Rationale and design of the dal-OUTCOMES trial: efficacy and safety of dalcetrapib in patients with recent acute coronary syndrome

HDL-cholesterol: perfection is the enemy of good?

An inverse relationship between the plasma concentration of high-density lipoprotein (HDL)-cholesterol and the risk of having a cardiovascular event has been shown in several epidemiologic studies. It is likely that this relationship is causal because HDL has several intrinsic properties that can potentially reverse atherosclerosis. However, this has not been conclusively shown in humans, and trying to achieve perfection with pharmacotherapy is possibly the enemy of good (ie, a healthy lifestyle). Patients with low HDL should be advised to change their lifestyle, including smoking cessation, weight reduction, and regular exercise.

Cholesteryl ester transfer protein inhibition to reduce cardiovascular risk: Where are we now?

Elevated low-density lipoprotein-cholesterol (LDL-C) and reduced high-density lipoprotein-cholesterol (HDL-C) are major risk factors for the development of cardiovascular disease. One approach to raising HDL-C is to inhibit the cholesteryl ester transfer protein (CETP), a plasma protein that promotes transfer of cholesteryl esters from HDL and other lipoprotein fractions. Drugs that inhibit CETP increase HDL-C and some lower LDL-C. However, the development of torcetrapib, the first CETP inhibitor to be tested in a human clinical outcomes trial, was terminated because it caused an excess of deaths and cardiovascular events. There is evidence, however, that torcetrapib had adverse off-target effects unrelated to CETP inhibition. This has opened the way for retesting of the hypothesis that CETP inhibitors will be anti-atherogenic in studies conducted with agents such as dalcetrapib and anacetrapib that do not share the off-target effects of torcetrapib. Clinical outcome trials with dalcetrapib and anacetrapib are currently under way.

Safety and efficacy of dalcetrapib on atherosclerotic disease using novel non-invasive multimodality imaging (dal-PLAQUE): a randomised clinical trial

BACKGROUND

Dalcetrapib modulates cholesteryl ester transfer protein (CETP) activity to raise high-density lipoprotein cholesterol (HDL-C). After the failure of torcetrapib it was unknown if HDL produced by interaction with CETP had pro-atherogenic or pro-inflammatory properties. dal-PLAQUE is the first multicentre study using novel non-invasive multimodality imaging to assess structural and inflammatory indices of atherosclerosis as primary endpoints.

METHODS

In this phase 2b, double-blind, multicentre trial, patients (aged 18-75 years) with, or with high risk of, coronary heart disease were randomly assigned (1:1) to dalcetrapib 600 mg/day or placebo for 24 months. Randomisation was done with a computer-generated randomisation code and was stratified by centre. Patients and investigators were masked to treatment. Coprimary endpoints were MRI-assessed indices (total vessel area, wall area, wall thickness, and normalised wall index [average carotid]) after 24 months and (18)F-fluorodeoxyglucose ((18)F-FDG) PET/CT assessment of arterial inflammation within an index vessel (right carotid, left carotid, or ascending thoracic aorta) after 6 months, with no-harm boundaries established before unblinding of the trial. Analysis was by intention to treat. This trial is registered at ClinicalTrials.gov, NCT00655473.

FINDINGS

189 patients were screened and 130 randomly assigned to placebo (66 patients) or dalcetrapib (64 patients). For the coprimary MRI and PET/CT endpoints, CIs were below the no-harm boundary or the adverse change was numerically lower in the dalcetrapib group than in the placebo group. MRI-derived change in total vessel area was reduced in patients given dalcetrapib compared with those given placebo after 24 months; absolute change from baseline relative to placebo was -4·01 mm(2) (90% CI -7·23 to -0·80; nominal p=0·04). The PET/CT measure of index vessel most-diseased-segment target-to-background ratio (TBR) was not different between groups, but carotid artery analysis showed a 7% reduction in most-diseased-segment TBR in the dalcetrapib group compared with the placebo group (-7·3 [90% CI -13·5 to -0·8]; nominal p=0·07). Dalcetrapib did not increase office blood pressure and the frequency of adverse events was similar between groups.

INTERPRETATION

Dalcetrapib showed no evidence of a pathological effect related to the arterial wall over 24 months. Moreover, this trial suggests possible beneficial vascular effects of dalcetrapib, including the reduction in total vessel enlargement over 24 months, but long-term safety and clinical outcomes efficacy of dalcetrapib need to be analysed.

FUNDING

F Hoffmann-La Roche Ltd.

