The evidence-base for the efficacy of lipoprotein apheresis in combating cardiovascular disease

Evinacumab: a new option in the treatment of homozygous familial hypercholesterolemia

INTRODUCTION

Familial hypercholesterolemia is a genetic disorder characterized by elevated levels of low-density lipoprotein cholesterol (LDL-C) since birth and an exceedingly high risk of premature cardiovascular disease, especially in the homozygous form (HoFH). Despite the availability of effective cholesterol-lowering drugs, substantial LDL-C and cardiovascular risk reductions in these patients are still problematic, especially in those carrying mutations in the low-density lipoprotein receptor (LDLR) gene.

AREAS COVERED

Loss-of-function mutations in angiopoietin-like 3 (ANGPTL3) encoding gene are associated with lower levels of LDL-C and reduced cardiovascular risk; the pharmacological inhibition of ANGPTL3 reduces LDL-C levels independently of LDLR. This approach can thus improve the treatment of HoFH using a monoclonal antibody targeting ANGPTL3 (evinacumab).

EXPERT OPINION

Most lipid-lowering agents available so far are insufficient to achieve an appropriate response in HoFH patients. The inhibition of ANGPTL3 with evinacumab halves LDL-C levels in HoFH patients by an LDLR-independent mechanism. The results obtained so far have clearly indicated a promising improvement in the management of these patients. As the reduction of CV risk is proportional to the absolute reduction in LDL-C levels, we can expect that treatment with evinacumab, added to the maximally tolerated lipid-lowering therapy, will turn into a significant clinical benefit.

Contemporary Management of Dyslipidemia

The treatment of dyslipidemia continues to be a dynamic and controversial topic. Even the most appropriate therapeutic range for lipid levels-including that of triglycerides and low-density lipoprotein cholesterol-remain actively debated. Furthermore, with ever-increasing options and available treatment modalities, the management of dyslipidemia has progressed in both depth and complexity. An understanding of appropriate lipid-lowering therapy remains an essential topic of review for practitioners across medical specialties. The goal of this review is to provide an overview of recent research developments and recommendations for patients with dyslipidemia as a means of better informing the clinical practice of lipid management. By utilizing a guideline-directed approach, we provide a reference point on optimal lipid-lowering therapies across the spectrum of dyslipidemia. Special attention is paid to long-term adherence to lipid-lowering therapies, and the benefits derived from instituting appropriate medications in a structured manner alongside monitoring. Novel therapies and their impact on lipid lowering are discussed in detail, as well as potential avenues for research going forward. The prevention of cardiovascular disease remains paramount, and this review provides a roadmap for instituting appropriate therapies in cardiovascular disease prevention.

Vascular access for lipid apheresis: a challenge in young children with homozygous familial hypercholesterolemia

Background

Homozygous familial hypercholesterolemia (hoFH) is a rare genetic disorder leading to extremely increased LDL-cholesterol (LDL-C), resulting in high cardiovascular risk in early childhood. Lipid apheresis (LA) is an effective treatment and should be started as early as possible to prevent premature cardiovascular events. As peripheral punctures in children can be challenging due to small vessels and anxiety, this study aimed to evaluate feasibility and safety of central venous catheters (CVCs) as vascular access for LA in young children with hoFH.

Methods

Retrospective analysis (2016-2019) on four children with hoFH aged 3-5 years, performing weekly or biweekly LA with a CVC.

Results

LDL-C decreased by> 60%. In three children, the use of a permanent CVC for 698, 595, and 411 days, respectively, avoided difficult peripheral access, without the occurrence of occlusion or thrombosis. Unfortunately, one child had recurrent CVC-related infections and needed an arteriovenous fistula from the age of 5. Although the mean dwell time per catheter was 212 days, there were, as expected, severe side effects of early catheter infections with sepsis and accidental self-removal. Starting LA at an early age improved or stabilized carotid intima-media thickness (IMT) in three children. However, IMT did increase in one child caused by intolerance to peripheral punctures and LA interruption.

Conclusions

Permanent CVCs are a viable temporary access choice for LA in young children with hoFH until peripheral venipuncture is practicable. The risk of CVC-related infections needs to be taken into account.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12887-022-03192-7.

Developing a second-generation clinical candidate AAV vector for gene therapy of familial hypercholesterolemia

Gene therapy for hypercholesterolemia offers the potential to sustainably ameliorate disease for life with a single dose. In this study, we demonstrate the combinatorial effects of codon and vector optimization, which significantly improve the efficacy of an adeno-associated virus (AAV) vector in the low-density lipoprotein receptor (LDLR)-deficient mouse model (Ldlr -/-, Apobec1 -/- double knockout [DKO]). This study investigated vector efficacy following the combination of intervening sequence 2 (IVS2) of the human beta-globin gene and codon optimization with the previously developed gain-of-function, human LDLR triple-mutant variant (hLDLR-L318D/K809R/C818A) in the treatment of homozygous familial hypercholesterolemia (HoFH). Vector doses as low as 3 × 1011 genome copies (GC)/kg achieved a robust reduction of serum low-density lipoprotein cholesterol (LDL-C) by 98% in male LDLR-deficient mice. Less efficient LDL-C reduction was observed in female mice, which was attributable to lower gene transfer efficiency in liver. We also observed persistent and stable transgene expression for 120 days, with LDL-C levels being undetectable in male DKO mice treated with the second-generation vector. In conclusion, codon and vector optimization enhanced transgene expression and reduced serum LDL-C levels effectively at a lower dose in LDLR-deficient mice. The second-generation clinical candidate vector we have developed has the potential to achieve therapeutic effects in HoFH patients.

