The genetics of familial hypercholesterolemia and emerging therapies

New Insights Into the Treatment of Hyperlipidemia: Pharmacological Updates and Emerging Treatments

Cardiovascular diseases are the leading causes of global mortality and morbidity. Hyperlipidemia is a significant risk factor for atherosclerosis and subsequent cardiovascular diseases. Hyperlipidemia is characterized by imbalances in blood cholesterol levels, particularly elevated low-density lipoprotein cholesterol and triglycerides, and is influenced by genetic and environmental factors. Current management consists of lifestyle modifications and pharmacological interventions most commonly consisting of statins. This review paper explores pathophysiology, management strategies, and pharmacotherapies including commonly used well-established medications including statins, fibrates, and ezetimibe, exciting novel therapies including proprotein convertase subtilisin/kexin type 9 (PCSK9) inhibitors, and RNA interference therapies (inclisiran), lomitapide, and bempedoic acid, highlighting their mechanisms of action, clinical efficacy, and safety profiles. Additionally, emerging therapies under clinical trials including ApoC-III inhibitors, DGAT2 inhibitors, ACAT2 Inhibitors, and LPL gene therapies are examined for their potential to improve lipid homeostasis and cardiovascular outcomes. The evolving landscape of hyperlipidemia management underscores the importance of continued research into both established therapies and promising new candidates, offering hope for more effective treatment strategies in the future.

Generalidades del metabolismo de los lípidos y del manejo de la de los lípidos y del manejo de la hipercolesterolemia

Introducción: los lípidos hacen parte fundamental de la biología humana y son precursores de la síntesis de hormonas esteroideas y derivados eicosanoides. Los requerimientos de lípidos son satisfechos a través de la vía endógena que consiste en la formación de lípidos a nivel celular y la exógena la cual se da con la ingesta y absorción de grasas provenientes de la dieta. El conocimiento de estas vías es importante ya que es el punto de partida para un abordaje terapéutico adecuado y oportuno, pero a pesar de la facilidad de las metodologías de laboratorio para su cuantificación y diagnóstico, la hipercolesterolemia familiar sigue siendo subdiagnosticada. Discusión: para los clínicos es importante pues es una de las causas de eventos cardiovasculares prematuros. La presentación heterocigota tiene una prevalencia aproximada de 1/500 personas. En su mayoría son secundarias a la incapacidad en la actividad de los receptores LDL para el procesamiento del colesterol. Este compromiso de receptores está dado por múltiples mutaciones. Conclusión: las manifestaciones clínicas están relacionadas con niveles de LDL elevados (mayores de 190 mg/dL) y colesterol total mayor de 300 mg/dL presentes desde el nacimiento. Las estatinas son la primera línea de tratamiento, pero pueden resultar insuficientes requiriendo tratamientos adicionales con ezetimiba, secuestradores de ácidos biliares e inhibidores de la PCSK9.

Alternative C3 Complement System: Lipids and Atherosclerosis

Familial hypercholesterolemia (FH) is increasingly associated with inflammation, a phenotype that persists despite treatment with lipid lowering therapies. The alternative C3 complement system (C3), as a key inflammatory mediator, seems to be involved in the atherosclerotic process; however, the relationship between C3 and lipids during plaque progression remains unknown. The aim of the study was to investigate by a systems biology approach the role of C3 in relation to lipoprotein levels during atherosclerosis (AT) progression and to gain a better understanding on the effects of C3 products on the phenotype and function of human lipid-loaded vascular smooth muscle cells (VSMCs). By mass spectrometry and differential proteomics, we found the extracellular matrix (ECM) of human aortas to be enriched in active components of the C3 complement system, with a significantly different proteomic signature in AT segments. Thus, C3 products were more abundant in AT-ECM than in macroscopically normal segments. Furthermore, circulating C3 levels were significantly elevated in FH patients with subclinical coronary AT, evidenced by computed tomographic angiography. However, no correlation was identified between circulating C3 levels and the increase in plaque burden, indicating a local regulation of the C3 in AT arteries. In cell culture studies of human VSMCs, we evidenced the expression of C3, C3aR (anaphylatoxin receptor) and the integrin α_Mβ₂ receptor for C3b/iC3b (RT-PCR and Western blot). C3mRNA was up-regulated in lipid-loaded human VSMCs, and C3 protein significantly increased in cell culture supernatants, indicating that the C3 products in the AT-ECM have a local vessel-wall niche. Interestingly, C3a and iC3b (C3 active fragments) have functional effects on VSMCs, significantly reversing the inhibition of VSMC migration induced by aggregated LDL and stimulating cell spreading, organization of F-actin stress fibers and attachment during the adhesion of lipid-loaded human VSMCs. This study, by using a systems biology approach, identified molecular processes involving the C3 complement system in vascular remodeling and in the progression of advanced human atherosclerotic lesions.

