Efficacy and Safety of Torcetrapib, a Novel Cholesteryl Ester Transfer Protein Inhibitor, in Individuals With Below-Average High-Density Lipoprotein Cholesterol Levels

Evacetrapib reduces preβ-1 HDL in patients with atherosclerotic cardiovascular disease or diabetes

BACKGROUND AND AIMS

Cholesteryl ester transfer protein (CETP) inhibitor-mediated induction of HDL-cholesterol has no effect on the protection from cardiovascular disease (CVD). However, the mechanism is still unknown. Data on the effects of this class of drugs on subclasses of HDL are either limited or insufficient. In this study, we investigated the effect of evacetrapib, a CETP inhibitor, on subclasses of HDL in patients with atherosclerotic cardiovascular disease or diabetes.

METHODS

Baseline and 3-month post-treatment samples from atorvastatin 40 mg plus evacetrapib 130 mg (n = 70) and atorvastatin 40 mg plus placebo (n = 30) arms were used for this purpose. Four subclasses of HDL (large HDL, medium HDL, small HDL, and preβ-1 HDL) were separated according to their size and quantified by densitometry using a recently developed native polyacrylamide gel electrophoresis (PAGE) system.

RESULTS

Relative to placebo, while evacetrapib treatment dramatically increased large HDL and medium HDL subclasses, it significantly reduced small HDL (27%) as well as preβ-1 HDL (36%) particles. Evacetrapib treatment reduced total LDL, but also resulted in polydisperse LDL with LDL particles larger and smaller than the LDL subclasses of the placebo group.

CONCLUSION

Evacetrapib reduced preβ-1 HDL and small HDL in patients with ASCVD or diabetes on statin. Preβ-1 HDL and medium HDL are negatively interrelated. The results could give a clue to understand the effect of CETP inhibitors on cardiovascular outcomes.

From lipid locus to drug target through human genomics

In the last decade, over 175 genetic loci have robustly been associated to levels of major circulating blood lipids. Most loci are specific to one or two lipids, whereas some (SUGP1, ZPR1, TRIB1, HERPUD1, and FADS1) are associated to all. While exposing the polygenic architecture of circulating lipids and the underpinnings of dyslipidaemia, these genome-wide association studies (GWAS) have provided further evidence of the critical role that lipids play in coronary heart disease (CHD) risk, as indicated by the 2.7-fold enrichment for macrophage gene expression in atherosclerotic plaques and the association of 25 loci (such as PCSK9, APOB, ABCG5-G8, KCNK5, LPL, HMGCR, NPC1L1, CETP, TRIB1, ABO, PMAIP1-MC4R, and LDLR) with CHD. These GWAS also confirmed known and commonly used therapeutic targets, including HMGCR (statins), PCSK9 (antibodies), and NPC1L1 (ezetimibe). As we head into the post-GWAS era, we offer suggestions for how to move forward beyond genetic risk loci, towards refining the biology behind the associations and identifying causal genes and therapeutic targets. Deep phenotyping through lipidomics and metabolomics will refine and increase the resolution to find causal and druggable targets, and studies aimed at demonstrating gene transcriptional and regulatory effects of lipid associated loci will further aid in identifying these targets. Thus, we argue the need for deeply phenotyped, large genetic association studies to reduce costs and failures and increase the efficiency of the drug discovery pipeline. We conjecture that in the next decade a paradigm shift will tip the balance towards a data-driven approach to therapeutic target development and the application of precision medicine where human genomics takes centre stage.

Navigating the Future of Cardiovascular Drug Development-Leveraging Novel Approaches to Drive Innovation and Drug Discovery: Summary of Findings from the Novel Cardiovascular Therapeutics Conference

PURPOSE

The need for novel approaches to cardiovascular drug development served as the impetus to convene an open meeting of experts from the pharmaceutical industry and academia to assess the challenges and develop solutions for drug discovery in cardiovascular disease.

METHODS

The Novel Cardiovascular Therapeutics Summit first reviewed recent examples of ongoing or recently completed programs translating basic science observations to targeted drug development, highlighting successes (protein convertase sutilisin/kexin type 9 [PCSK9] and neprilysin inhibition) and targets still under evaluation (cholesteryl ester transfer protein [CETP] inhibition), with the hope of gleaning key lessons to successful drug development in the current era. Participants then reviewed the use of innovative approaches being explored to facilitate rapid and more cost-efficient evaluations of drug candidates in a short timeframe.

RESULTS

We summarize observations gleaned from this summit and offer insight into future cardiovascular drug development.

CONCLUSIONS

The rapid development in genetic and high-throughput drug evaluation technologies, coupled with new approaches to rapidly evaluate potential cardiovascular therapies with in vitro techniques, offer opportunities to identify new drug targets for cardiovascular disease, study new therapies with better efficiency and higher throughput in the preclinical setting, and more rapidly bring the most promising therapies to human testing. However, there must be a critical interface between industry and academia to guide the future of cardiovascular drug development. The shared interest among academic institutions and pharmaceutical companies in developing promising therapies to address unmet clinical needs for patients with cardiovascular disease underlies and guides innovation and discovery platforms that are significantly altering the landscape of cardiovascular drug development.

