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

Research Progress in the Clinical Treatment of Familial Hypercholesterolemia

Familial hypercholesterolemia (FH) is an autosomal dominant inheritable disease with severe disorders of lipid metabolism. It is mainly marked by increasing levels of plasma total cholesterol (TC) and low-density lipoprotein cholesterol (LDL-C), xanthoma, corneal arch, and early-onset coronary heart disease (CHD). The prevalence of FH is high, and it is dangerous and clinically underdiagnosed. The clinical treatment for FH includes both pharmacological and non-pharmacological treatment, of which non-pharmacological treatment mainly includes therapeutic lifestyle change and dietary therapy, LDL apheresis, liver transplantation and gene therapy. In recent years, many novel drugs have been developed to treat FH more effectively. In addition, the continuous maturity of non-pharmacological treatment techniques has also brought more hope for the treatment of FH. This paper analyzes the pathogenic mechanism and the progress in clinical treatment of FH. Furthermore, it also summarizes the mechanism and structure-activity relationship of FH therapeutic drugs that have been marketed. In a word, this article provides a reference value for the research and development of FH therapeutic drugs.

Acute coronary syndrome in an 8-year-old child with familial hypercholesterolemia: a case report

Background

Familial hypercholesterolemia (FH) is the most commonly inherited metabolic disease and has an autosomal dominant mode of inheritance. Patients with FH usually present with high levels of low-density lipoprotein-cholesterol, xanthomas and early coronary artery disease. Children with FH are subject to developing early and enhanced atherosclerosis, leading to an increased risk of coronary events. We report here an 8-year-old patient with acute coronary syndrome (ACS) who was diagnosed with homozygous FH (HoFH) due to mutations in the low-density lipoprotein receptor (LDLR) gene and subsequently treated with percutaneous transluminal coronary angioplasty (PTCA) after filtration plasma. To the best of our knowledge, this patient is the youngest case of HoFH treated with filtration plasma followed by PTCA reported to date.

Case presentation

An 8-year-old Asian patient was admitted to Gansu Provincial Hospital presenting symptoms of ACS. Laboratory tests showed that the patient’s cholesterol and low-density lipid levels were extremely high. An electrocardiogram (ECG) revealed sinus arrhythmia and electric axis deviation to the right, but the ECG was roughly normal. Multiple cardiac function abnormalities were diagnosed on the ECG. Multiple sites of coronary artery stenosis were determined by computed tomography angiography. DNA sequencing of exons showed a C-to-A substitution at nucleotide 126 in exon 2, resulting in a LDLR mutation in the patient and seven other family members. Following combination treatment with lipid-lowering drugs, anti-thrombosis drugs, filtration plasma and PTCA, the patient’s symptoms were significantly improved and the patient discharged.

Conclusion

We report the rare case of a patient with ACS attributable to HoFH who was treated with PTCA following filtration plasma. The patient was shown to have clinically diagnosed and molecularly confirmed HoFH that resulted from a mutation in the LDLR gene. Children with HoFH have higher risk of early coronary events and death from myocardial infarction due to premature atherosclerosis than adults. Earlier intervention and treatment will bring great benefits to the long-term survival of pediatric 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.

Lipoprotein apheresis and PCSK9 inhibitors for severe familial hypercholesterolaemia: Experience from Australia and New Zealand

INTRODUCTION

Severe familial hypercholesterolaemia (FH) causes premature disability and death due to atherosclerotic cardiovascular disease and is refractory to standard lipid-lowering therapies. Lipoprotein apheresis (LA) has long been a standard of care for patients with severe FH, but is invasive, expensive and time-consuming for patients and their caregivers. Newer drug therapies, including the proprotein convertase subtilisin/kexin type 9 (PCSK9) inhibitors, may reduce the need for LA.

MATERIALS AND METHODS

We audited the records of 16 patients (eight homozygous, eight heterozygous) treated with LA in Australia and New Zealand, 14 of whom subsequently commenced PCSK9 inhibitor therapy. LA was performed by cascade filtration in all centres.

RESULTS

LDL-cholesterol was acutely lowered by 69 ± 7% in patients with homozygous FH and by 72 ± 9% in those with heterozygous FH, representing time-averaged reductions of 36 ± 12% and 34 ± 5%, respectively. LA was well-tolerated, and patients reported comparable quality of life to population and disease-related norms. After commencement of PCSK9 inhibitors, four of seven patients with homozygous FH had meaningful biochemical responses, with a reduction in the frequency of LA permitted in one patient and complete cessation in another. Four of seven patients with heterozygous FH were able to be managed without LA after commencing PCSK9 inhibitors.

