Monday Plenary Session focused on TG. While the role ofTG as a risk factor for coronary heart disease (CHD) has been debated for decades, there is now accumulating evidence from epidemiologic, genetic and mechanistic studies to support consideration ofTG as a treatment target in dyslipidaemia guidelines.¹    Evidence from the Copenhagen studies show that elevated TG are associated with increased risk for CV events, including stroke, as well as total mortality.^2-4    Mendelian randomization studies, which can be thought of as a ‘natural’ randomized trial, have shown causality with the individual components of TG-
rich lipoproteins, notably elevated remnants, and ischaemic heart disease (IHD). The underlying mechanism(s) of atherogenesis is likely to be similar to those implicated in the response to lipid retention mechanism proposed for low- density lipoprotein cholesterol (LDL-C).
 
Recent attention has renewed interest in apolipoprotein (apo) CIII, as discussed by Professor Anne Tybjærg-Hansen (Copenhagen University Hospital and Faculty of Health and Medical Sciences, University of Copenhagen, Denmark).
 

Population studies have consistently demonstrated that plasma apoCIII concentration strongly predicts CVD risk. Moreover, consistent evidence from two genetic studies shows that TG-lowering mutations in APOC3 (the gene coding for apoCIII) were associated with reduced risk of CHD.^5,6    Both studies showed that carriage of mutations in APOC3 not only produced consistent reduction in plasma TG levels (by 39-44%) but also reduced risk for CHD (by 40-41%). These findings provide compelling support that reducing APOC3 expression will reduce CHD risk. ProfessorTybjærg-Hansen discussed recent mechanistic evidence indicating that apoCIII exerts strong atherogenic effects, via mechanisms involved in hepatic assembly and secretion of TG-rich apoB-containing lipoproteins, activation of proinflammatory responses in vascular cells, including monocytes and endothelial cells, and, potentially, increased binding to proteoglycans. With the development of novel second generation antisense oligonucleotides targeting apoCIII, the stage is set to investigate whether modulating apoCIII can translate to reduction in CVD risk.
 
However, the role of fibrates, peroxisome proliferator- activated receptor alpha (PPAR-alpha) ligands, should not be discounted. These agents not only increase expression of genes involved in free fatty acid uptake and oxidation, but also decrease expression of apoCIII. The net effect of these actions is to increase very-low density lipoprotein (VLDL) clearance and high-density lipoprotein (HDL) production, as well as decrease VLDL production and increase LDL particle size. Furthermore, because PPARalpha can also repress transcription factors involved in vascular inflammation, they have the potential to reduce inflammation and thrombogenesis.⁷    While results from the individual fibrate trials were problematic (either for safety or efficacy reasons), subgroup analyses have shown that targeting patients with atherogenic dyslipidaemia, i.e. elevated TG and low HDL cholesterol (HDL-C), showed significant reduction in CVD events.⁸

The development of potent and selective PPARalpha modulators (SPPARMalpha) may offer therapeutic potential. One such agent in development, K-877, has shown a beneficial profile in phase II and III studies with improved lipid-modifying effects on TG and HDL-C levels compared with fenofibrate, together with a favourable tolerability profile, suggesting therapeutic potential for the management of patients with metabolic syndrome and type 2 diabetes. Furthermore, as discussed by Professor Jean-Charles Fruchart, President, Residual Risk Reduction Initiative,

such agents are also likely to have favourable effects in reducing the risk of residual macrovascular and microvascular complications, based on prior experience with fenofibrate in two major prospective studies.^9-14
 