Effect of Torcetrapib on Glucose, Insulin, and Hemoglobin A 1c in Subjects in the Investigation of Lipid Level Management to Understand its Impact in Atherosclerotic Events (ILLUMINATE) Trial

Background—

High-density lipoproteins have antidiabetic properties in vitro. Furthermore, elevated high-density lipoprotein levels accompanying a genetic deficiency of cholesteryl ester transfer protein are associated with decreased levels of plasma glucose. We now investigate effects on glucose homeostasis of inhibiting cholesteryl ester transfer protein with torcetrapib.

Methods and Results—

A post hoc analysis of the Investigation of Lipid Level Management to Understand its Impact in Atherosclerotic Events (ILLUMINATE) trial was conducted to investigate effects of the cholesteryl ester transfer protein inhibitor torcetrapib on glycemic control in the 6661 diabetic patients in the trial. At baseline, there were no differences between the 2 treatment arms with respect to plasma glucose, insulin, hemoglobin A 1c , or the homeostasis model assessment of insulin resistance. After 3 months, the diabetic subjects taking the combination of torcetrapib plus atorvastatin had plasma glucose levels 0.34 mmol/L lower ( P <0.0001) and insulin levels 11.7 μU/mL lower ( P <0.0001) than in those receiving atorvastatin alone. Homeostasis model assessment of insulin resistance values decreased from 49.1 to 47.3 ( P <0.0001) in the torcetrapib/atorvastatin arm compared with an increase in homeostasis model assessment of insulin resistance in the atorvastatin arm. At the 6-month time point, the mean hemoglobin A 1c level in the atorvastatin arm was 7.29% compared with 7.06% in the torcetrapib/atorvastatin arm ( P <0.0001). These effects of torcetrapib remained apparent for up to 12 months. Torcetrapib also lowered both glucose and insulin levels in the participants without diabetes mellitus, although the effects were not as great as in those with diabetes mellitus.

Conclusions—

Treatment with torcetrapib improves glycemic control in atorvastatin-treated patients with type 2 diabetes mellitus. It remains to be determined whether this effect is the consequence of raising high-density lipoprotein.at

Clinical Trial Registration—

http:www.clinicaltrials.gov . Unique identifier: NCT00134264.

Rationale and design of dal-PLAQUE: a study assessing efficacy and safety of dalcetrapib on progression or regression of atherosclerosis using magnetic resonance imaging and 18F-fluorodeoxyglucose positron emission tomography/computed tomography

dal-PLAQUE is a placebo-controlled multicenter study designed to assess the effect of dalcetrapib on imaging measures of plaque inflammation and plaque burden. dal-PLAQUE is a multimodality imaging study in the context of the large dal-HEART Program. Decreased high-density lipoprotein cholesterol is linked to increased risk of coronary heart disease (CHD). Dalcetrapib, a compound that increases high-density lipoprotein cholesterol by modulating cholesteryl ester transfer protein, is being studied to assess if it can reduce the progression of atherosclerotic disease and thereby decrease cardiovascular morbidity and mortality. Patients with CHD or CHD-risk equivalents were randomized to receive 600 mg dalcetrapib or placebo daily for 24 months, in addition to conventional lipid-lowering medication and other medications for cardiovascular risk factors. The primary outcomes are the effect of dalcetrapib on 18F-fluorodeoxyglucose positron emission tomography target-to-background ratio after 6 months and magnetic resonance imaging (MRI) plaque burden (wall area, wall thickness, total vessel area, and wall area/total vessel area ratio) after 12 months. Secondary objectives include positron emission tomography target-to-background ratio at 3 months and MRI plaque burden at 6 and 24 months; plaque composition at 6, 12, and 24 months; and aortic compliance at 6 months. A tertiary objective is to examine the dynamic contrast-enhanced MRI parameters of plaque neovascularization. In total, 189 subjects entered screening, and 130 were randomized. dal-PLAQUE will provide important information on the effects of dalcetrapib on markers of inflammation and atherosclerotic plaque burden and, thereby, on the safety of cholesteryl ester transfer protein modulation with dalcetrapib. Results are expected in 2011.

Safety, tolerability and pharmacokinetics of dalcetrapib following single and multiple ascending doses in healthy subjects: a randomized, double-blind, placebo-controlled, phase I study

BACKGROUND

Dalcetrapib is a modulator of cholesteryl ester transfer protein (CETP) activity developed to raise levels of high-density lipoprotein cholesterol (HDL-C) with the goal of further reduction of cardiovascular events additive to standard of care alone. In clinical studies, dalcetrapib has been shown to effectively increase levels of HDL-C with no significant safety concerns.

