Inhibition of microsomal triglyceride transfer protein alone or with ezetimibe in patients with moderate hypercholesterolemia

New insights into the therapeutic options to lower lipoprotein(a)

BACKGROUND

Elevated levels of lipoprotein(a) [Lp(a)] represent a risk factor for cardiovascular disease including aortic valve stenosis, myocardial infarction and stroke. While the patho-physiological mechanisms linking Lp(a) with atherosclerosis are not fully understood, from genetic studies that lower Lp(a) levels protect from CVD independently of other risk factors including lipids and lipoproteins. Hereby, Lp(a) has been considered an appealing pharmacological target.

RESULTS

However, approved lipid lowering therapies such as statins, ezetimibe or PCSK9 inhibitors have a neutral to modest effect on Lp(a) levels, thus prompting the development of new strategies selectively targeting Lp(a). These include antisense oligonucleotides and small interfering RNAs (siRNAs) directed towards apolipoprotein(a) [Apo(a)], which are in advanced phase of clinical development. More recently, additional approaches including inhibitors of Apo(a) and gene editing approaches via CRISPR-Cas9 technology entered early clinical development.

CONCLUSION

If the results from the cardiovascular outcome trials, designed to demonstrate whether the reduction of Lp(a) of more than 80% as observed with pelacarsen, olpasiran or lepodisiran translates into the decrease of cardiovascular mortality and major adverse cardiovascular events, will be positive, lowering Lp(a) will become a new additional target in the management of patients with elevated cardiovascular risk.

Consensus on lipoprotein(a) of the Spanish Society of Arteriosclerosis. Literature review and recommendations for clinical practice

The irruption of lipoprotein(a) (Lp(a)) in the study of cardiovascular risk factors is perhaps, together with the discovery and use of proprotein convertase subtilisin/kexin type 9 (iPCSK9) inhibitor drugs, the greatest novelty in the field for decades. Lp(a) concentration (especially very high levels) has an undeniable association with certain cardiovascular complications, such as atherosclerotic vascular disease (AVD) and aortic stenosis. However, there are several current limitations to both establishing epidemiological associations and specific pharmacological treatment. Firstly, the measurement of Lp(a) is highly dependent on the test used, mainly because of the characteristics of the molecule. Secondly, Lp(a) concentration is more than 80% genetically determined, so that, unlike other cardiovascular risk factors, it cannot be regulated by lifestyle changes. Finally, although there are many promising clinical trials with specific drugs to reduce Lp(a), currently only iPCSK9 (limited for use because of its cost) significantly reduces Lp(a). However, and in line with other scientific societies, the SEA considers that, with the aim of increasing knowledge about the contribution of Lp(a) to cardiovascular risk, it is relevant to produce a document containing the current status of the subject, recommendations for the control of global cardiovascular risk in people with elevated Lp(a) and recommendations on the therapeutic approach to patients with elevated Lp(a).

Advances in Pharmacological Approaches for Managing Hypercholesterolemia: A Comprehensive Overview of Novel Treatments

Hypercholesterolemia plays a crucial role in the formation of lipid plaques, particularly with elevated low-density lipoprotein (LDL-C) levels, which are linked to increased risks of cardiovascular disease, cerebrovascular disease, and peripheral arterial disease. Controlling blood cholesterol values, specifically reducing LDL-C, is widely recognized as a key modifiable risk factor for decreasing the morbidity and mortality associated with cardiovascular diseases. Historically, statins, by inhibiting the enzyme β-hydroxy β-methylglutaryl-coenzyme A (HMG)-CoA reductase, have been among the most effective drugs. However, newer non-statin agents have since been introduced into hypercholesterolemia therapy, providing a viable alternative with a favorable cost-benefit ratio. This paper aims to delve into the latest therapies, shedding light on their mechanisms of action and therapeutic benefits.

Consensus document on Lipoprotein(a) from the Italian Society for the Study of Atherosclerosis (SISA)

AIMS

In view of the consolidating evidence on the causal role of Lp(a) in cardiovascular disease, the Italian Society for the Study of Atherosclerosis (SISA) has assembled a consensus on Lp(a) genetics and epidemiology, together with recommendations for its measurement and current and emerging therapeutic approaches to reduce its plasma levels. Data on the Italian population are also provided.

DATA SYNTHESIS

Lp(a) is constituted by one apo(a) molecule and a lipoprotein closely resembling to a low-density lipoprotein (LDL). Its similarity with an LDL, together with its ability to carry oxidized phospholipids are considered the two main features making Lp(a) harmful for cardiovascular health. Plasma Lp(a) concentrations vary over about 1000 folds in humans and are genetically determined, thus they are quite stable in any individual. Mendelian Randomization studies have suggested a causal role of Lp(a) in atherosclerotic cardiovascular disease (ASCVD) and aortic valve stenosis and observational studies indicate a linear direct correlation between cardiovascular disease and Lp(a) plasma levels. Lp(a) measurement is strongly recommended once in a patient's lifetime, particularly in FH subjects, but also as part of the initial lipid screening to assess cardiovascular risk. The apo(a) size polymorphism represents a challenge for Lp(a) measurement in plasma, but new strategies are overcoming these difficulties. A reduction of Lp(a) levels can be currently attained only by plasma apheresis and, moderately, with PCSK9 inhibitor treatment.

CONCLUSIONS

Awaiting the approval of selective Lp(a)-lowering drugs, an intensive management of the other risk factors for individuals with elevated Lp(a) levels is strongly recommended.

Daring to dream: Targeting lipoprotein(a) as a causal and risk-enhancing factor

Lipoprotein(a) [Lp(a)], a distinct lipoprotein class, has become a major focus for cardiovascular research. This review is written in light of the recent guideline and consensus statements on Lp(a) and focuses on 1) the causal association between Lp(a) and cardiovascular outcomes, 2) the potential mechanisms by which elevated Lp(a) contributes to cardiovascular diseases, 3) the metabolic insights on the production and clearance of Lp(a) and 4) the current and future therapeutic approaches to lower Lp(a) concentrations. The concentrations of Lp(a) are under strict genetic control. There exists a continuous relationship between the Lp(a) concentrations and risk for various endpoints of atherosclerotic cardiovascular disease (ASCVD). One in five people in the Caucasian population is considered to have increased Lp(a) concentrations; the prevalence of elevated Lp(a) is even higher in black populations. This makes Lp(a) a cardiovascular risk factor of major public health relevance. Besides the association between Lp(a) and myocardial infarction, the relationship with aortic valve stenosis has become a major focus of research during the last decade. Genetic studies provided strong support for a causal association between Lp(a) and cardiovascular outcomes: carriers of genetic variants associated with lifelong increased Lp(a) concentration are significantly more frequent in patients with ASCVD. This has triggered the development of drugs that can specifically lower Lp(a) concentrations: mRNA-targeting therapies such as anti-sense oligonucleotide (ASO) therapies and short interfering RNA (siRNA) therapies have opened new avenues to lower Lp(a) concentrations more than 95%. Ongoing Phase II and III clinical trials of these compounds are discussed in this review.