Possible mechanisms of cholesterol elevation aggravating COVID-19

Importance: Despite the availability of a vaccine against the severe acute respiratory syndrome-coronavirus-2 (SARS-CoV-2), humans will have to live with this virus and the after-effects of the coronavirus disease 2019 (COVID-19) infection for a long time. Cholesterol plays an important role in the infection and prognosis of SARS-CoV-2, and the study of its mechanism is of great significance not only for the treatment of COVID-19 but also for research on generic antiviral drugs. Observations: Cholesterol promotes the development of atherosclerosis by activating NLR family pyrin domain containing 3 (NLRP3), and the resulting inflammatory environment indirectly contributes to COVID-19 infection and subsequent deterioration. In in vitro studies, membrane cholesterol increased the number of viral entry sites on the host cell membrane and the number of angiotensin-converting enzyme 2 (ACE2) receptors in the membrane fusion site. Previous studies have shown that the fusion protein of the virus interacts with cholesterol, and the spike protein of SARS-CoV-2 also requires cholesterol to enter the host cells. Cholesterol in blood interacts with the spike protein to promote the entry of spike cells, wherein the scavenger receptor class B type 1 (SR-B1) plays an important role. Because of the cardiovascular protective effects of lipid-lowering therapy and the additional anti-inflammatory effects of lipid-lowering drugs, it is currently recommended to continue lipid-lowering therapy for patients with COVID-19, but the safety of extremely low LDL-C is questionable. Conclusions and Relevance: Cholesterol can indirectly increase the susceptibility of patients to SARS-CoV-2 and increase the risk of death from COVID-19, which are mediated by NLRP3 and atherosclerotic plaques, respectively. Cholesterol present in the host cell membrane, virus, and blood may also directly participate in the virus cell entry process, but the specific mechanism still needs further study. Patients with COVID-19 are recommended to continue lipid-lowering therapy.

Case Report: Liver Transplantation in Homozygous Familial Hypercholesterolemia (HoFH)-Long-Term Follow-Up of a Patient and Literature Review

Homozygous familial hypercholesterolemia (HoFH) is a rare inherited metabolic disorder, frequently leading to an early cardiovascular death if not adequately treated. Since standard medications usually fail to reduce LDL-cholesterol (LDL-C) levels satisfactorily, LDL-apheresis is a mainstay of managing HoFH patients but, at the same time, very burdensome and suboptimally effective. Liver transplantation (LT) has been previously shown to be a promising alternative. We report on a 14 year-long follow-up after LT in a HoFH patient. At the age of 4, the patient was referred to our institution because of the gradually increasing number of xanthomas on the knees, elbows, buttocks, and later the homozygous mutation c.1754T>C (p.Ile585Thr) on the LDL-receptor gene was confirmed. Despite subsequent intensive treatment with the combination of diet, statins, bile acid sequestrant, probucol, and LDL-apheresis, the patient developed valvular aortic stenosis and aortic regurgitation by 12 years. At 16 years, the patient successfully underwent deceased-donor orthotopic LT. Nine years post-LT, we found total regression of the cutaneous xanthomas and atherosclerotic plaques and with normal endothelial function. Fourteen years post-LT, his clinical condition remained stable, but LDL-C levels have progressively risen. In addition, a systematic review of the literature and guidelines on the LT for HoFH patients was performed. Six of the 17 identified guidelines did not take LT as a treatment option in consideration at all. But still the majority of guidelines suggest LT as an exceptional therapeutic option or as the last resort option when all the other treatment options are inadequate or not tolerated. Most of the observed patients had some kind of cardiovascular disease before the LT. In 76% of LT, the cardiovascular burden did not progress after LT. According to our experience and in several other reported cases, the LDL-C levels are slowly increasing over time post LT. Most of the follow-up data were short termed; only a few case reports have followed patients for 10 or more years after LT. LT is a feasible therapeutic option for HoFH patients, reversing atherosclerotic changes uncontrollable by conservative therapy, thus importantly improving the HoFH patient's prognosis and quality of life.

The Impact of Lipoprotein Apheresis on Oxidative Stress Biomarkers and High-Density Lipoprotein Subfractions

Lipoprotein apheresis (LA) treatment results in a substantial reduction of low-density lipoprotein- (LDL-) cholesterol and lipoprotein(a) concentrations, which consequently decreases the rate of cardiovascular events. The additional benefit of LA may be associated with its impact on the composition and quality of high-density lipoprotein (HDL) particles, inflammation, and oxidative stress condition. To verify the effects of LA procedure, the current study is aimed at analyzing the effect of a single apheresis procedure with direct hemadsorption (DALI) and cascade filtration (MONET) on oxidative stress markers and HDL-related parameters. The study included eleven patients with familial hypercholesterolemia and hyperlipoproteinemia(a) treated with regular LA (DALI or MONET). We investigated the pre- and postapheresis concentration of the lipid-related oxidative stress markers 8-isoPGF2, oxLDL, TBARS, and PON-1. We also tracked potential changes in the main HDL apolipoproteins (ApoA-I, ApoA-II) and cholesterol contained in HDL subfractions. A single session of LA with DALI or MONET techniques resulted in a similar reduction of lipid-related oxidative stress markers. Concentrations of 8-isoPGF2 and TBARS were reduced by ~60% and ~30%, respectively. LA resulted in a 67% decrease in oxLDL levels along with a ~19% reduction in the oxLDL/ApoB ratio. Concentrations of HDL cholesterol, ApoA-I, ApoA-II, and PON-1 activity were also reduced by LA sessions, with more noticeable effects seen in the MONET technique. The quantitative proportions between HDL₂ and HDL₃ cholesterol did not change significantly by both methods. In conclusion, LA treatment with MONET or DALI system has a small nonselective effect on lowering HDL particles without any changes in the protein composition of these particles. Significant reduction in the level of oxidative stress parameters and less oxidation of LDL particles may provide an additional benefit of LA therapy.

