Review of the long-term safety of lomitapide: a microsomal triglycerides transfer protein inhibitor for treating homozygous familial hypercholesterolemia

Angiopoietin-like 3: An important protein in regulating lipoprotein levels

ANGPTL3 has emerged as a therapeutic target whose inhibition results in profound reductions of plasma lipids, including atherogenic triglyceride-rich lipoproteins and low-density lipoprotein cholesterol. The identification of ANGPTL3 deficiency as a cause of familial combined hypolipidemia in humans hastened the development of anti-ANGPTL3 therapeutic agents, including evinacumab (a monoclonal antibody inhibiting circulating ANGPTL3), vupanorsen (an antisense oligonucleotide [ASO] targeting hepatic ANGPTL3 mRNA for degradation), and others. Advances have also been made in ANGPTL3 vaccination and gene editing strategies, with the former still in preclinical phases and the latter in preparation for Phase 1 trials. Here, we review the discovery of ANGPTL3 as an important regulator of lipoprotein metabolism, molecular characteristics of the protein, mechanisms by which it regulates plasma lipids, and the clinical development of anti-ANGPTL3 agents. The clinical success of therapies inhibiting ANGPTL3 highlights the importance of this target as a novel approach in treating refractory hypertriglyceridemia and hypercholesterolemia.

Atherosclerotic plaque regression in homozygous familial hypercholesterolaemia: a case report of a long-term lipid-lowering therapy involving LDL-receptor-independent mechanisms

Background

Homozygous familial hypercholesterolaemia (HoFH) is a rare and life-threatening genetic disease characterized by extremely elevated low-density lipoprotein cholesterol (LDL-C) levels, important xanthomatosis and increased risk of premature atherosclerotic cardiovascular disease. Management of HoFH at an early stage is recommended but conventional lipid-lowering therapies (LLTs) dependent on the LDL-receptor for clearance of LDL particles, are usually not sufficient. However, agents acting independently of the LDL-receptor, such as inhibitors of microsomal triglyceride transfer protein (MTP) or angiopoietin-like protein 3 (ANGPTL3), administered in combination, on top of standard-of-care LLT constitute a promising therapy for HoFH.

Case summary

The present case describes a long-term (>10 years) follow-up of a 52-year-old woman with severe HoFH, who was treated with conventional lipid-lowering medications (i.e. statins and ezetimibe) for several years before experiencing the risks and benefits that were encountered with the use of LDL-receptor-independent agents (MTP and ANGPTL3 inhibitors). This combination therapy demonstrated a good long-term safety and efficacy profile, while continuous monitoring of hepatic enzymes (sometimes requiring dose adjustments) and fat accumulation is recommended when using lomitapide.

Discussion

Treating this HoFH patient with an LLT involving the combination of MTP and ANGPTL3 LDL-receptor-independent inhibitors (lomitapide and evinacumab, respectively) showed remarkable improvement in LDL-C levels, disappearance of xanthomatosis and regression in atherosclerotic plaques. In addition to safety and efficacy, one should question the affordability and access hurdle that emerging combination of expensive therapies might constitute in the future for the payers. These challenges could eventually limit the clinical use of those innovative treatments despite their clinical benefit.

Current Options and Future Perspectives in the Treatment of Dyslipidemia

Low-density lipoprotein cholesterol (LDL-C) plays a crucial role in the development of atherosclerosis. Statin therapy is the standard treatment for lowering LDL-C in primary and secondary prevention. However, some patients do not reach optimal LDL-C target levels or do not tolerate statins, especially when taking high doses long-term. Combining statins with different therapeutic approaches and testing other new drugs is the future key to reducing the burden of cardiovascular disease (CVD). Recently, several new cholesterol-lowering drugs have been developed and approved; others are promising results, enriching the pharmacological armamentarium beyond statins. Triglycerides also play an important role in the development of CVD; new therapeutic approaches are also very promising for their treatment. Familial hypercholesterolemia (FH) can lead to CVD early in life. These patients respond poorly to conventional therapies. Recently, however, new and promising pharmacological strategies have become available. This narrative review provides an overview of the new drugs for the treatment of dyslipidemia, their current status, ongoing clinical or preclinical trials, and their prospects. We also discuss the new alternative therapies for the treatment of dyslipidemia and their relevance to practice.

