Cholesteryl Ester Transfer Protein Inhibition Reduces Major Adverse Cardiovascular Events by Lowering Apolipoprotein B Levels

Cholesteryl Ester Transfer Protein Inhibitors and Cardiovascular Outcomes: A Systematic Review and Meta-Analysis

BACKGROUND

Atherosclerosis is a multi-factorial disease, and low-density lipoprotein cholesterol (LDL-C) is a critical risk factor in developing atherosclerotic cardiovascular disease (ASCVD). Cholesteryl-ester transfer-protein (CETP), synthesized by the liver, regulates LDL-C and high-density lipoprotein cholesterol (HDL-C) through the bidirectional transfer of lipids. The novelty of CETP inhibitors (CETPis) has granted new focus towards increasing HDL-C, besides lowering LDL-C strategies. To date, five CETPis that are projected to improve lipid profiles, torcetrapib, dalcetrapib, evacetrapib, anacetrapib, and obicetrapib, have reached late-stage clinical development for ASCVD risk reduction. Early trials failed to reduce atherosclerotic cardiovascular occurrences. Given the advent of some recent large-scale clinical trials (ACCELERATE, HPS3/TIMI55-REVEAL Collaborative Group), conducting a meta-analysis is essential to investigate CETPis' efficacy.

METHODS

We conducted a thorough search of randomized controlled trials (RCTs) that commenced between 2003 and 2023; CETPi versus placebo studies with a ≥6-month follow-up and defined outcomes were eligible.

PRIMARY OUTCOMES

major adverse cardiovascular events (MACEs), cardiovascular disease (CVD)-related mortality, all-cause mortality.

SECONDARY OUTCOMES

stroke, revascularization, hospitalization due to acute coronary syndrome, myocardial infarction (MI).

RESULTS

Nine RCTs revealed that the use of a CETPi significantly reduced CVD-related mortality (RR = 0.89; 95% CI: 0.81-0.98; p = 0.02; I2 = 0%); the same studies also reduced the risk of MI (RR = 0.92; 95% CI: 0.86-0.98; p = 0.01; I2 = 0%), which was primarily attributed to anacetrapib. The use of a CETPi did not reduce the likelihood any other outcomes.

CONCLUSIONS

Our meta-analysis shows, for the first time, that CETPis are associated with reduced CVD-related mortality and MI.

Bayesian network analysis of factors influencing type 2 diabetes, coronary heart disease, and their comorbidities

OBJECTIVE

Bayesian network (BN) models were developed to explore the specific relationships between influencing factors and type 2 diabetes mellitus (T2DM), coronary heart disease (CAD), and their comorbidities. The aim was to predict disease occurrence and diagnose etiology using these models, thereby informing the development of effective prevention and control strategies for T2DM, CAD, and their comorbidities.

METHOD

Employing a case-control design, the study compared individuals with T2DM, CAD, and their comorbidities (case group) with healthy counterparts (control group). Univariate and multivariate Logistic regression analyses were conducted to identify disease-influencing factors. The BN structure was learned using the Tabu search algorithm, with parameter estimation achieved through maximum likelihood estimation. The predictive performance of the BN model was assessed using the confusion matrix, and Netica software was utilized for visual prediction and diagnosis.

RESULT

The study involved 3,824 participants, including 1,175 controls, 1,163 T2DM cases, 982 CAD cases, and 504 comorbidity cases. The BN model unveiled factors directly and indirectly impacting T2DM, such as age, region, education level, and family history (FH). Variables like exercise, LDL-C, TC, fruit, and sweet food intake exhibited direct effects, while smoking, alcohol consumption, occupation, heart rate, HDL-C, meat, and staple food intake had indirect effects. Similarly, for CAD, factors with direct and indirect effects included age, smoking, SBP, exercise, meat, and fruit intake, while sleeping time and heart rate showed direct effects. Regarding T2DM and CAD comorbidities, age, FBG, SBP, fruit, and sweet intake demonstrated both direct and indirect effects, whereas exercise and HDL-C exhibited direct effects, and region, education level, DBP, and TC showed indirect effects.

CONCLUSION

The BN model constructed using the Tabu search algorithm showcased robust predictive performance, reliability, and applicability in forecasting disease probabilities for T2DM, CAD, and their comorbidities. These findings offer valuable insights for enhancing prevention and control strategies and exploring the application of BN in predicting and diagnosing chronic diseases.