OBJECTIVE

The primary objective was to investigate the safety of single ascending and multiple ascending doses of dalcetrapib at doses markedly greater than that intended therapeutically (600 mg/day). Secondary objectives were to investigate the pharmacokinetics/pharmacodynamics and dose proportionality of dalcetrapib.

STUDY DESIGN

Randomized, double-blind, placebo-controlled, combined single and multiple ascending dose phase I study. Healthy males (age 18-65 years, body mass index 18-32 kg/m2) were randomized to four of five dalcetrapib doses (2100, 2700, 3300, 3900 or 4500 mg) or placebo, with ≥10 days washout between doses (n = 15, single ascending doses) or to dalcetrapib (1800, 2100, 3000 or 3900 mg once daily) or placebo for 7 days (four cohorts, each n = 10, randomization 8 : 2, multiple ascending doses).

MAIN OUTCOME MEASURE

Tolerability and safety were assessed by monitoring adverse events (AEs), laboratory parameters, vital signs and 12-lead ECG recordings. Primary pharmacokinetic assessments were area under the plasma concentration-time curve (AUC) from time zero to infinity (AUC(∞)) and maximum observed plasma concentration (C(max)) [single doses] and AUC from time zero to 24 hours (AUC(24)) and C(max) (multiple doses). Pharmacodynamic assessments included CETP activity and lipids (multiple dosing only).

RESULTS

Exposure increased with dose but was less than proportional to increasing dose after single dosing, although deviation from dose proportionality could not be demonstrated for C(max). Dose proportionality was consistent following multiple doses. Steady state was modelled to have been reached by approximately 4 days, with little to no accumulation. CETP activity reduction was dose dependent (maximum -55% after 3900 mg; placebo -2.6%) at 6 hours post-dose on day 1, while HDL-C increased by 12-19% (placebo -13%) on day 8 following treatment with 1800-3900 mg/day for 7 days. All AEs were mild or moderate in intensity and there were no serious AEs, deaths or withdrawals due to AEs. No clinically relevant effects on laboratory parameters, cardiac parameters or vital signs were noted.

CONCLUSION

Single-dose dalcetrapib up to 4500 mg and multiple doses up to 3900 mg were generally safe and well tolerated.

Evolving concepts on benefits and risks associated with therapeutic strategies to raise HDL

PURPOSE OF REVIEW

To provide an update on high-density lipoprotein (HDL) biology and emerging new HDL-based therapies for athero-thrombosis.

RECENT FINDINGS

Atherosclerotic cardiovascular disease remains a major public health threat despite a significant decline over the past three decades. Although current medical therapies, specifically low-density lipoprotein lowering with statins, reduce cardiovascular events by about 25-35%, a substantial residual risk remains, leading to a search for additional therapeutic interventions. In this regard, HDL has emerged as one important target because of epidemiologic evidence linking HDL levels inversely to cardiovascular events, known vascular protective actions of HDL and experimental and clinical research supporting athero-protective actions of HDL. However, complexities of HDL composition, particle size, and metabolism have suggested that HDL functionality, and how HDL is increased, may be important determinants of its protective effects.

SUMMARY

Thus the possibility that HDL modification could address the residual risk has brought renewed focus on an old HDL-raising drug, niacin, and a number of newer strategies to exploit the vascular benefits of HDL.

Plasma cholesteryl ester transfer, but not cholesterol esterification, is related to lipoprotein-associated phospholipase A2: possible contribution to an atherogenic lipoprotein profile

CONTEXT

Plasma lipoprotein-associated phospholipase A(2) (Lp-PLA(2)) predicts incident cardiovascular disease and is associated preferentially with negatively charged apolipoprotein B-containing lipoproteins. The plasma cholesteryl ester transfer (CET) process, which contributes to low high-density lipoprotein cholesterol and small, dense low-density lipoproteins, is affected by the composition and concentration of apolipoprotein B-containing cholesteryl ester acceptor lipoproteins.

OBJECTIVE

We tested relationships of CET with Lp-PLA(2) in subjects with and without metabolic syndrome (MetS).

DESIGN AND SETTING

In 68 subjects with MetS and 74 subjects without MetS, plasma Lp-PLA(2) mass, cholesterol esterification (EST), lecithin:cholesterol acyltransferase (LCAT) activity level, CET, CET protein (CETP) mass, and lipoproteins were measured.