Cholesterol Efflux Capacity and Pre-Beta-1 HDL Concentrations Are Increased in Dyslipidemic Patients Treated With Evacetrapib

BACKGROUND

Potent cholesteryl ester transfer protein (CETP) inhibitors have been shown to substantially increase high-density lipoprotein cholesterol (HDL-C) and apolipoprotein A-I levels as monotherapy and combined with statins. However, data on the effects of this class of drugs on macrophage cholesterol efflux capacity (CEC), a functional assay that characterizes a key step in the process of reverse cholesterol transport, are limited.

OBJECTIVES

This study assessed the impact of evacetrapib, statins, or combination therapy on CEC.

METHODS

We analyzed samples from 377 subjects with elevated low-density lipoprotein cholesterol (LDL-C) or low HDL-C levels who were enrolled in a phase 2 trial of evacetrapib. Percent changes from baseline in CEC (total, non-ABCA1-, and ABCA1-specific) and HDL subpopulations were evaluated after 12 weeks of treatment with placebo, statin monotherapy, evacetrapib monotherapy, or evacetrapib combined with statins. Pre-beta-1 HDL levels were quantified by immunofixation and nondenaturing 2-dimensional gel electrophoresis (2DGE).

RESULTS

Relative to placebo, evacetrapib monotherapy increased dose-dependent total and non-ABCA1-specific CEC up to 34% and 47%, respectively. Evacetrapib monotherapy also increased ABCA1-specific CEC up to 26%. Relative to statin monotherapy, evacetrapib with statins also increased total, non-ABCA1-, and ABCA1-specific CEC by 21%, 27%, and 15%, respectively. In contrast, rosuvastatin and simvastatin significantly reduced total and ABCA1-specific CEC, whereas atorvastatin had no significant effect. Consistent with ABCA1-specific CEC, evacetrapib monotherapy and evacetrapib combined with statins significantly increased pre-beta-1 HDL levels as measured by either method.

CONCLUSIONS

Evacetrapib, as monotherapy and combined with statins, not only increased total CEC, but also increased ABCA1-specific CEC and pre-beta-1 HDL. The mechanisms by which potent CETP inhibition increases ABCA1-specific CEC and pre-beta-1 HDL require further study. (A Study of LY2484595 in Patients With High LDL-C or Low HDL-C; NCT01105975).

Antilipidemic Drug Therapy Today and in the Future

The armamentarium for the treatment of dyslipidemia today comprises six different modes of action with overall around 24 different drugs. The treatment of lipid disorders was revolutionized with the introduction of statins which have become the most important therapeutic option available today to reduce and prevent atherosclerosis and its detrimental consequences like cardiovascular diseases and stroke. With and optimized reduction of elevated LDL levels with statins, the risk for cardiovascular diseases (CVD) can be reduced by 30%, indicating a residual remaining risk of 70% for the development and progression of CVD notifying still a high medical need for more effective antilipidemic drugs. Consequently, the search for novel lipid-modifying drugs is still one of the most active areas in research and development in the pharmaceutical industry. Major focus lies on approaches to LDL-lowering drugs superior to statins with regard to efficacy, safety, and patient compliance and on approaches modifying plasma levels and functionality of HDL particles based on the clinically validated inverse relationship between high-plasma HDL levels and the risk for CVD. The available drugs today for the treatment of dyslipidemia are small organic molecules or nonabsorbable polymers for binding of bile acids to be applied orally. Besides small molecules for novel targets, biological drugs such as monoclonal antibodies, antisense or gene-silencing oligonucleotides, peptidomimetics, reconstituted synthetic HDL particles and therapeutic proteins are novel approaches in clinical development are which have to be applied by injection or infusion. The promising clinical results of several novel drug candidates, particularly for LDL cholesterol lowering with monoclonal antibodies raised against PCSK9, may indicate more than a decade after the statins, the entrance of new breakthrough therapies to treat lipid disorders.

Systematic review of CETP inhibitors for increasing high-density lipoprotein cholesterol: where do these agents stand in the approval process?

The role that low levels of high-density lipoprotein cholesterol (HDL-C) plays in coronary artery disease and ischemic heart disease is well established. As such, therapies targeting low HDL-C levels have been of great therapeutic interest. These therapies include nonpharmacological methods such as exercise, tobacco cessation, weight reduction, moderate alcohol intake, and increasing dietary monounsaturated fatty acids and polyunsaturated fatty acids. Additionally, pharmacological methods of increasing HDL-C have been of great interest, with 2 classes of drugs, fibric acid derivatives and nicotinic acid, and have mixed trial results when used on top of standard lipid therapy. However, a new class of medications, cholesteryl ester transfer protein inhibitors, has shown increases in HDL-C of over 100%. However, early trial results with torcetrapib showed an increase in mortality, although this was attributed to off-target toxicity. Dalcetrapib was found to be safer than torcetrapib, but data released in 2012 showed no additional benefit in patients suffering an acute coronary syndrome event. Two newer agents, anacetrapib and evacetrapib, in early-phase clinical trials have shown to be safer than torcetrapib and significantly more potent than dalcetrapib (both increase HDL-C by a greater amount and both have a significant effect on low-density lipoprotein cholesterol). It remains to be seen whether the use of cholesteryl ester transfer protein inhibitors will result in clinical benefit in large, randomized double-blind trials and whether any agents in this class will ever be approved for clinical use.

