Characterizing familial chylomicronemia syndrome: Baseline data of the APPROACH study

Diagnosis and Management of Acute Pancreatitis

Acute pancreatitis (AP) is increasing in incidence across the world, and in all age groups. Major changes in management have occurred in the last decade. Avoiding total parenteral nutrition and prophylactic antibiotics, avoiding overly aggressive fluid resuscitation, initiating early feeding, avoiding endoscopic retrograde cholangiopancreatography in the absence of concomitant cholangitis, same-admission cholecystectomy, and minimally invasive approaches to infected necrosis should now be standard of care. Increasing recognition of the risk of recurrence of AP, and progression to chronic pancreatitis, along with the unexpectedly high risk of diabetes and exocrine insufficiency after AP is the subject of large ongoing studies. In this review, we provide an update on important changes in management for this increasingly common disease.

Clinical characterization and mutation spectrum of patients with hypertriglyceridemia in a German outpatient clinic

BACKGROUND

Severe hypertriglyceridemia (HTG) has predominantly multifactorial causes (MCS). Yet a small subset of patients have the monogenetic form (FCS). It remains a challenge to distinguish patients clinically, since decompensated MCS might mimic FCS´s severity. Aim of the current study was to determine clinical criteria that could sufficiently distinguish both forms as well as to apply the FCS score proposed by Moulin and colleagues.

METHODS

We retrospectively studied 72 patients who presented with severe HTG in our clinic during a time span of seven years and received genetic testing. We classified genetic variants (ACMG-criteria), followed by genetic categorization into MCS or FCS. Clinical data were gathered from the medical records and the FCS score was calculated for each patient.

RESULTS

Molecular genetic screening revealed eight FCS patients and 64 MCS patients. Altogether, we found 13 pathogenic variants of which four have not been described before. The FCS patients showed a significantly higher median triglyceride level compared to the MCS. The FCS score yielded a sensitivity of 75% and a specificity of 93.7% in our cohort, and significantly differentiated between the FCS and MCS group (p<0.001).

CONCLUSIONS

In our cohort we identified several variables that significantly differentiated FCS from MCS. The FCS score performed similar to the original study by Moulin, thereby further validating the discriminatory power of the FCS score in an independent cohort.

Two successful pregnancies -in patients taking Volanesorsen for familial chylomicronemia syndrome

Familial chylomicronemia syndrome (FCS) is a rare inherited disorder characterized by severe hypertriglyceridemia, posing a heightened risk of acute pancreatitis. Recently, Volanesorsen, an APOC3 antisense oligonucleotide, gained approval for FCS treatment in the UK. Caution is advised during pregnancy due to limited safety data, although animal studies show no toxicity/teratogenicity. Two case scenarios are presented: In the first case, a patient with FCS continued Volanesorsen injections without having thrombocytopenia during an unplanned pregnancy until third trimester, maintaining triglyceride control. Upon discovering the pregnancy at 38 weeks, Volanesorsen was ceased, and a low-fat diet reinstated. Despite a heightened risk of pancreatitis, no episodes of pancreatitis occurred during the pregnancy. In the second case, stopping Volanesorsen before conception led to elevated triglycerides, and an episode of acute pancreatitis at 22 weeks, despite strict very low-fat diet and fibrate therapy from 14 weeks. At 23 weeks, Volanesorsen was reintroduced concurrently with regular therapeutic plasma exchange. No further episodes of pancreatitis occurred. In both case, fetal health was maintained throughout pregnancy, fetal scans revealed no anomalies, and planned C-sections delivered healthy babies without congenital issues. Both babies are well and developing normally at 24 and 19 months.

Xanthohumol, a prenylated chalcone, regulates lipid metabolism by modulating the LXRα/RXR-ANGPTL3-LPL axis in hepatic cell lines and high-fat diet-fed zebrafish models