Update on management of paediatric dyslipidaemia

PURPOSE OF REVIEW

Atherosclerosis and associated cardiovascular risk factors originate in childhood; hence, early management of dyslipidaemia is vital. However, hypercholesterolemia remains untreated or undertreated in many youths. We review current therapies, drugs under investigation and consider potential future directions for the management of paediatric dyslipidaemia to highlight the recent evidence and new therapeutic options for future use.

RECENT FINDINGS

Cardiovascular disease (CVD) risk factors in childhood, including dyslipidaemia, are associated with CVD risk and clinical CVD events in adulthood. Recent data show that initiation of statin therapy in childhood in children with familial hypercholesterolemia reduces the risk of CVD in adulthood. Several well tolerated and efficacious treatment options have become available in recent times for the management of dyslipidaemia in youth. Many new lipid-lowering drugs are under investigation to widen the available choices. Some of these drugs are now available for use in paediatrics, while some remain targets for future use.

SUMMARY

We review available treatment options for paediatric dyslipidaemia management, discuss potential limitations and propose future directions. We also acknowledge the need for continued research in paediatrics for optimal paediatric dyslipidaemia management.

Lipoprotein(a): a risk factor for atherosclerosis and an emerging therapeutic target

Lipoprotein(a) (Lp(a)) is a complex circulating lipoprotein, and increasing evidence has demonstrated its role as a risk factor for atherosclerotic cardiovascular disease (ASCVD) and as a possible therapeutic target. Lp(a) atherogenic effects are attributed to several potential mechanisms in addition to cholesterol accumulation in the arterial wall, including proinflammatory effects mainly mediated by oxidised phospholipids. Several studies have found a causal and independent relationship between Lp(a) levels and cardiovascular risk. Furthermore, several studies also suggest a causal association between Lp(a) levels and calcific aortic valve stenosis. Available lipid-lowering agents have at best moderate impact on Lp(a) levels. Among available therapies, antibody proprotein convertase subtilisin/kexin type 9 inhibitors are the most effective in reducing Lp(a). Potent Lp(a)-lowering treatments that target LPA expression are under development. Lp(a) level measurement poses some challenges due to the absence of a definitive reference method and the reporting of Lp(a) values as molar (nanomoles per litre (nmol/L)) or mass concentrations (milligrams per decilitre (mg/dL)) by different assays. Currently, Lp(a) measurement is recommended to refine cardiovascular risk in specific clinical settings, that is, in individuals with a family history of premature ASCVD, in patients with ASCVD not explained by standard risk factors or in those with recurrent events despite optimal management of traditional risk factors. Patients with high Lp(a) levels should be managed with more intensive approaches to treat other modifiable cardiovascular risk factors. Overall, this review focuses on Lp(a) as an ASCVD risk factor and therapeutic target. Furthermore, it reports practical recommendations for Lp(a) measurement and interpretation and updated evidence on Lp(a)-lowering approaches.

Recent lipoprotein(a) trials

PURPOSE OF REVIEW

Lipoprotein(a) (Lp(a)) is a genetically determined independent risk factor for cardiovascular disease and calcific aortic stenosis; thus, serum levels are minimally affected by conventional treatments for hypercholesterolemia and hypertriglyceridemia. New RNA therapies directly targeting Lp(a) have demonstrated efficacy in decreasing serum levels. Several recent trials have demonstrated efficacy and safety of these RNA therapeutics.

RECENT FINDINGS

Single-stranded antisense oligonucleotides (ASOs) and small interfering RNA (siRNA) are two classes of RNA-targeted therapeutics that specifically target the LPA gene, which encodes for apolipoprotein(a), a dominant and rate-limiting component in the hepatic synthesis of Lp(a) particle. Pelacarsen (ASO), olpasiran (siRNA) and SLN360 (siRNA) are novel drugs that have demonstrated efficacy in lowering Lp(a) levels and excellent safety profiles.

SUMMARY

Lp(a) is an independent risk factor for cardiovascular disease. RNA-directed therapies, pelacarsen, olpasiran and SLN360, have shown efficacy in dramatically lowering serum Lp(a) levels. Outcomes data will be the next frontier of Lp(a) trials.

Lipoprotein(a): Evidence for Role as a Causal Risk Factor in Cardiovascular Disease and Emerging Therapies

Lipoprotein(a) (Lp(a)) is an established risk factor for multiple cardiovascular diseases. Several lines of evidence including mechanistic, epidemiologic, and genetic studies support the role of Lp(a) as a causal risk factor for atherosclerotic cardiovascular disease (ASCVD) and aortic stenosis/calcific aortic valve disease (AS/CAVD). Limited therapies currently exist for the management of risk associated with elevated Lp(a), but several targeted therapies are currently in various stages of clinical development. In this review, we detail evidence supporting Lp(a) as a causal risk factor for ASCVD and AS/CAVD, and discuss approaches to managing Lp(a)-associated risk.

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.

Smoking and diabetes attenuate beneficial effects of PSCK9 inhibitors on arterial wall properties in patients with very high lipoprotein (a) levels

Background and aims

Elevated lipoprotein (a) (Lp(a)) and low-density lipoprotein cholesterol levels (LDL-C) are significant residual risk factors for cardiovascular events. Treatment with protein convertase subtilisin kexin type 9 (PCSK9) inhibitors reduces the levels of both. Less is known about effects of PCSK9 inhibitors on functional and morphological properties of the arterial wall. The aim of the present study was to determine whether other factors besides decreased LDL-C and Lp(a) are associated with functional (flow-mediated dilation [FMD]) and morphological (carotid intima-media thickness [c-IMT], pulse-wave velocity [PWV]) changes of the arterial wall properties in patients with coronary artery disease (CAD) treated with alirocumab and evolocumab.

