Pharmacogenetics-guided dalcetrapib therapy after an acute coronary syndrome: the dal-GenE trial.

AIMS: In a retrospective analysis of dal-Outcomes, the effect of dalcetrapib on cardiovascular events was influenced by an adenylate cyclase type 9 (ADCY9) gene polymorphism. The dal-GenE study was conducted to test this pharmacogenetic hypothesis. METHODS AND RESULTS: dal-GenE was a double-blind trial in patients with an acute coronary syndrome within 1-3 months and the AA genotype at variant rs1967309 in the ADCY9 gene. A total of 6147 patients were randomly assigned to receive dalcetrapib 600 mg or placebo daily. The primary endpoint was the time from randomization to first occurrence of cardiovascular death, resuscitated cardiac arrest, non-fatal myocardial infarction, or non-fatal stroke. After a median follow-up of 39.9 months, the primary endpoint occurred in 292 (9.5%) of 3071 patients in the dalcetrapib group and 327 (10.6%) of 3076 patients in the placebo group [hazard ratio 0.88; 95% confidence interval (CI) 0.75-1.03; P = 0.12]. The hazard ratios for the components of the primary endpoint were 0.79 (95% CI 0.65-0.96) for myocardial infarction, 0.92 (95% CI 0.64-1.33) for stroke, 1.21 (95% CI 0.91-1.60) for death from cardiovascular causes, and 2.33 (95% CI 0.60-9.02) for resuscitated cardiac arrest. In a pre-specified on-treatment sensitivity analysis, the primary endpoint event rate was 7.8% (236/3015) in the dalcetrapib group and 9.3% (282/3031) in the placebo group (hazard ratio 0.83; 95% CI 0.70-0.98). CONCLUSION: Dalcetrapib did not significantly reduce the risk of occurrence of the primary endpoint of ischaemic cardiovascular events at end of study. A new trial would be needed to test the pharmacogenetic hypothesis that dalcetrapib improves the prognosis of patients with the AA genotype. CLINICAL TRIAL REGISTRATION: Trial registration dal-GenE ClinicalTrials.gov Identifier: NCT02525939.

Advancing Beyond Failed High-density Lipoprotein Clinical Trials to Pharmacogenetic Studies of ADCY9 and Cholesterol Ester Transfer Protein Inhibition.

ABSTRACT: Atherosclerosis has been effectively avoided with many therapies that lower low-density lipoprotein cholesterol. However, significant cardiovascular burden remains. The effect of raising high-density lipoprotein (HDL) has been confounded by other factors (such as lowering triglycerides or LDL) and unsuccessful when attempting to solely increase HDL. Reviewing the available data, the failures of previous strategies may reflect the complexity of HDL in human metabolism and the heterogeneity of human genetics. dal-GenE (NCT02525939) represents the first large cardiovascular outcomes study to use a selective genomic test to identify the target population most likely to receive therapeutic benefit and uses a cholesterol ester transfer protein inhibitor, dalcetrapib. Both the cholesterol ester transfer protein target and the ADCY9 polymorphism identified by the diagnostic test are based on inheritance and an evolving understanding of inborn risk. Selective treatment of subpopulations may be the key to the conundrum of HDL as an actionable risk factor.

Site qualification and clinical interpretation standards for 99mTc-SPECT perfusion imaging in a multi-center study of MITNEC (Medical Imaging Trials Network of Canada).

BACKGROUND: Qualification and interpretation standards are essential for establishing 99mTc-SPECT MPI accuracy vs. alternative modalities. METHODS: Rest-stress 99mTc-SPECT phantom scans were acquired on 35 cameras. LV defects were quantified with summed stress (SSS) and difference scores (SDS) at 2 core labs. SDS ≥ 2 in the right coronary artery (RCA) was the qualifying standard. Twenty rest (R)-stress (S) patient images were acquired on qualified cameras and interpreted by core labs. Global scoring differences > 3 between labs or discordant clinical interpretations underwent review. Scoring, interpretation, image quality, and diagnostic parameter agreement were assessed. RESULTS: Phantom scans: visual scoring confirmed RCA-ischemia on all cameras. Regional SSS, SDS agreement was moderate to very good: ICC-r = 0.57, 0.84. Patient scans: 90% of global SSS, 85% of SDS differences were ≤ 3. Regional SSS, SDS agreement: ICC-r = 0.87, 0.86, and global abnormal (SSS ≥ 4) and ischemic (SDS ≥ 2) interpretation: ICC-r = 0.90 were excellent. Clinical interpretation agreement was 100% following review. Image quality agreement was 70%. Automated metrics also agreed: ischemic total perfusion deficit ICC-r = 0.75, reversible perfusion defect, transient ischemic dilation, and S-R LV ejection fraction ICC-r ≥ 0.90. CONCLUSION: Quantitative scoring and interpretation of scans were highly repeatable with site qualification and clinical interpretation standardization, indicating that dual-core lab interpretation is appropriate to determine 99mTc-SPECT MPI accuracy.