Improvement of oxidative stress status by lipoprotein apheresis in Chinese patients with familial hypercholesterolemia

BACKGROUND AND AIMS

Familial hypercholesterolemia (FH) characterized by severe high blood cholesterol levels usually presents an imbalance of systemic oxidative stress (OS). Lipoprotein apheresis (LA), which is the most effective therapy to reduce cholesterol levels, remains unclear in altering OS and scarce in Chinese patient studies. Our study aims to assess the impact of LA on OS status in Chinese patients with FH.

METHODS

About 31 patients (22 males, age: 12-69 years) with FH and receiving LA treatment were consecutive enrolled. Free oxygen radicals test (FORT) and free oxygen radicals defense (FORD) values were determined using the free oxygen radical monitor and kit immediately before and after LA, while blood samples were collected to measure plasma lipid levels and hs-CRP by conventional methods. Data were analyzed by paired t test or rank sum test and Spearman-rho correlation analysis.

RESULTS

Besides plasma lipid levels, the OS status showed that FORTs were significantly decreased and FORD values significantly enhanced immediately after LA treatment compared with before (both P < .01). In addition, the correlation analysis showed that the removal rates (△%) of TC were positively related to the increased rates (△%) of FORD value (ρ = 0.513, P = .003); LDL-C to FORD (ρ = 0.39, P = .03); Lp(a) to FORD (ρ = 0.473, P = .007); and non-HDL-C to FORD (ρ = 0.46, P = .009). However, no significant difference in hsCRP was found.

CONCLUSIONS

The present study indicated, besides effectively lowering plasma lipid levels, LA could significantly improve OS status in Chinese patients with FH.

Lipid Screening, Action, and Follow-up in Children and Adolescents

Purpose of Review

To create awareness for the devastating influence of high cholesterol in familial hypercholesterolaemia (FH) on vessel walls. Persons with high LDL-C and a known mutation associated with FH have a 22-fold increase in CVD compared with those with a normal LDL-C and no genetic mutation. If the awareness of the need to diagnose and treat this genetic disorder at an early stage increases, great atherosclerotic impact later in life could be avoided. Every minute a child with heterozygous FH is born somewhere in the world and every day a child with homozygous FH is born.

Recent Findings

Recent findings include effective therapy on statins from the age of 6 years, with already normalization of the intima-media thickness within 2 years. Newer types of drugs, with the same safety profile and perhaps even more effective, will become available in childhood in the near future. Open for discussion will be whom to treat and with what type of treatment. Next generation sequencing will perhaps easily select those in need of treatment and those at risk of adverse effects.

Summary

At the end of this review, statements and recommendations for children and adolescents with heterozygous FH are listed.

Genetic analysis in a compound heterozygote family with familial hypercholesterolemia

Homozygous familial hypercholesterolemia (FH) is rare, with an incidence of ~one in a million and commonly presents with a genetic mutation. The genetic variations of families with FH were clinically analyzed to investigate the association between the phenotype and genotype of patients. Direct sequencing was conducted for the proband and her parents to detect mutations in the fragment of 18 exons of the low‑density lipoprotein receptor (LDLR) and apolipoprotein B100 Q3500R in the peripheral blood genomic DNA. The gene sequences were compared with normal ones to find mutations using GenBank. The QX200 Droplet Digital PCR system was used to detect target DNA copy number variations of the proband and her parents. The functional alterations resulting from the novel mutations were verified by quantitative polymerase chain reaction, western blotting and flow cytometric analyses. The lipid levels of the proband and her parents were all elevated. Genetic testing results indicated that the proband and her mother had a novel heterozygous missense mutation (C377G, 28893T>G) in exon 8 of the LDLR gene, whereas the proband and her father had LDLR gene DNA fragment deletions in exon 18. Clinically, the proband was of a compound heterozygous genotype and her parents were of the simple heterozygous genotype. Furthermore, both mutations led to impaired expression and LDL binding and internalization function of LDLR in vitro. The proband's genotype was confirmed to be compound heterozygous FH, leading to clinical manifestations in line with the homozygous FH phenotype. The phenotype is highly associated with the genotype in this type of compound heterozygous FH.

Familial hypercholesterolaemia

Familial hypercholesterolaemia is a common inherited disorder characterized by abnormally elevated serum levels of low-density lipoprotein (LDL) cholesterol from birth, which in time can lead to cardiovascular disease (CVD). Most cases are caused by autosomal dominant mutations in LDLR, which encodes the LDL receptor, although mutations in other genes coding for proteins involved in cholesterol metabolism or LDLR function and processing, such as APOB and PCSK9, can also be causative, although less frequently. Several sets of diagnostic criteria for familial hypercholesterolaemia are available; common diagnostic features are an elevated LDL cholesterol level and a family history of hypercholesterolaemia or (premature) CVD. DNA-based methods to identify the underlying genetic defect are desirable but not essential for diagnosis. Cascade screening can contribute to early diagnosis of the disease in family members of an affected individual, which is crucial because familial hypercholesterolaemia can be asymptomatic for decades. Clinical severity depends on the nature of the gene that harbours the causative mutation, among other factors, and is further modulated by the type of mutation. Lifelong LDL cholesterol-lowering treatment substantially improves CVD-free survival and longevity. Statins are the first-line therapy, but additional drugs, such as ezetimibe, bile acid sequestrants, PCSK9 inhibitors and other emerging therapies, are often required.

