction (3118 events; OR, 1.14; 95% CI, 0.97-1.35), ischemic stroke (13 759 events; OR, 0.94; 95% CI, 0.86-1.02), intracerebral hemorrhage (6532 events; OR, 0.94; 95% CI, 0.83-1.06), or other vascular diseases or carotid plaque. Similarly, rs2303790 was not associated with any vascular diseases or plaque. No associations with nonvascular diseases were found other than an increased risk for eye diseases with rs2303790 (4090 events; OR, 1.43; 95% CI, 1.13-1.80; P = .003).

Conclusions and Relevance

CETP variants were associated with altered HDL metabolism but did not lower LDL cholesterol levels and had no significant association with risk for CVD. These results suggest that in the absence of reduced LDL cholesterol levels, increasing HDL cholesterol levels by inhibition of CETP may not confer significant benefits for CVD.

The conundrum of patients with obesity, exercise intolerance, elevated ventricular filling pressures and a measured ejection fraction in the normal range

Patients with obesity, a reduced exercise capacity, increased cardiac filling pressures and a measured left ventricular ejection fraction in the normal range do not have a homogeneous disorder, but instead, exhibit one of three phenotypes. First, many obese people exhibit sodium retention, plasma volume expansion and cardiac enlargement, and some are likely to have heart failure that is related to hypervolaemia, even though cardiac index and circulating levels of natriuretic peptides are not meaningfully increased. Second, in some middle-aged men and women (particularly those with minimal co-morbidities), levels of natriuretic peptides increase markedly and can lower systemic vascular resistance, thus leading to high-output heart failure (HOHF) and glomerular hyperfiltration. Third, older obese people, particularly women with multiple co-morbidities, exhibit the syndrome of heart failure with a preserved ejection fraction (HFpEF). Despite degrees of plasma volume expansion similar to HOHF, these patients exhibit only modestly increased ventricular dimensions and circulating levels of natriuretic peptides (despite a high prevalence of atrial fibrillation), and glomerular function is characteristically impaired. A conceptual framework is proposed to distinguish among the three phenotypes seen in obese patients with exercise intolerance, increased ventricular filling pressures and a measured left ventricular ejection fraction in the normal range, since they may respond differently to therapeutic interventions. Efforts are needed to enhance the recognition of heart failure in obese people and to ensure that clinical trials that are designed to study patients with HFpEF actually enrol those who have the disease.

Evidence-Based Precision Oncology with the Cancer Targetome

A core tenet of precision oncology is the rational choice of drugs to interact with patient-specific biological targets of interest, but it is currently difficult for researchers to obtain consistent and well-supported target information for pharmaceutical drugs. We review current drug-target interaction resources and critically assess how supporting evidence is handled. We introduce the concept of a unified Cancer Targetome to aggregate drug-target interactions in an evidence-based framework. We discuss current unmet needs and the implications for evidence-based clinical omics. The focus of this review is precision oncology but the discussion is highly relevant to targeted therapies in any area.

Design, Synthesis, and Biological Evaluation of N,N-Disubstituted-4-Arylthiazole-2-Methylamine Derivatives as Cholesteryl Ester Transfer Inhibitors

Cholesteryl ester transfer protein (CETP) has been identified as a potential target for cardiovascular disease (CVD) for its important role in the reverse cholesteryl transfer (RCT) process. In our previous work, compound 5 was discovered as a moderate CETP inhibitor. The replacement of the amide linker by heterocyclic aromatics and then a series of N,N-substituted-4-arylthiazole-2-methylamine derivatives were designed by utilizing a conformational restriction strategy. Thirty-six compounds were synthesized and evaluated for their CETP inhibitory activities. Structure-activity relationship studies indicate that electron donor groups substituted ring A, and electron-withdrawing groups at the 4-position of ring B were critical for potency. Among these compounds, compound 30 exhibited excellent CETP inhibitory activity (IC₅₀ = 0.79 ± 0.02 μM) in vitro and showed an acceptable metabolic stability.