Angiopoietin-like 3 (ANGPTL3) acts as an inhibitor of lipoprotein lipase (LPL), impeding the breakdown of triglyceride-rich lipoproteins (TGRLs) in circulation. Targeting ANGPTL3 is considered a novel strategy for improving dyslipidemia and atherosclerotic cardiovascular diseases (ASCVD). Hops (Humulus lupulus L.) contain several bioactive prenylflavonoids, including xanthohumol (Xan), isoxanthohumol (Isoxan), 6-prenylnaringenin (6-PN), and 8-prenylnaringenin (8-PN), with the potential to manage lipid metabolism. The aim of this study was to investigate the lipid-lowering effects of Xan, the effective prenylated chalcone in attenuating ANGPTL3 transcriptional activity, both in vitro using hepatic cells and in vivo using zebrafish models, along with exploring the underlying mechanisms. Xan (10 and 20 μM) significantly reduced ANGPTL3 mRNA and protein expression in HepG2 and Huh7 cells, leading to a marked decrease in secreted ANGPTL3 proteins via hepatic cells. In animal studies, orally administered Xan significantly alleviated plasma triglyceride (TG) and cholesterol levels in zebrafish fed a high-fat diet. Furthermore, it reduced hepatic ANGPTL3 protein levels and increased LPL activity in zebrafish models, indicating its potential to modulate lipid profiles in circulation. Furthermore, molecular docking results predicted that Xan exhibits a higher binding affinity to interact with liver X receptor α (LXRα) and retinoic acid X receptor (RXR) than their respective agonists, T0901317 and 9-Cis-retinoic acid (9-Cis-RA). We observed that Xan suppressed hepatic ANGPTL3 expression by antagonizing the LXRα/RXR-mediated transcription. These findings suggest that Xan ameliorates dyslipidemia by modulating the LXRα/RXR-ANGPTL3-LPL axis. Xan represents a novel potential inhibitor of ANGPTL3 for the prevention or treatment of ASCVD.

Multifactorial chylomicronemia syndrome

PURPOSE OF REVIEW

The aim of this review was to understand the role of multifactorial chylomicronemia syndrome (MFCS) as a cause of severe hypertriglyceridemia; to distinguish it from other causes of severe hypertriglyceridemia; and to provide a rational approach to treatment.

RECENT FINDINGS

There have been advances in understanding the genetic underpinning of MFCS, and a better appreciation as to how to differentiate it from the much rarer familial chylomicronemia syndrome, in which there are substantial differences in the approach to their treatment. New approaches to triglyceride lowering will help reduce the risk of pancreatitis, the major complication of MFCS.

SUMMARY

MCSF is a condition in which plasma triglyceride levels are severely elevated, usually to due exacerbation of common genetic forms of hypertriglyceridemia by secondary causes of hypertriglyceridemia and/or triglyceride-raising drugs. Triglyceride-induced pancreatitis can be prevented by markedly reducing triglyceride levels by treating secondary causes and/or eliminating of triglyceride-raising drugs, and by using triglyceride-lowering drugs, especially fibrates. MFCS also increases cardiovascular disease risk, for which lifestyle measures and drugs are required.

The Role of Triglyceride-rich Lipoproteins and Their Remnants in Atherosclerotic Cardiovascular Disease

Atherosclerotic cardiovascular disease (ASCVD) is the world's leading cause of death. ASCVD has multiple mediators that therapeutic interventions target, such as dyslipidaemia, hypertension, diabetes and heightened systemic inflammatory tone, among others. LDL cholesterol is one of the most well-studied and established mediators targeted for primary and secondary prevention of ASCVD. However, despite the strength of evidence supporting LDL cholesterol reduction by multiple management strategies, ASCVD events can still recur, even in patients whose LDL cholesterol has been very aggressively reduced. Hypertriglyceridaemia and elevated levels of triglyceride-rich lipoproteins (TRLs) may be key contributors to ASCVD residual risk. Several observational and genetic epidemiological studies have highlighted the causal role of triglycerides within the TRLs and/or their remnant cholesterol in the development and progression of ASCVD. TRLs consist of intestinally derived chylomicrons and hepatically synthesised very LDL. Lifestyle modification has been considered the first line intervention for managing hypertriglyceridaemia. Multiple novel targeted therapies are in development, and have shown efficacy in the preclinical and clinical phases of study in managing hypertriglyceridaemia and elevated TRLs. This comprehensive review provides an overview of the biology, pathogenicity, epidemiology, and genetics of triglycerides and TRLs, and how they impact the risk for ASCVD. In addition, we provide a summary of currently available and novel emerging triglyceride-lowering therapies in development.

Advances in Treatment of Dyslipidemia

Dyslipidemias have emerged as prevalent disorders among patients, posing significant risks for the development and progression of cardiovascular diseases. These conditions are characterized by elevated levels of total cholesterol (TC), triglycerides (TGs), and low-density lipoprotein cholesterol (LDL-C). This review delves into the current treatment approach, focusing on equalizing these parameters while enhancing the overall quality of life for patients. Through an extensive analysis of clinical trials, we identify disorders that necessitate alternative treatment strategies, notably familial hypercholesterolemia. The primary objective of this review is to consolidate existing information concerning drugs with the potential to revolutionize dyslipidemia management significantly. Among these promising pharmaceuticals, we highlight alirocumab, bempedoic acid, antisense oligonucleotides, angiopoietin-like protein inhibitors, apolipoprotein C-III (APOC3) inhibitors, lomitapide, and cholesterol ester transfer protein (CETP) inhibitors. Our review demonstrates the pivotal roles played by each of these drugs in targeting specific parameters of lipid metabolism. We outline the future landscape of dyslipidemia treatment, envisaging a more tailored and effective therapeutic approach to address this widespread medical concern.