Vascular access in lipoprotein apheresis: a retrospective analysis from the UK's largest lipoprotein apheresis centre

INTRODUCTION

Lipoprotein apheresis (LA) has proven to be an effective, safe and life-saving therapy. Vascular access is needed to facilitate this treatment but has recognised complications. Despite consistency in treatment indication and duration there are no guidelines in place. The aim of this study is to characterise vascular access practice at the UK's largest LA centre and forward suggestions for future approaches.

METHODS

A retrospective analysis of vascular access strategies was undertaken in all patients who received LA treatment in the low-density lipoprotein (LDL) Apheresis Unit at Harefield Hospital (Middlesex, UK) from November 2000 to March 2016.

RESULTS

Fifty-three former and current patients underwent 4260 LA treatments. Peripheral vein cannulation represented 79% of initial vascular access strategies with arteriovenous (AV) fistula use accounting for 15%. Last used method of vascular access was peripheral vein cannulation in 57% versus AV fistula in 32%. Total AV fistula failure rate was 37%.

CONCLUSIONS

Peripheral vein cannulation remains the most common method to facilitate LA. Practice trends indicate a move towards AV fistula creation; the favoured approach receiving support from the expert body in this area. AV fistula failure rate is high and of great concern, therefore we suggest the implementation of upper limb ultrasound vascular mapping in all patients who meet treatment eligibility criteria. We encourage close ties between apheresis units and specialist surgical centres to facilitate patient counselling and monitoring. Further prospective data regarding fistula failure is needed in this expanding treatment field.

Specific Lp(a) apheresis: A tool to prove lipoprotein(a) atherogenicity

BACKGROUND

An elevated lipoprotein(a) (Lp(a)) level is observed in more than 30% of patients with stable ischemic heart disease (SIHD). We conducted an investigation of the effects of specific Lp(a) apheresis on the progression of atherosclerosis in SIHD patients with Lp(a) levels greater than 50 mg/dL.

METHODS

We prospectively enrolled 15 patients diagnosed with SIHD based on symptom-driven coronary angiography findings, with Lp(a) ≥50 mg/dL and a low density lipoprotein cholesterol (LDL-C) ≤2.5 mmol/L, who were on long-term statin therapy. They underwent weekly Lp(a) apheresis using Lp(a) Lipopak^® adsorption columns which contain monospecific sheep polyclonal antibodies against human Lp(a). Fifteen age and gender matched SIHD patients receiving atorvastatin monotherapy served as controls. At baseline and 18 months post-treatment, quantitative coronary angiography, intracoronary ultrasound with virtual histology and carotid ultrasound were performed. Lipid profile, including Lp(a), was measured at the scheduled visits, and before and after each apheresis procedure. Levels of high-sensitivity C-reactive protein (hsCRP), matrix metalloproteinases (MMP)-7 and 9, and tissue inhibitor of matrix metalloproteinases (TIMP)-1 and 2 were determined at baseline and at the end of the study period.

RESULTS

Each specific Lp(a) apheresis procedure was carried out with two adsorption columns resulting in an average acute decrease in Lp(a) levels of 75% (from 110 ± 22 to 29 ± 16 mg/dL) without significant changes in other plasma components. Lp(a) reduction over the course of 18 months was associated with a decrease in the mean percent diameter stenosis of 5.05% and an increase in minimal lumen diameter of 14%; the mean total atheroma volume was reduced by 4.60 mm³ (p < 0.05 for all). There was a decrease in absolute common carotid intima-media thickness in the Lp(a) apheresis group of 0.07 ± 0.15 mm both from baseline and compared with the control group (p = 0.01). Levels of hsCRP were reduced by 40% in patients on Lp(a) apheresis without significant changes in the levels of other biomarkers at the end of the study.

CONCLUSION

Reduction of the atherosclerotic burden in coronary and carotid arteries was observed in patients treated with specific Lp(a) apheresis and statin over 18 months compared with statin therapy alone. These findings support the atherogenic role of Lp(a) and reinforce the need to assess the effects of Lp(a)-lowering on cardiovascular events and mortality. Trial Registration Clinicaltrials.gov (NCT02133807).

Statins, Ezetimibe, and Proprotein Convertase Subtilisin-Kexin Type 9 Inhibitors to Reduce Low-Density Lipoprotein Cholesterol and Cardiovascular Events

Multiple lines of evidence suggest that the physiologically normal levels of low-density lipoprotein cholesterol (LDL-C) and the thresholds for development of atherosclerosis and adverse coronary events are in the 30- to 70-mg/dl range. More patients have been studied in randomized controlled trials assessing the effects of statins on outcomes than any other drug class in the history of medicine. This cumulative body of evidence documents that atherosclerosis progression is halted and coronary heart disease events are minimized when statin therapy with or without ezetimibe, and possibly proprotein convertase subtilisin-kexin type 9 (PCSK9) inhibitors, is used to drive down the LDL-C to a range of about 30 to 50 mg/dl. Thus far, these agents appear to be safe even when LDL-C is lowered to about 50 mg/dl, although more robust outcome and safety data are required, particularly for the PCSK9 inhibitors and very low LDL-C levels (e.g., down to 25 mg/dl). In conclusion, the current national guidelines specifying only the use of a high-potency statin without specific LDL-C goals may lead to substantial undertreatment of high-risk patients, leaving them vulnerable to future adverse cardiovascular events.