Genetic variants in CETP increase risk of intracerebral hemorrhage

Objective

In observational epidemiologic studies, higher plasma high‐density lipoprotein cholesterol (HDL‐C) has been associated with increased risk of intracerebral hemorrhage (ICH). DNA sequence variants that decrease cholesteryl ester transfer protein (CETP) gene activity increase plasma HDL‐C; as such, medicines that inhibit CETP and raise HDL‐C are in clinical development. Here, we test the hypothesis that CETP DNA sequence variants associated with higher HDL‐C also increase risk for ICH.

Methods

We performed 2 candidate‐gene analyses of CETP. First, we tested individual CETP variants in a discovery cohort of 1,149 ICH cases and 1,238 controls from 3 studies, followed by replication in 1,625 cases and 1,845 controls from 5 studies. Second, we constructed a genetic risk score comprised of 7 independent variants at the CETP locus and tested this score for association with HDL‐C as well as ICH risk.

Results

Twelve variants within CETP demonstrated nominal association with ICH, with the strongest association at the rs173539 locus (odds ratio [OR] = 1.25, standard error [SE] = 0.06, p = 6.0 × 10⁻⁴) with no heterogeneity across studies (I² = 0%). This association was replicated in patients of European ancestry (p = 0.03). A genetic score of CETP variants found to increase HDL‐C by ∼2.85mg/dl in the Global Lipids Genetics Consortium was strongly associated with ICH risk (OR = 1.86, SE = 0.13, p = 1.39 × 10⁻⁶).

Interpretation

Genetic variants in CETP associated with increased HDL‐C raise the risk of ICH. Given ongoing therapeutic development in CETP inhibition and other HDL‐raising strategies, further exploration of potential adverse cerebrovascular outcomes may be warranted. Ann Neurol 2016;80:730–740

Design, synthesis and biological evaluation of novel cholesteryl ester transfer protein inhibitors bearing a cycloalkene scaffold

Cholesteryl ester transfer protein (CETP) is a potential target for cardiovascular disease therapy as inhibition of CETP leads to increased HDL-C in humans. Based on the structure of Merck's biphenyl CETP inhibitor, we designed novel N,N-substituted-cycloalkenyl-methylamine scaffold derivatives by utilizing core replacement and conformational restriction strategies. Consequently, twenty-eight compounds were synthesized and evaluated for their inhibitory activity against CETP. Their preliminary structure-activity relationships (SARs) studies indicate that polar substituents were tolerated in moiety A and hydrophobic alkyl groups at the 5-position of cyclohexene were critical for potency. Among them, compound 17a, bearing an N-(5-pyrazolyl-pyrimidin-2-yl)-cycloalkenyl- methylamine scaffold, exhibited excellent CETP inhibitory activity (IC50 = 0.07 μM) in vitro. Furthermore, it showed an acceptable pharmacokinetic profile in S-D rats and efficient HDL-C increase in high-fat fed hamsters.

Adipocytes, aldosterone and obesity-related hypertension

Understanding the mechanisms linking obesity with hypertension is important in the current obesity epidemic as it may improve therapeutic interventions. Plasma aldosterone levels are positively correlated with body mass index and weight loss in obese patients is reported to be accompanied by decreased aldosterone levels. This suggests a relationship between adipose tissue and the production/secretion of aldosterone. Aldosterone is synthesized principally by the adrenal glands, but its production may be regulated by many factors, including factors secreted by adipocytes. In addition, studies have reported local synthesis of aldosterone in extra-adrenal tissues, including adipose tissue. Experimental studies have highlighted a role for adipocyte-secreted aldosterone in the pathogenesis of obesity-related cardiovascular complications via the mineralocorticoid receptor. This review focuses on how aldosterone secretion may be influenced by adipose tissue and the importance of these mechanisms in the context of obesity-related hypertension.

