Clinical trials with cholesteryl ester transfer protein inhibitors

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.

High-Density Lipoproteins: A Role in Inflammation in COPD

Chronic obstructive pulmonary disease (COPD) is a widespread disease associated with high rates of disability and mortality. COPD is characterized by chronic inflammation in the bronchi as well as systemic inflammation, which contributes significantly to the clinically heterogeneous course of the disease. Lipid metabolism disorders are common in COPD, being a part of its pathogenesis. High-density lipoproteins (HDLs) are not only involved in lipid metabolism, but are also part of the organism's immune and antioxidant defense. In addition, HDL is a versatile transport system for endogenous regulatory agents and is also involved in the removal of exogenous substances such as lipopolysaccharide. These functions, as well as information about lipoprotein metabolism disorders in COPD, allow a broader assessment of their role in the pathogenesis of heterogeneous and comorbid course of the disease.

U-Shaped Association of High-Density Lipoprotein Cholesterol with All-Cause and Cardiovascular Mortality in Hypertensive Population

Purpose

Whether the paradox of high-density lipoprotein cholesterol (HDL-C) and elevated mortality risk extends to hypertensive patients is unclear. We aimed to investigate the association between HDL-C and all-cause and cardiovascular disease mortality in adults with hypertension.

Methods

In the National Health and Nutrition Examination Surveys, 11,497 hypertensive participants aged ≥18years old and examined at baseline between 1999 and 2014 were followed up until December 2015. We categorized the HDL-C concentration as ≤30, 31–40, 41–50, 51–60 (reference), 61–70, >70 mg/dL and examined their associations with all-cause and cardiovascular mortality, respectively. Multivariate Cox regression was used to calculated hazard ratio (HR) and 95% confidence interval (CI) for mortality risk.

Results

During follow-up (median: 9.2 ± 3.8 years), 3012 deaths and 713 cardiovascular deaths were observed. In the restrictive cubic curves, associations of HDL-C levels and all-cause and cardiovascular mortality were detected to be U-shaped. After multivariable adjustment, HRs for all-cause mortality were for the lowest HDL-C concentration (≤30 mg/dL) 1.29 (95% CI, 1.07–1.56) and the highest (>70 mg/dL) 1.20 (1.06–1.37), comparing with the reference group. For cardiovascular mortality, HRs were 1.31 (0.83–1.48) and 1.09 (0.83–1.43), respectively. Similar results were obtained in subgroups stratified by age, gender, race, and taking lipid-lowering drugs. The lowest all-cause mortality risk was observed at HDL-C 66 mg/dL (concentration) and 51–60 mg/dL (range).

Conclusion

Both lower and higher HDL-C concentration appeared to be associated with higher mortality in hypertensive population. Further investigation is warranted to clarify the underlying mechanisms.

ApoC2 deficiency elicits severe hypertriglyceridemia and spontaneous atherosclerosis: A rodent model rescued from neonatal death

RATIONALE

ApoC2 is an important activator for lipoprotein lipase-mediated hydrolysis of triglyceride-rich plasma lipoproteins. ApoC2-deficient patients display severe hypertriglyceridemia (sHTG) and recurrent acute pancreatitis. However, due to embryonic lethality in ApoC2 deleted mouse extensive understanding of ApoC2 function is limited in mammalian species.

OBJECTIVE

We sought to generate an animal model with ApoC2 deficiency in a rodent with some human-like features and then study the precise effects of ApoC2 on lipid and glucose homeostasis.

METHODS AND RESULTS

Using CRISPR/Cas9, we deleted Apoc2 gene from golden Syrian hamster and the homozygous (-/-) pups can be born in matured term but exhibited neonatal lethality. By continuous iv administration of normal hamster serum the ApoC2^-/- pups could survive till weaning and displayed severe HTG in adulthood on chow diet. A single iv injection of AAV-hApoC2 at birth can also rescue the neonatal death of ApoC2^-/- pups. Adult ApoC2^-/-hamsters exhibited a unique phenotype of sHTG with hypoglycemia, hypoinsulinemia and spontaneous atherosclerosis. The sHTG in ApoC2^-/- adult hamsters could not be corrected by various lipid-lowering medications, but partially ameliorated by medium chain triglyceride diet and completely corrected by AAV-hApoC2.

CONCLUSIONS

Our study provides a novel ApoC2-deleted mammalian model with severe hypertriglyceridemia that was fully characterized and highlights a potential therapeutic approach for the treatment of ApoC2 deficient patients.