Study design of Dal-GenE, a pharmacogenetic trial targeting reduction of cardiovascular events with dalcetrapib.

The objectives of precision medicine are to better match patient characteristics with the therapeutic intervention to optimize the chances of beneficial actions while reducing the exposure to unneeded adverse drug experiences. In a retrospective genome-wide association study of the overall neutral placebo-controlled dal-Outcomes trial, the effect of the cholesteryl ester transfer protein (CETP) modulator dalcetrapib on the composite of cardiovascular death, myocardial infarction or stroke was found to be influenced by a polymorphism in the adenylate cyclase type 9 (ADCY9) gene. Whereas patients with the AA genotype at position rs1967309 experienced fewer cardiovascular events with dalcetrapib, those with the GG genotype had an increased rate and the heterozygous AG genotype exhibited no difference from placebo. Measurements of cholesterol efflux and C-reactive protein (CRP) offered directionally supportive genotype-specific findings. In a separate, smaller, placebo-controlled trial, regression of ultrasonography-determined carotid intimal-medial thickness was only observed in dalcetrapib-treated patients with the AA genotype. Collectively, these observations led to the hypothesis that the cardiovascular effects of dalcetrapib may be pharmacogenetically determined, with a favorable benefit-risk ratio only for patients with this specific genotype. We describe below the design of dal-GenE, a precision medicine, placebo-controlled clinical outcome trial of dalcetrapib in patients with a recent acute myocardial infarction with the unique feature of selecting only those with the AA genotype at rs1967309 in the ADCY9 gene.

Role of Adenylate Cyclase 9 in the Pharmacogenomic Response to Dalcetrapib: Clinical Paradigm and Molecular Mechanisms in Precision Cardiovascular Medicine.

Following the neutral results of the dal-OUTCOMES trial, a genome-wide study identified the rs1967309 variant in the adenylate cyclase type 9 (ADCY9) gene on chromosome 16 as being associated with the risk of future cardiovascular events only in subjects taking dalcetrapib, a CETP (cholesterol ester transfer protein) modulator. Homozygotes for the minor A allele (AA) were protected from recurrent cardiovascular events when treated with dalcetrapib, while homozygotes for the major G allele (GG) had increased risk. Here, we present the current state of knowledge regarding the impact of rs1967309 in ADCY9 on clinical observations and biomarkers in dalcetrapib trials and the effects of mouse ADCY9 gene inactivation on cardiovascular physiology. Finally, we present our current model of the interaction between dalcetrapib and ADCY9 gene variants in the arterial wall macrophage, based on the intracellular role of CETP in the transfer of complex lipids from endoplasmic reticulum membranes to lipid droplets. Briefly, the concept is that dalcetrapib would inhibit CETP-mediated transfer of cholesteryl esters, resulting in a progressive inhibition of cholesteryl ester synthesis and free cholesterol accumulation in the endoplasmic reticulum. Reduced ADCY9 activity, by paradoxically leading to higher cyclic AMP levels and in turn increased cellular cholesterol efflux, could impart cardiovascular protection in rs1967309 AA patients. The ongoing dal-GenE trial recruited 6145 patients with the protective AA genotype and will provide a definitive answer to whether dalcetrapib will be protective in this population.

High-density lipoprotein/apolipoprotein A-I infusion therapy.