Discovery of Novel Indoline Cholesterol Ester Transfer Protein Inhibitors (CETP) through a Structure-Guided Approach

Using the collective body of known (CETP) inhibitors as inspiration for design, a structurally novel series of tetrahydroquinoxaline CETP inhibitors were discovered. An exemplar from this series, compound 5, displayed potent in vitro CETP inhibition and was efficacious in a transgenic cynomologus-CETP mouse HDL PD (pharmacodynamic) assay. However, an undesirable metabolic profile and chemical instability hampered further development of the series. A three-dimensional structure of tetrahydroquinoxaline inhibitor 6 was proposed from (1)H NMR structural studies, and this model was then used in silico for the design of a new class of compounds based upon an indoline scaffold. This work resulted in the discovery of compound 7, which displayed potent in vitro CETP inhibition, a favorable PK-PD profile relative to tetrahydroquinoxaline 5, and dose-dependent efficacy in the transgenic cynomologus-CETP mouse HDL PD assay.

A lipidologist perspective of global lipid guidelines and recommendations, part 2: Lipid treatment goals

Having knowledge of worldwide areas of harmonization and consensus regarding lipid guidelines and recommendations may provide clinicians a more global perspective on lipid management. This review examines 8 international scientific/medical organizations that have issued lipid guidelines, recommendations, and position papers: the National Lipid Association (2014), National Institute for Health and Care Excellence (2014), International Atherosclerosis Society (2013), American College of Cardiology/American Heart Association (2013), Canadian Cardiovascular Society (2013), Japan Atherosclerosis Society (2012), European Society of Cardiology/European Atherosclerosis Society (2012), and Adult Treatment Panel III (2001/2004). Part 1 of this perspective focused on sentinel components of these lipid guidelines and recommendations as applied to the role of atherogenic lipoprotein cholesterol levels, primary lipid target of therapy, other primary and secondary lipid treatment targets, and assessment of atherosclerotic cardiovascular disease (ASCVD) risk. This part 2 examines goals of lipid-altering therapy. While lipid guidelines and recommendations may differ regarding ASCVD risk assessment and lipid treatment goals, lipid guidelines and recommendations generally agree on the need to reduce atherogenic lipoprotein cholesterol levels, with statins being the first-line treatment of choice.

[Consecutive formation of the functions of high-, low-density and very-low-density lipoproteins during phylogenesis. Unique algorithm of the effects of lipid-lowering drugs]

During phylogenesis, all fatty acids (FA) were initially transported to cells by apoA-I high-density lipoproteins (HDL) in polar lipids. Later, active cellular uptake of saturated, monoenoic and unsaturated FA occurred via triglycerides (TG) in low-density lipoproteins (LDL). Active uptake of polyenoic FA (PUFA) required the following: a) PUFA re-esterified from polar phospholipids into nonpolar cholesteryl polyesters (poly-CLE), b) a novel protein, cholesteryl ester transfer protein (CETP), initiated poly-CLE transformation from HDL to LDL. CETP formed blood HDL-CETP-LDL complexes in which poly-CLE spontaneously came from polar lipids of TG in HDL to nonpolar TG in LDL. Then ligand LDLs formed and the cells actively absorbed PUFA via apoB-100 endocytosis. Some animal species (rats, mice, dogs) developed a spontaneous CETP-minus mutation followed by population death from atherosclerosis. However, there was another active CETP-independent uptake formed during phylogenesis; the cells internalized poly-CLE in HDL. Since apoA-I had no domain-ligand, another apoE/A-I ligand formed; the cells began synthesizing apoE/A-1 receptors. In cells of rabbits and primates absorbed cells PUFA consecutively: HDL-->LDL-->apoB-100 endocytosis; those of rats and dogs did HDL directly: HDL-->anoE/A-I endocytosis. In the rabbits, CETP was high, apoE in HDL was low, and the animals were sensitive to exogenous hypercholesterolemia. In the rats, CETP was low and ApoE in HDL-was high, and the animals were resistant to hypercholesterolemia. Reduced bioavailability of PUFA during their consecutive cellular uptake and develdpment of intercellular PUFA deficiency are fundamental to the pathogenesis of atherosclerosis.