K-877 was discussed at a number of presentations at ISA 2015. In the Clinical Breakthrough Session: lowering triglycerides as the next target in cardiovascular disease, Professor Borge Nordestgaard (University of Copenhagen, Denmark) discussed how K-877 improves the lipid profile in patients with atherogenic dyslipidaemia, based on the results from phase II clinical studies.¹⁵    K-877 has been shown to reduce apoCIII concentration, as well as remnant cholesterol (calculated as total cholesterol – LDL-C – HDL-C) and TG.
Thus, while clinical trials have shown a small increase

in LDL-C concentration, mechanistically there was no increase in LDL and remnant particles combined, as judged by no change in apoB100 concentration. There were indicators for improvement in other components of the lipid profile, notably an increase in LDL particle size, a decrease in small and
very small LDL particle concentration, as well as decreases in apoB48 and non-HDL-C. Thus, treatment with K-877 is associated with an overall reduction in the atherogenicity of the lipid profile.
Basic science research also showed that K-877 improved TG metabolism in an animal model of severe hypertriglyceridaemia.¹⁶ Zucker fatty and lean rats received either vehicle, K-877 (0.1, 0.3, 1 or 3 mg/kg) or fenofibrate (100 mg/kg) for 2 weeks. Treatment with K-877 was associated with marked reduction
in plasma TG (by up to 3-fold), accelerated TG clearance and reduced hepatic TG compared with control and fenofibrate. Importantly, K-877 also significantly increased hepatic expression of FGF21 (fibroblast growth factor 21), a metabolic hormone which plays a key role in the regulation of glucose and lipid metabolism through pleiotropic actions. In an in vitro model (isolated primary hepatocytes), K-877 increased gene expression and secretion of FGF21 compared with fenofibrate. These findings suggest that the action of K-877 on FGF21 may be highly relevant to the potency of this SPPARM in improving dyslipidaemia in patients with insulin-resistant conditions.

There were insights into the underlying mechanism(s) explaining attenuation of the development of atherosclerosis in a mouse model with the cholesteryl ester transfer protein (CETP) inhibitor, anacetrapib.¹⁷    In APOE*3 Leiden mice, fed a Western diet (with or without anacetrapib 30 mg/kg body weight/day), there was 47% reduction in plasma PCSK9 levels together with 28% reduction in hepatic PCSK9 mRNA expression and a 64% increase in hepatic LDL receptor protein expression. These findings were consistent with increased clearance (by 54%) and uptake (by 25%) of [14C] cholesteryl oleate-labelled VLDL remnants. Anacetrapib did not influence VLDL-TG production or clearance. Moreover, in APOE*3 Leiden mice that did not express CETP, anacetrapib still decreased plasma VLDL-cholesterol and PCSK9 levels. Taken together, these findings suggest that anacetrapib reduces VLDL-cholesterol by increasing hepatic remnant uptake by two mechanisms: 1) inhibition of CETP activity and 2) CETP- independent reduction of plasma PCSK9 levels.

 

Reduction in apoCIII may explain the TG-lowering effects of omega-3 carboxylic acids, according to an analysis from the EVOLVE study (Epanova For LoweringVery High Triglycerides) in 273 patients (fasting TG between 500- 2000 mg/dL or 5.6-22.6 mmol/L), randomised to Epanova (omega-3 carboxylic acids) 2 mg or 4 mg daily or placebo.¹⁸ Treatment with Epanova significantly reduced apoCIII relative to placebo (p<0.0001), as well as decreasing apoCIII concentration in HDL and LDL.

 

Data from the LURIC (Ludwigshafen Risk and Cardiovascular Health) study challenged whether apoCII should be considered as a potential target for the treatment of elevated TG.¹⁹    This analysis was based on data from 3,266 patients who had previously undergone coronary angiography. During a median follow-up period of 9.9 years, 608 patients died of CVD. Both apoCII and apoCIII concentrations were positively associated with plasma levels of TG and TG-rich lipoproteins; however, the association with severity of coronary artery disease was stronger for apoCII. These findings suggest that there may be merit in evaluating the potential of apoCII as a therapeutic target