Incubation of MDCO-216 (ApoA-IMilano/POPC) with Human Serum Potentiates ABCA1-Mediated Cholesterol Efflux Capacity, Generates New Prebeta-1 HDL, and Causes an Increase in HDL Size

MDCO-216 is a complex of dimeric ApoA-IMilano and palmitoyl oleoyl phosphatidylcholine (POPC), previously shown to reduce atherosclerotic plaque burden. Here we studied the effect of incubation of human plasma or serum with MDCO-216 on cholesterol efflux capacity from J774 cells, on prebeta-1 high density lipoprotein (prebeta-1 HDL) and on HDL size assessed by proton nuclear magnetic resonance (¹H-NMR). MDCO-216 incubated in buffer containing 4% human serum albumin stimulated both ABCA1-mediated efflux and ABCA1-independent cholesterol efflux from J774 macrophages. When incubated with human serum a dose- and time-dependent synergistic increase of the ABCA1-mediated efflux capacity were observed. Using a commercially available ELISA for prebeta-1 HDL, MDCO-216 as such was poorly detected (12–15% of nominal amount of protein). Prebeta-1 HDL was rapidly lost when human plasma alone is incubated at 37°C. In contrast, incubation of human plasma with MDCO-216 at 37°C produced a large amount of new prebeta-1 HDL. Native 2D electrophoresis followed by immunoblotting with an apoA-I antibody, which also detects ApoA-I Milano, confirmed the increase in prebeta-1 HDL upon incubation at 37°C. With the increase of prebeta-1 HDL, the concomitant disappearance of the small alpha-3 and alpha-4 HDL and MDCO-216 and an increase in the large alpha-1 and alpha-2 HDL were observed. Immunoblotting with Mab 17F3 specific for ApoA-I Milano showed the appearance of ApoA-I Milano in alpha-1 and alpha-2, but not in prebeta-1 HDL. ¹H-NMR analysis of plasma incubated with MDCO-216 confirmed rapid disappearance of small-sized HDL particles and increase of medium- and large-sized HDL particles accompanied with a decrease in total HDL particle number. In conclusion, incubation of human plasma or serum with MDCO-216 strongly enhanced ABCA1-mediated cholesterol efflux, caused a strong increase of prebeta-1 HDL, and drastically changed the distribution of HDL subpopulations. Overall, the results are in line with the hypothesis that MDCO-216 fuses with small alpha-migrating HDL particles forming larger particles containing both apoA-I WT and ApoA-I Milano, meanwhile liberating the endogenous wild-type apoA-I which enriches prebeta-1 HDL subpopulation.

Monogenic causes of elevated HDL cholesterol and implications for development of new therapeutics

Identification of the CETP, LIPG (encoding endothelial lipase) and APOC3 genes, and ana lysis of rare genetic variants in them, have allowed researchers to increase understanding of HDL metabolism significantly. However, development of cardiovascular risk-reducing therapeutics targeting the proteins encoded by these genes has been less straightforward. The failure of two CETP inhibitors is complex but illustrates a possible over-reliance on HDL cholesterol as a marker of therapeutic efficacy. The case of endothelial lipase exemplifies the importance of utilizing population-wide genetic studies of rare variants in potential therapeutic targets to gain information on cardiovascular disease end points. Similar population-wide studies of cardiovascular end points make apoC-III a potentially attractive target for lipid-related drug discovery. These three cases illustrate the positives and negatives of single-gene studies relating to HDL-related cardiovascular drug discovery; such studies should focus not only on HDL cholesterol and other components of the lipid profile, but also on the effect genetic variants have on cardiovascular end points.

Association between triglycerides and cardiovascular events in primary populations: a meta-regression analysis and synthesis of evidence

Background

Triglyceride levels were found to be independently predictive of the development of primary coronary heart disease in epidemiologic studies. The objective of this study was to determine whether triglyceride levels were predictive of cardiovascular events in randomized controlled trials (RCTs) of lipid-modifying drugs.

Methods

We performed a systematic review and meta-regression analysis of 40 RCTs of lipid-modifying drugs with cardiovascular events as an outcome. The log of the rate ratio of cardiovascular events (eg, coronary death or myocardial infarction) was plotted against the proportional difference between treatment and control groups in triglyceride and other lipid levels (high density lipoprotein cholesterol [HDL-C], low density lipoprotein cholesterol [LDL-C], and total cholesterol) for all trials and for trials of primary and secondary prevention populations. Linear regression was used to determine the statistical significance of the relationship between lipid values and cardiovascular events.

Results

The proportional difference in triglyceride levels was predictive of cardiovascular events in all trials (P=0.005 for the slope of the regression line; N=40) and in primary prevention trials (P=0.010; N=11), but not in secondary prevention trials (P=0.114; N=25). The proportional difference in HDL-C was not predictive of cardiovascular events in all trials (P=0.822; N=40), or in trials of primary (P=0.223; N=11) or secondary (P=0.487; N=25) prevention. LDL-C levels were predictive of cardiovascular events in both primary (P=0.002; N=11) and secondary (P<0.001; N=25) populations.

Conclusions

Changes in triglyceride levels were predictive of cardiovascular events in RCTs. This relationship was significant in primary prevention populations but not in secondary prevention populations.