Inhibition of cholesteryl ester transfer protein increases cholesteryl ester content of large HDL independently of HDL-to-HDL homotypic transfer: in vitro vs in vivo comparison using anacetrapib and dalcetrapib

The increase in high density lipoprotein (HDL)-cholesterol observed with cholesteryl ester transfer protein (CETP) inhibition is commonly attributed to blockade of cholesteryl ester (CE) transfer from HDL to low density lipoprotein particles. In vitro, it has been observed that CETP can mediate transfer of CE between HDL particles ("homotypic transfer"), and it is postulated that this contributes to HDL remodeling and generation of anti-atherogenic pre-beta HDL. Inhibition of CETP could limit this beneficial remodeling and reduce pre-beta HDL levels. We observed that anacetrapib does not reduce pre-beta HDL in vivo, but the role of HDL homotypic transfer was not examined. This study evaluated the effects of anacetrapib on homotypic transfer from HDL3 to HDL2 in vivo using deuterium-labeled HDL3, and compared this to in vitro settings, where homotypic transfer was previously described. In vitro, both anacetrapib and dalcetrapib inhibited transfer of CE from HDL3 to HDL2 particles. In CETP transgenic mice, anacetrapib did not inhibit the appearance of labeled CE derived from HDL3 in HDL2 particles, but rather promoted the appearance of labeled CE in HDL2. We concluded that inhibition of CETP by anacetrapib promoted HDL particle remodeling, and does not impair the flux of cholesterol ester into larger HDL particles when studied in vivo, which is not consistent with in vitro observations. We further conclude, therefore, that the in vitro conditions used to examine HDL-to-HDL homotypic transfer may not recapitulate the in vivo condition, where multiple mechanisms contribute to cholesteryl ester flux into and out of the HDL pool.

National lipid association recommendations for patient-centered management of dyslipidemia: part 1--full report

The leadership of the National Lipid Association convened an Expert Panel to develop a consensus set of recommendations for patient-centered management of dyslipidemia in clinical medicine. An Executive Summary of those recommendations was previously published. This document provides support for the recommendations outlined in the Executive Summary. The major conclusions include (1) an elevated level of cholesterol carried by circulating apolipoprotein B-containing lipoproteins (non-high-density lipoprotein cholesterol and low-density lipoprotein cholesterol [LDL-C], termed atherogenic cholesterol) is a root cause of atherosclerosis, the key underlying process contributing to most clinical atherosclerotic cardiovascular disease (ASCVD) events; (2) reducing elevated levels of atherogenic cholesterol will lower ASCVD risk in proportion to the extent that atherogenic cholesterol is reduced. This benefit is presumed to result from atherogenic cholesterol lowering through multiple modalities, including lifestyle and drug therapies; (3) the intensity of risk-reduction therapy should generally be adjusted to the patient's absolute risk for an ASCVD event; (4) atherosclerosis is a process that often begins early in life and progresses for decades before resulting a clinical ASCVD event. Therefore, both intermediate-term and long-term or lifetime risk should be considered when assessing the potential benefits and hazards of risk-reduction therapies; (5) for patients in whom lipid-lowering drug therapy is indicated, statin treatment is the primary modality for reducing ASCVD risk; (6) nonlipid ASCVD risk factors should also be managed appropriately, particularly high blood pressure, cigarette smoking, and diabetes mellitus; and (7) the measurement and monitoring of atherogenic cholesterol levels remain an important part of a comprehensive ASCVD prevention strategy.