Anti-sense oligonucleotide therapies for the treatment of hyperlipidaemia

INTRODUCTION

Anti-sense oligonucleotide (ASO) therapies are a new development in clinical pharmacology offering greater specificity compared to small molecule inhibitors and the ability to target intracellular process' not susceptible to antibody-based therapies.

AREAS COVERED

This article reviews the chemical biology of ASOs and related RNA therapeutics. It then reviews the data on their use to treat hyperlipidaemia. Data on mipomersen - an ASO to apolipoprotein B-100(apoB) licensed for treatment of homozygous familial hypercholesterolaemia (FH) is presented. Few effective therapies are available to reduce atehrogenic lipoprotein (a) levels. An ASO therapy to apolipoprotein(a) (ISIS Apo(a)Rx) specifically reduced lipoprotein (a) levels by up to 78%. Treatment options for patients with familial chylomicronaemia syndrome (lipoprotein lipase deficiency; LPLD) or lipodystrophies are highly limited and often inadequate. Volanesorsen, an ASO to apolipoprotein C-3, shows promise in the treatment of LPLD and severe hypertriglyceridaemia as it increases clearance of triglyceride-rich lipoproteins and can normalise triglycerides in these patients.

EXPERT OPINION

The uptake of the novel ASO therapies is likely to be limited to selected niche groups or orphan diseases. These will include homozygous FH, severe heterozygous FH for mipomersen; LPLD deficiency and lipodystrophy syndromes for volanesorsen and treatment of patients with high elevated Lp(a) levels.

Relationship between Sustained Reductions in Plasma Lipid and Lipoprotein Concentrations with Apheresis and Plasma Levels and mRNA Expression of PTX3 and Plasma Levels of hsCRP in Patients with HyperLp(a)lipoproteinemia

The effect of lipoprotein apheresis (Direct Adsorption of Lipids, DALI) (LA) on plasma levels of pentraxin 3 (PTX3), an inflammatory marker that reflects coronary plaque vulnerability, and expression of PTX3 mRNA was evaluated in patients with hyperLp(a)lipoproteinemia and angiographically defined atherosclerosis/coronary artery disease. Eleven patients, aged 55 ± 9.3 years (mean ± SD), were enrolled in the study. PTX3 soluble protein levels in plasma were unchanged by 2 sessions of LA; however, a downregulation of mRNA expression for PTX3 was observed, starting with the first session of LA (p < 0.001). The observed reduction was progressively increased in the interval between the first and second LA sessions to achieve a maximum decrease by the end of the second session. A statistically significantly greater treatment-effect correlation was observed in patients undergoing weekly treatments, compared with those undergoing treatment every 15 days. A progressive reduction in plasma levels of C-reactive protein was also seen from the first session of LA, with a statistically significant linear correlation for treatment-effect in the change in plasma levels of this established inflammatory marker (R² = 0.99; p < 0.001). Our findings suggest that LA has anti-inflammatory and endothelium protective effects beyond its well-established efficacy in lowering apoB100-containing lipoproteins.

Small, dense high-density lipoprotein 3 particles exhibit defective antioxidative and anti-inflammatory function in familial hypercholesterolemia: Partial correction by low-density lipoprotein apheresis

BACKGROUND

Familial hypercholesterolemia (FH) features elevated oxidative stress and accelerated atherosclerosis driven by elevated levels of atherogenic lipoproteins relative to subnormal levels of atheroprotective high-density lipoprotein (HDL). Small, dense HDL3 potently protects low-density lipoprotein (LDL) against proinflammatory oxidative damage.

OBJECTIVE

To determine whether antioxidative and/or anti-inflammatory activities of HDL are defective in FH and whether such defects are corrected by LDL apheresis.

METHODS

Antioxidative and antiinflammatory activities of HDL were evaluated as protection of reference LDL from oxidative stress and capacity to prevent accumulation of proinflammatory oxidised lipids, respectively. Lipid surface rigidity of HDL was assessed using a fluorescent probe. HDL components were measured by analytical approaches. Systemic oxidative stress was characterized as plasma 8-isoprostanes.

RESULTS

Pre-LDL-apheresis, FH patients (n = 10) exhibited elevated systemic oxidative stress (3.3-fold, P < 0.001) vs. sex- and age-matched normolipidemic controls (n = 10). Both antioxidative and antiinflammatory activity of HDL3 were impaired (up to -91%, P < 0.01) in FH. Sphingomyelin and saturated fatty acid contents were elevated in FH HDL3, resulting in enhanced lipid surface rigidity. The surface lipid content (phospholipids, free cholesterol) was reduced in FH (up to -15%, P < 0.001), whereas content of core lipids (cholesteryl esters, triglycerides) was elevated (up to +17%, P < 0.001). Molar apolipoprotein A-I content of HDL3 was subnormal in FH. A single LDL-apheresis session partially corrected (by up to 76%) deficient HDL antiatherogenic activities, attenuated systemic oxidative stress and partially normalised both the lipid composition and surface rigidity of HDL particles.

CONCLUSIONS

FH features elevated oxidative stress and deficient antioxidative and anti-inflammatory activities of small, dense HDL3; such functional deficiency is intimately linked to anomalies in lipid and protein composition, which may impair the capacity of HDL to acquire and inactivate oxidized lipids.

Optimizing Treatment of Familial Hypercholesterolemia in Children and Adolescents

Cardiovascular disease (CVD) is still the most prominent cause of death and morbidity in the world, and one of the major risk factors for developing CVD is hypercholesterolemia. Familial hypercholesterolemia (FH) is a dominantly inherited disorder characterized by markedly elevated plasma low-density lipoprotein cholesterol and premature coronary heart disease. Currently, several treatment options are available for children with FH. Lifestyle adjustments are the first step in treatment. If this is not sufficient, statins are the preferred initial pharmacological therapy and they have been proven effective and safe. However, treatment goals are often not achieved and, hence, there is a need for novel treatment options. Currently, several options are being studied in adults and first results are promising. However, studies in children are still to be awaited.

