Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0004153 (atherosclerosis)
 77,401 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

This review deals with four lipid transfer proteins (LTP): three are involved in cholesteryl ester (CE) synthesis or transport, the fourth deals with plasma phospholipid (PL) transfer. Experimental models of atherosclerosis, clinical and epidemiological studies provided information as to the relationship of these LTP(s) to atherosclerosis, which is the main focus of this review. Thus, inhibition of acyl-CoA:cholesterol acyltransferase (ACAT) 1 and 2 decreases cholesterol absorption, plasma cholesterol and aortic cholesterol esterification in the aorta. The discovery that tamoxifen is a potent ACAT inhibitor explained the plasma cholesterol lowering of the drug. The use of ACAT inhibition in humans is under current investigation. As low cholesteryl ester transfer protein (CETP) activity is connected with high HDL-C, several CETP inhibitors were tried in rabbits, with variable results. A new CETP inhibitor, Torcetrapib, was tested in humans and there was a 50-100% increase in HDL-C. Lecithin cholesterol acyl-transferase (LCAT) influences oxidative stress, which can be lowered by transient LCAT gene transfer in LCAT-/- mice. Phospholipid transfer protein (PLTP) deficiency reduced apo B production in apo E-/- mice, as well as oxidative stress in four models of mouse atherosclerosis. In conclusion, the ability to increase HDL-C so markedly by inhibitors of CETP introduces us into a new era in prevention and treatment of coronary heart disease (CHD).
Atherosclerosis 2005 Feb
PMID:Lipid transfer proteins (LTP) and atherosclerosis. 1569 28

Elevated blood levels of low-density lipoprotein cholesterol (LDL-C) are associated with an increased risk for atherosclerotic coronary heart disease (CHD). Atorvastatin is a statin drug that inhibits 3-hydroxy-3-methyl-glutaryl coenzyme A reductase (the rate-limiting step of cholesterol production) and primarily lowers LDL-C levels. Atorvastatin has also been shown to significantly reduce CHD events. However, as with all statins (and all other monotherapy lipid-altering drugs), atorvastatin alone reduces the risk of CHD in only a minority of patients relative to placebo. Conversely, it is low levels of high-density lipoprotein cholesterol that are associated with increased CHD risk. Torcetrapib is a cholesteryl ester transfer protein inhibitor that primarily raises high-density lipoprotein cholesterol levels, and cholesteryl ester transfer protein inhibition has generally been shown to reduce atherosclerosis in rabbits. Taken together, atorvastatin and torcetrapib provide striking improvements in lipid levels, and complementary actions upon important lipid parameters. This review examines the chemistry, mechanism of action, pharmacokinetics, metabolism, safety/tolerability and efficacy of the combination torcetrapib/atorvastatin agent that is currently in development and that provides complementary lipid benefits towards the goal of reducing CHD risk beyond that of atorvastatin alone.
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PMID:Torcetrapib/atorvastatin combination therapy. 1618 Oct 26

Over the past decades, lowering of LDL-cholesterol (LDL-c) levels has been established as the foundation for preventing atherosclerotic disease. It is, however, widely accepted that additional risk reduction has to come from modifying other risk factors than LDL-c. In this context, increasing HDL-cholesterol (HDL-c) levels by pharmacological inhibition of the cholesteryl ester transfer protein (CETP) is currently under intense investigation. Two small-molecule compounds, JTT-705 and Torcetrapib, have been shown to effectively increase HDL-c levels in humans, without inducing clinically significant side effects when used as monotherapy or combined with statins. Whether this approach will translate into a reduction in risk of atherosclerotic disease has not yet been established. Data from studies focusing on genetic CETP deficiency as well as those studying the relationship between CETP plasma levels and risk of atherosclerosis do not provide clear answers. Several long-term clinical studies addressing this crucial issue have recently been initiated, results of which will follow within the next few years. This review focuses on CETP, its role in human lipid metabolism and its relation to atherosclerotic disease. Furthermore, it summarizes the currently available data regarding pharmacological CETP inhibition. Finally, it will highlight a number of issues basic to the considerations of whether CETP inhibition will fulfill its promises.
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PMID:Increasing high-density lipoprotein cholesterol through cholesteryl Ester transfer protein inhibition: a next step in the fight against cardiovascular disease? 1650 68