Methods

One hundred patients with CAD after myocardial infarction before 55 years and with high Lp(a) were randomised to lipid-lowering therapies without PCSK9 inhibitors (control; N = 31), or with alirocumab 150 mg SC (N = 35) or evolocumab 140 mg SC (N = 34), every 2 weeks. All patients underwent blood sampling for biochemical analyses and ultrasound measurements for FMD, c-IMT and PWV.

Results

There were no significant changes in FMD for the control (10.7% ± 6.6%-11.1% ± 4.4%, p = 0.716) and alirocumab (10.7% ± 5.9%-11.2% ± 5.3%, p = 0.547) groups, while evolocumab promoted significant increase (11.2% ± 6.8%-14.1% ± 6.6%, p < 0.0001). Only in non-smokers and non-diabetics significant improvements in FMD (p < 0.0001) after treatment with PCSK9 inhibitors were observed.

Conclusion

These data show that for patients with CAD and high Lp(a) levels, beneficial effects of PCSK9 inhibitors on the arterial wall properties can be attenuated by specific risk factors, such as smoking and diabetes.

New Therapeutic Approaches in Treatment of Dyslipidaemia—A Narrative Review

Dyslipidaemia is a well-known risk factor for the development of cardiovascular disease, a leading cause of morbidity and mortality in developed countries. As a consequence, the medical community has been dealing with this problem for decades, and traditional statin therapy remains the cornerstone therapeutic approach. However, clinical trials have observed remarkable results for a few agents effective in the treatment of elevated serum lipid levels. Ezetimibe showed good but limited results when used in combination with statins. Bempedoic acid has been thoroughly studied in multiple clinical trials, with a reduction in LDL cholesterol by approximately 15%. The first approved monoclonal antibodies for the treatment of dyslipidaemia, PCSK9 inhibitors, are currently used as second-line treatment for patients with unregulated lipid levels on statin or statin combination therapy. A new siRNA molecule, inclisiran, demonstrates great potential, particularly concerning compliance, as it is administered twice yearly and pelacarsen, an antisense oligonucleotide that targets lipoprotein(a) and lowers its levels. Volanesorsen is the first drug that was designed to target chylomicrons and lower triglyceride levels, and olezarsen, the next in-line chylomicron lowering agent, is currently being researched. The newest possibilities for the treatment of dyslipidaemia are ANGPTL3 inhibitors with evinacumab, already approved by the FDA, and EMA for the treatment of familial hypercholesterolemia. This article provides a short summary of new agents currently used or being developed for lipid lowering treatment.

Novel efficacious microRNA-30c analogs reduce apolipoprotein B secretion in human hepatoma and primary hepatocyte cells

High plasma lipid levels have been demonstrated to increase cardiovascular disease risk. Despite advances in treatments to decrease plasma lipids, additional therapeutics are still needed because many people are intolerant or nonresponsive to these therapies. We previously showed that increasing cellular levels of microRNA-30c (miR-30c) using viral vectors or liposomes reduces plasma lipids and atherosclerosis. In this study, we aimed to synthesize potent miR-30c analogs that can be delivered to hepatoma cells without the aid of viral vectors and lipid emulsions. We hypothesized that modification of the passenger strand of miR-30c would increase the stability of miR-30c and augment its delivery to liver cells. Here, we report the successful synthesis of a series of miR-30c analogs by using different chemically modified nucleosides. In these analogs, we left the active sense strand untouched so that its biological activity remained unaltered, and we modified the passenger strand of miR-30c to enhance the stability and uptake of miR-30c by hepatoma cells through phosphorothiorate linkages and the addition of GalNAc. We show that these analogs significantly reduced apolipoprotein B secretion in Huh-7 human hepatoma cells and human primary hepatocytes without affecting apolipoprotein A1 secretion and cellular lipid levels. Our results provide a proof of concept that the passenger strand of miR-30c can be modified to increase its stability and delivery to cells while retaining the potency of the sense strand. We anticipate these miR-30c analogs will be useful in the development of more efficacious analogs for the treatment of hyperlipidemias and cardiovascular diseases.

Apo(a) and ApoB Interact Noncovalently Within Hepatocytes: Implications for Regulation of Lp(a) Levels by Modulation of ApoB Secretion

BACKGROUND

Elevated plasma Lp(a) (lipoprotein(a)) levels are associated with increased risk for atherosclerotic cardiovascular disease and aortic valve stenosis. However, the cell biology of Lp(a) biosynthesis remains poorly understood, with the locations of the noncovalent and covalent steps of Lp(a) assembly unclear and the nature of the apoB-containing particle destined for Lp(a) unknown. We, therefore, asked if apo(a) and apoB interact noncovalently within hepatocytes and if this impacts Lp(a) biosynthesis.

METHODS

Using human hepatocellular carcinoma cells expressing 17K (17 kringle) apo(a), or a 17KΔLBS7,8 variant with a reduced ability to bind noncovalently to apoB, we performed coimmunoprecipitation, coimmunofluorescence, and proximity ligation assays to document intracellular apo(a):apoB interactions. We used a pulse-chase metabolic labeling approach to measure apo(a) and apoB secretion rates.

RESULTS

Noncovalent complexes containing apo(a)/apoB are present in lysates from cells expressing 17K but not 17KΔLBS7,8, whereas covalent apo(a)/apoB complexes are absent from lysates. 17K and apoB colocalized intracellularly, overlapping with staining for markers of endoplasmic reticulum trans-Golgi, and early endosomes, and less so with lysosomes. The 17KΔLBS7,8 had lower colocalization with apoB. Proximity ligation assays directly documented intracellular 17K/apoB interactions, which were dramatically reduced for 17KΔLBS7,8. Treatment of cells with PCSK9 (proprotein convertase subtilisin/kexin type 9) enhanced, and lomitapide reduced, apo(a) secretion in a manner dependent on the noncovalent interaction between apo(a) and apoB. Apo(a) secretion was also reduced by siRNA-mediated knockdown of APOB.

CONCLUSIONS

Our findings explain the coupling of apo(a) and Lp(a)-apoB production observed in human metabolic studies using stable isotopes as well as the ability of agents that inhibit apoB biosynthesis to lower Lp(a) levels.