Homozygous autosomal dominant hypercholesterolaemia: prevalence, diagnosis, and current and future treatment perspectives

PURPOSE OF REVIEW

Homozygous autosomal dominant hypercholesterolemia (hoADH) is a rare genetic disorder caused by mutations in LDL receptor, apolipoprotein B, and/or proprotein convertase subtilisin-kexin type 9. Both the genetic mutations and the clinical phenotype vary largely among individual patients, but patients with hoADH are typically characterized by extremely elevated LDL-cholesterol (LDL-C) levels, and a very high-risk for premature cardiovascular disease. Current lipid-lowering therapies include bile acid sequestrants, statins, and ezetimibe. To further decrease LDL-C levels in hoADH, lipoprotein apheresis is recommended, but this therapy is not available in all countries.

RECENT FINDINGS

Recently, the microsomal triglyceride transfer protein inhibitor lomitapide and the RNA antisense inhibitor of apolipoprotein B mipomersen were approved by the Food and Drug Administration/European Medicine Agency and the Food and Drug Administration, respectively. Several other LDL-C-lowering strategies and therapeutics targeting the HDL-C pathway are currently in the clinical stage of development.

SUMMARY

Novel therapies have been introduced for LDL-C-lowering and innovative drug candidates for HDL-C modulation for the treatment of hoADH. Here, we review the current available literature on the prevalence, diagnosis, and therapeutic strategies for hoADH.

Familial hypercholesterolaemia in children and adolescents: gaining decades of life by optimizing detection and treatment

Familial hypercholesterolaemia (FH) is a common genetic cause of premature coronary heart disease (CHD). Globally, one baby is born with FH every minute. If diagnosed and treated early in childhood, individuals with FH can have normal life expectancy. This consensus paper aims to improve awareness of the need for early detection and management of FH children. Familial hypercholesterolaemia is diagnosed either on phenotypic criteria, i.e. an elevated low-density lipoprotein cholesterol (LDL-C) level plus a family history of elevated LDL-C, premature coronary artery disease and/or genetic diagnosis, or positive genetic testing. Childhood is the optimal period for discrimination between FH and non-FH using LDL-C screening. An LDL-C ≥5 mmol/L (190 mg/dL), or an LDL-C ≥4 mmol/L (160 mg/dL) with family history of premature CHD and/or high baseline cholesterol in one parent, make the phenotypic diagnosis. If a parent has a genetic defect, the LDL-C cut-off for the child is ≥3.5 mmol/L (130 mg/dL). We recommend cascade screening of families using a combined phenotypic and genotypic strategy. In children, testing is recommended from age 5 years, or earlier if homozygous FH is suspected. A healthy lifestyle and statin treatment (from age 8 to 10 years) are the cornerstones of management of heterozygous FH. Target LDL-C is <3.5 mmol/L (130 mg/dL) if >10 years, or ideally 50% reduction from baseline if 8–10 years, especially with very high LDL-C, elevated lipoprotein(a), a family history of premature CHD or other cardiovascular risk factors, balanced against the long-term risk of treatment side effects. Identifying FH early and optimally lowering LDL-C over the lifespan reduces cumulative LDL-C burden and offers health and socioeconomic benefits. To drive policy change for timely detection and management, we call for further studies in the young. Increased awareness, early identification, and optimal treatment from childhood are critical to adding decades of healthy life for children and adolescents with FH.

Comparison of two low-density lipoprotein apheresis systems in patients with homozygous familial hypercholesterolemia

Low-density lipoprotein (LDL) apheresis (LA) is a reliable method to decrease LDL-C concentrations and remains the gold standard therapy in homozygous familial hypercholesterolemia (HoFH). The objective of this study was to compare the efficacy of two LA systems [heparin-induced extracorporeal LDL precipitation (HELP) vs. dextran sulfate adsorption (DS) on the reduction of lipids, inflammatory markers, and adhesion molecules in a sample of genetically defined HoFH subjects (n = 9)]. Fasting blood samples were collected before and after LA. All subjects served as their own control and were first treated with the HELP system then with DS in this single sequence study. Compared with HELP, DS led to significantly greater reductions in total cholesterol (-63.3% vs. -59.9%; P = 0.05), LDL-C (-70.5% vs. -63.0%; P = 0.02), CRP (-75.3% vs. -48.8%; P < 0.0001), and TNF-α (-23.7% vs. +14.7%; P = 0.003). Reductions in the plasma levels of PCSK9 (-45.3% vs. -63.4%; P = 0.31), lipoprotein (a) (-70.6% vs. -65.0%; P = 0.30), E-selectin (-16.6% vs. -18.3%; P = 0.65), ICAM-1 (-4.0 vs. 5.6%; P = 0.56), and VCAM-1 (8.3% vs. -1.8%; P = 0.08) were not different between the two systems. For the same volume of filtered plasma (3,000 mL), however, HELP led to greater reductions in plasma apoB (-63.1% vs. -58.3%; P = 0.04), HDL-C (-20.6% vs. -6.5%; P = 0.003), and PCSK9 (-63.4% vs. -28.5%; P = 0.02) levels. These results suggest that both LA systems are effective in reducing plasma lipids and inflammatory markers in HoFH. Compared with HELP, greater reductions in lipid levels and inflammatory markers were achieved with DS, most likely because this method allows for a larger plasma volume to be filtered. J. Clin. Apheresis 31:359-367, 2016. © 2015 Wiley Periodicals, Inc.