RESULTS

EST, LCAT activity, CET (P < 0.001 for all), and CETP (P = 0.030) were increased, and Lp-PLA(2) was decreased (P = 0.043) in MetS. CET was correlated positively with Lp-PLA(2) in subjects with and without MetS (P < 0.05 for both). EST and LCAT activity were unrelated to Lp-PLA(2), despite a positive correlation between EST and CET (P < 0.001). After controlling for age, sex, and diabetes status, CET was determined by Lp-PLA(2) in the whole group (β = 0.245; P < 0.001), and in subjects with (β = 0.304; P = 0.001) and without MetS (β = 0.244; P = 0.006) separately, independently of triglycerides and CETP.

CONCLUSIONS

Plasma CET is related to Lp-PLA(2) in subjects with and without MetS. The process of CET, but not EST, may be influenced by Lp-PLA(2). These findings provide a rationale to evaluate whether maneuvers that inhibit Lp-PLA(2) will reduce CET, and vice versa to document effects of CETP inhibition on Lp-PLA(2).

Lack of clinically relevant drug-drug interactions when dalcetrapib is co-administered with ezetimibe

AIMS

Dalcetrapib, which targets cholesteryl ester transfer protein activity, is in development for prevention of cardiovascular events. Because dalcetrapib will likely be prescribed with other lipid-modifying therapies such as ezetimibe, a study was performed to investigate potential pharmacokinetic interactions between dalcetrapib and ezetimibe. Lipids changes and tolerability were secondary endpoints.

METHODS

Co-administration of dalcetrapib 900 mg (higher than the phase III dose) with ezetimibe was investigated in a three period, three treatment crossover study in healthy males: 7 days of dalcetrapib, 7 days of dalcetrapib plus ezetimibe, 7 days of ezetimibe alone. A full pharmacokinetic profile was performed on day 7 of each treatment.

RESULTS

Co-administration of dalcetrapib with ezetimibe was associated with minimal changes in dalcetrapib exposure compared with dalcetrapib alone. Least squares mean ratio (LSMR) (90% confidence interval) was 93.6 (87.1, 100.7) for AUC(0,24 h) and 99.0 (85.2, 115.0) for C(max) . Ezetimibe exposure was reduced with co-administration of ezetimibe with dalcetrapib compared with ezetimibe alone: LSMR 80.3 (74.6, 86.4) for AUC(0,24 h) and 88.9 (80.9, 99.9) for C(max) for total ezetimibe. High-density lipoprotein cholesterol increases associated with co-administration of dalcetrapib with ezetimibe (+29.8%) were comparable with those with dalcetrapib alone (+25.6%), while the reduction in low-density lipoprotein cholesterol with co-administration (-35.9%) was greater than with ezetimibe alone (-20.9%). Dalcetrapib was generally well tolerated when administered alone and when co-administered with ezetimibe.

CONCLUSION

Co-administration of dalcetrapib with ezetimibe was not associated with clinically significant changes in pharmacokinetic parameters or tolerability and did not diminish the lipid effects of either drug.

Dalcetrapib pharmacokinetics and metabolism in the cynomolgus monkey

The thioester dalcetrapib is undergoing Phase III clinical evaluation for the prevention and regression of atherosclerosis and the prevention of cardiovascular events through targeting cholesteryl ester transfer protein and increasing high-density lipoprotein cholesterol levels. Dalcetrapib undergoes rapid hydrolysis to generate the pharmacologically active form (dalcetrapib-thiol), which undergoes extensive metabolism via glucuronic acid conjugation, methylation, and hydroxylation, predominately forming the pharmacologically inactive S-methyl (dalcetrapib-S-Me) and S-glucuronide (dalcetrapib-S-Glu) metabolites. The purpose of this study was to characterize the absorption and disposition of dalcetrapib-thiol and its primary metabolites in cynomolgus monkeys following first pass through the intestines and liver using an in vivo dual portal and peripheral vein cannulation. Results showed the high influence of glucuronidation of dalcetrapib-thiol on the first-pass effect. Following passage through the primate intestinal wall, area under the plasma concentration-time curve indicated a marked loss (by ~85%) of active compound and formation of dalcetrapib-S-Glu and dalcetrapib-S-Me. Based on time to maximum drug concentrations (T(max)) values in the portal vein, metabolism of dalcetrapib-thiol to dalcetrapib-S-Glu appears to occur almost instantly (median T(max) 6.0 and 5.5 h, respectively), whereas methylation to dalcetrapib-S-Me occurs much more slowly (median T(max), 24 h). A relatively modest impact on systemic exposure followed hepatic first pass, with a further decrease in dalcetrapib-thiol exposure of 58% (AUC), a 3-fold reduction in exposure levels of dalcetrapib-S-Me and near-complete decrease in exposure of dalcetrapib-S-Glu. Passage of drug-related material through the intestinal wall and the liver results in an overall decrease of exposure to dalcetrapib-thiol of >90%.