Strategies to decrease the progression and burden of atherosclerosis by capitalizing on the protective effect of high-density lipoprotein (HDL) and/or apolipoprotein A1 (apoA-I) levels remain active. Although efforts to raise HDL through the administration of oral agents are still being pursued, the disappointing results demonstrated with torcetrapib, an agent that elevated serum HDL and apoA-I levels through the inhibition of cholesterol ester transfer protein, have raised questions regarding this approach. An alternate strategy that consists of short-term infusions of reconstituted HDL or apoA-I is currently under evaluation. Several infusion compounds have been evaluated in clinical trials that utilize cardiovascular imaging technologies and biomarkers to assess potential clinical efficacy. Although these compounds are still in early-stage development, the results of these trials have supported the viability of this line of investigation. This review addresses the potential of HDL and/or apoA-I infusions as a possible therapeutic strategy for the treatment of coronary artery disease.

Surrogate endpoints and emerging surrogate endpoints for risk reduction of cardiovascular disease.

This article reviews surrogate endpoints and emerging biomarkers that were discussed at the annual "Cardiovascular Biomarkers and Surrogate Endpoints" symposium cosponsored by the US Food and Drug Administration (FDA) and the Montreal Heart Institute. The FDA's Center for Food Safety and Applied Nutrition (CFSAN) uses surrogate endpoints in its scientific review of a substance/disease relationship for a health claim. CFSAN currently recognizes three validated surrogate endpoints: blood pressure, blood total cholesterol, and blood low-density lipoprotein (LDL) concentration in its review of a health claim for cardiovascular disease (CVD). Numerous potential surrogate endpoints of CVD are being evaluated as the pathophysiology of heart disease is becoming better understood. However, these emerging biomarkers need to be validated as surrogate endpoints before they are used by CFSAN in the evaluation of a CVD health claim.

Clinical Pharmacokinetics and Pharmacodynamics of Dalcetrapib.

The cholesterol ester transfer protein (CETP) inhibitor dalcetrapib has been under evaluation for its potential to prevent cardiovascular (CV) events for almost two decades. The current clinical development program, representing new advances in precision medicine and focused on a genetically defined population with acute coronary syndrome (ACS), is supported by a large body of pharmacokinetic and pharmacodynamic data as well as substantial clinical experience in over 13,000 patients and volunteers. Dalcetrapib treatment of 600 mg/day produces significant inhibition of CETP activity, and has been utilized in phase II and III studies, including CV endpoint trials. Numerous studies have investigated the interactions between dalcetrapib and most drugs commonly prescribed to CV patients and have not demonstrated any clinically significant effects. Evaluations in patients with renal and hepatic impairment demonstrate a greater exposure to dalcetrapib than in the non-impaired population, but long-term clinical studies including patients with mild to moderate hepatic and renal dysfunction demonstrate no increase in adverse events. Safety pharmacology and toxicology studies as well as the clinical safety experience support the continuing development of dalcetrapib as an adjunct to 'standard of care' for the ACS population. This article provides a full review of the pharmacokinetics, as well as pharmacodynamics and pharmacology, of dalcetrapib in the context of a large clinical program.

Vascular biomarkers and surrogates in cardiovascular disease.

Cardiovascular biomarker research efforts have resulted in the identification of new risk factors and novel drug targets, as well as the establishment of treatment guidelines. Government agencies, academic research institutions, diagnostic industries, and pharmaceutical companies all recognize the importance of biomarkers in advancing therapies to improve public health. In drug development, biomarkers are used to evaluate early signals of efficacy and safety, to select dose, and to identify the target population. The United States Food and Drug Administration has relied on biomarkers to support clinical applications in many therapeutic fields, including cardiovascular disease. The appropriate application of cardiovascular biomarkers requires an understanding of disease natural history, the mechanism of the intervention, and the characteristics and limitations of the biomarker. Channels of communication among researcher, developer, and regulator must remain open to maximize the success of future biomarker efforts. In 2003, 2004, and 2005, an international panel of cardiovascular biomarker experts convened at the "Cardiovascular Biomarker and Surrogate Endpoints Symposia" held in Bethesda, Md, to discuss the use of biomarkers in the development of improved cardiovascular diagnostics and therapeutics. The information presented in the present report summarizes the authors' perspective distilled from these proceedings.

Effects of reconstituted high-density lipoprotein infusions on coronary atherosclerosis: a randomized controlled trial.

