Lomitapide in homozygous familial hypercholesterolemia: cardiology perspective from a single-center experience

Consensus document on diagnosis and management of familial hypercholesterolemia from the Italian Society for the Study of Atherosclerosis (SISA)

AIMS

Familial Hypercholesterolemia (FH) is a genetic disorder of lipoprotein metabolism that causes an increased risk of premature atherosclerotic cardiovascular disease (ASCVD). Although early diagnosis and treatment of FH can significantly improve the cardiovascular prognosis, this disorder is underdiagnosed and undertreated. For these reasons the Italian Society for the Study of Atherosclerosis (SISA) assembled a Consensus Panel with the task to provide guidelines for FH diagnosis and treatment.

DATA SYNTHESIS

Our guidelines include: i) an overview of the genetic complexity of FH and the role of candidate genes involved in LDL metabolism; ii) the prevalence of FH in the population; iii) the clinical criteria adopted for the diagnosis of FH; iv) the screening for ASCVD and the role of cardiovascular imaging techniques; v) the role of molecular diagnosis in establishing the genetic bases of the disorder; vi) the current therapeutic options in both heterozygous and homozygous FH. Treatment strategies and targets are currently based on low-density lipoprotein cholesterol (LDL-C) levels, as the prognosis of FH largely depends on the magnitude of LDL-C reduction achieved by lipid-lowering therapies. Statins with or without ezetimibe are the mainstay of treatment. Addition of novel medications like PCSK9 inhibitors, ANGPTL3 inhibitors or lomitapide in homozygous FH results in a further reduction of LDL-C levels. LDL apheresis is indicated in FH patients with inadequate response to cholesterol-lowering therapies.

CONCLUSION

FH is a common, treatable genetic disorder and, although our understanding of this disease has improved, many challenges still remain with regard to its identification and management.

Beyond statins: New pharmacological targets to decrease LDL-cholesterol and cardiovascular events

The pharmacological treatment of dyslipidemia, a major modifiable risk factor for developing atherosclerotic cardiovascular disease (ASCVD), remains a debated and controversial issue, not only in terms of the most appropriate therapeutic range for lipid levels, but also with regard to the optimal strategy and sequence approach (stepwise vs upstream therapy). Current treatment guidelines for the management of dyslipidemia focus on the intensity of low-density lipoprotein cholesterol (LDL-C) reduction, stratified according to risk for developing ASCVD. Beyond statins and ezetimibe, different medications targeting LDL-C have been recently approved by regulatory agencies with potential innovative mechanisms of action, including proprotein convertase subtilisin/kexin type 9 modulators (monoclonal antibodies such as evolocumab and alirocumab; small interfering RNA molecules such as inclisiran), ATP-citrate lyase inhibitors (bempedoic acid), angiopoietin-like 3 inhibitors (evinacumab), and microsomal triglyceride transfer protein inhibitors (lomitapide). An understanding of their pharmacological aspects, benefit-risk profile, including impact on hard cardiovascular endpoints beyond LDL-C reduction, and potential advantages from the patient perspective (e.g., adherence) - the focus of this evidence-based review - is crucial for practitioners across medical specialties to minimize therapeutic inertia and support clinical practice.

EFFICACY AND SAFETY OF LOMITAPIDE IN HOMOZYGOUS FAMILIAL HYPERCHOLESTEROLEMIA: THE PAN-EUROPEAN RETROSPECTIVE OBSERVATIONAL STUDY

BACKGROUND

Lomitapide is a lipid-lowering agent indicated as adjunct therapy for adult HoFH.

OBJECTIVES

This study evaluated the medium-term effectiveness and safety of lomitapide in a large cohort of HoFH patients in Europe.

METHODS

In a multicenter retrospective, observational study including 75 HoFH patients treated with lomitapide in a real-world clinical setting from 9 European countries, LDL-C changes, adverse events (AEs) as well as major adverse cardiovascular events (MACE) were assessed.