Medical management of hypertriglyceridemia in pancreatitis

PURPOSE OF REVIEW

Hypertriglyceridemia-induced acute pancreatitis (HTG-AP) should be considered in all cases of acute pancreatitis and triglyceride levels measured early, so that appropriate early and long-term treatment can be initiated.

RECENT FINDINGS

In most cases of HTG-AP, conservative management (nothing by mouth, intravenous fluid resuscitation and analgesia) is sufficient to achieve triglyceride levels less than 500 mg/dl. Intravenous insulin and plasmapheresis are sometimes used, although prospective studies showing clinical benefits are lacking. Pharmacological management of hypertriglyceridemia (HTG) should start early and target triglyceride levels of less than 500 mg/dl to reduce the risk or recurrent acute pancreatitis. In addition to currently used fenofibrate and omega-3 fatty acids, several novel agents are being studied for long-term treatment of HTG. These emerging therapies focus mainly on modifying the action of lipoprotein lipase (LPL) through inhibition of apolipoprotein CIII and angiopoietin-like protein 3. Dietary modifications and avoidance of secondary factors that worsen triglyceride levels should also be pursued. In some cases of HTG-AP, genetic testing may help personalize management and improve outcomes.

SUMMARY

Patients with HTG-AP require acute and long-term management of HTG with the goal of reducing and maintaining triglyceride levels to less than 500 mg/dl.

Post-prandial analysis of fluctuations in the platelet count and platelet function in patients with the familial chylomicronemia syndrome

BACKGROUND

The familial chylomicronemia syndrome (FCS) is an ultra rare disease caused by lipoprotein lipase (LPL) deficiency associated with potentially lethal acute pancreatitis risk. Thrombocytopenia (platelet count < 150,000 × 10⁹/L) has been reported in patients with FCS, treated or not with volanesorsen, a second generation APOC3 anti-sense oligonucleotide. Chylomicrons are the lipoproteins delivering fat after a meal and FCS thus has a post-prandial origin. Platelet count and function have not been studied post-prandially in FCS.

OBJECTIVE

To evaluate post-prandial fluctuations in the platelet count (PLC) and functional defects of hemostasis in FCS.

METHODS

PLC, functional defects in hemostasis and hematologic variables were measured up-to 5 h after a meal in 6 homozygotes for FCS causing gene variants (HoLPL), 6 heterozygotes for LPL loss-of-function variants (HeLPL) and 7 normolipidemic controls.

RESULTS

Hourly post-prandial PLC was significantly lower in HoLPL than in controls (P < 0.009). Compared to the other groups, the PLC tended to decrease rapidly (in the first hour) post-meal in HoLPL (P = 0.03) and remained lower than baseline 5-h post-meal (P = 0.02) whereas it tended to slightly increase in normolipidemic controls (P = 0.02). Platelet function was not affected by the prandial status. In HoLPL, post-prandial fluctuations in the PLC positively correlated with the lymphocyte count (P = 0.005) and negatively with neutrophil/lymphocyte ratio (NLR).

CONCLUSION

The PLC decreases post-prandially in FCS (HoLPL), is not associated with changes in functional defects of hemostasis and correlates with the NLR, a marker of acute pancreatitis severity.

Long-term effects of volanesorsen on triglycerides and pancreatitis in patients with familial chylomicronaemia syndrome (FCS) in the UK Early Access to Medicines Scheme (EAMS)

BACKGROUND AND AIMS

The VOL4002 study assessed the efficacy and safety of volanesorsen in 22 adults with genetically confirmed familial chylomicronaemia syndrome (FCS) treated in the UK Early Access to Medicines Scheme (EAMS), with ("prior exposure") or without ("treatment naive") previous treatment in the APPROACH and/or APPROACH-OLE volanesorsen phase 3 studies.

METHODS

Data collection focused on triglyceride (TG) levels, platelet counts and pancreatitis events. Pancreatitis incidence during volanesorsen treatment was compared against the 5-year period preceding volanesorsen exposure. Volanesorsen 285 mg was self-administered subcutaneously once every 2 weeks.