Cholesteryl ester transfer protein inhibitors in the treatment of dyslipidemia: a systematic review and meta-analysis

Cholesteryl ester transfer protein (CETP) inhibitors are gaining substantial research interest for raising high density lipoprotein cholesterol levels. The aim of the research was to estimate the efficacy and safety of cholesteryl ester transfer protein inhibitors as novel lipid modifying drugs. Systematic searches of English literature for randomized controlled trials (RCT) were collected from MEDLINE, EBASE, CENTRAL and references listed in eligible studies. Two independent authors assessed the search results and only included the double-blind RCTs by using cholesteryl ester transfer protein inhibitors as exclusively or co-administrated with statin therapy irrespective of gender in enrolled adult subjects. Two independent authors extracted the data by using predefined data fields. Of 503 studies identified, 14 studies met the inclusion criteria, and 12 studies were included into the final meta-analysis. Our meta-analysis revealed that CETP inhibitors increased the HDL-c levels (n = 2826, p<0.00001, mean difference (MD) = 20.47, 95% CI [19.80 to 21.15]) and total cholesterol (n = 3423, p = 0.0002, MD = 3.57, 95%CI [1.69 to 5.44] to some extent combined with a reduction in triglyceride (n = 3739, p<0.00001, MD = -10.47, 95% CI [-11.91 to -9.03]) and LDL-c (n = 3159, p<0.00001, MD = -17.12, 95% CI [-18.87 to -15.36]) irrespective of mono-therapy or co-administration with statins. Subgroup analysis suggested that the lipid modifying effects varied according to the four currently available CETP inhibitors. CETP inhibitor therapy did not increase the adverse events when compared with control. However, we observed a slight increase in blood pressure (SBP, n = 2384, p<0.00001, MD = 2.73, 95% CI [2.14 to 3.31], DBP, n = 2384, p<0.00001, MD = 1.16, 95% CI [0.73 to 1.60]) after CETP inhibitor treatment, which were mainly ascribed to the torcetrapib treatment subgroup. CETP inhibitors therapy is associated with significant increase in HDL-c and decrease in triglyceride and LDL-c with satisfactory safety and tolerability in patients with dyslipidemia. However, the side-effect on blood pressure deserves more consideration in future studies.

Delivering enhanced cardiovascular (hypertension) disease care through private health facilities in Pakistan

Background

Cardiovascular diseases (CVDs) are one of the leading causes of death and disability in the world. Over 80% of CVD deaths take place in low-and middle-income countries. One-third of the population aged above 40 years suffers from Hypertension (HTN) and this is largely unreported as there is no registry for CVDs. No guidelines are available for use in health care facilities, especially private health facilities where practice among GPs varies considerably. We aim to conduct a Cluster Randomized Controlled trial delivering a quality HTN-CVD care package at strengthened private health facilities as compared to current practice at private health facilities.

Methods/Design

A pragmatic cluster randomized trial, with qualitative and economic studies, will be conducted in Sargodha district of Punjab, Pakistan, from January 2012 to December 2016. At least 912 hypertensives will be registered in the two arms, six clusters per arm. The proposed cluster randomized controlled trial will evaluate the effects of delivering quality HTN-CVD care, through enabled private health care facilities, to achieve better case registration, adherence and hypertension control also blood glucose and serum cholesterol control. The trial will be conducted through the doctors and paramedics at private health facilities. Main outcomes are mean difference in Systolic blood pressure among the two arms. Secondary outcomes are mean change in total serum cholesterol levels and mean change in glycaemic control achieved in the adult hypertensive patients. Individual and Cluster level analysis will be done according to intention-to-treat.

Discussion

Due to the high burden of disease where 1 in 3 individuals aged above 45 suffers from hypertension, topped with the fact that there is a dearth of a set of available, standardised guidelines for management, the disease is constantly on a hike in Pakistan. The government has made no effort to issue a set of guidelines adapted specifically for our population and this becomes more of a problem when managing CVD in urban population through private practitioners whose practices vary widely.If our set of context sensitive guidelines show an effectiveness in the proposed intervention districts it will be replicated in other such settings.

Trial registration

Current Controlled Trials ISRCTN34381594

High-density lipoprotein cholesterol, size, particle number, and residual vascular risk after potent statin therapy

BACKGROUND

Chemically measured high-density lipoprotein cholesterol (HDL-C) may not be the best clinical measure of HDL. Little is known about alternative HDL measures such as HDL size or particle number (HDL-P) as determinants of residual risk after potent statin therapy.

METHODS AND RESULTS

In Justification for the Use of statins in Prevention: an Intervention Trial Evaluating Rosuvastatin (JUPITER), HDL size and HDL-P were measured by nuclear magnetic resonance spectroscopy, and HDL-C and apolipoprotein A-I (apoA-I) were chemically assayed in 10 886 participants without cardiovascular disease (CVD) before and after random allocation to rosuvastatin 20 mg/d or placebo. Levels were examined with first CVD (n=234). HDL-P correlated better with apoA-I (Spearman r=0.69, P<0.0001) than with HDL-C (r=0.55, P<0.0001). Rosuvastatin lowered low-density lipoprotein cholesterol (49%) and raised HDL-C (6.1%), apoA-I (2.1%), HDL-P (3.8%), and HDL size (1.2%); all P<0.0001. Among placebo-allocated individuals, on-treatment HDL-C, apoA-I, and HDL-P had similar inverse associations with CVD (risk factor-adjusted hazard ratio and 95% confidence interval per 1 standard deviation: 0.79 [0.63-0.98], 0.75 [0.62-0.92], and 0.81 [0.67-0.97], respectively). Among rosuvastatin-allocated individuals, on-treatment HDL-P had a statistically significant and somewhat stronger association with CVD (0.73, 0.57-0.93, P=0.01) than HDL-C (0.82, 0.63-1.08, P=0.16) or apoA-I (0.86, 0.67-1.10, P=0.22). Among rosuvastatin-allocated individuals, on-treatment HDL-P remained significant (0.72, 0.53-0.97, P=0.03) after additionally adjusting for HDL-C. In risk factor-adjusted models, HDL size showed no significant association with CVD.