CONCLUSION

While PCSK9 inhibitors have reduced the need for LA, some patients with severe FH continue to require LA, and will require it for the foreseeable future. However, emerging therapies, including angiopoetin-like 3 inhibitors, may further reduce the need for LA.

Familial hypercholesterolemia with early coronary atherosclerotic heart disease: A case report

Patients with familial hypercholesterolemia usually present with high levels of serum low-density lipoprotein, xanthomas and early coronary artery disease. A 13 years old female patient was admitted to Children's Hospital of Chongqing Medical University presenting symptoms of heart failure. Laboratory tests showed that her cholesterol and low-density lipid levels were extremely high. Electrocardiogram test revealed that she had sinus tachycardia, QT lengthening and ST-T change. Multiple cardiac function abnormalities were diagnosed by echocardiogram. Multiple coronary artery stenosis was determined by computed tomography angiography. After the combination of lipid lowering, anti-thrombosis, and cardiac remodeling therapies, the patient's symptoms were significantly improved and the patient was discharged.

PCSK9 in context: A contemporary review of an important biological target for the prevention and treatment of atherosclerotic cardiovascular disease

The identification of the critical role of proprotein convertase subtilisin/kexin type 9 (PCSK9) has rapidly led to the development of PCSK9 inhibition with monoclonal antibodies (mAbs). PCSK9 mAbs are already in limited clinical use and are the subject of major cardiovascular outcomes trials, which, if universally positive, could see much wider clinical application of these agents. Patients with familial hypercholesterolaemia are the most obvious candidates for these drugs, but other patients with elevated cardiovascular risk, statin intolerance or hyperlipoproteinaemia(a) may also benefit. PCSK9 mAbs, administered once or twice monthly, reduce LDL cholesterol levels by 50% to 70%, and appear to be safe and acceptable to patients over at least 2 years of treatment; however, treatment-emergent adverse effects are not always identified in clinical trials, as well-evidenced by statin myopathy. Inclisiran is a promising RNA-based therapy that promotes the degradation of PCSK9 mRNA transcripts and has similar efficacy to mAbs, but with a much longer duration of action. The cost-effectiveness and long-term safety of therapies targeted at inhibiting PCSK9 remain to be demonstrated if they are to be used widely in coronary prevention.

Knowns and unknowns in the care of pediatric familial hypercholesterolemia

Familial hypercholesterolemia (FH) is a common genetic disorder that causes elevated LDL cholesterol levels from birth. Untreated FH accelerates atherosclerosis and predisposes individuals to premature coronary artery disease (CAD) in adulthood. Mendelian randomization studies have demonstrated that LDL cholesterol has both a causal and cumulative effect on the risk of CAD. This supports clinical recommendations that children with FH commence pharmacological treatment from the age of 8 to 10 years, to reduce the burden of hypercholesterolemia. Worldwide, the majority of children with FH remain undiagnosed. Recent evidence suggests that the frequency of FH is at least 1 in 250 and this constitutes a public health issue. We review and identify the knowns and unknowns concerning the detection and management of pediatric FH that impact on the developing model of care for this condition.

Progress in the care of familial hypercholesterolaemia: 2016

Familial hypercholesterolaemia (FH) is the most common autosomal dominant condition, with a prevalence of between one in 200 and one in 350 people in the general population. Untreated FH is associated with premature atherosclerotic cardiovascular disease (CVD). The prevalence of homozygous or compound heterozygous FH is now considered to be about one in 300 000 people. Treating children with FH reduces progression of atherosclerotic CVD and future CVD events. Most individuals with FH are undiagnosed, which together with the recent frequency data in the population and in individuals with premature coronary disease creates a public health challenge and mandates a key role for primary care. Childhood is the optimal period for detecting FH, since low-density lipoprotein cholesterol (LDL-c) concentrations better differentiate affected from unaffected individuals. In an Australian community setting, over 70% of adults with an LDL-c level ≥ 6.5 mmol/L have clinical FH; of these, 30% have a detectable mutation. The community laboratory has an important role in identifying FH, with interpretive comments leading to additional reductions in LDL-c concentrations, and a phone call from the pathologist to the general practitioner improving detection of cases. Cascade screening using DNA testing is cost-effective and acceptable to screenees. Next generation genetic sequencing may differentiate people with polygenic hypercholesterolaemia alone from those with FH. Smoking, hypertension, elevated lipoprotein(a) levels, chronic kidney disease and diabetes are additional atherosclerotic CVD risk factors in FH. Equations for assessing absolute risk of CVD in primary prevention underestimate risk in FH. The adult LDL-c goal is a greater than 50% reduction in LDL-c levels, followed by a target of < 2.5 mmol/L, or < 1.8 mmol/L for individuals with CVD or other CVD risk factors. Proprotein convertase subtilisin/kexin type 9 inhibitors significantly reduce LDL-c and lipoprotein(a) levels in people with FH. Registries are essential for improving the care of people with FH.