RESULTS

Individual patient volanesorsen exposure ranged from 6 to 51 months (total cumulative exposure, 589 months). Among treatment-naive patients (n = 12), volanesorsen treatment resulted in an averaged median 52% reduction (-10.6 mmol/L) from baseline (26.4 mmol/L) in TG levels at 3 months, which were maintained through time points over 15 months of treatment (47%-55% reductions). Similarly, prior-exposure patients (n = 10) experienced a 51% reduction (-17.8 mmol/L) from pre-treatment baseline (28.0 mmol/L), with reductions of 10%-38% over 21 months of treatment. A comparison of pancreatitis event rates found a 74% reduction from the 5-year period before (one event/2.8 years) and during (one event/11.0 years) volanesorsen treatment. Platelet declines were consistent with observations in phase 3 clinical trials. No patient recorded a platelet count <50 × 109/L.

CONCLUSIONS

This longitudinal study supports the efficacy of volanesorsen in patients with FCS for lowering TG levels over treatment periods up to 51 months with no apparent safety signals related to increased duration of exposure.

Role of lipoprotein lipase activity measurement in the diagnosis of familial chylomicronemia syndrome

BACKGROUND

Activity assays for lipoprotein lipase (LPL) are not standardised for use in clinical settings.

OBJECTIVE

This study sought to define and validate a cut-off points based on a ROC curve for the diagnosis of patients with familial chylomicronemia syndrome (FCS). We also evaluated the role of LPL activity in a comprehensive FCS diagnostic workflow.

METHODS

A derivation cohort (including an FCS group (n = 9), a multifactorial chylomicronemia syndrome (MCS) group (n = 11)), and an external validation cohort (including an FCS group (n = 5), a MCS group (n = 23) and a normo-triglyceridemic (NTG) group (n = 14)), were studied. FCS patients were previously diagnosed by the presence of biallelic pathogenic genetic variants in the LPL and GPIHBP1 genes. LPL activity was also measured. Clinical and anthropometric data were recorded, and serum lipids and lipoproteins were measured. Sensitivity, specificity and cut-offs for LPL activity were obtained from a ROC curve and externally validated.

RESULTS

All post-heparin plasma LPL activity in the FCS patients were below 25.1 mU/mL, that was cut-off with best performance. There was no overlap in the LPL activity distributions between the FCS and MCS groups, conversely to the FCS and NTG groups.

CONCLUSION

We conclude that, in addition to genetic testing, LPL activity in subjects with severe hypertriglyceridemia is a reliable criterium in the diagnosis of FCS when using a cut-off of 25.1 mU/mL (25% of the mean LPL activity in the validation MCS group). We do not recommend the NTG patient based cut-off values due to low sensitivity.

Qualitative development of the PROMIS Profile v1.0-Familial Chylomicronemia Syndrome (FCS) 28

PURPOSE

Familial chylomicronemia syndrome (FCS) is a rare genetic disorder characterized by high triglyceride levels, significant disease burden, and negative impacts on health-related quality of life. This project aimed to create a PROMIS-based patient-reported outcome measure that represents valid and important concerns for patients with FCS.

METHODS

We reviewed the literature and data from a previous qualitative study of FCS to identify key FCS symptoms and impacts, which were mapped to PROMIS domains to create a pool of eligible items. Candidate items were reduced per expert feedback and patients with FCS completed cognitive interviews to confirm content validity and measure content.

RESULTS

Literature and qualitative data review identified ten key symptoms and 12 key impacts of FCS, including abdominal pain, fatigue, difficulty thinking, and worry about pancreatitis attacks. We identified 96 items primarily from PROMIS, supplemented with items from the Quality of Life in Neurological Disorders™ (Neuro-QoL™) and the Functional Assessment of Chronic Illness Therapy (FACIT) measurement systems. This pool was reduced to 32 candidate items, which were assessed via cognitive interviews with eight participants with FCS. Cognitive interview results and additional expert feedback led to the removal of four items and finalization of the PROMIS Profile v1.0-familial chylomicronemia syndrome (FCS) 28.

CONCLUSIONS

The PROMIS Profile v1.0-familial chylomicronemia syndrome (FCS) 28 provides strong content validity for assessing quality of life among patients with FCS. The benefits of PROMIS, including norm-referenced mean values for each measure, will facilitate comparison of patients with FCS to other clinical populations.

Assessment of efficacy and safety of volanesorsen for treatment of metabolic complications in patients with familial partial lipodystrophy: Results of the BROADEN study: Volanesorsen in FPLD; The BROADEN Study

BACKGROUND

Volanesorsen, an antisense oligonucleotide, is designed to inhibit hepatic apolipoprotein C-III synthesis and reduce plasma apolipoprotein C-III and triglyceride concentrations.

OBJECTIVE

The present study assessed efficacy and safety of volanesorsen in patients with familial partial lipodystrophy (FPLD) and concomitant hypertriglyceridemia and diabetes.