Cholesteryl ester-transfer protein inhibitors stimulate aldosterone biosynthesis in adipocytes through Nox-dependent processes

Hyperaldosteronism and hypertension were unexpected side effects observed in trials of torcetrapib, a cholesteryl ester-transfer protein (CETP) inhibitor that increases high-density lipoprotein. Given that CETP inhibitors are lipid soluble, accumulate in adipose tissue, and have binding sites for proteins involved in adipogenesis, and that adipocytes are a source of aldosterone, we questioned whether CETP inhibitors (torcetrapib, dalcetrapib, and anacetrapib) influence aldosterone production by adipocytes. Studies were performed using human adipocytes (SW872), which express CETP, and mouse adipocytes (3T3-L1), which lack the CETP gene. Torcetrapib, dalcetrapib, and anacetrapib increased expression of CYP11B2, CYP11B1, and steroidogenic acute regulatory protein, enzymes involved in mineralocorticoid and glucocorticoid generation. These effects were associated with increased reactive oxygen species formation. Torcetrapib, dalcetrapib, and anacetrapib upregulated signal transducer and activator of transcription 3 (STAT3) and peroxisome proliferation-activated receptor-γ, important in adipogenesis, but only torcetrapib stimulated production of chemerin, a proinflammatory adipokine. To determine mechanisms whereby CETP inhibitors mediate effects, cells were pretreated with inhibitors of Nox1/Nox4 [GKT137831; 2-(2-chlorophenyl)-4-[3-(dimethylamino)phenyl]-5-methyl-1H-pyrazolo[4,3-c]pyridine-3,6(2H,5H)-dione], Nox1 (ML171 [2-acetylphenothiazine]), mitochondria (rotenone), and STAT3 (S3I-201 [2-hydroxy-4-(((4-methylphenyl)sulfonyloxy)acetyl)amino)-benzoic acid]). In torcetrapib-stimulated cells, Nox inhibitors, rotenone, and S3I-201 downregulated CYP11B2 and steroidogenic acute regulatory protein and reduced aldosterone. Dalcetrapib and anacetrapib effects on aldosterone were variably blocked by GKT137831, ML171, rotenone, and S3I-201. In adipocytes, torcetrapib, dalcetrapib, and anacetrapib inhibit enzymatic pathways responsible for aldosterone production through Nox1/Nox4- and mitochondrial-generated reactive oxygen species and STAT3. CETP inhibitors also influence adipokine production. These processes may be CETP independent. Our findings identify novel adipocyte-related mechanisms whereby CETP inhibitors increase aldosterone production. Such phenomena may contribute to hyperaldosteronism observed in CETP inhibitor clinical trials.

Haemodynamic Assessment in Safety Pharmacology

Evaluation of the effects of a drug on arterial blood pressure is important in nonclinical safety pharmacology assessment. Detecting large and obvious changes in blood pressure is an unchallenging task. Detecting small changes is more difficult, and interpretation of findings requires careful risk/benefit evaluation. Detecting subtle and small changes in blood pressure is important in particular with respect to increases, since blood pressure above the normal range is associated with increased risk of stroke and sudden cardiac death. Cardiovascular safety pharmacology has been preoccupied with drug-induced changes in the electrocardiogram, and by comparison, there has been little in the way of contemporaneous improvements in the level of complexity and sophistication involved in blood pressure assessment. Thus, it is important to understand the nature of drug-induced changes in blood pressure, appreciate the plethora of agents currently used clinically (and over the counter) that alter blood pressure and understand safety pharmacology study design in order to optimize assessment of a new chemical entity (NCE) or biologic agent in this context.

Future of cholesteryl ester transfer protein inhibitors

The cholesteryl ester transfer protein (CETP) plays an integral role in the metabolism of plasma lipoproteins. Despite two failures, CETP inhibitors are still in clinical development. We review the genetics of CETP and coronary disease, preclinical data on CETP inhibition and atherosclerosis, and the effects of CETP inhibition on cholesterol efflux and reverse cholesterol transport. We discuss the two failed CETP inhibitors, torcetrapib and dalcetrapib, and attempt to extract lessons learned. Two CETP inhibitors, anacetrapib and evacetrapib, are in phase III development, and we attempt to differentiate them from the failed drugs. Whether pharmacologic CETP inhibition will reduce the risk of cardiovascular disease is one of the most fascinating and important questions in the field of cardiovascular medicine.