Lessons learned from the evinacumab trials in the treatment of homozygous familial hypercholesterolemia

Homozygous familial hypercholesterolemia (HoFH) is a life-threatening disease characterized by extremely elevated LDL cholesterol (LDL-C) levels which result in premature atherosclerotic cardiovascular disease. As conventional lipid-lowering therapies, which mainly depend on LDL receptors for LDL particle clearance, remain insufficient for reaching the recommended LDL-C levels in HoFH, agents acting independently of LDL receptors, such as ANGPTL3 inhibitors, constitute a promising target. Evinacumab, a monoclonal antibody directed against ANGPTL3, was approved in the USA in 2021 for treating patients with HoFH. Evinacumab has shown an adequate safety profile with strong LDL-lowering efficacy. This review highlights the development path of evinacumab and provides insight on the lessons learned from trials as well as the hurdles facing accessibility.

Genetic burden linked to founder effects in Saguenay-Lac-Saint-Jean illustrates the importance of genetic screening test availability

The Saguenay–Lac-Saint-Jean (SLSJ) region located in the province of Quebec was settled in the 19th century by pioneers issued from successive migration waves starting in France in the 17th century and continuing within Quebec until the beginning of the 20th century. The genetic structure of the SLSJ population is considered to be the product of a triple founder effect and is characterised by a higher prevalence of some rare genetic diseases. Several studies were performed to elucidate the historical, demographic and genetic background of current SLSJ inhabitants to assess the origins of these rare disorders and their distribution in the population. Thanks to the development of new sequencing technologies, the genes and the variants responsible for the most prevalent conditions were identified. Combined with other resources such as the BALSAC population database, identifying the causal genes and the pathogenic variants allowed to assess the impacts of some of these founder mutations on the population health and to design precision medicine public health strategies based on carrier testing. Furthermore, it stimulated the establishment of many public programmes.

We report here a review and an update of a subset of inherited disorders and founder mutations in the SLSJ region. Data were collected from published scientific sources. This work expands the knowledge about the current frequencies of these rare disorders, the frequencies of other rare genetic diseases in this population, the relevance of the carrier tests offered to the population, as well as the current available treatments and research about future therapeutic avenues for these inherited disorders.

Lipid-lowering therapy: Guidelines to precision medicine

Dyslipidemia is correlated with a series of health problems, such as obesity, insulin resistance, and the development of cardiovascular disease (CVD). Currently, accumulating evidence sheds light on the fact that β-hydroxy β-methylglutaryl-CoA reductase inhibitors, named statins, could lower circulating lipid-density lipoprotein cholesterol (LDL-C) and represent a revolution for the prevention of metabolic disorder diseases. In addition, statins remain the cornerstone of LDL-C-lowering treatments, together with ezetimibe and bile acid sequestrants, which are used either in combination with statins or as monotherapies in the case of statin intolerance or side effects. On the other hand, other medicines that reduce circulating LDL-C have also been researched, including inhibitors of protein convertase subtilisin/kexin type 9 (PCSK9). More recently, PCSK9 inhibitors have been approved for the secondary prevention of CVD and for the atherogenic dyslipidemia therapy. Here, we summarize the latest guidelines for the management of dyslipidemia and its relation to CVD, focusing on LDL-C-lowering medicines that are either available in daily clinical practice or under investigation. In addition, we also discuss the "who, when, and how" with respect to treating patients with dyslipidemia according to LDL-C reduction as an individualized clinical precision medicine.

Management of Familial Hypercholesterolemia: Current Status and Future Perspectives

Familial hypercholesterolemia (FH) is the most common monogenic disorder associated with premature atherosclerotic cardiovascular disease. Early diagnosis and effective treatment can significantly improve prognosis. Recent advances in the field of lipid metabolism have shed light on the molecular defects in FH and new therapeutic options have emerged. A search of PubMed database up to March 2020 was performed for this review using the following keywords: “familial hypercholesterolemia,” “diagnosis,” “management,” “guideline,” “consensus,” “genetics,” “screening,” “lipid lowering agents.” The prevalence rate of heterozygous FH is approximately 1 in 200 to 250 and FH is underdiagnosed and undertreated in many parts of the world. Diagnostic criteria have been developed to aid the clinical diagnosis of FH. Genetic testing is now available but not widely used. Cascade screening is recommended to identify affected family members, and the benefits of early interventions are clear. Treatment strategy and target is currently based on low-density lipoprotein (LDL) cholesterol levels as the prognosis of FH largely depends on the magnitude of LDL cholesterol-lowering that can be achieved by lipid-lowering therapies. Statins with or without ezetimibe are the mainstay of treatment and are cost-effective. Addition of newer medications like PCSK9 inhibitors is able to further lower LDL cholesterol levels substantially, but the cost is high. Lipoprotein apheresis is indicated in homozygous FH or severe heterozygous FH patients with inadequate response to cholesterol-lowering therapies. In conclusion, FH is a common, treatable genetic disorder, and although our understanding of this disease has improved, many challenges still remain for its optimal management.

