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.

Future of cholesteryl ester transfer protein (CETP) inhibitors: a pharmacological perspective

In almost 30 years since the introduction of HMG-CoA reductase inhibitors (statins), no other class of lipid modulators has entered the market. Elevation of high-density lipoprotein-cholesterol (HDL-C) via inhibiting cholesteryl ester transfer protein (CETP) is an attractive strategy for reducing the risk of cardiovascular events in high-risk patients. Transfer of triglyceride and cholesteryl ester (CE) between lipoproteins is mediated by CETP; thus inhibition of this pathway can increase the concentration of HDL-C. Torcetrapib was the first CETP inhibitor evaluated in phase III clinical trials. Because of off-target effects, torcetrapib raised blood pressure and increased the concentration of serum aldosterone, leading to higher cardiovascular events and mortality. Torcetrapib showed positive effects on cardiovascular risk especially in patients with a greater increase in HDL-C and apolipoprotein A-1 (apoA-1) levels. The phase III clinical trial of dalcetrapib, the second CETP inhibitor that has entered clinical development, was terminated because of ineffectiveness. Dalcetrapib is a CETP modulator that elevated HDL-C levels but did not reduce the concentration of low-density lipoprotein cholesterol (LDL-C). Both heterotypic and homotypic CE transfer between lipoproteins are mediated by some CETP inhibitors, including torcetrapib, anacetrapib, and evacetrapib, while dalcetrapib only affects the heterotypic CE transfer. Dalcetrapib has a chemical structure that is distinct from other CETP inhibitors, with a smaller molecular weight and a lack of trifluoride moieties. Moreover, dalcetrapib is a pro-drug that must be hydrolyzed to a pharmacologically active thiol form. Two other CETP inhibitors, anacetrapib and evacetrapib, are currently undergoing evaluation in phase III clinical trials. Both molecules have shown beneficial effects by increasing HDL-C and decreasing LDL-C concentration. The success of anacetrapib and evacetrapib remains to be confirmed upon the completion of phase III clinical trials in 2017 and 2015, respectively. Generally, the concentration of HDL-C has been considered a biomarker for the activity of CETP inhibitors. However, it is not clear whether a fundamental relationship exists between HDL-C levels and the risk of coronary artery diseases. The most crucial role for HDL is cholesterol efflux capacity in which HDL can reverse transport cholesterol from foam cells in atherosclerotic plaques. In view of the heterogeneity in HDL particle size, charge, and composition, the mere concentration of HDL-C may not be a good surrogate marker for HDL functionality. Recent clinical studies have reported that increased HDL functionality inversely correlates with the development of atherosclerotic plaque. Future development of CETP inhibitors may therefore benefit from the use of biomarkers of HDL functionality.

A reappraisal of the risks and benefits of treating to target with cholesterol lowering drugs

Atherosclerotic cardiovascular disease (CVD) is the number one cause of death globally, and lipid modification, particularly lowering of low density lipoprotein cholesterol (LDLc), is one of the cornerstones of prevention and treatment. However, even after lowering of LDLc to conventional goals, a sizeable number of patients continue to suffer cardiovascular events. More aggressive lowering of LDLc and optimization of other lipid parameters like triglycerides (TG) and high density lipoprotein cholesterol (HDLc) have been proposed as two potential strategies to address this residual risk. These strategies entail use of maximal doses of highly potent HMG CoA reductase inhibitors (statins) and combination therapy with other lipid modifying agents. Though statins in general are fairly well tolerated, adverse events like myopathy are dose related. There are further risks with combination therapy. In this article, we review the adverse effects of lipid modifying agents used alone and in combination and weigh these effects against the evidence demonstrating their efficacy in reducing cardiovascular events, cardiovascular mortality, and all cause mortality. For patients with established CVD, statins are the only group of drugs that have shown consistent reductions in hard outcomes. Though more aggressive lipid lowering with high dose potent statins can reduce rates of non fatal events and need for interventions, the incremental mortality benefits remain unclear, and their use is associated with a higher rate of drug related adverse effects. Myopathy and renal events have been a significant concern with the use of high potency statin drugs, in particular simvastatin and rosuvastatin. For patients who have not reached target LDL levels or have residual lipid abnormalities on maximal doses of statins, the addition of other agents has not been shown to improve clinical outcomes and carries an increased risk of adverse events. The clinical benefits of drugs to raise HDLc remain unproven. In patients without known cardiovascular disease, there is conflicting evidence as to the benefits of aggressive pursuit of numerical lipid targets, particularly with respect to all cause mortality. Certainly, in statin intolerant patients, alternative agents with a low side effect profile are desirable. Bile acid sequestrants are an effective and safe choice for decreasing LDLc, and omega-3 fatty acids are safe agents to decrease TG. There remains an obvious need to design and carry out large scale studies to help determine which agents, when combined with statins, have the greatest benefit on cardiovascular disease with the least added risk. These studies should be designed to assess the impact on clinical outcomes rather than surrogate endpoints, and require a comprehensive assessment and reporting of safety outcomes.