Epidemiological studies have identified both low-density lipoproteins (LDL) and high-density lipoproteins (HDL) as independent factors that modulate the risk of cardiovascular disease. Statins (HMG-CoA reductase inhibitors) that lower LDL and triglyceride levels are widely used for the treatment of hypercholesterolemia. Recently, a new class of drugs, cholesterol ester transfer protein (CETP) inhibitors, which significantly raise HDL and lower LDL, has been developed. Torcetrapib, a CETP inhibitor, has been shown to be effective, safe and well tolerated when used in combination with atorvastatin therapy. Torcetrapib has been shown to increase HDL cholesterol levels by 46% when given alone and by 61% when given in combination with atorvastatin, as well as to decrease LDL cholesterol levels by more than that achieved by atorvastatin alone. When the dosage of torcetrapib was doubled (at maximum tolerated dose), HDL increased by over 100%. Combination therapy appeared safe and well tolerated. Large trials evaluating the efficacy and safety of torcetrapib in combination therapy with atorvastatin are now in progress in order to establish whether CETP inhibition in combined therapy with statins will reduce the risk for atherosclerosis.
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PMID:Torcetrapib and atorvastatin: a novel combination therapy for dyslipidemia. 1654 Nov 86

Torcetrapib is a highly lipophilic (Clog P=7.45) and water insoluble cholesteryl ester transfer protein (CETP) inhibitor developed for the treatment of atherosclerosis. Self-emulsifying drug delivery system (SEDDS) formulations have been developed to reduce the food effect observed in early clinical trials using medium chain triglyceride (MCT) softgels and to increase the dose per capsule. MCT/Triacetin/Polysorbate 80/Capmul MCM (20/30/20/30) (MTPC) increased fasted exposure and thus reduced the food effect from 5- to 3-fold in dogs at a dose of 90 mg. Self-emulsifying formulations also accelerated absorption and generally decreased variability. Use of the lipophilic, GRAS cosolvent triacetin allowed a 2-fold increase in the dose per capsule. For the three formulations evaluated in dogs that showed significant differences in absorption, emulsion droplet size did not appear to play a significant role. Absorption did increase with Cremophor RH40 content, and at 50% Cremophor RH40 there was no food effect (at 30 mg). High polar surfactant content also resulted in poor dose proportionality, while there was good dose proportionality for MTPC. Studies of in vitro lipolysis are being conducted to aid in understanding the in vitro/in vivo relationships for torcetrapib SEDDS absorption.
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PMID:Development of a self-emulsifying formulation that reduces the food effect for torcetrapib. 1802 21

Atherosclerosis is the leading cause of death and disability in the developed world. Although the low-density lipoprotein (LDL) cholesterol lowering drugs reduce the mortality and morbidity associated with coronary artery disease, considerable mortality and morbidity remains. Reverse cholesterol transport mediated by high-density lipoproteins (HDL) may provide an independent pathway for lipid removal from atheroma. The current NCEP ATPIII include HDL-cholesterol > or =1.6 mmol/l as a negative risk factor. Torcetrapib is an inhibitor of cholesteryl ester-transfer protein (CETP) that increases high-density lipoprotein (HDL) cholesterol levels. The drug increases HDL-cholesterol and apolipoprotein A-I levels and decreases LDL-cholesterol and apolipoprotein B levels. The effect is showed in monotherapy and when administered in combination with statins. In addition, torcetrapib did not significantly change the serum levels of cholesterol and triglycerides. The raising HDL-cholesterol with torcetrapib could be a new approach to atherosclerotic cardiovascular disease although new trials based on hard clinical end points are necessary.
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PMID:New approaches to atherosclerotic cardiovascular disease. the potentialities of torcetrapib. 1822 Oct 79

Inhibition of cholesteryl ester transfer protein (CETP) is generally regarded as a promising strategy to reduce atherosclerosis by increasing HDL cholesterol. Therefore, the potent CETP inhibitor torcetrapib was given in addition to atorvastatin in half of the 15,067 patients with a high cardiovascular risk in the randomized, double-blind 'Investigation of lipid level management to understand its impact in atherosclerotic events' (ILLUMINATE) study. Torcetrapib caused a large increase of 72.1% in HDL cholesterol and a concomitant reduction of 24.9% in LDL-cholesterol. However, the trial was terminated prematurely because of an increased risk of cardiovascular events and death. Besides increasing blood pressure, torcetrapib decreased potassium and increased sodium, bicarbonate and aldosterone in serum. Post hoc analyses showed an increased risk of death in patients whose change in electrolytes was greater than the median change. These adverse effects of torcetrapib are presumably compound-specific, but should be taken into account in future studies with novel CETP inhibitors. Furthermore, it is suggested that the efficacy of CETP inhibition with regard to cardiovascular event reduction may depend on the lipid profile of the patient.
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PMID:[Torcetrapib increases mortality in patients with a high risk of cardiovascular disorders]. 1855 62