Genetic Risk Assessment for Atherosclerotic Cardiovascular Disease: A Guide for the General Cardiologist

Genetic testing for cardiovascular (CV) disease has had a profound impact on the diagnosis and evaluation of monogenic causes of CV disease, such as hypertrophic and familial cardiomyopathies, long QT syndrome, and familial hypercholesterolemia (FH). The success in genetic testing for monogenic diseases has prompted special interest in utilizing genetic information in the risk assessment of more common diseases such as atherosclerotic cardiovascular disease (ASCVD). Polygenic risk scores (PRS) have been developed to assess the risk of coronary artery disease (CAD) that now include millions of single-nucleotide polymorphisms (SNPs) that have been identified through genome-wide association studies (GWAS). While these PRS have demonstrated a strong association with CAD in large cross-sectional population studies, there remains intense debate regarding the added value that PRS contribute to existing clinical risk prediction models such as the pooled cohort equations (PCEs). In this review, we provide a brief background of genetic testing for monogenic drivers of CV disease and then focus on the recent developments in genetic risk assessment of ASCVD, including the use of PRS. We outline the genetic testing that is currently available to all cardiologists in the clinic and discuss the evolving sphere of specialized cardiovascular genetics programs (CVGPs) that integrate the expertise of cardiologists, geneticists, and genetic counselors. Finally, we review the possible implications that PRS and pharmacogenomic data may soon have on clinical practice in the care for patients with or at risk of developing ASCVD.

Development and Clinical Applications of Antisense Oligonucleotide Gapmers

DNA-like molecules called antisense oligonucleotides have opened new treatment possibilities for genetic diseases by offering a method of regulating gene expression. Antisense oligonucleotides are often used to suppress the expression of mutated genes which may interfere with essential downstream pathways. Since antisense oligonucleotides have been introduced for clinical use, different chemistries have been developed to further improve efficacy, potency, and safety. One such chemistry is a chimeric structure of a central block of deoxyribonucleotides flanked by sequences of modified nucleotides. Referred to as a gapmer, this chemistry produced promising results in the treatment of genetic diseases. Mipomersen and inotersen are examples of recent FDA-approved antisense oligonucleotide gapmers used for the treatment of familial hypercholesterolemia and hereditary transthyretin amyloidosis, respectively. In addition, volanesorsen was conditionally approved in the EU for the treatment of adult patients with familial chylomicronemia syndrome (FCS) in 2019. Many others are being tested in clinical trials or under preclinical development. This chapter will cover the development of mipomersen and inotersen in clinical trials, along with advancement in gapmer treatments for cancer, triglyceride-elevating genetic diseases, Huntington's disease, myotonic dystrophy, and prion diseases.

The Digenic Causality in Familial Hypercholesterolemia: Revising the Genotype-Phenotype Correlations of the Disease

Genetically inherited defects in lipoprotein metabolism affect more than 10 million individuals around the globe with preponderance in some parts where consanguinity played a major role in establishing founder mutations. Mutations in four genes have been so far linked to the dominant and recessive form of the disease. Those players encode major proteins implicated in cholesterol regulation, namely, the low-density lipoprotein receptor (LDLR) and its associate protein 1 (LDLRAP1), the proprotein convertase substilin/kexin type 9 (PCSK9), and the apolipoprotein B (APOB). Single mutations or compound mutations in one of these genes are enough to account for a spectrum of mild to severe phenotypes. However, recently several reports have identified digenic mutations in familial cases that do not necessarily reflect a much severe phenotype. Yet, data in the literature supporting this notion are still lacking. Herein, we review all the reported cases of digenic mutations focusing on the biological impact of gene dosage and the potential protective effects of single-nucleotide polymorphisms linked to hypolipidemia. We also highlight the difficulty of establishing phenotype-genotype correlations in digenic familial hypercholesterolemia cases due to the complexity and heterogeneity of the phenotypes and the still faulty in silico pathogenicity scoring system. We finally emphasize the importance of having a whole exome/genome sequencing approach for all familial cases of familial hyperlipidemia to better understand the genetic and clinical course of the disease.