Obicetrapib on top of maximally tolerated lipid-modifying therapies in participants with or at high risk for atherosclerotic cardiovascular disease: rationale and designs of BROADWAY and BROOKLYN

BACKGROUND

Obicetrapib, a novel, selective cholesteryl ester transfer protein (CETP) inhibitor, reduces low-density lipoprotein cholesterol (LDL-C), LDL particles, apolipoprotein (Apo) B, and lipoprotein(a) [Lp(a)] and increases high-density lipoprotein cholesterol (HDL-C) when added to statins with or without ezetimibe. By substantially reducing LDL-C, obicetrapib has the potential to lower atherogenic lipoproteins in patients with atherosclerotic cardiovascular disease (ASCVD) or heterozygous familial hypercholesterolemia (HeFH) whose LDL-C levels remain high despite treatment with available maximally tolerated lipid-modifying therapies, addressing an unmet medical need in a patient population at high risk for cardiovascular events.

METHODS AND RESULTS

BROADWAY (NCT05142722) and BROOKLYN (NCT05425745) are ongoing placebo-controlled, double-blind, randomized Phase III trials designed to examine the efficacy, safety, and tolerability of obicetrapib as an adjunct to dietary intervention and maximally tolerated lipid-modifying therapies in participants with a history of ASCVD and/or underlying HeFH whose LDL-C is not adequately controlled. The primary efficacy endpoint was the percent change in LDL-C from baseline to day 84. Other endpoints included changes in Apo B, non-HDL-C, HDL-C, Apo A1, Lp(a), and triglycerides in addition to parameters evaluating safety, tolerability, and pharmacokinetics. BROADWAY also included an adjudicated assessment of major adverse cardiovascular events, measurements of glucose homeostasis, and an ambulatory blood pressure monitoring substudy. A total of 2,532 participants were randomized in BROADWAY and 354 in BROOKLYN to receive obicetrapib 10 mg or placebo (2:1) for 365 days with follow-up through 35 days after the last dose. Results from both trials are anticipated in 2024.

CONCLUSION

These trials will provide safety and efficacy data to support the potential use of obicetrapib among patients with ASCVD or HeFH with elevated LDL-C for whom existing therapies are not sufficiently effective or well-tolerated.

Discordance among apoB, non-high-density lipoprotein cholesterol, and triglycerides: implications for cardiovascular prevention

BACKGROUND AND AIMS

Despite growing evidence that apolipoprotein B (apoB) is the most accurate marker of atherosclerotic cardiovascular disease (ASCVD) risk, its adoption in clinical practice has been low. This investigation sought to determine whether low-density lipoprotein cholesterol (LDL-C), non-high-density lipoprotein cholesterol (HDL-C), and triglycerides are sufficient for routine cardiovascular care.

METHODS

A sample of 293 876 UK Biobank adults (age: 40-73 years, 42% men), free of cardiovascular disease, with a median follow-up for new-onset ASCVD of 11 years was included. Distribution of apoB at pre-specified levels of LDL-C, non-HDL-C, and triglycerides was examined graphically, and 10-year ASCVD event rates were compared for high vs. low apoB. Residuals of apoB were constructed after regressing apoB on LDL-C, non-HDL-C, and log-transformed triglycerides and used as predictors in a proportional hazards regression model for new-onset ASCVD adjusted for standard risk factors, including HDL-C.

RESULTS

ApoB was highly correlated with LDL-C and non-HDL-C (Pearson's r = .96, P < .001 for both) but less so with log triglycerides (r = .42, P < .001). However, apoB ranges necessary to capture 95% of all observations at pre-specified levels of LDL-C, non-HDL-C, or triglycerides were wide, spanning 85.8-108.8 md/dL when LDL-C 130 mg/dL, 88.3-112.4 mg/dL when non-HDL-C 160 mg/dL, and 67.8-147.4 md/dL when triglycerides 115 mg/dL. At these levels (±10 mg/dL), 10-year ASCVD rates for apoB above mean + 1 SD vs. below mean - 1 SD were 7.3 vs. 4.0 for LDL-C, 6.4 vs. 4.6 for non-HDL-C, and 7.0 vs. 4.6 for triglycerides (all P < .001). With 19 982 new-onset ASCVD events on follow-up, in the adjusted model, residual apoB remained statistically significant after accounting for LDL-C and HDL-C (hazard ratio 1.06, 95% confidence interval 1.0-1.07), after accounting for non-HDL-C and HDL-C (hazard ratio 1.04, 95% confidence interval 1.03-1.06), and after accounting for triglycerides and HDL-C (hazard ratio 1.13, 95% confidence interval 1.12-1.15). None of the residuals of LDL-C, non-HDL-C, or of log triglycerides remained significant when apoB was included in the model.