Disease control via intensified lipoprotein apheresis in three siblings with familial hypercholesterolemia

BACKGROUND

Familial hypercholesterolemia (FH), the prevalent monogenic form of hypercholesterolemia, carries the risk of premature coronary heart disease. Lipoprotein-apheresis is established in children with severe dyslipidemia. We present 3 siblings with a negative/negative residual low-density lipoprotein (LDL) receptor mutation (p.Trp577Arg), unresponsive to drug treatment.

OBJECTIVE

Intensified lipoprotein-apheresis is well tolerated and results in permanently low lipid values without harming the health-related quality of life in children.

METHODS

Three homozygous FH siblings, aged 7-13 years, had been treated with statins and ezetimibe for 12 months but still showed highly elevated low-density lipoprotein cholesterol (LDL-C) plasma concentrations. They were started on double-filtration plasmapheresis that was subsequently intensified according to plasma lipid levels.

RESULTS

Each lipoprotein apheresis session reduced LDL-C concentration by 66% to 70%. Treated plasma volume was doubled after 6 months due to a sustained rebound of LDL-C between sessions. However, the rebound remained unchanged. Only an increase in frequency of sessions to every 3 to 4 days resulted in acceptable pre-treatment LDL-C concentrations (Cmax). Neither cessation of statins nor reduction of plasma exchange volume to 1.5 fold in follow-up influenced Cmax. Intensified therapy did not harm health-related quality of life as assessed by PedsQL and was well tolerated.

CONCLUSIONS

In pediatric FH patients unresponsive to drug treatment, intensified lipoprotein apheresis can normalize plasma lipid levels. Apparently, treatment frequency rather than volume has greater influence on its efficacy. The potential burden of intensified therapy to daily life has to be regarded. Serum lipid levels in FH should be normalized to minimize cardiovascular risk.

Progress in the care of common inherited atherogenic disorders of apolipoprotein B metabolism

Familial hypercholesterolaemia, familial combined hyperlipidaemia (FCH) and elevated lipoprotein(a) are common, inherited disorders of apolipoprotein B metabolism that markedly accelerate the onset of atherosclerotic cardiovascular disease (ASCVD). These disorders are frequently encountered in clinical lipidology and need to be accurately identified and treated in both index patients and their family members, to prevent the development of premature ASCVD. The optimal screening strategies depend on the patterns of heritability for each condition. Established therapies are widely used along with lifestyle interventions to regulate levels of circulating lipoproteins. New therapeutic strategies are becoming available, and could supplement traditional approaches in the most severe cases, but their long-term cost-effectiveness and safety have yet to be confirmed. We review contemporary developments in the understanding, detection and care of these highly atherogenic disorders of apolipoprotein B metabolism.

Anacetrapib for the treatment of dyslipidaemia: the last bastion of the cholesteryl ester transfer protein inhibitors?

INTRODUCTION

Inhibition of cholesteryl ester transfer protein (CETP) has emerged as a potential way to decrease cardiovascular risk by raising high density lipoprotein (HDL) cholesterol and lowering low density lipoprotein (LDL) cholesterol concentrations. However, high profile withdrawals of several CETP inhibitors have cast doubt over this hypothesis. Despite this concern, anacetrapib appears to be safe, well-tolerated and delivers a substantial increases in HDL cholesterol and reductions in LDL cholesterol as monotherapy and when combined with a statin.

AREAS COVERED

We discuss the role of CETP and HDL cholesterol as therapeutic targets, describe the pharmacokinetics and pharmacodynamics of anacetrapib, as well as report on the recent clinical trials.

EXPERT OPINION

The focus of CETP inhibition has shifted from HDL cholesterol-raising to LDL cholesterol-lowering. Although anacetrapib appears to be safe and is effective in altering lipid-related biochemical parameters of interest, its effect on cardiovascular outcomes remains unknown. Extrapolation of LDL cholesterol lowering to improved cardiovascular outcomes is not possible, because LDL and HDL functionality in the setting of anacetrapib treatment is unclear. The results of the phase III REVEAL randomised controlled trial will be critical for anacetrapib to establish a place in clinical care.