CONTEXT: High-density lipoprotein (HDL) cholesterol is an inverse predictor of coronary atherosclerotic disease. Preliminary data have suggested that HDL infusions can induce atherosclerosis regression. OBJECTIVE: To investigate the effects of reconstituted HDL on plaque burden as assessed by intravascular ultrasound (IVUS). DESIGN AND SETTING: A randomized placebo-controlled trial was conducted at 17 centers in Canada. Intravascular ultrasound was performed to assess coronary atheroma at baseline and 2 to 3 weeks after the last study infusion. PATIENTS: Between July 2005 and October 2006, 183 patients had a baseline IVUS examination and of those, 145 had evaluable serial IVUS examinations after 6 weeks. INTERVENTION: Sixty patients were randomly assigned to receive 4 weekly infusions of placebo (saline), 111 to receive 40 mg/kg of reconstituted HDL (CSL-111); and 12 to receive 80 mg/kg of CSL-111. MAIN OUTCOME MEASURES: The primary efficacy parameter was the percentage change in atheroma volume. Nominal changes in plaque volume and plaque characterization index on IVUS and coronary score on quantitative coronary angiography were also prespecified end points. RESULTS: The higher-dosage CSL-111 treatment group was discontinued early because of liver function test abnormalities. The percentage change in atheroma volume was -3.4% with CSL-111 and -1.6% for placebo (P = .48 between groups, P<.001 vs baseline for CSL-111). The nominal change in plaque volume was -5.3 mm3 with CSL-111 and -2.3 mm3 with placebo (P = .39 between groups, P<.001 vs baseline for CSL-111). The mean changes in plaque characterization index on IVUS (-0.0097 for CSL-111 and 0.0128 with placebo) and mean changes in coronary score (-0.039 mm for CSL-111 and -0.071 mm with placebo) on quantitative coronary angiography were significantly different between groups (P = .01 and P =.03, respectively). Administration of CSL-111 40 mg/kg was associated with mild, self-limiting transaminase elevation but was clinically well tolerated. CONCLUSIONS: Short-term infusions of reconstituted HDL resulted in no significant reductions in percentage change in atheroma volume or nominal change in plaque volume compared with placebo but did result in statistically significant improvement in the plaque characterization index and coronary score on quantitative coronary angiography. Elevation of HDL remains a valid target in vascular disease and further studies of HDL infusions, including trials with clinical end points, appear warranted. TRIAL REGISTRATION: clinicaltrials.gov Identifier: NCT00225719

Quantitative relation between hemodynamic changes during intravenous adenosine infusion and the magnitude of coronary hyperemia: implications for myocardial perfusion imaging.

OBJECTIVES: The goal of this study was to determine the relationship between changes in cardiac hemodynamics during intravenous adenosine (ADO) infusion, and myocardial blood flow (MBF). BACKGROUND: The relationship between changes in MBF and the peripheral hemodynamic effects during peak adenosine infusion is unknown. METHODS: We studied 348 (age 57 +/- 11 years; 106 females) without evidence of obstructive coronary artery disease by positron emission tomography (PET). Patients underwent [(13)N]ammonia PET imaging to measure MBF and coronary vascular resistance (CVR) at rest and during a standard 6-min ADO infusion. Changes in heart rate (HR) and mean arterial pressure (MAP) were measured at baseline and during peak hyperemia. RESULTS: During ADO, HR increased (delta: 24 +/- 11 beats/min) and MAP decreased (delta: -2 +/- 10 mm Hg). Overall, delta HR correlated poorly with hyperemic MBF (R = 0.10, p = 0.06) and with CVR (R = 0.11, p = 0.04). Delta MAP also showed a weak correlation with hyperemic MBF (R = 0.04, p = 0.44) and with CVR (R = 0.11, p = 0.04). Patients in the lowest tertile for delta HR showed a 7% lower hyperemic MBF (1.84 +/- 0.6 ml/min/g vs. 1.98 +/- 0.6 ml/min/g, p = 0.022) and an 8% higher CVR (54 +/- 20 mm Hg/ml/min/g vs. 50 +/- 17 mm Hg/ml/min/g, p = 0.056) compared with those in the highest tertile. Patients in the lowest tertile for delta MAP (i.e., greatest decline) showed similar hyperemic MBF, and an 8% lower CVR compared with those in the highest tertile (p = NS for both). These small differences between tertiles remain, even after adjusting for differences in age, gender, smoking status, and lipid profile. CONCLUSIONS: Changes in cardiac hemodynamics during intravenous ADO are generally poor predictors of changes in MBF and CVR during peak hyperemia, and, thus, they should not be used to assess the effectiveness of vasodilator stress in myocardial perfusion imaging.