Cholesteryl ester transfer protein inhibitors for dyslipidemia: focus on dalcetrapib

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

An update on the clinical development of dalcetrapib (RO4607381), a cholesteryl ester transfer protein modulator that increases HDL cholesterol levels

CETP is the target of CETP inhibitors such as anacetrapib and the modulator dalcetrapib. Both molecules have entered Phase III clinical trials, with the ultimate goal of reducing cardiovascular events by raising HDL cholesterol. At the 600-mg dose selected for the dal-OUTCOMES study, dalcetrapib is expected to inhibit CETP activity by approximately 30% and raise HDL-C by approximately 30% with limited effects on LDL cholesterol. Importantly, dalcetrapib does not raise blood pressure or aldosterone levels, two effects previously associated with the CETP inhibitor torcetrapib. Dalcetrapib has been well tolerated at the 600-mg dose. In the dal-PLAQUE atherosclerosis imaging study, dalcetrapib reduced the enlargement of total vessel area over time. In May 2012, following the results of the second interim analysis of dal-OUTCOMES, the Data and Safety Monitoring Board recommended stopping the study owing to a lack of clinically significant benefit, which was followed by Roche’s (Basel, Switzerland) decision to terminate the study and the dalcetrapib program (dal-HEART). Contrary to anacetrapib, a potent CETP inhibitor that markedly increases HDL cholesterol and significantly reduces LDL cholesterol, dalcetrapib has allowed us to test the hypothesis that an isolated, moderate elevation in HDL cholesterol prevents cardiovascular events.

Dalcetrapib , a cholesteryl ester transfer protein modulator

INTRODUCTION

Cholesteryl ester transfer protein (CETP) plays an important role in reverse cholesterol transport by transferring cholesteryl esters from high-density lipoprotein (HDL) to the apolipoprotein B-containing lipoproteins. Inhibition of CETP is a target to increase HDL-cholesterol and potentially reduce atherosclerosis. Dalcetrapib is an orally administered CETP inhibitor developed for the treatment of primary hypercholesterolaemia and mixed hyperlipidaemia.

AREAS COVERED

AREAS COVERED are: mode of action, preclinical development and clinical trials of dalcetrapib, a CETP modulator. The article provides an understanding of the pharmacokinetic and pharmacodynamic characteristics of dalcetrapib and insight into its clinical efficacy and safety. In clinical trials, dalcetrapib produced significant elevations in HDL-cholesterol when taken alone or in combination with statin with no effect on blood pressure or expression of genes involved in the renin-angiotensin-aldosterone system.

EXPERT OPINION

Although dalcetrapib is the least potent CETP inhibitor, it does not impair the formation of CETP-induced pre-β HDL, which might be needed to increase reverse cholesterol transport. While dalcetrapib is well-tolerated and does not show major side effects, the recent interim results of the Phase III dal-OUTCOMES trial have shown the lack of a clinically meaningful benefit, and further testing of the drug has been halted.

Simvastatin interactions with other drugs

INTRODUCTION

Statins, the mainstay of lipid-lowering therapy, are among the most commonly used drugs due to their beneficial effects in cardiovascular morbidity and mortality. Simvastatin, one of the most well-studied statins, is available in several generic forms both as monotherapy and with ezetimibe and is frequently prescribed worldwide. Despite its overall favorable risk profile, several previously stated concerns regarding high-dose simvastatin were recently formalized by the Food and Drug Administration (FDA).