Recent advances in the understanding and care of familial hypercholesterolaemia: significance of the biology and therapeutic regulation of proprotein convertase subtilisin/kexin type 9

Familial hypercholesterolaemia (FH) is an autosomal co-dominant disorder that markedly raises plasma low-density lipoprotein-cholesterol (LDL-C) concentration, causing premature atherosclerotic coronary artery disease (CAD). FH has recently come under intense focus and, although there is general consensus in recent international guidelines regarding diagnosis and treatment, there is debate about the value of genetic studies. Genetic testing can be cost-effective as part of cascade screening in dedicated centres, but the full mutation spectrum responsible for FH has not been established in many populations, and its use in primary care is not at present logistically feasible. Whether using genetic testing or not, cholesterol screening of family members of index patients with an abnormally raised LDL-C must be used to determine the need for early treatment to prevent the development of CAD. The metabolic defects in FH extend beyond LDL, and may affect triacylglycerol-rich and high-density lipoproteins, lipoprotein(a) and oxidative stress. Achievement of the recommended targets for LDL-C with current treatments is difficult, but this may be resolved by new drug therapies. Lipoprotein apheresis remains an effective treatment for severe FH and, although expensive, it costs less than the two recently introduced orphan drugs (lomitapide and mipomersen) for homozygous FH. Recent advances in understanding of the biology of proprotein convertase subtilisin/kexin type 9 (PCSK9) have further elucidated the regulation of lipoprotein metabolism and led to new drugs for effectively treating hypercholesterolaemia in FH and related conditions, as well as for treating many patients with statin intolerance. The mechanisms of action of PCSK9 inhibitors on lipoprotein metabolism and atherosclerosis, as well as their impact on cardiovascular outcomes and cost-effectiveness, remain to be established.

Familial hypercholesterolemia: developments in diagnosis and treatment

BACKGROUND

Familial hypercholesterolemia (FH) is a congenital disorder of lipid metabolism characterized by a marked elevation of the plasma concentration of LDL (low-density lipoprotein) cholesterol beginning in childhood and by the early onset of coronary heart disease. It is among the commonest genetic disorders, with an estimated prevalence in Germany of at least 1 per 500 persons.

METHOD

Review of pertinent literature retrieved by a selective search.

RESULTS

FH is underdiagnosed and undertreated in Germany. It is clinically diagnosed on the basis of an elevated LDL cholesterol concentration (>190 mg/dL [4.9 mmol/L]), a family history of hypercholesterolemia, and early coronary heart disease, or the demonstration of xanthomas. The gold standard of diagnosis is the identification of the underlying genetic defect, which is possible in 80% of cases and enables the identification of affected relatives of the index patient. The recommended goals of treatment, based on the results of observational studies, are to lower the LDL cholesterol concentration by at least 50% or to less than 100 mg/dL (2.6 mmol/L) (for children: <135 mg/dL [3.5 mmol/L]). The target value is lower for patients with clinically overt atherosclerosis (<70 mg/dL [1.8 mmol/L]). Statins, combined with a health-promoting lifestyle, are the treatment of choice. Lipoprotein apheresis is used in very severe cases; its therapeutic effects on clinical endpoints and its side effect profile have not yet been documented in randomized controlled trials.

CONCLUSION

Familial hypercholesterolemia is a common disease that can be diagnosed simply and reliably on clinical grounds and by molecular genetic testing. Timely diagnosis and appropriate treatment can lower the risk of atherosclerosis in heterozygous patients to that of the general population.

New therapies targeting apoB metabolism for high-risk patients with inherited dyslipidaemias: what can the clinician expect?

Apolipoprotein B (apoB) has a key role in the assembly and secretion of very low-density lipoprotein (VLDL) from the liver. Plasma apoB concentration affects the number of circulating atherogenic particles, and serves as an independent predictor of the risk of atherosclerotic cardiovascular disease. While statins are the most potent apoB-lowering agents currently prescribed, their efficacy in achieving therapeutic targets for low-density lipoprotein cholesterol (LDL-C) in high-risk patients, such as those with familial hypercholesterolaemia (FH), is limited. Resistance and intolerance to statins also occurs in a significant number of patients, necessitating new types of lipid-lowering therapies. Monoclonal antibodies against proprotein convertase subtilisin/kexin type 9 (PCSK9; AMG 145 and REGN727), a sequence-specific antisense oligonucleotide against apoB mRNA (mipomersen) and a synthetic inhibitor of microsomal triglyceride transfer protein (MTTP; lomitapide) have been tested in phase III clinical trials, particularly in patients with FH. The trials demonstrated the efficacy of these agents in lowering apoB, LDL-C, non-high-density lipoprotein cholesterol and lipoprotein(a) by 32-55 %, 37-66 %, 38-61 % and 22-50 % (AMG 145), 21-68 %, 29-72 %, 16-60 % and 8-36 % (REGN727), 16-71 %, 15-71 %, 12-66 % and 23-49 % (mipomersen) and 24-55 %, 25-51 %, 27-50 % and 15-19 % (lomitapide), respectively. Monoclonal antibodies against PCSK9 have an excellent safety profile and may be indicated not only in heterozygous FH, but also in statin-intolerant patients and those with other inherited dyslipidemias, such as familial combined hyperlipidaemia and familial elevation in Lp(a). Mipomersen and lomitapide increase hepatic fat content and are at present indicated for treating adult patients with homozygous FH alone.