CONCLUSIONS

In the setting of potent statin therapy, HDL particle number may be a better marker of residual risk than chemically measured HDL-C or apoA-I. This has potential implications for evaluating novel therapies targeting HDL.

CLINICAL TRIAL REGISTRATION URL

http://www.clinicaltrials.gov. Unique identifier: NCT00239681.

In vivo effects of anacetrapib on preβ HDL: improvement in HDL remodeling without effects on cholesterol absorption

Cholesteryl ester transfer protein (CETP) transfers cholesteryl ester and triglyceride between HDL and apoB-containing lipoproteins. Anacetrapib (ANA), a reversible inhibitor of CETP, raises HDL cholesterol and lowers LDL cholesterol in dyslipidemic patients. We previously demonstrated that ANA increases macrophage-to-feces reverse cholesterol transport and fecal cholesterol excretion in hamsters, and increased preβ HDL-dependent cholesterol efflux via ABCA1 in vitro. However, the effects of ANA on in vivo preβ HDL have not been characterized. In vitro, ANA inhibited the formation of preβ, however in ANA-treated dyslipidemic hamsters, preβ HDL levels (measured by two-dimensional gel electrophoresis) were increased, in contrast to in vitro findings. Because changes in plasma preβ HDL have been proposed to potentially affect markers of cholesterol absorption with other CETP inhibitors, a dual stable isotope method was used to directly measure cholesterol absorption in hamsters. ANA treatment of hamsters (on either dyslipidemic or normal diet) had no effect on cholesterol absorption, while dalcetrapib-treated hamsters displayed an increase in cholesterol absorption. Taken together, these data support the notion that ANA promotes preβ HDL functionality in vivo, with no effects on cholesterol absorption.

Cardiovascular disease risk reduction by raising HDL cholesterol--current therapies and future opportunities

Since the first discovery of an inverse correlation between high-density lipoprotein-cholesterol (HDL-C) levels and coronary heart disease in the 1950s the life cycle of HDL, its role in atherosclerosis and the therapeutic modification of HDL-C levels have been major research topics. The Framingham study and others that followed could show that HDL-C is an independent cardiovascular risk factor and that the increase of HDL-C of only 10 mg·L(-1) leads to a risk reduction of 2-3%. While statin therapy and therefore low-density lipoprotein-cholesterol (LDL-C) reduction could lower coronary heart disease considerably; cardiovascular morbidity and mortality still occur in a significant portion of subjects already receiving therapy. Therefore, new strategies and therapies are needed to further reduce the risk. Raising HDL-C was thought to achieve this goal. However, established drug therapies resulting in substantial HDL-C increase are scarce and their effect is controversial. Furthermore, it is becoming increasingly evident that HDL particle functionality is at least as important as HDL-C levels since HDL particles not only promote reverse cholesterol transport from the periphery (mainly macrophages) to the liver but also exert pleiotropic effects on inflammation, haemostasis and apoptosis. This review deals with the biology of HDL particles, the established and future therapeutic options to increase HDL-C and discusses the results and conclusions of the most important studies published in the last years. Finally, an outlook on future diagnostic tools and therapeutic opportunities regarding coronary artery disease is given.

A physiologically based in silico kinetic model predicting plasma cholesterol concentrations in humans

Increased plasma cholesterol concentration is associated with increased risk of cardiovascular disease. This study describes the development, validation, and analysis of a physiologically based kinetic (PBK) model for the prediction of plasma cholesterol concentrations in humans. This model was directly adapted from a PBK model for mice by incorporation of the reaction catalyzed by cholesterol ester transfer protein and contained 21 biochemical reactions and eight different cholesterol pools. The model was calibrated using published data for humans and validated by comparing model predictions on plasma cholesterol levels of subjects with 10 different genetic mutations (including familial hypercholesterolemia and Smith-Lemli-Opitz syndrome) with experimental data. Average model predictions on total cholesterol were accurate within 36% of the experimental data, which was within the experimental margin. Sensitivity analysis of the model indicated that the HDL cholesterol (HDL-C) concentration was mainly dependent on hepatic transport of cholesterol to HDL, cholesterol ester transfer from HDL to non-HDL, and hepatic uptake of cholesterol from non-HDL-C. Thus, the presented PBK model is a valid tool to predict the effect of genetic mutations on cholesterol concentrations, opening the way for future studies on the effect of different drugs on cholesterol levels in various subpopulations in silico.

Dyslipidemia: evidence of efficacy of the pharmacological and non-pharmacological treatment in the elderly

The clinical decision to control risk factors for cardiovascular disease (CVD) in the elderly takes the followings into consideration: (1) the elderly life expectancy; (2) the elderly biological age and functional capacity; (3) the role of cardiovascular disease in the elderly group; (4) the prevalence of risk factors in the elderly; and (5) The effectiveness of treatment of risk factors in the elderly. A large number of studies showed the efficacy of secondary and primary prevention of dyslipidemia in the elderly. However, the only trial that included patients over 80 years was the Heart Protection Study (HPS). Statins are considered the first line therapy for lowering low-density lipoprotein cholesterol (LDL-C). Because lifestyle changes are very difficult to achieve, doctors in general tend to prescribe many drugs to control cardiovascular risk factors. However, healthy food consumption remains a cornerstone in primary and secondary cardiovascular prevention and should be implemented by everyone.