RESULTS

After a median 19 months (IQR 11-41 months) of treatment with a mean dosage of 20 mg of lomitapide. LDL-C decreased by 60%, from baseline 280.5 mg/dL (191.8-405.0 mg/dl) to 121.6 mg/dl (61.0-190.5 mg/dl). At the last visit, 32.0% of patients achieved LDL-C < 100mg/dL and 18.7% <70 mg/dL. At baseline, 38 HoFH patients were receiving LDL apheresis (LA), but after initiation of lomitapide 36.8% of patients discontinued LA. During follow-up, lomitapide was permanently interrupted in 13% of patients. Gastrointestinal (GI) AEs occurred in 40% and liver transaminases increased (3-5 x ULN) in 13% of patients. Among patients with liver ultrasound evaluation (n = 45), a modest increase in hepatic steatosis was noted during treatment; however liver stiffness measured by elastography in 30 of them remained within the normal range. Among HoFH patients exposed to lomitapide for at least 2 years, MACE incident rate was 7.4 per 1000 person-years in the 2 years after as compared to 21.2 per 1000 person-years before treatment with lomitapide.

CONCLUSIONS

In this medium-term real-world experience, lomitapide proved to be very effective in reducing LDL-C in HoFH. GI AEs were common, but liver safety was reassuring with no sign of increased risk of liver fibrosis. A signal of cardiovascular protection was also observed.

Rastreamento para Hipercolesterolemia Familiar em Pequenos Municípios: A Experiência do Programa HipercolBrasil em 11 Municípios Brasileiros

Fundamento

A hipercolesterolemia familiar (HF) é uma doença genética dominante que se caracteriza por níveis sanguíneos elevados de colesterol de lipoproteína de baixa densidade (LDL-C), e está associada à ocorrência de doença cardiovascular precoce. No Brasil, o HipercolBrasil, que é atualmente o maior programa de rastreamento em cascata para HF, já identificou mais de 2.000 indivíduos com variantes genéticas causadoras de HF. A abordagem padrão baseia-se no rastreamento em cascata de casos índices referidos, indivíduos com hipercolesterolemia e suspeita clínica de HF.

Objetivos

Realizar rastreamento direcionado de 11 pequenos municípios brasileiros com suspeita de alta prevalência de indivíduos com HF.

Métodos

A seleção dos municípios ocorreu de 3 maneiras: 1) municípios em que houve suspeita de efeito fundador (4 municípios); 2) municípios em uma região com altas taxas de infarto do miocárdio precoce, conforme descrito pelo banco de dados do Sistema Único de Saúde (2 municípios); e 3) municípios geograficamente próximos a outros municípios com alta prevalência de indivíduos com HF (5 municípios). A significância estatística foi considerada como valor p < 0,05.

Resultados

Foram incluídos 105 casos índices e 409 familiares de primeiro grau. O rendimento dessa abordagem foi de 4,67 familiares por caso índice, o qual é significativamente melhor (p < 0,0001) do que a taxa geral do HipercolBrasil (1,59). Identificamos 36 CIs com variante patogênica ou provavelmente patogênica para HF e 240 familiares de primeiro grau afetados. Conclusão: Nossos dados sugerem que, uma vez detectadas, regiões geográficas específicas justificam uma abordagem direcionada para a identificação de aglomerações de indivíduos com HF.

New Frontiers in the Treatment of Homozygous Familial Hypercholesterolemia

Homozygous familial hypercholesterolemia (HoFH) is a rare genetic disorder. The most common cause is a mutation in both alleles of the gene encoding for the low-density lipoprotein (LDL) receptor, although other causative mutations have been identified. Complications of atherosclerotic cardiovascular disease are common in these patients; therefore, reducing the elevated LDL-cholesterol burden is critical in their management. Conventionally, this is achieved by patients initiating lipid-lowering therapy, but this can present challenges in clinical practice. Fortunately, novel therapeutic strategies have enabled promising innovations in HoFH treatment. This review highlights recent and ongoing studies examining new therapeutic options for patients with HoFH.