The role of advanced lipid testing in the prediction of cardiovascular disease

Advanced lipid testing has been suggested by some experts to identify patients with substantial residual risk for more aggressive targeting of lifestyle and pharmacologic therapies. It measures the subpopulation of lipoproteins and apolipoproteins, which include lipoprotein (a), apolipoprotein A-I, and apolipoprotein B, and measures of lipoprotein particle composition such as LDL particle (LPL-P) and HDL particle (HDL-P) number and size. Obesity is associated with smaller LDL-P and HDL-P sizes. Moderate weight loss via fasting/calorie restriction is associated with LDL-P size increase, whereas moderate weight loss via endurance exercise is associated with HDL-P size increase. Diets high in carbohydrates are associated with a more atherogenic advanced lipoprotein profile characterized by smaller LDL-P and HDL-P sizes. In summary, lifestyle changes such as weight loss, exercise, and dietary modification correlate with improvement in the profile of advanced lipoproteins. Regrettably, therapies targeting HDL and HDL composition have been disappointing to date.

Anacetrapib reduces progression of atherosclerosis, mainly by reducing non-HDL-cholesterol, improves lesion stability and adds to the beneficial effects of atorvastatin

BACKGROUND

The residual risk that remains after statin treatment supports the addition of other LDL-C-lowering agents and has stimulated the search for secondary treatment targets. Epidemiological studies propose HDL-C as a possible candidate. Cholesteryl ester transfer protein (CETP) transfers cholesteryl esters from atheroprotective HDL to atherogenic (V)LDL. The CETP inhibitor anacetrapib decreases (V)LDL-C by ∼15-40% and increases HDL-C by ∼40-140% in clinical trials. We evaluated the effects of a broad dose range of anacetrapib on atherosclerosis and HDL function, and examined possible additive/synergistic effects of anacetrapib on top of atorvastatin in APOE*3Leiden.CETP mice.

METHODS AND RESULTS

Mice were fed a diet without or with ascending dosages of anacetrapib (0.03; 0.3; 3; 30 mg/kg/day), atorvastatin (2.4 mg/kg/day) alone or in combination with anacetrapib (0.3 mg/kg/day) for 21 weeks. Anacetrapib dose-dependently reduced CETP activity (-59 to -100%, P < 0.001), thereby decreasing non-HDL-C (-24 to -45%, P < 0.001) and increasing HDL-C (+30 to +86%, P < 0.001). Anacetrapib dose-dependently reduced the atherosclerotic lesion area (-41 to -92%, P < 0.01) and severity, increased plaque stability index and added to the effects of atorvastatin by further decreasing lesion size (-95%, P < 0.001) and severity. Analysis of covariance showed that both anacetrapib (P < 0.05) and non-HDL-C (P < 0.001), but not HDL-C (P = 0.76), independently determined lesion size.

CONCLUSION

Anacetrapib dose-dependently reduces atherosclerosis, and adds to the anti-atherogenic effects of atorvastatin, which is mainly ascribed to a reduction in non-HDL-C. In addition, anacetrapib improves lesion stability.

Effects of the cholesteryl ester transfer protein inhibitor evacetrapib on lipoproteins, apolipoproteins and 24-h ambulatory blood pressure in healthy adults

Objectives

We investigated the safety, tolerability, pharmacokinetics and pharmacodynamics of evacetrapib.

Methods

Healthy volunteers received multiple daily doses of evacetrapib (10–600 mg) administered for up to 15 days in a placebo-controlled study.