Mixed dyslipidemias in primary care patients in France

OBJECTIVE

To determine the prevalence of single and mixed dyslipidemias among patients treated with statins in clinical practice in France.

METHODS

This is a prospective, observational, cross-sectional, pharmacoepidemiologic study with a total of 2544 consecutive patients treated with a statin for at least 6 months.

MAIN OUTCOME MEASURES

Prevalence of isolated and mixed dyslipidemias of low density lipoprotein cholesterol (LDL-C), high density lipoprotein cholesterol (HDL-C), and triglycerides among all patients and among patients at high cardiovascular risk; clinical variables associated with attainment of lipid targets/normal levels in French national guidelines.

RESULTS

At least one dyslipidemia was present in 50.8% of all patients and in 71.1% of high-risk patients. Dyslipidemias of LDL-C, HDL-C, and triglycerides were present in 27.7%, 12.4%, and 28.7% of all patients, respectively, and in 51.0%, 18.2%, and 32.5% of high-risk patients, respectively. Among all subjects with any dyslipidemia, 30.9% had mixed dyslipidemias and 69.4% had low HDL-C and/or elevated triglycerides, while 30.6% had isolated elevated LDL-C; corresponding values for high-risk patients were 36.8%, 58.9%, and 41.1%. Age, gender, body mass index and Framingham Risk Score >20% were the factors significantly associated with attainment of normal levels for ≥2 lipid levels.

CONCLUSIONS

At least one dyslipidemia persisted in half of all patients and two-thirds of high cardiovascular risk patients treated with a statin. Dyslipidemias of HDL-C and/or triglycerides were as prevalent as elevated LDL-C among high cardiovascular risk patients.

Preventive aspects in peripheral artery disease

The prevalence of peripheral artery disease is steadily increasing and is associated with significant morbidity, including a significant percentage of amputations. Peripheral artery disease often goes undiagnosed, making its prevention increasingly important. Patients with peripheral arterial disease are at increased risk of adverse cardiovascular outcomes which makes prevention even more important. Several risk factors have been identified in the pathophysiology of peripheral artery disease which should be modified to decrease risk. Smoking, hyperlipidemia, hypertension, and diabetes are among proven risk factors for the development of peripheral artery disease, thus smoking cessation, lipid control, blood pressure control, and glucose control have been tried and shown to be effective in preventing the morbidity associated with this disease. Pharmacologic agents such as aspirin and clopidogrel alone or in combination have been shown to be effective, though risk of bleeding might be increased with the combination. Anticoagulation use is recommended only for acute embolic cases. Other treatment modalities that have been tried or are under investigation are estrogen replacement, naftidrofuryl, pentoxifylline, hyperbaric oxygen, therapeutic angiogenesis, and advanced glycation inhibitors. The treatment for concomitant vascular diseases does not change in the presence of peripheral artery disease, but aggressive management of risk factors should be undertaken in such cases.

Anacetrapib promotes reverse cholesterol transport and bulk cholesterol excretion in Syrian golden hamsters

Cholesteryl ester transfer protein (CETP) transfers cholesteryl ester (CE) and triglyceride between HDL and apoB-containing lipoproteins. Anacetrapib (ANA), a reversible inhibitor of CETP, raises HDL cholesterol (HDL-C) and lowers LDL cholesterol in dyslipidemic patients; however, the effects of ANA on cholesterol/lipoprotein metabolism in a dyslipidemic hamster model have not been demonstrated. To test whether ANA (60 mg/kg/day, 2 weeks) promoted reverse cholesterol transport (RCT), ³H-cholesterol-loaded macrophages were injected and (3)H-tracer levels were measured in HDL, liver, and feces. Compared to controls, ANA inhibited CETP (94%) and increased HDL-C (47%). ³H-tracer in HDL increased by 69% in hamsters treated with ANA, suggesting increased cholesterol efflux from macrophages to HDL. ³H-tracer in fecal cholesterol and bile acids increased by 90% and 57%, respectively, indicating increased macrophage-to-feces RCT. Mass spectrometry analysis of HDL from ANA-treated hamsters revealed an increase in free unlabeled cholesterol and CE. Furthermore, bulk cholesterol and cholic acid were increased in feces from ANA-treated hamsters. Using two independent approaches to assess cholesterol metabolism, the current study demonstrates that CETP inhibition with ANA promotes macrophage-to-feces RCT and results in increased fecal cholesterol/bile acid excretion, further supporting its development as a novel lipid therapy for the treatment of dyslipidemia and atherosclerotic vascular disease.

HDL Measures, Particle Heterogeneity, Proposed Nomenclature, and Relation to Atherosclerotic Cardiovascular Events

BACKGROUND

A growing body of evidence from epidemiological data, animal studies, and clinical trials supports HDL as the next target to reduce residual cardiovascular risk in statin-treated, high-risk patients. For more than 3 decades, HDL cholesterol has been employed as the principal clinical measure of HDL and cardiovascular risk associated with low HDL-cholesterol concentrations. The physicochemical and functional heterogeneity of HDL present important challenges to investigators in the cardiovascular field who are seeking to identify more effective laboratory and clinical methods to develop a measurement method to quantify HDL that has predictive value in assessing cardiovascular risk.