No clinically relevant drug-drug interactions when dalcetrapib is co-administered with atorvastatin

OBJECTIVES

Dalcetrapib, which targets cholesteryl ester transfer protein, is in clinical development for prevention of cardiovascular events and is likely to be used concomitantly with statins. Two studies investigated co-administration of dalcetrapib with atorvastatin and any effects of the timing of atorvastatin on the pharmacokinetics of dalcetrapib.

RESEARCH DESIGN AND METHODS

Two crossover studies were performed in healthy subjects: a two-period study of dalcetrapib 900 mg concurrently with atorvastatin (concurrent dosing study) and a three-period study of dalcetrapib 600 mg (dose chosen for Phase III) with atorvastatin concurrently or serially 4 h after dalcetrapib (interval dosing study).

MAIN OUTCOME MEASURES

The primary pharmacokinetic end points were AUC(0 - 24) and C(max); lipid effects and tolerability were secondary end points.

RESULTS

In the concurrent study (n = 26), co-administration reduced dalcetrapib AUC(0 - 24) and C(max) and caused small changes in AUC(0 - 24) and C(max) of atorvastatin and its active metabolites. In the interval study (n = 52), serial and concurrent co-administration of atorvastatin resulted in similar reductions in dalcetrapib exposure that were comparable to those observed in the concurrent dosing study. Co-administration did not decrease the efficacy of dalcetrapib or atorvastatin and was generally well tolerated.

CONCLUSIONS

These results indicate no clinically relevant interactions for co-administration of dalcetrapib with atorvastatin.

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.

LDL cholesterol goals and cardiovascular risk during statin treatment: the IDEAL study

AIMS

We assessed the proportion of patients treated with either simvastatin 20 or 40 mg or atorvastatin 80 mg who achieved low-density lipoprotein cholesterol (LDL-C) goals of 2.5 or 2.0 mmol/l in the Incremental Decrease in End Points Through Aggressive Lipid Lowering (IDEAL) study. We explored how lipoprotein components related to cardiovascular disease (CVD) outcomes in these groups.

METHODS AND RESULTS

For subjects who reached on-treatment LDL-C goals, Cox regression models were used to assess the ability of lipoprotein components to predict CVD events. Treatment with simvastatin or atorvastatin resulted in 40 per cent and 80 per cent of patients, respectively, reaching the 2.5 mmol/l goal and 12 per cent and 52 per cent, respectively, reaching the 2.0 mmol/l goal, after 1 year (all p < 0.001 between groups). Adjusting for baseline LDL-C levels, hazard ratio (HR) for those reaching 2.0-2.5 mmol/l LDL-C versus those reaching <2.0 mmol/l was 1.16 (95% confidence interval [CI], 1.02-1.33, p = 0.023). An increase of the apolipoprotein B/A1 (apoB/A1) ratio by 1 standard deviation in participants who reached 2.0 mmol/l showed a HR for CVD of 1.14 (95% CI, 1.04-1.25, p = 0.004).

CONCLUSION

More CVD patients treated with atorvastatin than simvastatin achieved either LDL-C goal and those reaching the 2.0 mmol/l goal exhibited significantly less CVD than those only reaching 2.5 mmol/l. In those reaching the 2.0 mmol/l goal, the apoB/A1 ratio still bears a relation to CVD outcome. The use of apoB/A1 ratio may provide additional predictive value to that of LDL-C.

Anacetrapib and dalcetrapib: two novel cholesteryl ester transfer protein inhibitors

OBJECTIVE

To evaluate the role of cholesteryl ester transfer protein (CETP) in the cholesterol transport system and review the pharmacology, pharmacokinetic properties, efficacy, and adverse effects of the CETP inhibitors, anacetrapib and dalcetrapib, for the treatment of dyslipidemia.

DATA SOURCES

A literature search was conducted in Ovid/MEDLINE (1950 to week 4 December 2010), PubMed/MEDLINE (up to December 2010), EMBASE (2000 to December 2010), and International Pharmaceutical Abstracts (1970 to December 2010) using the MeSH terms and key words anacetrapib, MK 0859, dalcetrapib, and JTT 705. The search was limited to publications in English.

STUDY SELECTION AND DATA EXTRACTION

Studies evaluating the pharmacology, pharmacokinetics, safety, and efficacy of anacetrapib and dalcetrapib for the treatment of dyslipidemia were included. Clinical reviews evaluating the characterization of CETP and its inhibition as a mechanism for reducing cardiovascular risk were also included.