Key findings

Mean peak plasma concentrations of evacetrapib occurred at 4–6 h and terminal half-life ranged 24–44 h. Steady state was achieved at approximately 10 days; all subjects had undetectable levels of evacetrapib 3 weeks after their last dose. The trough inhibition of cholesteryl ester transfer protein (CETP) activity was 65 and 84% at 100 and 300 mg, respectively. At the highest dose (600 mg), evacetrapib significantly inhibited CETP activity (91%), increased HDL-C (87%) and apo AI (42%), and decreased LDL-C (29%) and apo B (26%) relative to placebo. For the highest dose tested, levels of evacetrapib, CETP activity, CETP mass, HDL-C and LDL-C returned to levels at or near baseline after a 2-week washout period. Evacetrapib at the highest dose tested did not produce any significant effect on 24-h ambulatory systolic or diastolic blood pressure.

Conclusions

Multiple doses of evacetrapib potently inhibited CETP activity, leading to substantial elevations in HDL-C and lowering of LDL-C. Evacetrapib was devoid of clinically relevant effects on blood pressure and mineralocorticoid levels.

Novel therapies focused on the high-density lipoprotein particle

Cardiovascular disease (CVD) remains a major burden for morbidity and mortality in the general population, despite current efficacious low-density lipoprotein-cholesterol-lowering therapies. Consequently, novel therapies are required to reduce this residual risk. Prospective epidemiological studies have shown that high-density lipoprotein-cholesterol (HDL-C) levels are inversely correlated with cardiovascular disease risk, and this initiated the quest for HDL-C-increasing therapies. Consequently, several different targets in HDL metabolism have been identified. Initial studies addressing the effect of cholesteryl ester transfer protein inhibition on cardiovascular disease outcome have been discontinued for reasons of futility or increased mortality. As of yet, 2 cholesteryl ester transfer protein inhibitors are still in phase III studies. Other HDL-based interventions, such as apolipoprotein A1-based compounds, ABC-transporter upregulators, selective peroxisome proliferator-activated receptor modulators and lecithin-cholesterol acyltransferase-based therapy, hold great promise for the future. The aim of this review is to provide a comprehensive overview of HDL-targeted pharmaceutical strategies in humans, both in early development as well as in late stage clinical trials.

Activation of paraoxonase 1 is associated with HDL remodeling ex vivo

BACKGROUND

We hypothesize that during high density lipoprotein (HDL) remodeling PON1 reaches an optimal distribution in HDL subclasses by which it achieves maximum activity. We conducted this study to gain insight on PON1 fate and activation during short-term HDL remodeling ex vivo.

METHODS

Serum from 8 healthy volunteers was either frozen at -80°C (time 0) or incubated under sterile conditions for up to 48h at 37°C or at 4°C. Aliquots were taken at 3, 6, 9, 24 and 48 h and immediately frozen at -80°C. PON1 activities were measured, as well as PON1 and apolipoprotein distributions in HDL subclasses by gradient gel electrophoresis.

RESULTS

The first novel finding in our study is the evidence provided for a significant activation of both lactonase and arylesterase activities of PON1 that ensues in a very short time frame of incubation of serum ex vivo at 37°C. All subjects studied displayed these changes, the activation was apparent in <3h, peaked at 6h and amounted to >20%. This is associated with a temperature and time-dependent redistribution of PON1 activity in HDL subclasses, with an increase in activity in both very large HDL2 and small HDL3 in the first phase (3-9h), followed by a progressive transfer of PON1 to very large HDL2 as the particles mature. These changes are paralleled by the appearance of weak, but apparent PON1 activity at subspecies that correspond to sdLDL. During the first phase of PON1 activation and shifts, a parallel shift of apoE can be evidenced: at 3-9h, apoE increases in sdLDL, after that time it is lost from HDL and also from sdLDL and stays in VLDL at the origin of the run. ApoA-I shifts towards larger particles, which parallels the change in PON1. As HDL matures there is a progressive shift of apoA-II towards larger HDL. Low levels of apoA-IV at the initiation of the incubation are followed by time dependent quick disappearance of apoA-IV in HDL which parallels the changes in PON1, apoE and A-II.