Severe dyslipidemia in pregnancy: The role of therapeutic apheresis

During pregnancy physiological changes occur in the lipid metabolism due to changing hormonal conditions: the LDL cholesterol (LDL-C), triglycerides (TG) and lipoprotein(a) [Lp(a)] increase throughout pregnancy. Common lipoprotein disorders are associated in pregnancy with two major clinical disorders: severe hypertriglyceridemia (SHTG) is a potent risk factor for development of acute pancreatitis and elevated cholesterol due to greater concentrations of LDL and remnant lipoproteins and reduced levels of HDL promote atherosclerosis. The combination of homozygous Familial Hypercholesterolemia (HoFH) and pregnancy can be a fatal condition. Therapeutic plasma exchange (TPE) may be used for an urgent need of a fast and effective lowering of TG levels in order to prevent a severe pancreatitis episode or hypertriglyceridemia-induced complications during pregnancy. LDL apheresis can decrease LDL-C and prevent complications and can be considered in the treatment of pregnancies complicated by high LDL-C. These conditions are configured in patients with HeFH who were taking statins before pregnancy (selected cases), patients already receiving apheresis before pregnancy suffering from HoFH, patients suffering from hypertriglyceridemia due to familial hyperlipoproteinemia types I and V, and cases of hypertriglyceridemia secondary to diabetes.

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.

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.

Emerging risk biomarkers in cardiovascular diseases and disorders

Present review article highlights various cardiovascular risk prediction biomarkers by incorporating both traditional risk factors to be used as diagnostic markers and recent technologically generated diagnostic and therapeutic markers. This paper explains traditional biomarkers such as lipid profile, glucose, and hormone level and physiological biomarkers based on measurement of levels of important biomolecules such as serum ferritin, triglyceride to HDLp (high density lipoproteins) ratio, lipophorin-cholesterol ratio, lipid-lipophorin ratio, LDL cholesterol level, HDLp and apolipoprotein levels, lipophorins and LTPs ratio, sphingolipids, Omega-3 Index, and ST2 level. In addition, immunohistochemical, oxidative stress, inflammatory, anatomical, imaging, genetic, and therapeutic biomarkers have been explained in detail with their investigational specifications. Many of these biomarkers, alone or in combination, can play important role in prediction of risks, its types, and status of morbidity. As emerging risks are found to be affiliated with minor and microlevel factors and its diagnosis at an earlier stage could find CVD, hence, there is an urgent need of new more authentic, appropriate, and reliable diagnostic and therapeutic markers to confirm disease well in time to start the clinical aid to the patients. Present review aims to discuss new emerging biomarkers that could facilitate more authentic and fast diagnosis of CVDs, HF (heart failures), and various lipid abnormalities and disorders in the future.

Liver transplantation for the treatment of homozygous familial hypercholesterolaemia in an era of emerging lipid-lowering therapies

Homozygous familial hypercholesterolaemia (FH) causes severe premature coronary artery disease because of very high levels of low density lipoprotein (LDL)-cholesterol. Standard lipid-lowering drugs and LDL-apheresis may not be sufficiently effective. Liver transplantation replaces defective LDL receptors and vastly improves the lipid profile, and we present the first report of an Australian adult to receive this treatment. Emerging drug treatments for FH may be alternatives to LDL-apheresis and transplantation, but long-term safety and efficacy data are lacking for all of these options.

Impact of hydrophobic chain composition on amphiphilic macromolecule antiatherogenic bioactivity

Amphiphilic macromolecules (AMs) composed of sugar backbones modified with branched aliphatic chains and a poly(ethylene glycol) (PEG) tail can inhibit macrophage uptake of oxidized low-density lipoproteins (oxLDL), a major event underlying atherosclerosis development. Previous studies indicate that AM hydrophobic domains influence this bioactivity through interacting with macrophage scavenger receptors, which can contain basic and/or hydrophobic residues within their binding pockets. In this study, we compare two classes of AMs to investigate their ability to promote athero-protective potency via hydrogen-bonding or hydrophobic interactions with scavenger receptors. A series of ether-AMs, containing methoxy-terminated aliphatic arms capable of hydrogen-bonding, was synthesized. Compared to analogous AMs containing no ether moieties (alkyl-AMs), ether-AMs showed improved cytotoxicity profiles. Increasing AM hydrophobicity via incorporation of longer and/or alkyl-terminated hydrophobic chains yielded macromolecules with enhanced oxLDL uptake inhibition. These findings indicate that hydrophobic interactions and the length of AM aliphatic arms more significantly influence AM bioactivity than hydrogen-bonding.