CONTENT

In this report, we critically evaluate the diverse physical and chemical methods that have been employed to characterize plasma HDL. To facilitate future characterization of HDL subfractions, we propose the development of a new nomenclature based on physical properties for the subfractions of HDL that includes very large HDL particles (VL-HDL), large HDL particles (L-HDL), medium HDL particles (M-HDL), small HDL particles (S-HDL), and very-small HDL particles (VS-HDL). This nomenclature also includes an entry for the pre-β-1 HDL subclass that participates in macrophage cholesterol efflux.

SUMMARY

We anticipate that adoption of a uniform nomenclature system for HDL subfractions that integrates terminology from several methods will enhance our ability not only to compare findings with different approaches for HDL fractionation, but also to assess the clinical effects of different agents that modulate HDL particle structure, metabolism, and function, and in turn, cardiovascular risk prediction within these HDL subfractions.

Emerging options in the treatment of dyslipidemias: a bright future?

INTRODUCTION

Hypercholesterolemia is a major risk factor for cardiovascular disease (CVD). Low-density lipoprotein cholesterol (LDL-C) reduction has been demonstrated to decrease CVD-related morbidity and mortality. However, several patients do not reach LDL-C target levels with the currently available lipid lowering agents, particularly statins. Lipid and non-lipid parameters other than LDL-C may account for the residual CVD risk after adequate LDL-C lowering with statins.

AREAS COVERED

This review focuses on the efficacy and safety of emerging drugs aiming at high-density lipoprotein cholesterol (HDL-C) elevation (i.e., recombinant or plasma-derived wild-type apolipoprotein (apo) A-I, apo A-I mimetic peptides, reconstituted mutant HDL, partially delipidated HDL and cholesterol ester transfer protein inhibitors), microsomal triglyceride transfer protein inhibitors and antisense oligonucleotides.

EXPERT OPINION

Several lipid modifying agents in development may potently reduce the residual CVD risk. Ongoing and future studies with clinical outcomes will clarify their efficacy in clinical practice.

Nanotechnology for synthetic high-density lipoproteins

Atherosclerosis is the disease mechanism responsible for coronary heart disease (CHD), the leading cause of death worldwide. One strategy to combat atherosclerosis is to increase the amount of circulating high-density lipoproteins (HDL), which transport cholesterol from peripheral tissues to the liver for excretion. The process, known as reverse cholesterol transport, is thought to be one of the main reasons for the significant inverse correlation observed between HDL blood levels and the development of CHD. This article highlights the most common strategies for treating atherosclerosis using HDL. We further detail potential treatment opportunities that utilize nanotechnology to increase the amount of HDL in circulation. The synthesis of biomimetic HDL nanostructures that replicate the chemical and physical properties of natural HDL provides novel materials for investigating the structure-function relationships of HDL and for potential new therapeutics to combat CHD.

The obesity, metabolic syndrome, and type 2 diabetes mellitus pandemic: II. Therapeutic management of atherogenic dyslipidemia

J Clin Hypertens (Greenwich). 2009;11:520-527. (c)2009 Wiley Periodicals, Inc.Strategies for the effective management of cardiovascular risk factors in patients with the metabolic syndrome (MS) or type 2 diabetes mellitus (T2DM) are essential to help reduce cardiovascular morbidity and mortality. Treatment strategies should be multifactorial and include the promotion of therapeutic lifestyle changes, as well as pharmacologic therapies to treat individual risk factors according to current guidelines. In an accompanying article, the importance of atherogenic dyslipidemia as a risk factor for the development of cardiovascular disease in patients with MS or T2DM was highlighted. Current treatment options for managing this characteristic form of atherogenic dyslipidemia are limited and tend to be only moderately effective. The focus of this review is the current pharmacotherapies available for the management of atherogenic dyslipidemia in patients with the MS or T2DM, highlighting the rationale for combining available treatments. Novel strategies currently in clinical development are also discussed.

Cholesteryl ester transfer protein and its inhibition

Cholesteryl ester transfer protein (CETP) is a plasma glycoprotein that facilitates the transfer of cholesteryl esters from the atheroprotective high density lipoprotein (HDL) to the proatherogenic low density lipoprotein cholesterol (LDL) and very low density lipoprotein cholesterol (VLDL) leading to lower levels of HDL but raising the levels of proatherogenic LDL and VLDL. Inhibition of CETP is considered a potential approach to treat dyslipidemia. However, discussions regarding the role of CETP-mediated lipid transfer in the development of atherosclerosis and CETP inhibition as a potential strategy for prevention of atherosclerosis have been controversial. Although many animal studies support the hypothesis that inhibition of CETP activity may be beneficial, negative phase III studies on clinical endpoints with the CETP inhibitor torcetrapib challenged the future perspectives of CETP inhibitors as potential therapeutic agents. The review provides an update on current understanding of the molecular mechanisms involved in CETP activity and its inhibition.

Anacetrapib: hope for CETP inhibitors?