Cholesterol Metabolism: A Double-Edged Sword in Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) represents a leading cause of cancer-related deaths globally. The rising incidence of metabolic syndrome and its hepatic manifestation, nonalcoholic fatty liver disease (NAFLD), have emerged as the fastest-growing cause of HCC in recent years. Cholesterol, a major lipid component of the cell membrane and lipoprotein particles, is primarily produced and metabolized by the liver. Numerous studies have revealed an increased cholesterol biosynthesis and uptake, reduced cholesterol exportation and excretion in HCC, which all contribute to lipotoxicity, inflammation, and fibrosis, known HCC risk factors. In contrast, some clinical studies have shown that higher cholesterol is associated with a reduced risk of HCC. These contradictory observations imply that the relationship between cholesterol and HCC is far more complex than initially anticipated. Understanding the role of cholesterol and deciphering the underlying molecular events in HCC development is highly relevant to developing new therapies. Here, we discuss the current understanding of cholesterol metabolism in the pathogenesis of NAFLD-associated HCC, and the underlying mechanisms, including the roles of cholesterol in the disruption of normal function of specific cell types and signaling transduction. We also review the clinical progression in evaluating the association of cholesterol with HCC. The therapeutic effects of lowering cholesterol will also be summarized. We also interpret reasons for the contradictory observations from different preclinical and human studies of the roles of cholesterol in HCC, aiming to provide a critical assessment of the potential of cholesterol as a therapeutic target.

Lipoprotein(a)

Lipoprotein(a) [Lp(a)] is an atherogenic lipoprotein with a strong genetic regulation. Up to 90% of the concentrations are explained by a single gene, the LPA gene. The concentrations show a several-hundred-fold interindividual variability ranging from less than 0.1 mg/dL to more than 300 mg/dL. Lp(a) plasma concentrations above 30 mg/dL and even more above 50 mg/dL are associated with an increased risk for cardiovascular disease including myocardial infarction, stroke, aortic valve stenosis, heart failure, peripheral arterial disease, and all-cause mortality. Since concentrations above 50 mg/dL are observed in roughly 20% of the Caucasian population and in an even higher frequency in African-American and Asian-Indian ethnicities, it can be assumed that Lp(a) is one of the most important genetically determined risk factors for cardiovascular disease.Carriers of genetic variants that are associated with high Lp(a) concentrations have a markedly increased risk for cardiovascular events. Studies that used these genetic variants as a genetic instrument to support a causal role for Lp(a) as a cardiovascular risk factor are called Mendelian randomization studies. The principle of this type of studies has been introduced and tested for the first time ever with Lp(a) and its genetic determinants.There are currently no approved pharmacologic therapies that specifically target Lp(a) concentrations. However, some therapies that target primarily LDL cholesterol have also an influence on Lp(a) concentrations. These are mainly PCSK9 inhibitors that lower LDL cholesterol by 60% and Lp(a) by 25-30%. Furthermore, lipoprotein apheresis lowers both, Lp(a) and LDL cholesterol, by about 60-70%. Some sophisticated study designs and statistical analyses provided support that lowering Lp(a) by these therapies also lowers cardiovascular events on top of the effect caused by lowering LDL cholesterol, although this was not the main target of the therapy. Currently, new therapies targeting RNA such as antisense oligonucleotides (ASO) or small interfering RNA (siRNA) against apolipoprotein(a), the main protein of the Lp(a) particle, are under examination and lower Lp(a) concentrations up to 90%. Since these therapies specifically lower Lp(a) concentrations without influencing other lipoproteins, they will serve the last piece of the puzzle whether a decrease of Lp(a) results also in a decrease of cardiovascular events.

Lipoprotein(a) Testing and Emerging Therapies

The study of lipoprotein(a) [Lp(a)] over the years has been a source of both enlightenment and frustration for the medical community. Accumulating evidence from large sample observational studies, Mendelian randomization studies, and genome-wide association studies has strengthened the association between Lp(a) and the development of atherosclerotic cardiovascular disease. This evidence supports the testing of Lp(a) in certain high-risk populations in order for clinicians to improve the risk profile of patients. Despite a variety of medical therapies that have been proven to reduce Lp(a) levels, the connection between the medical management of serum Lp(a) and improved cardiovascular outcomes remains elusive, due to the lack of specificity that current therapies have in targeting the Lp(a) production pathway. A new frontier in Lp(a) research has emerged with antisense-oligonucleotide therapy and RNA interference therapy, both of which target Lp(a) production at the level of mRNA translation. These therapies provide a pathway for investigating the effect of medical management of serum Lp(a) on cardiovascular outcomes.

General Perspectives for the Treatment of Atherosclerosis

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Atherosclerosis, a cardiovascular disease, is at the top of the list among the diseases leading to death. Although the biochemical and pathophysiological cascades involved within the development of atherosclerosis have been identified clearly, its nature is quite complex to be treated with a single agent targeting a pathway. Therefore, many natural and synthetic compounds have been suggested for the treatment of the disease. The majority of the drugs employed target one of the single components of the pathological outcomes, resulting in many times less effective and longterm treatments. In most cases, treatment options prevent further worsening of the symptoms rather than a radical treatment. Consequently, the current review has been prepared to focus on the validated and non-validated targets of atherosclerosis as well as the alternative treatment options such as hydroxymethyl glutaryl coenzyme A (HMG-CoA) reductase inhibitors, acyl-CoA cholesterol acyl transferase (ACAT) inhibitors, lipoprotein lipase stimulants, bile acid sequestrants, and some antioxidants. Related to the topic, both synthetic compounds designed employing medicinal chemistry skills and natural molecules becoming more popular in drug development are scrutinized in this mini review.