Familial Hypercholesterolemia in Premature Acute Coronary Syndrome. Insights from CholeSTEMI Registry

Familial hypercholesterolemia (FH) is an underdiagnosed genetic inherited condition that may lead to premature coronary artery disease (CAD). FH has an estimated prevalence in the general population of about 1:313. However, its prevalence in patients with premature STEMI (ST-elevation myocardial infarction) has not been widely studied. This study aimed to evaluate the prevalence of FH in patients with premature STEMI. Cardiovascular risk factors, LDLc (low-density lipoprotein cholesterol) evolution, and differences between genders were also evaluated. Consecutive patients were referred for cardiac catheterization to our center due to STEMI suspicion in 2018. From the 80 patients with confirmed premature CAD (men < 55 and women < 60 years old with confirmed CAD), 56 (48 men and eight women) accepted to be NGS sequenced for the main FH genes. Clinical information and DLCN (Dutch Lipid Clinic Network) score were analyzed. Only one male patient had probable FH (6-7 points) and no one reached a clinically definite diagnosis. Genetic testing confirmed that the only patient with a DLCN score ≥6 has HF (1.8%). Smoking and high BMI the most frequent cardiovascular risk factors (>80%). Despite high doses of statins being expected to reduce LDLc levels at STEMI to current dyslipidemia guidelines LDL targets (<55 mg/dL), LDLc control levels were out of range. Although still 5.4 times higher than in general population, the prevalence of FH in premature CAD is still low (1.8%). To improve the genetic yield, genetic screening may be considered among patients with probable or definite FH according to clinical criteria. The classical cardiovascular risk factors prevalence far exceeds FH prevalence in patients with premature STEMI. LDLc control levels after STEMI were out range, despite intensive hypolipemiant treatment. These findings reinforce the need for more aggressive preventive strategies in the young and for intensive lipid-lowering therapy in secondary prevention.

A Brief Review of Cardiovascular Diseases, Associated Risk Factors and Current Treatment Regimes

Cardiovascular diseases (CVDs) are the leading cause of premature death and disability in humans and their incidence is on the rise globally. Given their substantial contribution towards the escalating costs of health care, CVDs also generate a high socio-economic burden in the general population. The underlying pathogenesis and progression associated with nearly all CVDs are predominantly of atherosclerotic origin that leads to the development of coronary artery disease, cerebrovascular disease, venous thromboembolism and, peripheral vascular disease, subsequently causing myocardial infarction, cardiac arrhythmias or stroke. The aetiological risk factors leading to the onset of CVDs are well recognized and include hyperlipidaemia, hypertension, diabetes, obesity, smoking and, lack of physical activity. They collectively represent more than 90% of the CVD risks in all epidemiological studies. Despite high fatality rate of CVDs, the identification and careful prevention of the underlying risk factors can significantly reduce the global epidemic of CVDs. Beside making favorable lifestyle modifications, primary regimes for the prevention and treatment of CVDs include lipid-lowering drugs, antihypertensives, antiplatelet and anticoagulation therapies. Despite their effectiveness, significant gaps in the treatment of CVDs remain. In this review, we discuss the epidemiology and pathology of the major CVDs that are prevalent globally. We also determine the contribution of well-recognized risk factors towards the development of CVDs and the prevention strategies. In the end, therapies for the control and treatment of CVDs are discussed.

Effects of a low-fat dietary regimen enriched with soy in children affected with heterozygous familial hypercholesterolemia

INTRODUCTION

Familial hypercholesterolemia (FH) is an inheritable, autosomal dominant disorder leading to pathologically increased levels of low-density-lipoprotein cholesterol (LDL-C). Dietary treatment remains an important tool in the management of affected children even after the decision for the initiation of pharmacotherapy is made. However, little evidence is available regarding the optimal dietary regimen for the treatment of children affected with FH.

METHODS

We present results from a randomized controlled trial in paediatric patients affected with heterozygous FH, assessing the effect of a soy-enriched fat modified diet (soy group) compared to fat modified diet (Control group) alone on LDL-C over a period of 13 weeks. Furthermore, we monitored isoflavone levels in plasma and urine as markers of adherence to the dietary treatments.