Novel therapeutic targets and agents for pediatric dyslipidemia

Landmark studies have convincingly demonstrated that atherosclerosis begins in youth. While generally asymptomatic, an increasing number of youth with disorders of lipid and lipoprotein metabolism, such as familial hypercholesterolemia, are being identified through selective and universal screening. While a heart healthy lifestyle is the foundation of treatment for all youth with dyslipidemia, lipid-lowering therapy may be required by some to prevent morbidity and premature mortality, especially when initiated at a young age. When appropriate, use of statins has become standard of care for reducing low-density lipoprotein cholesterol, while fibrates may be beneficial in helping to lower triglycerides. Many therapeutic options commonly used in adults are not yet approved for use in youth less than 18 years of age. Although currently available lipid-lowering therapy is well tolerated and safe when administered to youth, response to treatment may vary and some conditions lack an efficient therapeutic option. Thus, newer agents are needed to aid in management. Many are in development and clinical trials in youth are currently in progress but will require FDA approval before becoming commercially available. Many utilize novel approaches to favorably alter lipid and lipoprotein metabolism. In the absence of long-term outcome data of youth who were treated beginning at an early age, clinical registries may prove to be useful in monitoring safety and efficacy and help to inform clinical decision-making. In this manuscript, we review currently available and novel therapeutic agents in development for the treatment of elevated cholesterol and triglycerides.

Lomitapide-a Microsomal Triglyceride Transfer Protein Inhibitor for Homozygous Familial Hypercholesterolemia

PURPOSE OF REVIEW

Homozygous familial hypercholesterolemia (HoFH) is a rare, genetic condition characterized by high levels of Low density lipoprotein cholesterol (LDL-C); overt, early-onset atherosclerotic cardiovascular disease (ASCVD); and premature cardiovascular events and mortality. Lomitapide is a first-in-class microsomal triglyceride transfer protein inhibitor for the treatment of HoFH. This review provides an update on data emerging from real-world studies of lomitapide following on from its pivotal phase 3 clinical trial in HoFH.

RECENT FINDINGS

Recent registry data have confirmed that HoFH is characterized by delayed diagnosis, with many patients not receiving effective therapy until they are approaching the age when major adverse cardiovascular events may occur. Data from case series of varying sizes, and from a 163-patient registry of HoFH patients receiving lomitapide, have demonstrated that lomitapide doses are lower and adverse events less severe than in the phase 3 study. Lomitapide enables many patients to reach European Atherosclerosis Society LDL-C targets. Some patients are able to reduce frequency of lipoprotein apheresis or, in some cases, stop the procedure altogether-unless there is significant elevation of lipoprotein (a). Modelling analyses based on historical and clinical trial data indicate that lomitapide has the potential to improve cardiovascular outcomes and survival in HoFH. Real-world clinical experience with lomitapide has shown the drug to be effective with manageable, less marked adverse events than in formal clinical studies. Event modelling data suggest a survival benefit with lomitapide in HoFH.

Beyond cholesterol metabolism: The pleiotropic effects of proprotein convertase subtilisin/kexin type 9 (PCSK9). Genetics, mutations, expression, and perspective for long-term inhibition

Proprotein convertase subtilisin/kexin type 9 (PCSK9) has a crucial role in lipid metabolism, particularly due to its function in low-density lipoprotein receptor degradation. Gain-of-function genetic mutations of PCSK9 result in autosomal dominant familial hypercholesterolemia, characterized by high levels of low-density lipoprotein cholesterol (LDL-C) and clinical signs of early atherosclerosis. In recent years, PCSK9 has become an important therapeutic target for cholesterol-lowering therapy. Particularly, its inhibition with monoclonal antibodies has shown excellent efficacy in decreasing LDL-C and reducing cardiovascular events. However, PCSK9, first identified in the brain, seems to be a ubiquitous protein with different tissue-specific functions also independent of cholesterol metabolism. Accordingly, it appears to be involved in the immune response, haemostasis, glucose metabolism, neuronal survival, and several other biological functions. This review provides a comprehensive overview of the genetics, biochemical structure, expression, and function of PCSK9 and discusses the potential implications of its long-term pharmacological inhibition.