Lower or higher HDL-C levels are associated with cardiovascular events in the general population in rural China

BACKGROUND

The present study aims to estimate whether high-density lipoprotein cholesterol (HDL-C) is correlated with cardiovascular events (CVEs) and cardiovascular mortality (CVM) in a large sample of the general population in rural areas of China.

METHODS

Adult participants (n = 10,266, age = 53.79 ± 10.49 years; 46.5% men) were enrolled from the Northeast China Rural Cardiovascular Health Study (NCRCHS). Laboratory testing, blood pressure, weight, height, and questionnaires about socioeconomic status were collected.

RESULTS

In all, 585 nonfatal or fatal CVEs and 212 cardiovascular deaths were documented during a 4.66-year follow-up. Compared to the reference groups (HDL-C between 1.5 and 1.99 mmol/L), either lower or higher levels of HDL-C were correlated with an increased incidence of CVEs but not CVM [hazard ratio (HR) _{the lowest} = 1.369, 95% confidence interval, 1.007-1.861; HR _{the highest} = 1.044, 0.509-2.231]. Elevated CVM was seen in the lowest HDL-C category (1.840; 1.121-3.021).

CONCLUSIONS

Lower or higher HDL-C was associated with a higher incidence of CVEs but not CVM in the general population of rural China. Perhaps if an appropriate level of HDL-C is maintained, CVEs can be effectively prevented.

Effect of Food on the Pharmacokinetics of 2 Formulations of DRL-17822, a Novel Selective Cholesteryl Ester Transfer Protein (CETP) Inhibitor, in Healthy Males

DRL-17822 is a novel selective cholesteryl ester transfer protein inhibitor that showed an increased exposure, including an increase of >20-fold of maximum concentration and area under the plasma concentration-time curve from time zero to the time of the last quantifiable concentration, following a high-fat breakfast using a nanocrystal formulation. To reduce this effect of food, we generated an amorphous solid dispersion formulation. In this study, we compared the food effect of both formulations of DRL-17822 in a 2-part randomized, open-label, 4-way crossover study involving healthy adult males 18-45 years of age. In both parts of the study, 12 subjects received both formulations of DRL-17822 in both the fasted and fed states; a low-fat breakfast was provided in the first part and a high-fat breakfast in the second part. Compared to the nanocrystal formulation, the amorphous solid dispersion formulation substantially increased DRL-17822 exposure in the fasted state, including increased maximum concentration, area under the plasma concentration-time curve from time zero to the time of the last quantifiable concentration, and area under plasma concentration-time curve from time zero to infinity. Following a high-fat breakfast, DRL-17822 exposure was increased to a lesser extent in the amorphous solid dispersion formulation compared to the nanocrystal formulation (P < .001). Moreover, compared to the nanocrystal formulation the amorphous solid dispersion formulation caused a more pronounced increase in high-density lipoprotein in the fasted state. Consuming breakfast increased the effect of DRL-17822 on high-density lipoprotein. Taken together, our results indicate that by improving its formulation, DRL-17822 has a favorable exposure profile and therefore a more predictable food effect profile.

New strategies for the development of lipid-lowering therapies to reduce cardiovascular risk

The very high occurrence of cardiovascular events presents a major public health issue, because treatment remains suboptimal. Lowering LDL cholesterol (LDL-C) with statins or ezetimibe in combination with a statin reduces major adverse cardiovascular events. The cardiovascular risk reduction in relation to the absolute LDL-C reduction is linear for most interventions without evidence of attenuation or increase in risk at low LDL-C levels. Opportunities for innovation in dyslipidaemia treatment should address the substantial risk of lipid-associated cardiovascular events among patients optimally treated per guidelines but who cannot achieve LDL-C goals and who could benefit from additional LDL-C-lowering therapy or experience side effects of statins. Fresh approaches are needed to identify promising drug targets early and develop them efficiently. The Cardiovascular Round Table of the European Society of Cardiology (ESC) convened a workshop to discuss new lipid-lowering strategies for cardiovascular risk reduction. Opportunities to improve treatment approaches and the efficient study of new therapies were explored. Circulating biomarkers may not be fully reliable proxy indicators of the relationship between treatment effect and clinical outcome. Mendelian randomization studies may better inform development strategies and refine treatment targets before Phase 3. Trials should match the drug to appropriate lipid and patient profile, and guidelines may move towards a precision-based approach to individual patient management. Stakeholder collaboration is needed to ensure continued innovation and better international coordination of both regulatory aspects and guidelines. It should be noted that risk may also be addressed through increased attention to other risk factors such as smoking, hypertension, overweight, and inactivity.