DATA SYNTHESIS

Anacetrapib and dalcetrapib represent a novel treatment option for patients who have dyslipidemia and low levels of high-density lipoprotein cholesterol (HDL-C). Anacetrapib and dalcetrapib increase HDL-C by inhibiting CETP-mediated transfer of cholesteryl ester and triglyceride. Studies evaluating the safety and efficacy of anacetrapib and dalcetrapib concluded that both agents safely and effectively augment HDL-C. Their mechanism of action, potential for significant raising of HDL-C, once-daily dosing regimen, and favorable lipid-altering effects when added to hydroxymethylglutaryl-CoA reductase inhibitors are key elements. Anacetrapib and dalcetrapib are well tolerated, with mild gastrointestinal complaints reported more than with placebo. Although another CETP inhibitor, torcetrapib, was withdrawn from clinical development secondary to increased morbidity and mortality, neither anacetrapib nor dalcetrapib has demonstrated the adverse off-target effects portrayed with torcetrapib.

CONCLUSIONS

Inhibition of CETP by anacetrapib and dalcetrapib represents an encouraging development in the management of dyslipidemia, particularly in patients with low HDL-C levels. Results of future trials are much anticipated, as these will clarify the role of anacetrapib and dalcetrapib in reduction of cardiovascular disease.

Rationale and design of dal-VESSEL: a study to assess the safety and efficacy of dalcetrapib on endothelial function using brachial artery flow-mediated vasodilatation

OBJECTIVE

Dalcetrapib increases high-density lipoprotein cholesterol (HDL-C) levels through effects on cholesteryl ester transfer protein (CETP). As part of the dalcetrapib dal-HEART clinical trial programme, the efficacy and safety of dalcetrapib is assessed in coronary heart disease (CHD) patients in the dal-VESSEL study (ClinicalTrials.gov identifier: NCT00655538), the design and methods of which are presented here. RESEARCH DESIGN AND STUDY METHOD: Men and women with CHD or CHD risk equivalent, with HDL-C levels <50  mg/dL were recruited for a 36-week, double-blinded, placebo-controlled trial. After a pre-randomisation phase of up to 8 weeks, patients received dalcetrapib 600  mg/day or placebo in addition to their existing treatments. Brachial flow-mediated dilatation (FMD) measured by B-mode ultrasound represents endothelial function and is a validated marker for early atherosclerosis and cardiovascular disease risk.

MAIN OUTCOME MEASURES

The primary efficacy outcome is change from baseline in brachial FMD after 12 weeks. The primary safety endpoint is 24-hour ambulatory blood pressure monitoring (ABPM) assessed at week 4. Secondary endpoints include brachial FMD at 36 weeks, ABPM at 12 and 36 weeks, lipid profile, CETP mass and activity, and markers of inflammation, oxidation, and cardiovascular risk. Clinical endpoints are assessed as a composite endpoint for the dal-HEART Program.

CURRENT STATUS

In 19 European clinical centres, 476 subjects met inclusion criteria and have entered the study. In conclusion, the dal-VESSEL study is the largest multicentre trial with brachial FMD ever performed. The study assesses efficacy and safety of dalcetrapib on endothelial function, blood pressure, lipids, and clinical outcomes in CHD patients with below average HDL-C and will therefore provide vital information regarding its potential role in the preventative treatment of CHD risk.

Atherosclerosis regression and high-density lipoproteins

Atherosclerosis regression has been demonstrated clearly in animal experimental models and, to a lesser extent, in human clinical studies. Imaging techniques for study of the arterial wall are playing a key role in promoting our appreciation of regression. LDL lowering remains the mainstay of current lipid treatment, but given the multiple antiatherosclerotic functions of HDL, including reverse cholesterol transport, agents that target HDL may represent the next generation of treatment for atherosclerotic disease. Currently available agents, including nicotinic acid, have documented antiatherosclerotic effects and trials examining clinical outcomes in the context of contemporary LDL treatment are now underway. Future approaches to HDL treatment may include cholesteryl ester transfer protein inhibitors and apolipoprotein A-I mimetics.

Emerging therapies for atherosclerosis prevention and management

Atherosclerosis is a chronic immunoinflammatory disease involving medium and large arteries, resulting from a complex interaction between genetic and environmental risk factors. Acute atherosclerotic vascular disease largely results from thrombosis that supervenes on a disrupted atherosclerotic plaque. A healthy lifestyle coupled with management of modifiable risk factors reduces the adverse clinical consequences of atherothrombosis. Reducing low-density lipoprotein cholesterol levels using statins and other agents is the primary pharmacologic approach to stabilize atherosclerosis, but a large residual risk burden remains, stimulating the search for additional therapies for atherosclerosis management. This review focuses on new and emerging therapeutic strategies targeting atherosclerosis.