High-density lipoprotein (HDL) cholesterol levels bear an inverse relationship to cardiovascular risk. To date, however, no intervention specifically targeting HDL has been demonstrated to reduce cardiovascular risk. Cholesterol ester transfer protein (CETP) mediates transfer of cholesterol ester from HDL to apolipoprotein B-containing particles. Most, but not all observational cohort studies indicate that genetic polymorphisms of CETP associated with reduced activity and higher HDL cholesterol levels are also associated with reduced cardiovascular risk. Some, but not all studies indicate that CETP inhibition in rabbits retards atherosclerosis, whereas transgenic CETP expression in mice promotes atherosclerosis. Torcetrapib, the first CETP inhibitor to reach phase III clinical development, was abandoned due to excess mortality associated with increases in aldosterone and blood pressure. Two other CETP inhibitors have entered phase III clinical development. Anacetrapib is a potent inhibitor of CETP that produces very large increases in HDL cholesterol and large reductions in low-density lipoprotein (LDL) cholesterol, beyond those achieved with statins. Dalcetrapib is a less potent CETP inhibitor that produces smaller increases in HDL cholesterol with minimal effect on LDL cholesterol. Both agents appear to allow efflux of cholesterol from macrophages to HDL in vitro, and neither agent affects blood pressure or aldosterone in vivo. Two large cardiovascular outcomes trials, one with anacetrapib and one with dalcetrapib, should provide a conclusive test of the hypothesis that inhibition of CETP decreases cardiovascular risk.
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PMID:New horizons for cholesterol ester transfer protein inhibitors. 2208 34

Biomarkers and imaging trials have often been used as guideposts in the development of drugs for atherosclerosis. This article explores the role of biomarkers and imaging trials in the development of 4 drugs: rimonabant, torcetrapib, ezetimibe, and niacin. Rimonabant, a selective cannabinoid-1 receptor, causes weight loss and exerts favourable effects on lipid biomarkers. An intracoronary ultrasound study showed no effect for the primary but significant benefit for the secondary end point. A large clinical outcomes trial was halted when it became apparent that the drug caused serious psychiatric side effects, including suicide. Torcetrapib, a cholesteryl ester transfer protein inhibitor, lowers low-density lipoprotein (LDL) cholesterol and induces a marked increase in high-density lipoprotein (HDL) cholesterol. However, a large clinical outcomes trial was halted very prematurely due to a 58% increase in all-cause mortality. Neutral imaging studies were reported later. Ezetimibe lowers low density lipoprotein cholesterol but did not reduce carotid intima-media thickness, and there is as yet no clinical trial evidence that it reduces cardiovascular events after a decade on the market. Niacin exerts favourable effects on lipid biomarkers and has shown regression of atherosclerosis in small carotid imaging trials, but did not reduce events in a recent clinical trial that was stopped early due to a lack of efficacy. In summary, favourable effects on lipid biomarkers often do not translate into clinical benefit, and imaging trials, which focus on a narrow measurement of atherosclerosis, are also often not helpful.
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PMID:Utility of biomarkers and imaging in the development of drugs for the treatment of coronary atherosclerosis. 2262 47

Atherosclerotic cardiovascular diseases are the leading cause of death in developed and developing countries. HDL-raising therapeutic modalities (such as cholesterol ester transferase protein (CETP) inhibitors) are being developed to combat these diseases. However, recent setback of two CETP inhibitors (Torcetrapib and Dalcetrapib) has highlighted the importance of measuring qualitative functionality of HDL particles, rather than focusing quantitatively on HDL cholesterol serum concentrations. It has been known that, HDL from patients with coronary artery disease (CAD) (i.e., HDL(CAD)) limits the anti-inflammatory and endothelial repair properties of normal HDL, due to the activation of lectin-like oxidized LDL receptor-1 (LOX-1), thereby causing failure in endothelial nitric oxide (NO) production. A more recent study (Immunity 2013; 38: 754-768) also demonstrates that HDL from patients with chronic kidney dysfunction (CKD) (i.e., HDL(CKD)), unlike its healthy counterpart (i.e., HDL(Healthy)), promotes superoxide production, reduces NO bioavailability and raises blood pressure via toll-like receptor-2 (TLR-2) activation. This study provides novel insights into understanding why HDL-raising agents failed to demonstrate beneficial effects on cardiovascular mortality in large clinical trials and why CKD accelerates the development of atherosclerosis in CAD patients. Further research is warranted to elucidate whether HDL(CKD) and HDL(CAD) participate in other cellular processes in atherosclerosis, such as foam cell formation, the proliferation and migration of smooth muscle cells, and most importantly, plaque destabilization.
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PMID:HDL cholesterol in cardiovascular diseases: the good, the bad, and the ugly? 2347 38


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