Emerging RNA Therapeutics to Lower Blood Levels of Lp(a): JACC Focus Seminar 2/4

Lipoprotein(a) [Lp(a)] has risen to the level of an accepted cardiovascular disease risk factor, but final proof of causality awaits a randomized trial of Lp(a) lowering. Inhibiting apolipoprotein(a) production in the hepatocyte with ribonucleic acid therapeutics has emerged as an elegant and effective solution to reduce plasma Lp(a) levels. Phase 2 clinical trials have shown that the antisense oligonucleotide pelacarsen reduced mean Lp(a) levels by 80%, allowing 98% of subjects to reach on-treatment levels of <125 nmol/l (∼50 mg/dl). The phase 3 Lp(a)HORIZON (Assessing the Impact of Lipoprotein(a) Lowering With TQJ230 on Major Cardiovascular Events in Patients With CVD) outcomes trial is currently enrolling approximately 7,680 patients with history of myocardial infarction, ischemic stroke, and symptomatic peripheral arterial disease and controlled low-density lipoprotein cholesterol to pelacarsen versus placebo. The co-primary endpoints are major adverse cardiovascular events in subjects with Lp(a) >70 mg/dl and >90 mg/dl, in which either of the two being positive will lead to a successful trial. Additional ribonucleic acid-targeted therapies to lower Lp(a) are in preclinical and clinical development. The testing of the Lp(a) hypothesis will provide proof whether Lp(a)-mediated risk can be abolished by potent Lp(a) lowering.

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.

New Therapeutic Approaches for Familial Hypercholesterolemia

Familial hypercholesterolemia (FH) is a common genetic condition characterized by elevated plasma levels of low-density lipoprotein cholesterol (LDL-C), premature atherosclerotic cardiovascular disease, and considerable unmet medical need with conventional LDL-C-lowering therapies. Between 2012 and 2015, the US Food and Drug Administration approved four novel LDL-C-lowering agents for use in patients with FH based on the pronounced LDL-C-lowering efficacy of these medicines. We review the four novel approved agents, as well as promising LDL-C-lowering agents in clinical development, with a focus on their mechanism of action, efficacy in FH cohorts, and safety.

Lipid management in patients with chronic kidney disease

An increased risk of cardiovascular disease, independent of conventional risk factors, is present even at minor levels of renal impairment and is highest in patients with end-stage renal disease (ESRD) requiring dialysis. Renal dysfunction changes the level, composition and quality of blood lipids in favour of a more atherogenic profile. Patients with advanced chronic kidney disease (CKD) or ESRD have a characteristic lipid pattern of hypertriglyceridaemia and low HDL cholesterol levels but normal LDL cholesterol levels. In the general population, a clear relationship exists between LDL cholesterol and major atherosclerotic events. However, in patients with ESRD, LDL cholesterol shows a negative association with these outcomes at below average LDL cholesterol levels and a flat or weakly positive association with mortality at higher LDL cholesterol levels. Overall, the available data suggest that lowering of LDL cholesterol is beneficial for prevention of major atherosclerotic events in patients with CKD and in kidney transplant recipients but is not beneficial in patients requiring dialysis. The 2013 Kidney Disease: Improving Global Outcomes (KDIGO) Clinical Practice Guideline for Lipid Management in CKD provides simple recommendations for the management of dyslipidaemia in patients with CKD and ESRD. However, emerging data and novel lipid-lowering therapies warrant some reappraisal of these recommendations.

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.

To test, or not to test: that is the question for the future of lipoprotein(a)

INTRODUCTION

Lipoprotein(a) [Lp(a)] is a potent, highly heritable and common risk factor for atherosclerotic cardiovascular disease (ASCVD). Evidence for a causal association between elevated Lp(a) and ASCVD has been provided by large epidemiological investigations that have demonstrated a curvilinear association with increased risk, as well as from genetic examinations and cellular and transgenic animal studies. Although there are several therapies available for lowering Lp(a), none are selective for Lp(a) and there is no clinical trial data that has specifically shown that lowering Lp(a) reduces the risk of ASCVD. Hence, screening for elevated Lp(a) is not routinely incorporated into clinical practice. Areas covered: This paper reviews the current evidence supporting the causal role of Lp(a) in the primary and secondary prevention of ASCVD, screening approaches for high Lp(a), current guidelines on testing Lp(a), and barriers to the routine screening of elevated Lp(a) in clinical practice. Expert opinion: At present, there is a moderate level of evidence supporting the routine screening of elevated Lp(a). Current guidelines recommend testing for elevated Lp(a) in individuals at intermediate or high risk of ASCVD.

New Frontiers in Lp(a)-Targeted Therapies

Interest in lipoprotein (a) [Lp(a)] has exploded over the past decade with the emergence of genetic and epidemiological studies pinpointing elevated levels of this unique lipoprotein as a causal risk factor for atherosclerotic cardiovascular disease (ASCVD) and calcific aortic valve disease (CAVD). This review summarizes the most recent discoveries regarding therapeutic approaches to lower Lp(a) and presents these findings in the context of an emerging, although far from complete, understanding of the biosynthesis and catabolism of Lp(a). Application of Lp(a)-specific lowering agents to outcome trials will be the key to opening this new frontier in the battle against CVD.

Dietary natural products as emerging lipoprotein(a)-lowering agents

Elevated plasma lipoprotein(a) (Lp(a)) levels are associated with an increased risk of cardiovascular disease (CVD). Hitherto, niacin has been the drug of choice to reduce elevated Lp(a) levels in hyperlipidemic patients but its efficacy in reducing CVD outcomes has been seriously questioned by recent clinical trials. Additional drugs may reduce to some extent plasma Lp(a) levels but the lack of a specific therapeutic indication for Lp(a)-lowering limits profoundly reduce their use. An attractive therapeutic option is natural products. In several preclinical and clinical studies as well as meta-analyses, natural products, including l-carnitine, coenzyme Q ₁₀ , and xuezhikang were shown to significantly decrease Lp(a) levels in patients with Lp(a) hyperlipoproteinemia. Other natural products, such as pectin, Ginkgo biloba, flaxseed, red wine, resveratrol and curcuminoids can also reduce elevated Lp(a) concentrations but to a lesser degree. In conclusion, aforementioned natural products may represent promising therapeutic agents for Lp(a) lowering.

The Impact of Egg Nutrient Composition and Its Consumption on Cholesterol Homeostasis

Nutrient deficiencies and excess are involved in many aspects of human health. As a source of essential nutrients, eggs have been used worldwide to support the nutritional needs of human societies. On the other hand, eggs also contain a significant amount of cholesterol, a lipid molecule that has been associated with the development of cardiovascular diseases. Whether the increase of egg consumption will lead to elevated cholesterol absorption and disruption of cholesterol homeostasis has been a concern of debate for a while. Cholesterol homeostasis is regulated through its dietary intake, endogenous biosynthesis, utilization, and excretion. Recently, some research interests have been paid to the effects of egg consumption on cholesterol homeostasis through the intestinal cholesterol absorption. Nutrient components in eggs such as phospholipids may contribute to this process. The goals of this review are to summarize the recent progress in this area and to discuss some potential benefits of egg consumption.