Treatment with liraglutide, a long-acting glucagon-like peptide-1 receptor agonist, improved atherogenic dyslipidaemia and subclinical atherosclerosis in individuals with metabolic syndrome.²⁰    This study included 109 subjects with type 2 diabetes and metabolic syndrome (66 men and 43 women, mean age 62 years). None of the subjects had
a previous CV event. Subjects were treated with liraglutide 1.2 mg/day, in addition to metformin 1500 mg/day. Carotid intima media thickness was evaluated by B-mode ultrasonography. Over the 18-month follow-up period, treatment with liraglutide was associated with improvement in TG (by 21%, p=0.008), as well as body mass index (p=0.032), fasting glycaemia (p<0.0001) and LDL-C levels (p<0.05); HDL-C levels did not change significantly. In addition, treatment with liraglutide was associated with significant reduction in carotid intima media thickness over 18 months (0.97±0.17 mm to 0.82±0.16 mm, p=0.026). There was a significant association between changes in carotid intima- media thickness and TG (p=0.026).

 

Another study showed beneficial effects on atherogenic remnant lipoproteins with sitagliptin, a dipeptidyl peptidase-4 (DPP-4) inhibitor.²¹    In total, 38 type 2 diabetes patients (HbA1c <8.4%) were treated with sitagliptin, started at a dose of 50 mg/day and uptitrated to 100 mg daily, in addition to other glucose-lowering treatment, in order to attain an HbA1c <7.4%. Sitagliptin decreased fasting glucose (150±47 mg/dL versus 129±27 mg/dL, p<0.01), HbA1c (7.1± 0.6% versus 6.6±0.7%, p<0.01), as well as fasting TG (161±90 mg/dL versus 130±66 mg/dL) and non-HDL-C (129±29 mg/dL versus 116±20 mg/dL). There was also significant reduction in remnant cholesterol (15.3±9.5 mg/dL versus 12.0±7.9 mg/dL, p<0.05), as well as levels of apoB, apoCII, apoCIII, and apoE. Moreover, cholesterol and TG concentrations of the VLDL and LDL fractions were also decreased. These findings suggest that favourable effects on the lipid and lipoprotein profile with sitagliptin may be mediated by a decrease in atherogenic remnant lipoproteins.

Finally, with ongoing interest in PCSK9 monoclonal antibody therapy, there was reassuring news that these agents are effective in patients with mixed dyslipidaemia, or elevated TG/low HDL-C.

 
In the first report,²² data from four 12-week phase III randomised trials (n=1,148 patients) evaluated the efficacy of evolocumab in patients with mixed dyslipidaemia, baseline mean LDL-C 3.4 mmol/L (or 132 mg/dL), median (interquartile range)TG 2.0 (1.6-2.5) mmol/L (or 180 [140- 220] mg/dL) and mean HDL-C 1.2 mmol/L (or 46 mg/dL). The reduction in LDL-C with evolocumab in patients with mixed dyslipidaemia was similar to that observed in other patient groups (67% versus placebo and 42% versus ezetimibe). Evolocumab has recently received a positive opinion from the Committee for Medicinal Products for Human Use of the European Medicines Agency for the treatment of adults with primary hypercholesterolaemia or mixed dyslipidaemia, as an adjunct to diet; in combination with a statin or statin with other lipid-lowering therapies in patients unable to reach LDL-C goals with the maximum tolerated dose of a statin; alone or in combination with other lipid-lowering therapies in patients who are statin-intolerant, or for whom a statin is contraindicated; and for the treatment of adults and adolescents aged 12 years and over with homozygous familial hypercholesterolemia in combination with other lipid-lowering therapies.²³

 

The second report²⁴ included data from two trials with alirocumab 150 mg every 2 weeks versus placebo (n=2,416), and eight trials with alirocumab 75 mg, titrating to 150 mg every 2 weeks versus either ezetimibe or placebo (n=2,499). There was no difference in the efficacy of alirocumab in patients with baseline TG above/below 1.69 mmol/L (or 150 mg/dL) or HDL-C below/above 1.03 mmol/L (or 40 mg/dL).