Modulating cholesteryl ester transfer protein activity maintains efficient pre-β-HDL formation and increases reverse cholesterol transport

The mechanism by which cholesteryl ester transfer protein (CETP) activity affects HDL metabolism was investigated using agents that selectively target CETP (dalcetrapib, torcetrapib, anacetrapib). In contrast with torcetrapib and anacetrapib, dalcetrapib requires cysteine 13 to decrease CETP activity, measured as transfer of cholesteryl ester (CE) from HDL to LDL, and does not affect transfer of CE from HDL3 to HDL2. Only dalcetrapib induced a conformational change in CETP, when added to human plasma in vitro, also observed in vivo and correlated with CETP activity. CETP-induced pre-β-HDL formation in vitro in human plasma was unchanged by dalcetrapib ≤3 µM and increased at 10 µM. A dose-dependent inhibition of pre-β-HDL formation by torcetrapib and anacetrapib (0.1 to 10 µM) suggested that dalcetrapib modulates CETP activity. In hamsters injected with [³H]cholesterol-labeled autologous macrophages, and given dalcetrapib (100 mg twice daily), torcetrapib [30 mg once daily (QD)], or anacetrapib (30 mg QD), only dalcetrapib significantly increased fecal elimination of both [³H]neutral sterols and [³H]bile acids, whereas all compounds increased plasma HDL-[³H]cholesterol. These data suggest that modulation of CETP activity by dalcetrapib does not inhibit CETP-induced pre-β-HDL formation, which may be required to increase reverse cholesterol transport.

Insights from recent meta-analysis: role of high-density lipoprotein cholesterol in reducing cardiovascular events and rates of atherosclerotic disease progression

BACKGROUND

Although low-density lipoprotein cholesterol (LDL-C) traditionally has been the focus of treatment guidelines and clinical trials of lipid therapy, patients continue to have cardiovascular disease (CVD) events despite effective lowering of their LDL-C levels, suggesting the influence of other risk factors. High-density lipoprotein cholesterol (HDL-C) levels have been shown to be inversely associated with CVD risk in epidemiological studies.

METHODS

Meta-analyses and clinical trials that reported on the potential relation between HDL-C and CVD were reviewed.

RESULTS

Low HDL-C level is associated with increased CVD risk. Statins reduce CVD events in patients with low HDL-C, and fibrates benefit patients with low HDL-C and high triglyceride levels. The benefit of statins on event reduction may be related to their effects on HDL-C. However, not all therapies that increase HDL-C reduce CVD events. Imaging trials have provided evidence of the combined influence of HDL-C and LDL-C on surrogate end points.

CONCLUSION

Drugs in the same class may have different effects on HDL-C, and these different lipid effects may translate into different effects on atherosclerosis and CVD events. A new class of agents, cholesteryl ester transfer protein inhibitors, is being examined in ongoing trials to determine whether dalcetrapib may have different effects than torcetrapib, which increased levels of HDL-C but was associated with increased adverse events. In addition, ongoing trials are examining whether targeting both HDL-C and LDL-C, by combining a second agent such as niacin with a statin, leads to greater benefit on CVD and clinical events.

Dalcetrapib: a review of Phase II data

IMPORTANCE OF THE FIELD

While statins reduce the risk of cardiovascular disease by up to 50%, many patients remain at increased risk due to low levels of high-density lipoprotein cholesterol (HDL-C). Whether pharmacologically raising HDL-C per se with drug therapy will reduce cardiovascular events remains to be determined.

AREAS COVERED IN THIS REVIEW

Review of HDL-C-raising compounds, with a focus on cholesteryl ester transfer protein (CETP) inhibitors.

WHAT THE READER WILL GAIN

An overview of the CETP inhibitor dalcetrapib. Despite 70% increases in HDL-C, development of the CETP inhibitor torcetrapib was halted due to excess mortality, attributed largely to activation of the renin-angiotensin-aldosterone system resulting in hypertensive effects. Development of the CETP inhibitors dalcetrapib and anacetrapib is ongoing. Dalcetrapib has a unique chemical structure and induces a conformational change in CETP rather than forming a non-productive CETP/HDL-C complex as do the other CETP inhibitors. Although dalcetrapib is the least potent CETP inhibitor of the three in terms of CETP activity, the 900-mg dose did not increase blood pressure or raise aldosterone levels over 48 weeks of follow-up. The 600-mg dose of dalcetrapib is moving forward and raises HDL-C by 25 - 30% when used alone or in combination with a statin, with little effect on low-density lipoprotein cholesterol levels.