Host-targeting therapies for hepatitis C virus infection: current developments and future applications

Chronic hepatitis C virus (HCV) infection is a leading cause of chronic liver diseases and hepatocellular carcinoma (HCC) worldwide. In the past few years, anti-HCV therapies have undergone a revolution with the approval of multiple direct-acting antivirals (DAAs), which enable interferon-free treatments with considerable improvement of sustained virologic response in patients. Today, DAAs have become the standard of care for HCV therapy. However, several limitations remain, which include access to therapy, treatment failure in a subset of patients and persistent risk of HCC development following cure in patients with advanced fibrosis. By targeting conserved host proteins involved in the HCV life cycle, host-targeting agents (HTAs) offer opportunities for pan-genotypic antiviral approaches with a high barrier to drug resistance. Moreover, when applied in combination with DAAs, HTAs could improve the management of difficult-to-treat patients by acting through a complementary mechanism of action. In this review, we summarize the different HTAs evaluated in preclinical and clinical development and discuss their potential role for anti-HCV therapies.

Lipoprotein(a) in clinical practice: New perspectives from basic and translational science

Elevated plasma concentrations of lipoprotein(a) (Lp(a)) are a causal risk factor for coronary heart disease (CHD) and calcific aortic valve stenosis (CAVS). Genetic, epidemiological and in vitro data provide strong evidence for a pathogenic role for Lp(a) in the progression of atherothrombotic disease. Despite these advancements and a race to develop new Lp(a) lowering therapies, there are still many unanswered and emerging questions about the metabolism and pathophysiology of Lp(a). New studies have drawn attention to Lp(a) as a contributor to novel pathogenic processes, yet the mechanisms underlying the contribution of Lp(a) to CVD remain enigmatic. New therapeutics show promise in lowering plasma Lp(a) levels, although the complete mechanisms of Lp(a) lowering are not fully understood. Specific agents targeted to apolipoprotein(a) (apo(a)), namely antisense oligonucleotide therapy, demonstrate potential to decrease Lp(a) to levels below the 30-50 mg/dL (75-150 nmol/L) CVD risk threshold. This therapeutic approach should aid in assessing the benefit of lowering Lp(a) in a clinical setting.

microRNA-30c reduces plasma cholesterol in homozygous familial hypercholesterolemic and type 2 diabetic mouse models

High plasma cholesterol levels are found in several metabolic disorders and their reductions are advocated to reduce the risk of atherosclerosis. A way to lower plasma lipids is to curtail lipoprotein production; however, this is associated with steatosis. We previously showed that microRNA (miR)-30c lowers diet-induced hypercholesterolemia and atherosclerosis in C57BL/6J and Apoe^-/- mice. Here, we tested the effect of miR-30c on plasma lipids, transaminases, and hepatic lipids in different mouse models. Hepatic delivery of miR-30c to chow-fed leptin-deficient (ob/ob) and leptin receptor-deficient (db/db) hypercholesterolemic and hyperglycemic mice reduced cholesterol in total plasma and VLDL/LDL by ∼28% and ∼25%, respectively, without affecting triglyceride and glucose levels. And these mice had lower plasma transaminases and creatine kinase activities than controls. Moreover, miR-30c significantly lowered plasma cholesterol and atherosclerosis in Western diet-fed Ldlr^-/- mice with no effect on plasma triglyceride, glucose, and transaminases. In these studies, hepatic lipids were similar in control and miR-30c-injected mice. Mechanistic studies showed that miR-30c reduced hepatic microsomal triglyceride transfer protein activity and lipid synthesis. Thus miR-30c reduced plasma cholesterol in several diet-induced and diabetic hypercholesterolemic mice. We speculate that miR-30c may be beneficial in lowering plasma cholesterol in different metabolic disorders independent of the origin of hypercholesterolemia.

Emerging Therapeutic Options for Lowering of Lipoprotein(a): Implications for Prevention of Cardiovascular Disease

PURPOSE OF REVIEW

Elevated plasma concentrations of lipoprotein(a) (Lp(a)) are an independent and causal risk factor for cardiovascular diseases including coronary artery disease, ischemic stroke, and calcific aortic valve stenosis. This review summarizes the rationale for Lp(a) lowering and surveys relevant clinical trial data using a variety of agents capable of lowering Lp(a).

RECENT FINDINGS

Contemporary guidelines and recommendations outline populations of patients who should be screened for elevated Lp(a) and who might benefit from Lp(a) lowering. Therapies including drugs and apheresis have been described that lower Lp(a) levels modestly (∼20 %) to dramatically (∼80 %). Existing therapies that lower Lp(a) also have beneficial effects on other aspects of the lipid profile, with the exception of Lp(a)-specific apheresis and an antisense oligonucleotide that targets the mRNA encoding apolipoprotein(a). No clinical trials conducted to date have managed to answer the key question of whether Lp(a) lowering confers a benefit in terms of ameliorating cardiovascular risk, although additional outcome trials of therapies that lower Lp(a) are ongoing. It is more likely, however, that Lp(a)-specific agents will provide the most appropriate approach for addressing this question.

Efficacy and Safety of Lomitapide in Hypercholesterolemia

BACKGROUND

Despite extensive use of statins, patients with hypercholesterolemia, especially homozygous familial hypercholesterolemia (HoFH), do not achieve recommended targets of low-density lipoprotein cholesterol (LDL-C). There is an urgent need for novel options that could reduce proatherogenic lipoprotein cholesterol levels. Lomitapide, a microsomal triglyceride transport protein (MTP) inhibitor, was approved three years ago as an orphan drug for the treatment of patients with HoFH.

OBJECTIVE

Our aim was to systematically evaluate the efficacy and safety of lomitapide and to provide guidance for clinicians.

METHODS

We searched the PubMed, Embase, and Cochrane library databases and ClinicalTrials.gov to identify valid studies published before 31 October 2016 that included lomitapide-treated patients who did or did not undergo lipid-lowering therapy. We assessed the quality of different studies. Data were extracted and evaluated for quality by two reviewers.