RESULTS

LDL-C decrease was statistically significantly greater in the soy group compared to the control group at week 7 (Control group 176.3 ± 27.8 mg/dl, soy group 154.7 ± 29.2 mg/dl, p = 0.038), and showed a trend towards significant at week 13 (Control group 179.9 ± 41.8 mg/dl, soy group 155.0 ± 30.2 mg/dl, p = 0.089). Relative LDL-C decrease correlated significantly with the following plasma isoflavone concentrations measured in week 7: daidzein (p < 0.004, r = 0.576) and genistein (p < 0.017, r = 0.490).

CONCLUSIONS

We provide evidence from a small randomized-controlled trial for the effectiveness and safety of a dietary treatment with soy in paediatric patients affected with heterozygous FH. The decrease in LDL-C was highly correlated with isoflavone levels, further highlighting a direct effect of soy ingestion. This study was registered under ClinicalTrials.gov Identifier No. NCT03563547.

Current pharmacotherapeutic options for primary dyslipidemia in adults

INTRODUCTION

Atherosclerotic cardiovascular disease (ASCVD) and its clinical manifestations, remain a leading cause of death and disability worldwide. One of the major risk factors of ASCVD is dyslipidemia and all the available guidelines suggest the importance of strategies for lipid control in a remarkable proportion of the general population.

AREAS COVERED

This review focuses on the therapeutic options available for the management of lipid disorders in adults.

EXPERT OPINION

A large body of evidence supports that statins are still the first-line option for the management of hypercholesterolemia in a large percentage of patients. Statins should be given at the appropriate dose and considering the differences in lipid-lowering potency across the different medications. The main current challenge in the treatment of lipid disorders is the need of improving patient adherence and persistence to lipid-lowering treatments beyond the drug choice and the target lipid component. To achieve this goal, the best strategy would be to treat the patients by using the appropriate drugs given at adequate doses to reach the treatment target. We should also avoid drug interactions, monitor possible untoward side effects and promote adherence to treatment by tailoring treatment strategies to each patient.

miR-505-3p controls chemokine receptor up-regulation in macrophages: role in familial hypercholesterolemia

Familial hypercholesterolemia (FH) conveys a high risk of premature atherosclerosis as a result of lifelong exposure to high LDL cholesterol levels that are not fully reduced by standard-of-care lipid-lowering treatment. Inflammatory mediators have played a role in the progression of atherosclerotic lesions. Here, we investigated whether innate immunity cells in patients with FH have a specific proinflammatory phenotype that is distinct from that of cells in normal participants. To this end, miR-505-3p-a microRNA related to chronic inflammation-and its target genes were investigated in monocyte-derived macrophages (MACs) of patients with FH (FH-MACs) and non-FH controls (co-MACs). On the basis of the profiler PCR array analysis of agomiR-505-3p-transfected MACs, we identified the chemokine receptors, CCR3, CCR4, and CXCR1, as genes that are regulated by miR-505-3p via the transcription factor, RUNX1. miR-505-3p was significantly down-regulated, whereas CCR3, CCR4, CXCR, and RUNX1 were increased in FH-MAC compared with co-MAC, with the increase being more evident in the proinflammatory M1-like FH-MAC. Chemokine receptor levels were unrelated to LDL plasma levels at entry, but correlated with age in patients with FH, not in controls. In summary, we demonstrate for first time to our knowledge that MACs from FH-MACs have an inflammatory phenotype that is characterized by the up-regulation of CCR3, CCR4, and CXCR1 under the control of miR-505-3p. These results suggest a chronic inflammatory condition in FH innate immunity cells that is not reverted by standard lipid-lowering treatment.-Escate, R., Mata, P., Cepeda, J. M., Padró, T., Badimon, L. miR-505-3p controls chemokine receptor up-regulation in macrophages: role in familial hypercholesterolemia.

Treatment Preferences in Germany Differ Among Apheresis Patients with Severe Hypercholesterolemia

BACKGROUND

Severe hypercholesterolemia is a major risk factor of death in patients with coronary heart disease. New adjunctive drug therapies (proprotein convertase subtilisin/kexin type 9 [PCSK9] inhibitors) have gained approval in Europe and the USA.

OBJECTIVE

In this empirical study, we documented preferences regarding adjuvant drug therapy in apheresis-treated patients with severe familial hypercholesterolemia.