TAKE HOME MESSAGE

Before regulatory approval is granted, results from the ongoing dal-OUTCOMES trial evaluating the effects of dalcetrapib 600 mg daily over standard statin therapy on mortality and morbidity in > 15,000 high-risk CHD patients will be needed. The Dalcetrapib HDL Evaluation, Atherosclerosis and Reverse Cholesterol Transport (dal-HEART) program also includes three surrogate end point trials, dal-VESSEL, dal-PLAQUE and dal-PLAQUE 2, which will provide further information as to the contribution of CETP to cardiovascular disease.

Safety and tolerability of dalcetrapib (RO4607381/JTT-705): results from a 48-week trial

Aims

Co-primary objectives were to evaluate dalcetrapib (JTT-705/RO4607381), which targets cholesteryl ester transfer protein (CETP), effects on high-density lipoprotein cholesterol (HDL-C) in participants with coronary heart disease or risk equivalents and to evaluate potential changes in mesenteric lymph nodes.

Methods and results

Double-blind trial with participants randomized (2:1) to dalcetrapib 900 mg/day (higher than 600 mg phase III dose) or placebo, both with atorvastatin, for 24 weeks (n = 135; one without post-baseline efficacy data was excluded from intent-to-treat population); a subset continued for 24-week extension (n = 77). Lipid changes and safety parameters were assessed. Mesenteric lymph nodes were evaluated by magnetic resonance imaging. Dalcetrapib increased HDL-C (33.4%, Week 24; 33.8%, Week 48), decreased CETP activity (–53.5%, Week 24; –56.5%, Week 48), and increased apolipoprotein A-I (11.4%, Week 24; 16.4%, Week 48). Dalcetrapib showed no clinically relevant differences vs. placebo in adverse events, laboratory parameters including aldosterone, electrocardiograms, and vital signs including blood pressure (BP). Dalcetrapib had no measurable, clinically relevant effect on lymph node size.

Conclusion

Dalcetrapib 900 mg administered for up to 48 weeks showed no clinically relevant changes in lymph nodes, BP, or other safety parameters. Dalcetrapib effectively increased HDL-C over 48 weeks of treatment.

ABC transporters, atherosclerosis and inflammation

Atherosclerosis, driven by inflamed lipid-laden lesions, can occlude the coronary arteries and lead to myocardial infarction. This chronic disease is a major and expensive health burden. However, the body is able to mobilize and excrete cholesterol and other lipids, thus preventing atherosclerosis by a process termed reverse cholesterol transport (RCT). Insight into the mechanism of RCT has been gained by the study of two rare syndromes caused by the mutation of ABC transporter loci. In Tangier disease, loss of ABCA1 prevents cells from exporting cholesterol and phospholipid, thus resulting in the build-up of cholesterol in the peripheral tissues and a loss of circulating HDL. Consistent with HDL being an athero-protective particle, Tangier patients are more prone to develop atherosclerosis. Likewise, sitosterolemia is another inherited syndrome associated with premature atherosclerosis. Here mutations in either the ABCG5 or G8 loci, prevents hepatocytes and enterocytes from excreting cholesterol and plant sterols, including sitosterol, into the bile and intestinal lumen. Thus, ABCG5 and G8, which from a heterodimer, constitute a transporter that excretes cholesterol and dietary sterols back into the gut, while ABCA1 functions to export excess cell cholesterol and phospholipid during the biogenesis of HDL. Interestingly, a third protein, ABCG1, that has been shown to have anti-atherosclerotic activity in mice, may also act to transfer cholesterol to mature HDL particles. Here we review the relationship between the lipid transport activities of these proteins and their anti-atherosclerotic effect, particularly how they may reduce inflammatory signaling pathways. Of particular interest are recent reports that indicate both ABCA1 and ABCG1 modulate cell surface cholesterol levels and inhibit its partitioning into lipid rafts. Given lipid rafts may provide platforms for innate immune receptors to respond to inflammatory signals, it follows that loss of ABCA1 and ABCG1 by increasing raft content will increase signaling through these receptors, as has been experimentally demonstrated. Moreover, additional reports indicate ABCA1, and possibly SR-BI, another HDL receptor, may directly act as anti-inflammatory receptors independent of their lipid transport activities. Finally, we give an update on the progress and pitfalls of therapeutic approaches that seek to stimulate the flux of lipids through the RCT pathway.