Cholesteryl ester transfer protein and its inhibitors

Most of the cholesterol in plasma is in an esterified form that is generated in potentially cardioprotective HDLs. Cholesteryl ester transfer protein (CETP) mediates bidirectional transfers of cholesteryl esters (CEs) and triglycerides (TGs) between plasma lipoproteins. Because CE originates in HDLs and TG enters the plasma as a component of VLDLs, activity of CETP results in a net mass transfer of CE from HDLs to VLDLs and LDLs, and of TG from VLDLs to LDLs and HDLs. As inhibition of CETP activity increases the concentration of HDL-cholesterol and decreases the concentration of VLDL- and LDL-cholesterol, it has the potential to reduce atherosclerotic CVD. This has led to the development of anti-CETP neutralizing monoclonal antibodies, vaccines, and antisense oligonucleotides. Small molecule inhibitors of CETP have also been developed and four of them have been studied in large scale cardiovascular clinical outcome trials. This review describes the structure of CETP and its mechanism of action. Details of its regulation and nonlipid transporting functions are discussed, and the results of the large scale clinical outcome trials of small molecule CETP inhibitors are summarized.

High density lipoprotein with apolipoprotein C-III is associated with carotid intima-media thickness among generally healthy individuals

BACKGROUND AND AIMS

About 6-7% of high density lipoprotein (HDL) has a protein called apolipoprotein (apo) C-III that regulates lipoprotein metabolism and can provoke an inflammatory response. HDL without apoC-III is inversely associated with coronary heart disease (CHD), whereas HDL with apoC-III is directly associated with CHD. We investigated how the presence of apoC-III affects the association between HDL and early stages of atherosclerosis measured as carotid intima-media thickness (cIMT).

METHODS

We examined the cross-sectional associations between the apoA-I concentrations of HDL subspecies with and without apoC-III and cIMT measured by high resolution B-mode carotid ultrasonography among 847 participants from the European multi-center Relationship between Insulin Sensitivity and Cardiovascular disease (RISC) study.

RESULTS

HDL with and without apoC-III demonstrated significantly opposite associations with both cIMT indexes (p-heterogeneity of associations comparing the two subspecies was 0.002 for cIMT at common carotid artery (cIMT at CCA) and 0.006 for the maximum cIMT in any carotid segment (cIMT max)). Compared to the lowest quintile, the highest quintile of apoA-I in HDL without apoC-III was associated with 3.7% lower cIMT at CCA (p-trend = 0.01) or 7.3% lower cIMT max (p-trend = 0.003), while the highest quintile of apoA-I in HDL with apoC-III was associated with 4.4% higher cIMT at CCA (p-trend = 0.001) or 7.9% higher cIMT max (p-trend = 0.002). Total apoA-I as well as total HDL cholesterol was not associated with cIMT whereas higher levels of total apoC-III and apoC-III contained in HDL were significantly associated with higher cIMT (p-trend<0.01).

CONCLUSIONS

HDL apoC-III is a promising target for atherosclerosis prevention and treatment.

Incorporation of PCSK9 inhibitors into prevention of atherosclerotic cardiovascular disease

Primary and secondary prevention of atherosclerotic cardiovascular disease (ASCVD) has become recently more complex than ever, leaving the clinicians perplexed with outdated guidelines and emerging evidence about new LDL-C lowering therapies. 2013 American College of Cardiology (ACC)/American Heart Association (AHA) guidelines have focused on high intensity statin therapy for specific groups of patients, while abandoning long established LDL-C goals, a strategy which no longer seems valid. PCSK9 (proprotein convertase subtilisin/kexin type 9) inhibitors have emerged as the add-on therapy on top of statins and/or ezetimibe for the treatment of hypercholesterolemia and ASCVD prevention. In several clinical trials, PCSK9 inhibitors have demonstrated their safety and robust LDL-C-lowering power. One completed cardiovascular (CV) outcomes trial (FOURIER; Further Cardiovascular Outcomes Research with PCSK9 Inhibitions in Subjects with Elevated Risk) has demonstrated that PCSK9 inhibition reduces rates of CV death as well as non-fatal stroke and MI, while another major CV outcome trial is under way (ODYSSEY-OUTCOMES). Several trials studying CV benefits of novel LDL-C-lowering therapies are also being conducted. Prompt revision of ACC/AHA guidelines is necessary. In the meantime, physicians need to use clinical judgment integrating the most recent evidence into their practice.