RESULTS

Studies reporting lomitapide therapy included one randomized controlled trial, three single-arm studies, and five case reports. In patients with HoFH, lomitapide reduced levels of LDL-C, total cholesterol, apolipoprotein B, and triglycerides with or without other lipid-lowering therapy, including apheresis. In non-HoFH patients with moderate hypercholesterolemia and hypertriglyceridemia, lomitapide also showed favorable effects on changes in LDL-C and triglycerides. However, both HoFH and non-HoFH patients experienced a reduction in high-density lipoprotein cholesterol (HDL-C) and apolipoprotein A-1 (ApoA-1). The most common adverse event was gastrointestinal disorder, and others included liver transaminase elevation and hepatic fat accumulation. Long-term use of lomitapide was associated with an increased risk of progressing to steatohepatitis and fibrosis.

CONCLUSIONS

Lomitapide improved most lipid parameters but not HDL-C or ApoA-1 in patients with HoFH and in non-HoFH patients, and gastrointestinal disorders were the most common adverse event. The possible benefits of lomitapide should be further evaluated and viewed against its possible long-term side effects.

Long-term statin therapy could be efficacious in reducing the lipoprotein (a) levels in patients with coronary artery disease modified by some traditional risk factors

BACKGROUND

Lipoprotein (a) [Lp (a)] is a well-established risk factor for coronary artery disease (CAD). However, up till now, treatment of patients with higher Lp (a) levels is challenging. This current study aimed to investigate the therapeutic effects of short-, medium and long-term statin use on the Lp (a) reduction and its modifying factors.

METHODS

The therapeutic duration was categorized into short-term (median, 39 days), medium term (median, 219 days) and long-term (median, 677 days). The lipid profiles before therapy served as baselines. Patients at short-, medium or long-term exactly matched with those at baseline. Every patient's lipid profiles during the follow-ups were compared to his own ones at baselines.

RESULTS

The current study demonstrated that long-term statin therapy significantly decreased the Lp (a) levels in CAD patients while short-term or medium term statin therapy didn't. When grouped by statin use, only long-term simvastatin use significantly decreased the Lp (a) levels while long-term atorvastatin use insignificantly decreased the Lp (a) levels. Primary hypertension (PH), DM, low density lipoprotein cholesterol (LDL-C) and high density lipoprotein cholesterol (HDL-C) could modify the therapeutic effects of statin use on the Lp (a) levels in CAD patients.

CONCLUSIONS

The long-term statin therapy could be efficacious in reducing the Lp (a) levels in CAD patients, which has been modified by some traditional risk factors. In the era of commercial unavailability of more reliable Lp (a) lowering drugs, our findings will bolster confidence in fighting higher Lp (a) abnormalities both for patients and for doctors.

Inflammation and beyond: new directions and emerging drugs for treating atherosclerosis

INTRODUCTION

Cardiovascular (CV) atherosclerotic disease remains the leading cause of morbidity and mortality worldwide, despite the advances in contemporary therapies. Inflammation is an important process in atherosclerosis, leading to plaque rupture and acute coronary syndrome. Although statin therapy has substantially reduced CV events in primary and secondary prevention, many treated patients will have recurrent adverse CV events despite the standard of care. Thus, drug development aiming to target inflammatory pathways seems a promising avenue for novel therapies in atherosclerosis. Areas covered: Statins have been extensively studied and are the most effective lipid-lowering drugs available for CV prevention. Novel anti-inflammatory drugs are being tested in Phase II and III trials, targeting pathways like interleukin-1, leukotrienes, TNF-α, P-selectin, CCL2-CCR2 and MAP Kinase. Expert opinion: Novel anti-inflammatory therapies seem promising additions to address the residual CV risk present despite the current standard of care, but large clinical trials have not yet shown beneficial effects on clinical events. PCSK9 inhibitors have been shown to substantially reduce LDL-C, however their long-term safety and effects on CV risk are currently being investigated. Pharmacogenomics holds great potential in future lipid trials, enabling the identification of patients who will respond with greater benefits and smaller risk to therapies and to decrease failure rates in drug development, as genotype-dependent effects of the CETP inhibitor dalcetrapib were shown in the dal-OUTCOMES and dal-PLAQUE-2 trials.

Human Genetics and the Causal Role of Lipoprotein(a) for Various Diseases

Lipoprotein(a) [Lp(a)] is a highly atherogenic lipoprotein that is under strong genetic control by the LPA gene locus. Genetic variants including a highly polymorphic copy number variation of the so called kringle IV repeats at this locus have a pronounced influence on Lp(a) concentrations. High concentrations of Lp(a) as well as genetic variants which are associated with high Lp(a) concentrations are both associated with cardiovascular disease which very strongly supports causality between Lp(a) concetrations and cardiovascular disease. This method of using a genetic variant that has a pronounced influence on a biomarker to support causality with an outcome is called Mendelian randomization approach and was applied for the first time two decades ago with data from Lp(a) and cardiovascular disease. This approach was also used to demonstrate a causal association between high Lp(a) concentrations and aortic valve stenosis, between low concentrations and type-2 diabetes mellitus and to exclude a causal association between Lp(a) concentrations and venous thrombosis. Considering the high frequency of these genetic variants in the population makes Lp(a) the strongest genetic risk factor for cardiovascular disease identified so far. Promising drugs that lower Lp(a) are on the horizon but their efficacy in terms of reducing clinical outcomes still has to be shown.

Lipoprotein(a) in postmenopausal women: assessment of cardiovascular risk and therapeutic options

INTRODUCTION

Lipoprotein(a) [Lp(a)], a low-density lipoprotein (LDL)-like particle, has been independently associated with increased cardiovascular disease (CVD) risk in various populations, such as postmenopausal women. The purpose of this narrative review is to present current data on the role of Lp(a) in augmenting CVD risk in postmenopausal women and focus on the available therapeutic strategies.

METHODS

PubMed was searched for English language publications until November 2015 under the following terms: "therapy" OR "treatment" AND ["lipoprotein (a)" OR "Lp(a)"] AND ("postmenopausal women" OR "menopausal women" OR "menopause").