A Global Review on the Utility of Genetic Testing for Familial Hypercholesterolemia

Familial hypercholesterolemia (FH) is a genetic disorder of cholesterol metabolism that affects an estimated 1/250 persons in the United States and abroad. FH is hallmarked by high low-density lipoprotein (LDL) cholesterol and an increased risk of premature atherosclerotic cardiovascular disease. This review summarizes recent global evidence showing the utility of FH genetic testing across diverse populations. Clinical and other qualitative outcomes following FH genetic testing were improved FH diagnosis, treatment initiation or continued treatment, treatment modification, improved total or LDL cholesterol levels, education on lifestyle management, and genetic counseling. This summary of evidence should be considered by those seeking overall evidence and knowledge gaps on the utility of FH genetic testing from a global perspective and for certain ethnic and age populations. These findings can be used to inform insurance policies and coverage decisions for FH genetic testing, policy recommendations to reduce the clinical and public health burden of FH, clinical practice and guidelines to improve the management of FH populations, and ongoing research involving FH genetic testing. We conclude that further investigations are needed to examine: (1) non-clinical outcomes following FH genetic testing; (2) patient-reported outcomes following FH genetic testing to convey patient experiences, values, and goals; and (3) clinical outcomes following FH genetic testing in non-Caucasian and pediatric populations in the United States and abroad.

Lomitapide and Mipomersen-Inhibiting Microsomal Triglyceride Transfer Protein (MTP) and apoB100 Synthesis

PURPOSE OF REVIEW

The goal of this review is to evaluate the role of inhibiting the synthesis of lipoproteins when there is no or little residual LDL-receptor function as in patients with homozygous familial hypercholesterolaemia. Lomitapide is administered orally once a day while mipomersen is given by subcutaneous injection once a week. Lomitapide inhibits microsomal triglyceride transfer protein while mipomersen is an antisense oligonucleotide directed against apoB100.

RECENT FINDINGS

The pivotal registration trials for lomitapide and mipomersen were published in 2013 and 2010, respectively. More recently published data from extension trials and cohort studies provides additional information on long-term safety and efficacy. The mean LDL cholesterol reduction was 50% with lomitapide in its single-arm open-label registration trial. Mipomersen reduced LDL cholesterol by approximately 25% in its double-blind, placebo-controlled registration study. Both lomitapide and mipomersen therapy are associated with variable increases in hepatic fat content. The long-term safety of increased hepatic fat content in patients receiving these therapies is uncertain and requires further study. Both drugs may cause elevated transaminase in some patients, but no cases of severe liver injury have been reported. Lomitapide may also cause gastrointestinal discomfort and diarrhoea, especially if patients consume high-fat meals and patients are advised to follow a low-fat diet supplemented with essential fatty acids and fat-soluble vitamins. Mipomersen may cause injection-site and influenza-like reactions. The effect of lomitapide and mipomersen on cardiovascular outcomes has not been studied, but circumstantial evidence suggests that the LDL cholesterol lowering achieved with these two agents may reduce cardiovascular event rates.

Barriers and Facilitators to Genetic Testing for Familial Hypercholesterolemia in the United States: A Review

Familial Hypercholesterolemia (FH) is an underdiagnosed condition in the United States (US) and globally, affecting an estimated 1/250 individuals. It is a genetic risk factor for premature cardiovascular disease and is responsible for an estimated 600,000 to 1.2 million preventable vascular events. Studies show that FH genetic testing can identify a causal gene variant in 60 to 80% of clinically suspected FH cases. However, FH genetic testing is currently underutilized in clinical settings in the US despite clinical recommendations and evidence supporting its use. Reasons for underutilization are not well understood. We conducted a literature review in the PubMed/MEDLINE database and eight peer-reviewed journals. After filtering for and reviewing 2340 articles against our inclusion criteria, we included nine commentaries or expert opinions and eight empirical studies reported between January 2014 and March 2019 in our review. After applying the Consolidated Framework for Implementation Research (CFIR), we identified a total of 26 potential barriers and 15 potential facilitators (estimated barrier to facilitator ratio of 1.73). We further estimated ratios of potential barriers to facilitators for each CFIR domain (Characteristics of Intervention, Outer Setting, Inner Setting, Characteristics of Individuals, and Process). Findings derived from our systematic approach to the literature and calculations of estimated baseline ratios of barriers and facilitators can guide future research to understand FH genetic testing implementation in diverse clinical settings. Our systematic approach to the CFIR could also be used as a model to understand or compare barriers and facilitators to other evidence-based genetic testing processes in health care settings in the US and abroad.