CONCLUSIONS

High variability of apoB at individual levels of LDL-C, non-HDL-C, and triglycerides coupled with meaningful differences in 10-year ASCVD rates and significant residual information contained in apoB for prediction of new-onset ASCVD events demonstrate that LDL-C, non-HDL-C, and triglycerides are not adequate proxies for apoB in clinical care.

Optimal Medical Therapy for Stable Ischemic Heart Disease in 2024: Focus on Blood Pressure and Lipids

Hypertension and dyslipidemia are 2 highly prevalent and modifiable risk factors in patients with stable ischemic heart disease. Multiple lines of evidence demonstrate that lowering blood pressure and low-density lipoprotein cholesterol improves clinical outcomes in patients with ischemic heart disease. Accordingly, clinical guidelines recommend intensive treatment targets for these high-risk patients. This article summarizes the pathophysiology, supporting evidence, and treatment recommendations for management of hypertension and dyslipidemia among patients with manifest ischemic heart disease and points to future research and unmet clinical needs.

ApoB100 and Atherosclerosis: What's New in the 21st Century?

ApoB is the main protein of triglyceride-rich lipoproteins and is further divided into ApoB48 in the intestine and ApoB100 in the liver. Very low-density lipoprotein (VLDL) is produced by the liver, contains ApoB100, and is metabolized into its remnants, intermediate-density lipoprotein (IDL) and low-density lipoprotein (LDL). ApoB100 has been suggested to play a crucial role in the formation of the atherogenic plaque. Apart from being a biomarker of atherosclerosis, ApoB100 seems to be implicated in the inflammatory process of atherosclerosis per se. In this review, we will focus on the structure, the metabolism, and the function of ApoB100, as well as its role as a predictor biomarker of cardiovascular risk. Moreover, we will elaborate upon the molecular mechanisms regarding the pathophysiology of atherosclerosis, and we will discuss the disorders associated with the APOB gene mutations, and the potential role of various drugs as therapeutic targets.

Obicetrapib: Reversing the Tide of CETP Inhibitor Disappointments

PURPOSE OF REVIEW

To discuss the history of cardiovascular outcomes trials of cholesteryl ester transfer protein (CETP) inhibitors and to describe obicetrapib, a next-generation, oral, once-daily, low-dose CETP inhibitor in late-stage development for dyslipidemia and atherosclerotic cardiovascular disease (ASCVD).

RECENT FINDINGS

Phase 1 and 2 trials have evaluated the safety and lipid/lipoprotein effects of obicetrapib as monotherapy, in conjunction with statins, on top of high-intensity statins (HIS), and with ezetimibe on top of HIS. In ROSE2, 10 mg obicetrapib monotherapy and combined with 10 mg ezetimibe, each on top of HIS, significantly reduced low-density lipoprotein cholesterol (LDL-C), non-high-density lipoprotein cholesterol (non-HDL-C), apolipoprotein B, total LDL particles, small LDL particles, small, dense LDL-C, and lipoprotein (a), and increased HDL-C. Phase 3 pivotal registration trials including a cardiovascular outcomes trial are underway. Obicetrapib has an excellent safety and tolerability profile and robustly lowers atherogenic lipoproteins and raises HDL-C. As such, obicetrapib may be a promising agent for the treatment of ASCVD.