RESULTS

Only hormone replacement therapy (mainly oral estrogens) and tibolone have been specifically studied in postmenopausal women and can reduce Lp(a) concentrations by up to 44%, although evidence indicating a concomitant reduction in CVD risk associated with Lp(a) is lacking. As alternative treatments for women who cannot, or will not, take hormonal therapies, niacin and the upcoming proprotein convertase subtilisin / kexin type 9 (PCSK-9) inhibitors are effective in reducing Lp(a) concentrations by up to 30%. Statins have minimal or no effect on Lp(a). However, data for these and other promising Lp(a)-lowering therapies including mipomersen, lomitapide, cholesterol-ester-transfer protein inhibitors and eprotirome are derived from studies in the general, mainly high CVD risk, population, and include only subpopulations of postmenopausal women.

CONCLUSIONS

Past, present and emerging therapies can reduce Lp(a) concentrations to a varying extent. Overall, it remains to be proven whether the aforementioned reductions in Lp(a) by these therapeutic options are translated into CVD risk reduction in postmenopausal women.

Targeting microsomal triglyceride transfer protein and lipoprotein assembly to treat homozygous familial hypercholesterolemia

Homozygous familial hypercholesterolemia (HoFH) is a polygenic disease arising from defects in the clearance of plasma low-density lipoprotein (LDL), which results in extremely elevated plasma LDL cholesterol (LDL-C) and increased risk of atherosclerosis, coronary heart disease, and premature death. Conventional lipid-lowering therapies, such as statins and ezetimibe, are ineffective at lowering plasma cholesterol to safe levels in these patients. Other therapeutic options, such as LDL apheresis and liver transplantation, are inconvenient, costly, and not readily available. Recently, lomitapide was approved by the Federal Drug Administration as an adjunct therapy for the treatment of HoFH. Lomitapide inhibits microsomal triglyceride transfer protein (MTP), reduces lipoprotein assembly and secretion, and lowers plasma cholesterol levels by over 50%. Here, we explain the steps involved in lipoprotein assembly, summarize the role of MTP in lipoprotein assembly, explore the clinical and molecular basis of HoFH, and review pre-clinical studies and clinical trials with lomitapide and other MTP inhibitors for the treatment of HoFH. In addition, ongoing research and new approaches underway for better treatment modalities are discussed.

Therapeutic Management of Familial Hypercholesterolemia: Current and Emerging Drug Therapies

Familial hypercholesterolemia (FH) is a genetic disorder characterized by significantly elevated low-density lipoprotein cholesterol (LDL-C) concentrations that result from mutations of the LDL receptor, apolipoprotein B (apo B-100), and proprotein convertase subtilisin/kexin type 9 (PCSK9). Early and aggressive treatment can prevent premature atherosclerotic cardiovascular disease in these high-risk patients. Given that the cardiovascular consequences of FH are similar to typical hypercholesterolemia, traditional therapies are utilized to decrease LDL-C levels. Patients with FH should receive statins as first-line treatment; high-potency statins at high doses are often required. Despite the use of statins, additional treatments are often necessary to achieve appropriate LDL-C lowering in this patient population. Novel drug therapies that target the pathophysiologic defects of the condition are continuously emerging. Contemporary therapies including mipomersen (Kynamro, Genzyme), an oligonucleotide inhibitor of apo B-100 synthesis; lomitapide (Juxtapid, Aegerion), a microsomal triglyceride transfer protein inhibitor; and alirocumab (Praluent, Sanofi-Aventis/Regeneron) and evolocumab (Repatha, Amgen), PCSK9 inhibitors, are currently approved by the U.S. Food and Drug Administration for use in FH. This review highlights traditional as well as emerging contemporary therapies with supporting clinical data to evaluate current recommendations and discuss the future direction of FH management.

Novel Therapies for Low-Density Lipoprotein Cholesterol Reduction

Although many clinical trials and meta-analyses have demonstrated that lower serum low-density lipoprotein cholesterol (LDL-C) levels are associated with proportionately greater reductions in the risk of cardiovascular disease events, not all patients with hypercholesterolemia are able to attain risk-stratified LDL-C goals with statin monotherapy. Elucidation of the pathophysiology of genetic disorders of lipid metabolism (e.g., familial hypercholesterolemia) has led to the development of several novel lipid-lowering strategies, including blocking the degradation of hepatic LDL-C receptors that are important in LDL-C clearance, or the inhibition of apoprotein synthesis and lipidation. Mipomersen and lomitapide are highly efficacious new agents available for the treatment of patients with homozygous familial hypercholesterolemia. The recent introduction of PCSK9 inhibitors (alirocumab and evolocumab) have made it possible for many patients to achieve very low LDL-C concentrations (e.g., <40 mg/dl) that are usually not attainable with statin monotherapy. Ongoing clinical trials are examining the impact of very low LDL-C levels on cardiovascular disease event rates and the long-term safety of this approach.

MicroRNA-30c Mimic Mitigates Hypercholesterolemia and Atherosclerosis in Mice

High plasma cholesterol levels are a major risk factor for atherosclerosis. Plasma cholesterol can be reduced by inhibiting lipoprotein production; however, this is associated with steatosis. Previously we showed that lentivirally mediated hepatic expression of microRNA-30c (miR-30c) reduced hyperlipidemia and atherosclerosis in mice without causing hepatosteatosis. Because viral therapy would be formidable, we examined whether a miR-30c mimic can be used to mitigate hyperlipidemia and atherosclerosis without inducing steatosis. Delivery of a miR-30c mimic to the liver diminished diet-induced hypercholesterolemia in C57BL/6J mice. Reductions in plasma cholesterol levels were significantly correlated with increases in hepatic miR-30c levels. Long term dose escalation studies showed that miR-30c mimic caused sustained reductions in plasma cholesterol with no obvious side effects. Furthermore, miR-30c mimic significantly reduced hypercholesterolemia and atherosclerosis in Apoe(-/-) mice. Mechanistic studies showed that miR-30c mimic had no effect on LDL clearance but reduced lipoprotein production by down-regulating microsomal triglyceride transfer protein expression. MiR-30c had no effect on fatty acid oxidation but reduced lipid synthesis. Additionally, whole transcriptome analysis revealed that miR-30c mimic significantly down-regulated hepatic lipid synthesis pathways. Therefore, miR-30c lowers plasma cholesterol and mitigates atherosclerosis by reducing microsomal triglyceride transfer protein expression and lipoprotein production and avoids steatosis by diminishing lipid syntheses. It mitigates atherosclerosis most likely by reducing lipoprotein production and plasma cholesterol. These findings establish that increasing hepatic miR-30c levels is a viable treatment option for reducing hypercholesterolemia and atherosclerosis.