Effect of atherosclerotic regression on total luminal size of coronary arteries as determined by intravascular ultrasound.

We assessed vascular changes during atherosclerosis regression. Compensatory enlargement of coronary arteries accommodates plaque burden during atherosclerosis development. Lipid-lowering therapy has altered the natural history of coronary atherosclerosis, but the arterial changes that occur during disease regression need to be clarified. Intravascular ultrasound was performed at baseline and after approximately 18 months in 432 patients with coronary disease. Mean plaque, lumen, and total vessel area were computed in a 30-mm coronary segment of interest. Mean low-density lipoprotein cholesterol level was 2.4 mmol/L, and 88% of patients received statins. Overall, changes in plaque and total vessel areas were highly correlated (r = 0.82, p <0.0001). Among the 227 patients with plaque regression, the plaque area decrease was -0.58 +/- 0.54 mm(2), and changes in total vessel and lumen areas were -1.02 +/- 1.10 and -0.44 +/- 0.86 mm(2), respectively. The decrease in plaque area correlated better with the change in total vessel area (r = 0.64, p <0.0001) than with the change in lumen area (r = 0.20, p = 0.003). The relation between plaque regression and decrease in total vessel area was significantly better (p = 0.019) for patients with a >40% atheroma area (r = 0.72; p <0.0001) than for those with

Coronary vasodilator reserve and Framingham risk scores in subjects at risk for coronary artery disease.

BACKGROUND: The relationship between coronary vasodilator reserve and risk of coronary heart disease (CHD) in subjects without coronary artery disease (CAD) is not well known. METHODS AND RESULTS: We studied 289 subjects (mean age, 58 +/- 10 years) without overt CAD and at low (< 10%) to intermediate risk (10%-20%) for CHD based on Framingham risk scores (RAMPART [Relative and Absolute Myocardial Perfusion changes as measured by Positron Emission Tomography to Assess the Effects of ACAT Inhibition: A Double-Blind, Randomized, Controlled, Multicenter Trial]). Coronary flow reserve (CFR) and coronary vascular resistance (CVR) were calculated from rest and adenosine nitrogen 13 ammonia positron emission tomography studies. Framingham-estimated CHD risk was used to as a surrogate for outcomes. Compared with subjects with low-risk scores (n = 150), those with intermediate-risk scores (n = 139) had a higher minimal CVR (49.3 +/- 17.41 mm Hg x mL(-1) x min(-1) x g(-1) vs 52.4 +/- 16.4 mm Hg x mL(-1) x min(-1) x g(-1), P = .05) and lower CFR (2.8 +/- 1.0 vs 2.5 +/- 0.8, P = .02). CFR was inversely related to CHD risk (R = -0.2, P = .006), and CVR was directly related to CHD risk (R = 0.2, P < .001). The mean CFR was significantly lower in patients in the first quartile of CHD risk compared with those in the fourth quartile (2.3 +/- 0.7 vs 2.8 +/- 1.0, P = .02), and the minimal CVR was significantly higher (44 +/- 15 mm Hg x mL(-1) x min(-1) x g(-1) vs 53 +/- 14 mm Hg x mL(-1) x min(-1) x g(-1), P < or = .05). CONCLUSIONS: In subjects without clinical CAD and at low to intermediate risk, CFR assessed by positron emission tomography is inversely related to estimated 10-year CHD risk.

The Role of Biomarkers in Decreasing Risk of Cardiac Toxicity after Cancer Therapy.