AREAS COVERED

This paper discusses the interactions between simvastatin and other drugs and presents the latest FDA recommendations regarding the safe use of this statin. Relevant articles were identified through a PubMed search (up to December 2011). Furthermore, the latest FDA warning (June 2011) regarding simvastatin use was taken into account.

EXPERT OPINION

Simvastatin may have serious side effects particularly when used in high doses and in combination with certain drugs. Physicians need to adjust the recent recommendations made by the FDA in clinical practice in order to prevent treatment complications.

Pharmacological actions of statins: a critical appraisal in the management of cancer

Statins, among the most commonly prescribed drugs worldwide, are cholesterol-lowering agents used to manage and prevent cardiovascular and coronary heart diseases. Recently, a multifaceted action in different physiological and pathological conditions has been also proposed for statins, beyond anti-inflammation and neuroprotection. Statins have been shown to act through cholesterol-dependent and -independent mechanisms and are able to affect several tissue functions and modulate specific signal transduction pathways that could account for statin pleiotropic effects. Typically, statins are prescribed in middle-aged or elderly patients in a therapeutic regimen covering a long life span during which metabolic processes, aging, and concomitant novel diseases, including cancer, could occur. In this context, safety, toxicity, interaction with other drugs, and the state of health have to be taken into account in subjects treated with statins. Some evidence has shown a dichotomous effect of statins with either cancer-inhibiting or -promoting effects. To date, clinical trials failed to demonstrate a reduced cancer occurrence in statin users and no sufficient data are available to define the long-term effects of statin use over a period of 10 years. Moreover, results from clinical trials performed to evaluate the therapeutic efficacy of statins in cancer did not suggest statin use as chemotherapeutic or adjuvant agents. Here, we reviewed the pharmacology of the statins, providing a comprehensive update of the current knowledge of their effects on tissues, biological processes, and pathological conditions, and we dissected the disappointing evidence on the possible future use of statin-based drugs in cancer therapy.

Investigational CETP antagonists for hyperlipidemia and atherosclerosis prevention

INTRODUCTION

Reverse cholesterol transport (RCT) is a function of high-density lipoproteins (HDL) in humans and higher species. It is enabled by the cholesteryl ester transfer protein (CETP), a high molecular weight protein exchanging cholesteryl esters in HDL for triglycerides in very low-density lipoproteins (VLDL). Inhibition of CETP may provide a useful strategy to raise HDL, the protective lipoprotein fraction in plasma.

AREAS COVERED

Evaluation based on clinical and experimental findings of the three drugs developed or in advanced development for CETP inhibition.

EXPERT OPINION

Inhibition of CETP, both inherited and drug induced, at times leads to dramatic elevations of HDL-cholesterol (HDL-C) levels. Epidemiological data presently available do not, however, provide convincing evidence that reduced CETP levels or activity due to genetic factors and associated with HDL-C elevations, reduce cardiovascular risk. Indeed, the opposite may be true in some instances. All the three CETP inhibitors were the object of experimental and clinical evaluation. Large clinical trials with torcetrapib led to very negative findings, that is, raised cardiovascular morbidity and mortality in addition to raised risk of cancer and sepsis. Off-target effects of the drug, such as aldosterone retention and raised blood pressure, were believed to provide an explanation for these negative findings. The two newer agents, dalcetrapib and anacetrapib, do not exert off-target effects. The two drugs differ because anacetrapib has a more dramatic effect on HDL cholesterolemia (+139%) versus more moderate effects of dalcetrapib (+20-30%). Anacetrapib, however, may impair formation of pre-β HDL, that is, the primary particles in the process of cholesterol removal. The initial large trial with anacetrapib (DEFINE study) in coronary patients on statin treatment, appeared to confirm a remarkable HDL raising property, together with some reduction in vascular end points, in particular coronary procedures. The issue of other potentially harmful effects of CETP inhibition (sepsis and others) has yet to be clarified. Large clinical end-point trials, however, will be necessary to provide convincing evidence that, in addition to raising HDL-C, CETP inhibitors provide a valid additional treatment, for example, to statins in patients with coronary heart disease (CHD) or at high risk of CHD.

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.

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%.

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.