Cholesteryl Ester Transfer Protein (CETP) Variations in Relation to Lipid Profiles and Cardiovascular Diseases: An Update

Lipid metabolism plays an essential role in the pathogenesis of cardiovascular and metabolic diseases. Cholesteryl ester transfer protein (CETP) is a crucial glycoprotein involved in lipid metabolism by transferring cholesteryl esters (CE) and triglycerides (TG) between plasma lipoproteins. CETP activity results in reduced HDL-C and increased VLDL- and LDL-C concentrations, thus increasing the risk of cardiovascular and metabolic diseases. In this review, we discuss the structure of CETP and its mechanism of action. Furthermore, we focus on recent experiments on animal CETP-expressing models, deciphering the regulation and functions of CETP in various genetic backgrounds and interaction with different external factors. Finally, we discuss recent publications revealing the association of CETP single nucleotide polymorphisms (SNPs) with the risk of cardiovascular and metabolic diseases, lifestyle factors, diet and therapeutic interventions. While CETP SNPs can be used as effective diagnostic markers, diet, lifestyle, gender and ethnic specificity should also be considered for effective treatment.

The pathophysiology of excess plasma-free cholesterol

PURPOSE OF REVIEW

Several large studies have shown increased mortality due to all-causes and to atherosclerotic cardiovascular disease. In most clinical settings, plasma HDL-cholesterol is determined as a sum of free cholesterol and cholesteryl ester, two molecules with vastly different metabolic itineraries. We examine the evidence supporting the concept that the pathological effects of elevations of plasma HDL-cholesterol are due to high levels of the free cholesterol component of HDL-C.

RECENT FINDINGS

In a small population of humans, a high plasma HDL-cholesterol is associated with increased mortality. Similar observations in the HDL-receptor deficient mouse (Scarb1 -/- ), a preclinical model of elevated HDL-C, suggests that the pathological component of HDL in these patients is an elevated plasma HDL-FC.

SUMMARY

Collective consideration of the human and mouse data suggests that clinical trials, especially in the setting of high plasma HDL, should measure free cholesterol and cholesteryl esters and not just total cholesterol.

Impaired HDL-associated enzymes and proteins in children and adolescents with weight disorders and their association with novel cardiometabolic indexes

BACKGROUND AND AIMS

Overweight/obesity (OW/OB) is associated with modifications in lipoprotein (Lp)-associated enzymes and proteins, such as cholesteryl ester transfer protein (CETP), Lp-associated phospholipase A2 (LpPLA2) and paraoxonase (PON)1. No evidence is available regarding underweight (UW). The following indexes have been proposed to better assess atherogenic risk related to weight alterations: triglycerides-glucose index (TyG), visceral adiposity index (VAI) and height-corrected lipid accumulation product (HLAP).

AIM

To analyze the presence of alterations in Lp-associated enzymes and proteins in children and adolescents with UW and OW/OB and their relation to novel cardiometabolic indexes.

METHODS AND RESULTS

Thirty male children and adolescents with UW, 66 with normal weight (NW) and 30 with OW/OB were included. Anthropometric parameters, glucose, Lp profile and the activities of CETP, LpPLA2 and PON1 were evaluated. Body mass index (BMI)-z, TyG, VAI and HLAP were calculated. UW and NW showed lower CETP activity than OW/OB (Mean ± SD) (218 ± 38vs.224 ± 26vs.237 ± 26%/mL.h; p < 0.05). UW and OW/OB showed lower PON1 activity than NW (318 ± 170vs.409 ± 200vs.310 ± 184 nmol/mL.min; p < 0.05). TyG was higher in OW/OB than UW (p < 0.01), whilst both HLAP (p < 0.05) and VAI (p < 0.01) followed a linear trend across weight categories. After adjusting for age and BMI-z, TyG was an independent predictor of CETP (r2 = 0.25, β = -0.22, p < 0.01) and LpPLA2 (r2 = 0.21,β = -0.21,p < 0.05), while VAI (r2 = 0.21,β = -0.32,p < 0.01) and HLAP (r2 = 0.20,β = -0.31,p < 0.01) of CETP.

CONCLUSIONS

Both UW and OW/OB showed impaired antioxidant PON1 activity. Moreover, TyG, VAI and HLAP were all capable of predicting alterations in crucial modulators of Lp metabolism and vascular inflammation in children and adolescents with varying degrees of alterations in body weight.

HDL as a Treatment Target: Should We Abandon This Idea?

PURPOSE OF REVIEW

High-density lipoproteins (HDL) have long been regarded as an antiatherogenic lipoprotein species by virtue of their role in reverse cholesterol transport (RCT), as well as their established anti-inflammatory and antioxidant properties. For decades, HDL have been an extremely appealing therapeutic target to combat atherosclerotic cardiovascular diseases (ASCVD).