CONCLUSION

Short, ex vivo incubation of serum leads to quick activation of PON1 associated with transfers to HDL3c, large HDL and sdLDL. The process is blocked by CETP and LCAT inhibitors. The data suggest that HDL maturation optimizes PON1 activity. These findings may be of interest for future studies aimed at modulating PON-1 activity for its cardioprotective effects and suggest a new mechanism whereby CETP inhibitors failed in clinical trials.

Clinical relevance of target identity and biology: implications for drug discovery and development

Many of the most commonly used drugs precede techniques for target identification and drug specificity and were developed on the basis of efficacy and safety, an approach referred to as classical pharmacology and, more recently, phenotypic drug discovery. Although substantial gains have been made during the period of focus on target-based approaches, particularly in oncology, these approaches have suffered a high overall failure rate and lower productivity in terms of new drugs when compared with phenotypic approaches. This review considers the importance of target identity and biology in clinical practice from the prescriber's viewpoint. In evaluating influences on prescribing behavior, studies suggest that target identity and mechanism of action are not significant factors in drug choice. Rather, patients and providers consistently value efficacy, safety, and tolerability. Similarly, the Food and Drug Administration requires evidence of safety and efficacy for new drugs but does not require knowledge of drug target identity or target biology. Prescribers do favor drugs with novel mechanisms, but this preference is limited to diseases for which treatments are either not available or suboptimal. Thus, while understanding of drug target and target biology is important from a scientific perspective, it is not particularly important to prescribers, who prioritize efficacy and safety.

Novel pharmacotherapies of familial hyperlipidemia

Familial hyperlipidemia is an inherited metabolic disorder characterized by elevated lipid and/or lipoprotein levels in the blood. Despite improvements in lipid-lowering therapy during the last decades, it still remains a substantial contributor to the incidence of cardiovascular disease since patients on current conventional therapies do not achieve their target LDL-cholesterol levels. With a view to lower LDL-cholesterol levels, a number of new therapeutic strategies have been developed over recent years. In this review, we provide an overview of these treatment options that are currently in clinical development and may offer alternative or adjunctive therapies for this high-risk population.

Opening up drug development to everyone

Effective drug therapies are a cornerstone of medical practice. The path from drug discovery to approval is expensive and commonly associated with failure. The cost of drug development exceeds 800 million dollars per product. Late failure due to lack of clinical efficacy is a common cause of high costs. Recent attempts to improve the process of drug development involve the formation of public-private partnerships, which are facilitating the creation of new collaborations among corporate and nonprofit entities to find solutions that will accelerate innovative drug discovery.

Cholesteryl ester transfer protein inhibitors for dyslipidemia: focus on dalcetrapib

Among the noteworthy recent stories in the management and prevention of atherosclerotic cardiovascular disease (CVD) is the saga of the development of pharmacological inhibitors of cholesteryl ester transfer protein (CETP). Inhibiting CETP significantly raises plasma concentrations of high-density lipoprotein cholesterol, which has long been considered a marker of reduced CVD risk. However, the first CETP inhibitor, torcetrapib, showed a surprising increase in CVD events, despite a dramatic increase in high-density lipoprotein cholesterol levels. This paradox was explained by putative off-target effects not related to CETP inhibition that were specific to torcetrapib. Subsequently, three newer CETP inhibitors, namely dalcetrapib, anacetrapib, and evacetrapib, were at various phases of clinical development in 2012. Each of these had encouraging biochemical efficacy and safety profiles. Dalcetrapib even had human arterial imaging results that tended to look favorable. However, the dalcetrapib development program was recently terminated, presumably because interim analysis of a large CVD outcome trial indicated no benefit. These events raise important questions regarding the validity of the mechanism of CETP inhibition and the broader issue of whether pharmacological raising of high-density lipoprotein cholesterol itself is a useful strategy for CVD risk reduction.