Lomitapide for treatment of homozygous familial hypercholesterolemia: The Québec experience

BACKGROUND AND AIMS

Homozygous familial hypercholesterolemia (HoFH) is an orphan disease, most often caused by bi-allelic mutations of the LDLR gene. Patients with HoFH have elevated LDL-C levels >13 mmol/L, tendinous xanthomata and severe, premature atherosclerotic cardiovascular disease (ASCVD). Untreated, most HoFH patients die of ASCVD in youth. New therapeutic modalities include lomitapide, an inhibitor of microsomal triglyceride transfer protein that lowers hepatic LDL-C production. We have recently identified 79 Canadian patients with HoFH. Here, we describe our experience with lomitapide in the province of Quebec, a geographic area known to have a high prevalence of HoFH.

METHODS

This is a retrospective case series of 12 HoFH patients followed at three lipidology centers in the province of Quebec.

RESULTS

Mean age of the patients was 44 ± 18 years; age at time of HoFH diagnosis ranged from 2 to 59 years. All patients were on a statin and ezetimibe 10 mg/day and five patients were treated with LDL apheresis. Treatment with lomitapide reduced LDL-C levels by 38% (intention-to-treat). Intolerable gastrointestinal side effects were observed in 3/12 patients and were the main reason for treatment discontinuation. Three patients tolerated lomitapide at doses ranging between 5 and 30 mg/day without major side effects. Downwards drug titration was necessary in the 6 remaining patients because of gastrointestinal side effects (n = 5) and elevated liver enzymes (n = 1), and 2 of them finally discontinued treatment.

CONCLUSIONS

Lomitapide may be used to further decrease LDL-C in HoFH patients; gastrointestinal side effects and hepatic toxicity may limit adherence.

Evidence for improved survival with treatment of homozygous familial hypercholesterolemia

PURPOSE OF REVIEW

Homozygous familial hypercholesterolemia (HoFH) is an orphan disease caused by biallelic mutations at the LDL receptor (LDLR) gene, with a prevalence estimated at 1 : 250 000 to 1 : 630 000. HoFH is characterized by extremely elevated plasma levels of LDL-C greater than 10 mmol/l (>387 mg/dl), tendinous and cutaneous xanthomas in youth and premature atherosclerotic cardiovascular disease (ASCVD). The expected prevalence varies from country to country depending on the presence of founder effects, genetic probability and life expectancy. Untreated, HoFH is a fatal condition before age 30. Plasma levels of LDL-C are the major cause of mortality and the therapeutic target. Statin therapy led to a remarkable improvement in survival but is of limited use in loss-of-function LDLR gene variants or 'null' mutations. Inhibitors of PCSK9 are a useful adjunct in patients with LDLR mutations with residual activity. Extracorporeal LDL filtration has improved survival since its introduction three decades ago.

RECENT FINDINGS

Novel therapies, not dependent on a functioning LDLR include lomitapide and mipomersen, which decrease hepatic apolipoprotein B secretion, and evinacumab, directed at the angiopoietin like-3 protein (ANGPLT-3).

SUMMARY

Over the past 3-4 decades, the survival of patients with HoFH has increased markedly. New therapeutic options offer new hope.

Lomitapide: a review of its clinical use, efficacy, and tolerability

Lomitapide is an inhibitor of MTP, an enzyme located in the endoplasmic reticulum of hepatocytes and enterocytes. This enzyme is responsible for the synthesis of very low-density lipoproteins in the liver and chylomicrons in the intestine. Lomitapide has been approved by the US Food and Drug Administration, European Medicines Agency, and other regulatory agencies for the treatment of hypercholesterolemia in adult patients with homozygous familial hypercholesterolemia. Clinical trials have shown that lomitapide reduces low-density-lipoprotein cholesterol levels by around 40% in homozygous familial hypercholesterolemia patients on treatment with statins with or without low-density-lipoprotein apheresis, with an acceptable safety and tolerance profile. The most common adverse events are gastrointestinal symptoms that decrease in frequency with long-term treatment, and the increase in liver fat remains stable. This review analyzes the clinical use, efficacy, and tolerability of lomitapide.