RECENT FINDINGS

Unfortunately, neither increasing HDL with drugs nor direct infusions of reconstituted HDL have convincedly proven to be positive strategies for cardiovascular health, raising the question of whether we should abandon the idea of considering HDL as a treatment target. The results of two large clinical trials, one testing the latest CETP inhibitor Obicetrapib and the other testing the infusion of patients post-acute coronary events with reconstituted HDL, are still awaited. If they prove negative, these trials will seal the fate of HDL as a direct therapeutic target. However, using HDL as a therapeutic agent still holds promise if we manage to optimize their beneficial properties for not only ASCVD but also outside the cardiovascular field.

The evolving role of cholesteryl ester transfer protein inhibition beyond cardiovascular disease

The main role of cholesteryl ester transfer protein (CETP) is the transfer of cholesteryl esters and triglycerides between high-density lipoprotein (HDL) particles and triglyceride-rich lipoprotein and low-density lipoprotein (LDL) particles. There is a long history of investigations regarding the inhibition of CETP as a target for reducing major adverse cardiovascular events. Initially, the potential effect on cardiovascular events of CETP inhibitors was hypothesized to be mediated by their ability to increase HDL cholesterol, but, based on evidence from anacetrapib and the newest CETP inhibitor, obicetrapib, it is now understood to be primarily due to reducing LDL cholesterol and apolipoprotein B. Nevertheless, evidence is also mounting that other roles of HDL, including its promotion of cholesterol efflux, as well as its apolipoprotein composition and anti-inflammatory, anti-oxidative, and anti-diabetic properties, may play important roles in several diseases beyond cardiovascular disease, including, but not limited to, Alzheimer's disease, diabetes, and sepsis. Furthermore, although Mendelian randomization analyses suggested that higher HDL cholesterol is associated with increased risk of age-related macular degeneration (AMD), excess risk of AMD was absent in all CETP inhibitor randomized controlled trial data comprising over 70,000 patients. In fact, certain HDL subclasses may, in contrast, be beneficial for treating the retinal cholesterol accumulation that occurs with AMD. This review describes the latest biological evidence regarding the relationship between HDL and CETP inhibition for Alzheimer's disease, type 2 diabetes mellitus, sepsis, and AMD.

CETP inhibitor evacetrapib enters mouse brain tissue

High levels of plasma cholesterol, especially high levels of low-density lipoprotein cholesterol (LDL-C), have been associated with an increased risk of Alzheimer's disease. The cholesteryl ester transfer protein (CETP) in plasma distributes cholesteryl esters between lipoproteins and increases LDL-C in plasma. Epidemiologically, decreased CETP activity has been associated with sustained cognitive performance during aging, longevity, and a lower risk of Alzheimer's disease. Thus, pharmacological CETP inhibitors could be repurposed for the treatment of Alzheimer's disease as they are safe and effective at lowering CETP activity and LDL-C. Although CETP is mostly expressed by the liver and secreted into the bloodstream, it is also expressed by astrocytes in the brain. Therefore, it is important to determine whether CETP inhibitors can enter the brain. Here, we describe the pharmacokinetic parameters of the CETP inhibitor evacetrapib in the plasma, liver, and brain tissues of CETP transgenic mice. We show that evacetrapib crosses the blood-brain barrier and is detectable in brain tissue 0.5 h after a 40 mg/kg i.v. injection in a non-linear function. We conclude that evacetrapib may prove to be a good candidate to treat CETP-mediated cholesterol dysregulation in Alzheimer's disease.