METHODS

We conducted a systematic literature search to identify patient-relevant outcomes in patients with severe hypercholesterolemia currently undergoing apheresis. Data were used to generate a semi-structured qualitative interview that enabled seven patient-relevant characteristics with three levels each to be identified. For the discrete choice experiment, an experimental design (7 × 3) was generated using NGene Software that consisted of 96 choices divided into eight blocks. The survey was conducted between November 2015 and April 2016 using computer-assisted personal interviews.

RESULTS

The survey was completed by 348 patients (64.9% male). The random parameter logit estimation showed predominance for the attribute 'reduction of LDL-C (low-density lipoprotein cholesterol) level'. 'Risk of myopathy' and 'frequency of apheresis' dominated next. Within the random parameter logit estimation, all coefficients were significant (P ≤ 0.01). The latent class analysis identified three patient groups. The first group (126 patients) found 'reduction of LDL-C level in blood' to be most important. This group focused solely on this treatment outcome independently of apheresis frequency or additional injections. The second group (106 patients) focused on three attributes: 'frequency of apheresis', 'risk of myopathy', and 'reduction of LDL-C level in blood'. Respondents clearly considered a high frequency of apheresis to have a negative impact. The third group (116 patients) demonstrated the highest preference for apheresis. These patients have adjusted to apheresis for > 10 years.

CONCLUSION

Regarding patient preference, clinical efficacy seems to dominate. Hence, 'reduction of LDC-C in blood' was ranked highest above patient-relevant modes of administration and adverse effects. In the patient groups identified, reduction of apheresis was important for only a subsegment (30%) of patients. Another 30% wanted effective LDL-C reduction by whatever means necessary. Most strikingly, another 30% preferred higher frequencies of apheresis.

miR-505-3p controls chemokine receptor up-regulation in macrophages: role in familial hypercholesterolemia

Familial hypercholesterolemia (FH) conveys a high risk of premature atherosclerosis as a result of lifelong exposure to high LDL cholesterol levels that are not fully reduced by standard-of-care lipid-lowering treatment. Inflammatory mediators have played a role in the progression of atherosclerotic lesions. Here, we investigated whether innate immunity cells in patients with FH have a specific proinflammatory phenotype that is distinct from that of cells in normal participants. To this end, miR-505-3p-a microRNA related to chronic inflammation-and its target genes were investigated in monocyte-derived macrophages (MACs) of patients with FH (FH-MACs) and non-FH controls (co-MACs). On the basis of the profiler PCR array analysis of agomiR-505-3p-transfected MACs, we identified the chemokine receptors, CCR3, CCR4, and CXCR1, as genes that are regulated by miR-505-3p via the transcription factor, RUNX1. miR-505-3p was significantly down-regulated, whereas CCR3, CCR4, CXCR, and RUNX1 were increased in FH-MAC compared with co-MAC, with the increase being more evident in the proinflammatory M1-like FH-MAC. Chemokine receptor levels were unrelated to LDL plasma levels at entry, but correlated with age in patients with FH, not in controls. In summary, we demonstrate for first time to our knowledge that MACs from FH-MACs have an inflammatory phenotype that is characterized by the up-regulation of CCR3, CCR4, and CXCR1 under the control of miR-505-3p. These results suggest a chronic inflammatory condition in FH innate immunity cells that is not reverted by standard lipid-lowering treatment.-Escate, R., Mata, P., Cepeda, J.M., Padró, T., Badimon, L. miR-505-3p controls chemokine receptor up-regulation in macrophages: role in familial hypercholesterolemia. FASEB J. 32, 601-612 (2018). www.fasebj.org.

Unmet Needs in LDL-C Lowering: When Statins Won't Do!

The use of low-density lipoprotein cholesterol (LDL-C)-lowering medications has led to a significant reduction of cardiovascular risk in both primary and secondary prevention. Statin therapy, one of the cornerstones for the prevention and treatment of cardiovascular disease (CVD), has been demonstrated to be effective in lowering LDL-C levels and in reducing the risk for CVD and is generally well-tolerated. However, compliance with statins remains suboptimal. One of the main reasons is limitations by adverse events, notably myopathies, which can lead to non-compliance with the prescribed statin regimen. Reducing the burden of elevated LDL-C levels is critical in patients with CVD as well as in patients with very high baseline levels of LDL-C (e.g. patients with familial hypercholesterolaemia), as statin therapy is insufficient for optimally reducing LDL-C below target values. In this review, we discuss alternative treatment options after maximally tolerated doses of statin therapy, including ezetimibe, proprotein convertase subtilisin/kexin type 9 (PCSK9) inhibitors, and cholesteryl ester transfer protein (CETP) inhibitors. Difficult-to-treat patients may benefit from combination therapy with ezetimibe or a PCSK9 inhibitor (evolocumab or alirocumab, which are now available). Updates of treatment guidelines are needed to guide the management of patients who will best benefit from these new treatments.