Inhibition of cholesteryl ester transfer protein (CETP), a key protein involved in reverse cholesterol transport, can lead to increases in high-density lipoprotein cholesterol (HDL-C) levels and thus, is under evaluation as an antiatherogenic strategy. Several CETP inhibitors have been under development including anacetrapib, dalcetrapib, and torcetrapib. To date, anacetrapib demonstrates the greatest HDL-C raising and low-density lipoprotein cholesterol (LDL-C) lowering potential. Phase I and phase II trials with anacetrapib have revealed that anacetrapib is well-tolerated and does not seem to possess the pressor effects associated with torcetrapib. This article will briefly review the HDL-C raising through CETP inhibition as an antiatherogenic strategy with a specific focus on anacetrapib.

Separating the mechanism-based and off-target actions of cholesteryl ester transfer protein inhibitors with CETP gene polymorphisms

BACKGROUND

Cholesteryl ester transfer protein (CETP) inhibitors raise high-density lipoprotein (HDL) cholesterol, but torcetrapib, the first-in-class inhibitor tested in a large outcome trial, caused an unexpected blood pressure elevation and increased cardiovascular events. Whether the hypertensive effect resulted from CETP inhibition or an off-target action of torcetrapib has been debated. We hypothesized that common single-nucleotide polymorphisms in the CETP gene could help distinguish mechanism-based from off-target actions of CETP inhibitors to inform on the validity of CETP as a therapeutic target.

METHODS AND RESULTS

We compared the effect of CETP single-nucleotide polymorphisms and torcetrapib treatment on lipid fractions, blood pressure, and electrolytes in up to 67 687 individuals from genetic studies and 17 911 from randomized trials. CETP single-nucleotide polymorphisms and torcetrapib treatment reduced CETP activity and had a directionally concordant effect on 8 lipid and lipoprotein traits (total, low-density lipoprotein, and HDL cholesterol; HDL2; HDL3; apolipoproteins A-I and B; and triglycerides), with the genetic effect on HDL cholesterol (0.13 mmol/L, 95% confidence interval [CI] 0.11 to 0.14 mmol/L) being consistent with that expected of a 10-mg dose of torcetrapib (0.13 mmol/L, 95% CI 0.10 to 0.15). In trials, 60 mg of torcetrapib elevated systolic and diastolic blood pressure by 4.47 mm Hg (95% CI 4.10 to 4.84 mm Hg) and 2.08 mm Hg (95% CI 1.84 to 2.31 mm Hg), respectively. However, the effect of CETP single-nucleotide polymorphisms on systolic blood pressure (0.16 mm Hg, 95% CI -0.28 to 0.60 mm Hg) and diastolic blood pressure (-0.04 mm Hg, 95% CI -0.36 to 0.28 mm Hg) was null and significantly different from that expected of 10 mg of torcetrapib.

CONCLUSIONS

Discordance in the effects of CETP single-nucleotide polymorphisms and torcetrapib treatment on blood pressure despite the concordant effects on lipids indicates the hypertensive action of torcetrapib is unlikely to be due to CETP inhibition or shared by chemically dissimilar CETP inhibitors. Genetic studies could find a place in drug-development programs as a new source of randomized evidence for drug-target validation in humans.

The genetics of high-density lipoprotein metabolism: clinical relevance for therapeutic approaches

The risk for coronary artery disease (CAD) is inversely correlated with high-density lipoprotein (HDL) cholesterol plasma levels. These plasma HDL cholesterol levels are influenced by the activity of a number of enzymes and receptors, and therefore, variations in the genes encoding for these proteins may consequently result in an altered CAD risk. Identification of such pivotal players in HDL cholesterol metabolism that are also strongly associated with CAD risk is crucial for the materialization of novel therapeutic modalities. A large amount of knowledge has been obtained by studies involving families with extreme HDL phenotypes specific to molecular defects. In fact, thus far, monogenetic defects have been described in the genes coding for apolipoprotein A-I, adenosine triphosphate-binding cassette transporter A1, cholesterol ester transfer protein, the lack of endothelial lipase (LIPG), phospholipid transfer protein, and lecithin-cholesterol acyltransferase. Despite the fact that the total number of carriers of such mutations is rather small, much can be gained by extensively studying the metabolic and vascular consequences of these mutations. Surrogate markers for atherosclerosis have proved to be useful to overcome this sample size limitation and have been widely exploited to study families with decreased or increased HDL cholesterol levels in order to correlate HDL cholesterol phenotypes to atherosclerotic burden in cases and controls. Apart from such extreme phenotype approaches, novel population-based genome-wide association studies have been used to decipher the link between genetic loci and HDL cholesterol levels, and the identification of novel HDL cholesterol-related genes is eagerly awaited. These might be instrumental in the ongoing fight against atherosclerosis.

The pharmacology and off-target effects of some cholesterol ester transfer protein inhibitors

Inhibitors of cholesterol ester transfer protein (CETP) have the capacity to increase plasma high-density lipoprotein cholesterol to unprecedented levels. Still, hopes that CETP inhibition could reduce atherosclerosis were dented when the clinical development of one such inhibitor, torcetrapib, was halted because of an unexpected finding of increased cardiovascular and noncardiovascular mortality against a background of elevated blood pressure and plasma aldosterone levels. Recently, evidence has accumulated to show that these untoward effects may have been largely attributable to off-target toxicity of the compound, unrelated to the mechanism of CETP inhibition and not shared by other CETP inhibitors. In this review, we explore the rationale for CETP inhibition, compare the pharmacology of the small molecule CETP inhibitors that reached clinical development, and address the evidence relating to off-target adverse effects.