Effects of Lipid-Modifying and Other Drugs on Lipoprotein(a) Levels-Potent Clinical Implications

The past few years have shown an ongoing interest in lipoprotein(a) (Lp(a)), a lipid molecule that has been proven to have atherogenic, thrombogenic, and inflammatory properties. Several lines of evidence, indeed, have demonstrated an increased risk of cardiovascular disease as well as calcific aortic valve stenosis in patients with elevated Lp(a) levels. Statins, the mainstay of lipid-lowering therapy, slightly increase Lp(a) levels, while most other lipid-modifying agents do not significantly alter Lp(a) concentrations, except for proprotein convertase subtilisin/kexin type 9 (PCSK9) inhibitors. The latter have been shown to reduce Lp(a) levels; however, the clinical significance of this effect has not been clearly elucidated. Of note, the pharmaceutical lowering of Lp(a) may be achieved with novel treatments specifically designed for this purpose (i.e., antisense oligonucleotides (ASOs) and small interfering RNAs (siRNAs)). Large clinical trials with cardiovascular outcomes with these agents are ongoing, and their results are eagerly awaited. Furthermore, several non-lipid-modifying drugs of various classes may influence Lp(a) concentrations. We have searched MEDLINE, EMBASE, and CENTRAL databases up to 28 January 2023 and summarized the effects of established and emerging lipid-modifying drugs and other medications on Lp(a) levels. We also discuss the potent clinical implications of these alterations.

Measurement of Serum Low Density Lipoprotein Cholesterol and Triglyceride-Rich Remnant Cholesterol as Independent Predictors of Atherosclerotic Cardiovascular Disease: Possibilities and Limitations

The serum low density lipoprotein cholesterol (LDL-C) concentration is the dominant clinical parameter to judge a patient's risk of developing cardiovascular disease (CVD). Recent evidence supports the theory that cholesterol in serum triglyceride-rich lipoproteins (TRLs) contributes significantly to the atherogenic risk, independent of LDL-C. Therefore, combined analysis of both targets and adequate treatment may improve prevention of CVD. The validity of TRL-C calculation is solely dependent on the accuracy of the LDL-C measurement. Direct measurement of serum LDL- C is more accurate than established estimation procedures based upon Friedewald, Martin-Hopkins, or Sampson equations. TRL-C can be easily calculated as total C minus high density lipoprotein C (HDL-C) minus LDL-C. Enhanced serum LDL-C or TRL-C concentrations require different therapeutic approaches to lower the atherogenic lipoprotein C. This review describes the different atherogenic lipoproteins and their possible analytical properties and limitations.

Higher serum apolipoprotein B level will reduce the bone mineral density and increase the risk of osteopenia or osteoporosis in adults

Objective: There is very limited evidence in the NHANES database linking serum apolipoprotein B and lumbar bone mineral density (BMD) in adults aged 20-59 years. There are few studies associating apolipoprotein B concentrations with BMD, and there is some debate about the association between obesity and BMD. Therefore, the purpose of this study was to determine the association between serum apolipoprotein B concentrations and lumbar spine BMD in adults aged 20-59 years and to predict its association with risk of osteopenia or osteoporosis. Methods: A cross-sectional study of the entire US ambulatory population was conducted using data from the National Health and Nutrition Examination Survey (NHANES) database. Weighted multiple regression equation models were used to assess the association between serum apolipoprotein B and lumbar BMD. A logistic weighted regression model was used to assess the association between serum apolipoprotein B concentrations and risk of osteopenia or osteoporosis. Subsequent stratified analyses were performed to refine the primary population of association. Results: Our study showed a significant negative association between serum apolipoprotein B concentration and lumbar BMD and a significant positive association with the risk of osteoporosis or osteopenia in the total population. After stratifying by sex, age and race, we concluded differently. The association of serum apolipoprotein B concentration with lumbar spine BMD and risk of osteopenia or osteoporosis was significant in male, but not in female. After stratification by age, the negative association between serum apolipoprotein B concentrations and lumbar BMD and the positive association with risk of osteopenia or osteoporosis was more significant in the 30-39 and 50-59 years age groups. When stratified by race, serum apolipoprotein B concentrations were significantly negatively associated with lumbar BMD and positively associated with risk of osteopenia or osteoporosis in Mexican American and non-Hispanic black populations. Thus, these findings suggest that these associations are influenced by sex, age, and race, respectively. Conclusion: Our results suggest that the association between serum apolipoprotein B levels and the risk of lumbar BMD and osteopenia or osteoporosis varies by sex, age, and race. In men, elevated serum apolipoprotein B levels were negative for bone quality. Elevated serum apolipoprotein B levels in the age groups 30-39 and 50-59 years also had a negative effect on bone quality. In the Mexican American and Non-Hispanic Black populations, elevated serum apolipoprotein B levels also had a significant negative effect on bone quality.