The Molecular Genetic Background of Familial Hypercholesterolemia: Data From the Slovak Nation-Wide Survey

Familial hypercholesterolemia (FH) is most frequently caused by LDLR or APOB mutations. Therefore, the aim of our study was to examine the genetic background of Slovak patients suspected of FH. Patients with clinical suspicion of FH (235 unrelated probands and 124 family relatives) were recruited throughout Slovakia during the years 2011-2015. The order of DNA analyses in probands was as follows: 1. APOB mutation p.Arg3527Gln by real-time PCR method, 2. direct sequencing of the LDLR gene 3. MLPA analysis of the LDLR gene. We have identified 14 probands and 2 relatives with an APOB mutation p.Arg3527Gln, and 89 probands and 75 relatives with 54 different LDLR mutations. Nine of LDLR mutations were novel (i.e. p.Asp90Glu, c.314-2A>G, p.Asp136Tyr, p.Ser177Pro, p.Lys225_Glu228delinsCysLys, p.Gly478Glu, p.Gly675Trpfs*42, p.Leu680Pro, p.Thr832Argfs*3). This is the first study on molecular genetics of FH in Slovakia encompassing the analysis of whole LDLR gene. Genetic etiology of FH was confirmed in 103 probands (43.8 %). Out of them, 86.4 % of probands carried the LDLR gene mutation and remaining 13.6 % probands carried the p.Arg3527Gln APOB mutation.

Mutation detection in Chinese patients with familial hypercholesterolemia

Background

Familial hypercholesterolemia (FH) is the first molecularly and clinically characterized genetic disease of lipid metabolism. It is an autosomal dominant disorder with significantly elevated levels of total cholesterol and low density of lipoprotein cholesterol in serum, which would lead to extensive xanthomas and premature coronary heart disease. Mutations in low density lipoprotein receptor (LDLR), proprotein convertase subtilisin/kexin type 9 and Apo lipoprotein B-100 (APOB) have been identified to be the underlying cause of this disease.

Methods

Genetic testing and reports of the mutations in the Chinese population are still limited. In this study, 11 unrelated Chinese FH families were enrolled to detect the candidate gene variants by DNA direct sequencing.

Results and conclusion

We identified 12 mutations (11 in LDLR and one in APOB) in ten FH families. Three novel LDLR mutations (c.516C>A/p.D172E, c.1720C>A/p.R574S and c.760C>T/p.Q254X) were identified and co-segregated with the affected individuals in the families. Our discoveries not only further supports the significant role of LDLR in FH, but also expands the spectrum of LDLR mutations. These new insights will contribute to the genetic diagnosis and counseling of FH patients.

The panorama of familial hypercholesterolemia in Latin America: a systematic review

The burden caused by familial hypercholesterolemia (FH) varies among countries and ethnic groups. The prevalence and characteristics of FH in Latin American (LA) countries is largely unknown. We present a systematic review (following the PRISMA statement) of FH in LA countries. The epidemiology, genetics, screening, management, and unique challenges encountered in these countries are discussed. Published reports discussing FH in Hispanic or LA groups was considered for analysis. Thirty studies were included representing 10 countries. The bulk of the data was generated in Brazil and Mexico. Few countries have registries and there was little commonality in FH mutations between LA countries. LDL receptor mutations predominate; APOB and PCSK9 mutations are rare. No mutation was found in an FH gene in nearly 50% of cases. In addition, some country-specific mutations have been reported. Scant information exists regarding models of care, cascade screening, cost, treatment effectiveness, morbidity, and mortality. In conclusion, FH is largely underdiagnosed and undertreated in the LA region. The genetic admixture with indigenous populations, producing mestizo's groups, may influence the mutational findings in Latin America. Potential opportunities to close gaps in knowledge and health care are identified.

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.