With the improvement of cancer therapy, survival related to malignancy has improved, but the prevalence of long-term cardiotoxicity has also increased. Cancer therapies with known cardiac toxicity include anthracyclines, biologic agents (trastuzumab), and multikinase inhibitors (sunitinib). The most frequent presentation of cardiac toxicity is dilated cardiomyopathy associated with poorest prognosis. Monitoring of cardiac toxicity is commonly performed by assessment of left ventricular (LV) ejection fraction, which requires a significant amount of myocardial damage to allow detection of cardiac toxicity. Accordingly, this creates the impetus to search for more sensitive and reproducible biomarkers of cardiac toxicity after cancer therapy. Different biomarkers have been proposed to that end, the most studied ones included troponin release resulting from cardiomyocyte damage and natriuretic peptides reflecting elevation in LV filling pressure and wall stress. Increase in the levels of troponin and natriuretic peptides have been correlated with cumulative dose of anthracycline and the degree of LV dysfunction. Troponin is recognized as a highly efficient predictor of early and chronic cardiac toxicity, but there remains some debate regarding the clinical usefulness of the measurement of natriuretic peptides because of divergent results. Preliminary data are available for other biomarkers targeting inflammation, endothelial dysfunction, myocardial ischemia, and neuregulin-1. The purpose of this article is to review the available data to determine the role of biomarkers in decreasing the risk of cardiac toxicity after cancer therapy.

Effects of the acyl coenzyme A:cholesterol acyltransferase inhibitor avasimibe on human atherosclerotic lesions.

BACKGROUND: Inhibition of the acyl coenzyme A:cholesterol acyltransferase (ACAT) enzyme may prevent excess accumulation of cholesteryl esters in macrophages. The ACAT inhibitor avasimibe was shown to reduce experimental atherosclerosis. This study was designed to investigate the effects of avasimibe on human coronary atherosclerosis. METHODS AND RESULTS: This randomized, double-blind, placebo-controlled trial assessed the effects of avasimibe at dosages of 50, 250, and 750 mg QD on the progression of coronary atherosclerosis as assessed by intravascular ultrasound (IVUS). All patients received background lipid-lowering therapy if necessary to reach a target baseline LDL level <125 mg/dL (3.2 mmol/L). IVUS and coronary angiography were performed at baseline and repeated after up to 24 months of treatment. Approximately equal percentages of patients across groups received concurrent statin therapy (87% to 89%). The mean total plaque volume at baseline was approximately 200 mm3, and the least squares mean change at end of treatment was 0.7 mm3 for placebo and 7.7, 4.1, and 4.8 mm3 for the avasimibe 50, 250, and 750 mg groups, respectively (adjusted P=0.17 [unadjusted P=0.057], 0.37, and 0.37, respectively). Percent atheroma volume increased by 0.4% with placebo and by 0.7%, 0.8%, and 1.0% in the respective avasimibe groups (P=NS). LDL cholesterol increased during the study by 1.7% with placebo but by 7.8%, 9.1%, and 10.9% in the respective avasimibe groups (P<0.05 in all groups). CONCLUSIONS: Avasimibe did not favorably alter coronary atherosclerosis as assessed by IVUS. This ACAT inhibitor also caused a mild increase in LDL cholesterol.

Avasimibe, an ACAT inhibitor, enhances the lipid lowering effect of atorvastatin in subjects with homozygous familial hypercholesterolemia.

This study assessed the efficacy and safety of avasimibe (CI-1011), an inhibitor of acyl coenzyme A-cholesterol acyltransferase (ACAT) in subjects with homozygous familial hypercholesterolemia (HoFH). Twenty seven subjects were enrolled in a double-blind, randomized, 3-sequence crossover trial of atorvastatin 80 mg QD, avasimibe 750 mg QD, and the combined treatment of atorvastatin 80 mg QD and avasimibe 750 mg QD after a washout period of 4 weeks. Each treatment period was administered over 6 weeks for a total of 18 weeks. There were no significant lipid changes resulting from the administration of avasimibe monotherapy. Avasimibe in combination with atorvastatin resulted in a significantly better reduction of total cholesterol (TC) as compared to atorvastatin alone (-22% versus -18%) (P < 0.05). All other lipid changes were not statistically significant for combination therapy compared to atorvastatin monotherapy, however there were greater reductions in triglycerides (TG) (-24% versus -13%), low-density lipoprotein cholesterol (LDL-C) (-23% versus -19%), very low-density lipoprotein cholesterol (VLDL-C) (-24% versus -13%) and high-density lipoprotein cholesterol (HDL-C) (-11% versus -6%). Avasimibe may modestly enhance the lipid-reducing effect of atorvastatin by further inhibiting the production of intracellular cholesterol through mechanisms that appear to be compatible in this population.