Lipoprotein apheresis and new therapies for severe familial hypercholesterolemia in adults and children

Familial hypercholesterolemia (FH), the most common and severe monogenic form of hypercholesterolemia, is an autosomal co-dominant disease characterized by an increased plasma low density lipoprotein (LDL)-cholesterol concentration and premature coronary heart disease (CHD). The clinical phenotype depends on the gene involved and severity of mutation (or mutations) present. Patients with homozygous or compound heterozygous FH have severe hypercholesterolemia (LDL-cholesterol >13 mmol/L) due to a gene dosing effect and without treatment have accelerated atherosclerotic CHD from birth, and frequently die of CHD before age 30. Cholesterol-lowering therapies have been shown to reduce both mortality and major adverse cardiovascular events in individuals with FH. Lipoprotein apheresis concomitant with lipid-lowering therapy is the treatment of choice for homozygous FH. This article describes the rationale and role of lipoprotein apheresis in the treatment of severe FH and outlines the recent advances in new pharmacotherapies for this condition.

Inhibition of hepatic microsomal triglyceride transfer protein - a novel therapeutic option for treatment of homozygous familial hypercholesterolemia

Familial hypercholesterolemia (FH) is an autosomal dominant disease caused by mutations in the low-density lipoprotein (LDL)-receptor gene (LDLR). Patients with homozygous FH (hoFH) have inherited a mutated LDLR gene from both parents, and therefore all their LDL-receptors are incapable of functioning normally. In hoFH, serum LDL levels often exceed 13 mmol/L and tendon and cutaneous xanthomata appear early (under 10 years of age). If untreated, this extremely severe form of hypercholesterolemia may cause death in childhood or in early adulthood. Based on recent data, it can be estimated that the prevalence of hoFH is about 1:500,000 or even 1:400,000. Until now, the treatment of hoFH has been based on high-dose statin treatment combined with LDL apheresis. Since the LDL cholesterol-lowering effect of statins is weak in this disease, and apheresis is a cumbersome treatment and not available at all centers, alternative novel pharmaceutical therapies are needed. Lomitapide is a newly introduced drug, capable of effectively decreasing serum LDL cholesterol concentration in hoFH. It inhibits the microsomal triglyceride transfer protein (MTTP). By inhibiting in hepatocytes the transfer of triglycerides into very low density lipoprotein particles, the drug blocks their assembly and secretion into the circulating blood. Since the very low density lipoprotein particles are precursors of LDL particles in the circulation, the reduced secretion of the former results in lower plasma concentration of the latter. The greatest concern in lomitapide treatment has been the increase in liver fat, which can be, however, counteracted by strictly adhering to a low-fat diet. Lomitapide is a welcome addition to the meager selection of drugs currently available for the treatment of refractory hypercholesterolemia in hoFH patients.

Lomitapide: a review of its use in adults with homozygous familial hypercholesterolemia

Lomitapide (Juxtapid(TM)), an orally administered inhibitor of the microsomal triglyceride transfer protein, inhibits the synthesis of chylomicrons and very low-density lipoprotein, thereby reducing plasma levels of low-density lipoprotein cholesterol (LDL-C). Lomitapide is used to lower lipid levels in adults with homozygous familial hypercholesterolemia, a rare, potentially life-threatening genetic disease that is commonly caused by mutations in the LDL receptor gene or other genes that affect the function of the LDL receptor. In a multinational single-arm, open-label, 78-week, phase III trial, lomitapide reduced mean plasma LDL-C levels by 50 % from baseline in 23 evaluable adults with homozygous familial hypercholesterolemia over a 26 week treatment period. Reductions from baseline in LDL-C levels were sustained for up to 78 weeks with continued lomitapide treatment. In this study, the initial dosage of lomitapide was 5 mg once daily for two weeks, with upward titration thereafter to 10, 20, 40, and 60 mg at weeks 2, 6, 10, and 14, respectively, or until an individually assessed maximum dosage was achieved. Prior to the start of treatment with lomitapide, other lipid-lowering therapy (including LDL apheresis) was stabilized over a 6-week period, and then continued throughout the lomitapide treatment phase. Lomitapide was generally well tolerated; the most common adverse events in the phase III trial were gastrointestinal events.

Current Phase II proprotein convertase subtilisin/kexin 9 inhibitor therapies for dyslipidemia

INTRODUCTION

Reduction of plasma low-density lipoprotein (LDL) cholesterol concentration with statins reduces adverse cardiovascular outcomes. However, lack of efficacy and intolerance of statins in many patients requires alternative treatments. Currently available non-statin alternatives include bile acid sequestrants, the cholesterol absorption inhibitor ezetimibe, niacin-based preparations and fibrates; however, each of these has limitations. Newer agents for LDL cholesterol reduction include the cholesterol ester transfer protein inhibitors, the microsomal triglyceride transfer protein inhibitor lomitapide, the apolipoprotein B antisense oligonucleotide mipomersen and several molecules that inhibit or interfere with proprotein convertase subtilisin/kexin 9 (PCSK9).

AREAS COVERED

Among the various PCSK9 inhibitors, human data are available for monoclonal antibodies against PCSK9 of which the two most advanced are alirocumab (SAR236553/REGN727) and AMG 145. Phase II studies of these agents as monotherapy or in combination with statins have shown reductions of LDL cholesterol by > 70%, with acceptable safety and tolerability so far.

EXPERT OPINION

Despite their biochemical efficacy, clinical efficacy, reflected by reduction of cardiovascular end points, remains to be shown for two leading monoclonal antibodies against PSCK9. Other issues to be evaluated with these agents over the longer term include development of rare adverse effects and potential attenuation of efficacy.