Pediatric experience with mipomersen as adjunctive therapy for homozygous familial hypercholesterolemia

BACKGROUND

Homozygous familial hypercholesterolemia (HoFH) is a rare, inherited condition resulting in severely elevated low-density lipoprotein cholesterol levels (LDL-C) leading to premature cardiovascular disease and, often, death. Mipomersen is an antisense oligonucleotide that inhibits apolipoprotein B (apo B) synthesis, lowering LDL-C levels. Mipomersen has demonstrated efficacy in adult HoFH patients, possibly providing a therapeutic option for pediatric patients. Study objectives were to summarize mipomersen efficacy and safety in the pediatric cohort of a phase 3 randomized controlled trial (RCT) and subsequent open-label extension study (OLE).

METHODS

Seven patients aged 12-18 years were randomized to 200-mg mipomersen or placebo weekly (26 weeks) and received mipomersen in the OLE (52 or 104 weeks). Plasma LDL-C and apo B concentrations and adverse events were assessed.

RESULTS

All pediatric patients completed the RCT and entered OLE. The 3 mipomersen patients in the RCT experienced mean reductions from baseline to RCT end of 42.7% and 46.1% for LDL-C and apo B, respectively. Of the 4 placebo patients, 3 responded well to mipomersen during OLE, with reductions in LDL-C of 26.5%-42.1%. Three patients completed OLE treatment, and 4 patients discontinued therapy due to adverse events. Lipid level fluctuations were observed and were likely due to poor compliance.

CONCLUSIONS

Long-term mipomersen treatment was successful regarding efficacy parameters for pediatric HoFH patients. The safety profile was consistent with other phase 3 clinical trials. Long-term compliance was an issue. Measures supporting adherence should be encouraged.

Effect of Dietary Docosahexaenoic Acid Supplementation on the Participation of Vasodilator Factors in Aorta from Orchidectomized Rats

Benefits of n-3 polyunsaturated fatty acids (PUFAs) against cardiovascular diseases have been reported. Vascular tone regulation is largely mediated by endothelial factors whose release is modulated by sex hormones. Since the incidence of cardiovascular pathologies has been correlated with decreased levels of sex hormones, the aim of this study was to analyze whether a diet supplemented with the specific PUFA docosahexaenoic acid (DHA) could prevent vascular changes induced by an impaired gonadal function. For this purpose, control and orchidectomized rats were fed with a standard diet supplemented with 5% (w/w) sunflower oil or with 3% (w/w) sunflower oil plus 2% (w/w) DHA. The lipid profile, the blood pressure, the production of prostanoids and nitric oxide (NO), and the redox status of biological samples from control and orchidectomized rats, fed control or DHA-supplemented diet, were analyzed. The vasodilator response and the contribution of NO, prostanoids and hyperpolarizing mechanisms were also studied. The results showed that orchidectomy negatively affected the lipid profile, increased the production of prostanoids and reactive oxygen species (ROS), and decreased NO production and the antioxidant capacity, as well as the participation of hyperpolarizing mechanisms in the vasodilator responses. The DHA-supplemented diet of the orchidectomized rats decreased the release of prostanoids and ROS, while increasing NO production and the antioxidant capacity, and it also improved the lipid profile. Additionally, it restored the participation of hyperpolarizing mechanisms by activating potassium. Since the modifications induced by the DHA-supplemented diet were observed in the orchidectomized, but not in the healthy group, DHA seems to exert cardioprotective effects in physiopathological situations in which vascular dysfunction exists.

Lessons from rare diseases of cartilage and bone

Studying severe phenotypes of rare syndromes can elucidate disease mechanisms of more common disorders and identify potential therapeutic targets. Lessons from rare bone diseases contributed to the development of the most successful class of bone active agents, the bisphosphonates. More recent research on rare bone diseases has helped elucidate key pathways and identify new targets in bone resorption and bone formation including cathepsin K and sclerostin, for which drugs are now in clinical trials. By contrast, there has been much less focus on rare cartilage diseases and osteoarthritis (OA) remains a common disease with no effective therapy. Investigation of rare cartilage syndromes is identifying new potential targets in OA including GDF5 and lubricin. Research on the arthropathy of the ultra-rare disease alkaptonuria has identified several new features of the OA phenotype, including high density mineralized protrusions (HDMPs) which constitute a newly identified mechanism of joint destruction.