Design features of the Avasimibe and Progression of coronary Lesions assessed by intravascular UltraSound (A-PLUS) clinical trial.

BACKGROUND: Although statins have been shown to be beneficial in the management of hyperlipidemia and the reduction of cardiovascular morbidity and mortality, rates of major cardiovascular events remain high despite their use. Inhibition of the acyl coenzyme A: cholesterol acyltransferase (ACAT) enzyme in the arterial wall may prevent excess accumulation of cholesteryl esters in macrophages. In addition to ACAT inhibitor monotherapy, combination of a statin with an ACAT inhibitor may be a promising approach to further prevent the progression of atherosclerosis. METHODS: This report describes the design and methodologic features of a double-blind, randomized, placebo-controlled trial to assess the effect of the ACAT inhibitor avasimibe at 50-, 250-, and 750-mg daily dosages on the progression of coronary atherosclerosis as assessed by intravascular ultrasound (IVUS). All patients receive background lipid-lowering therapy when necessary. The study population consists of patients with at least one 20% to 50% diameter stenosis in a coronary artery with a reference diameter of > or =2.5 mm. IVUS and coronary angiography are performed at baseline and repeated at 24 months. The primary study end point is the change from baseline in plaque volume in a 30-mm segment of the coronary artery assessed by 3-dimensional IVUS. Several other IVUS and angiographic end points are measured. CONCLUSIONS: The Avasimibe and Progression of coronary Lesions assessed by intravascular UltraSound (A-PLUS) trial is among the first large imaging trials to use IVUS as a primary end point and assesses the effects of the ACAT inhibitor avasimibe on atherosclerosis progression.

Acyl coenzyme A:cholesterol acyltransferase inhibition: potential atherosclerosis therapy or springboard for other discoveries?

Cholesterol is an essential building block without which humans and other animals could not exist. As with most necessities, under certain conditions, excess can sharply tip the scale and lead to an unfavourable outcome. Excess cholesterol is stored as cholesteryl ester through an esterification process regulated in part by acyl coenzyme A:cholesterol acyltransferase (ACAT). ACAT is found in many tissue types which require the storage of cholesterol. Most notably, for cardiovascular disease ACAT activity is significant in intestinal and hepatic tissue and arterial macrophages. Several ACAT inhibitors have been investigated for their potential to favourably alter serum lipoprotein levels by blocking intestinal absorption, hepatic inhibition and/or slowing the progression of atherosclerosis through a non-lipid arterial inhibition. Recent evaluations of ACAT and ACAT inhibitors have provided some insight into the therapeutic potential and risks of ACAT inhibition as a means of treating atherosclerosis.

Atherosclerosis imaging and the Canadian Atherosclerosis Imaging Network.

Atherosclerosis exacts a large toll on society in the form of cardiovascular morbidity, mortality, and resource use and is exacerbated by the epidemics of obesity and diabetes. Consequently, there is a critical need for more-effective methods of diagnosis, treatment, and prevention of the complications of atherosclerosis. Careful and well-conducted large population studies are needed in order to truly understand the natural history of the disease, its imaging biomarkers, and their links to patient outcomes. The Canadian Atherosclerosis Imaging Network (CAIN) is a unique research network funded by the Canadian Institutes of Health Research and the Canada Foundation for Innovation and designed to address these needs and to enable large population-based imaging studies. The central objective of CAIN is to move innovations in imaging toward their broad application in clinical research and clinical practice for the improved evaluation of cardiac and neurologic vascular disease. CAIN is established as an international resource for studying the natural history, progression, and regression of atherosclerosis, as well as novel therapeutic interventions aimed at atherosclerosis. The network represents Canada's leading atherosclerosis imaging experts, embodying both basic imaging science and clinical imaging research. The network is improving methods of detection and treatment of atherosclerosis and, through a better understanding of the underlying disease itself, improving strategies for disease prevention. The benefits are expected to appear in the next 2 to 3 years. CAIN will drive innovation in imaging technology within the field of cardiology and neurology and improve health outcomes in Canada and worldwide.