METHODS

BROADEN was a randomized, placebo-controlled, phase 2/3, 52-week study with open-label extension and post-treatment follow-up periods. Patients received weekly subcutaneous volanesorsen 300 mg or placebo. The primary endpoint was percent change from baseline in fasting triglycerides at 3 months. Secondary endpoints included relative percent change in hepatic fat fraction (HFF), visceral adiposity, and glycated hemoglobin levels.

RESULTS

Forty patients (11 men, 29 women) were enrolled, majority of whom were aged <65 years (mean, 47 years) and White. Least squares mean (LSM) percent change in triglycerides from baseline to 3 months was -88% (95% CI, -134 to -43) in the volanesorsen group versus -22% (95% CI, -61 to 18) in the placebo group, with a difference in LSM of -67% (95% CI, -104 to -30; P=0.0009). Volanesorsen induced a significant LSM relative reduction in HFF of 53% at month 12 versus placebo (observed mean [SD]: 9.7 [7.65] vs. 18.0 [8.89]; P=0.0039). No statistically significant changes were noted in body volume measurements (fat, liver, spleen, visceral/subcutaneous adipose tissue) or glycated hemoglobin. Serious adverse events in patients assigned to volanesorsen included 1 case each of sarcoidosis, anaphylactic reaction, and systemic inflammatory response syndrome.

CONCLUSION

In BROADEN, volanesorsen significantly reduced serum triglyceride levels and hepatic steatosis in patients with FPLD.

Novel pathogenic variant combination in LPL causing familial chylomicronemia syndrome in an Asian family and experimental validation in vitro: a case report

BACKGROUND

Familial chylomicronemia syndrome (FCS) is a rare autosomal recessive disorder, typically caused by biallelic pathogenic variants in the lipoprotein lipase (LPL) gene. Lipoprotein lipase, encoded by the LPL gene, catalyzes the hydrolysis of triglycerides, and its deficiency or dysfunction can lead to chylomicronemia and potentially fatal recurrent acute pancreatitis.

CASE DESCRIPTION

Here, we report an Asian child with FCS due to compound heterozygous LPL variants. The 4-year-old patient presented with splenomegaly and severe hypertriglyceridemia, specifically chylomicronemia which resulted in abnormal coagulation measured by a turbidity-based assay. Based on the clinical features and family history, the diagnosis of FCS was suspected, and confirmed by the identification of compound heterozygous variants in the LPL gene (c.461A>G; p.His154Arg and c.788T>A; p.Leu263Gln) in the patient, inheriting one from each parent. According to the clinical and genetic findings, the patient was diagnosed with FCS. In vitro experimental validation found that the LPL p.H154R variant reduced the expression of lipoprotein lipase and decreased its lipolytic activity, while the LPL p.L263Q variant mainly impaired its lipolytic activity.

CONCLUSIONS

FCS was molecularly diagnosed using whole exome sequencing in the case presented. When interpreting abnormal coagulation profiles measured by turbidity-based assay, the possibility of lipemic blood (or chylomicronemia) should be considered and the presence of this phenomenon might indicate the diagnosis of FCS. In vitro experiments showed that the two LPL variants impaired lipoprotein lipase expression and/or function making them likely to be pathogenic.

Low circulating PCSK9 levels in LPL homozygous children with chylomicronemia syndrome in a syrian refugee family in Lebanon

Familial chylomicronemia syndrome is a rare autosomal recessive disorder of lipoprotein metabolism characterized by the presence of chylomicrons in fasting plasma and an important increase in plasma triglycerides (TG) levels that can exceed 22.58 mmol/l. The disease is associated with recurrent episodes of abdominal pain and pancreatitis, eruptive cutaneous xanthomatosis, lipemia retinalis, and hepatosplenomegaly. A consanguineous Syrian family who migrated to Lebanon was referred to our laboratory after perceiving familial chylomicronemia syndrome in two children. The LPL and PCSK9 genes were sequenced and plasma PCSK9 levels were measured. Sanger sequencing of the LPL gene revealed the presence of the p.(Val227Phe) pathogenic variant in exon 5 at the homozygous state in the two affected children, and at the heterozygous state in the other recruited family members. Interestingly, PCSK9 levels in homozygous carriers of the p.(Val227Phe) were ≈50% lower than those in heterozygous carriers of the variant (p-value = 0.13) and ranged between the 5th and the 7.5th percentile of PCSK9 levels in a sample of Lebanese children of approximately the same age group. Moreover, this is the first reported case of individuals carrying simultaneously an LPL pathogenic variant and PCSK9 variants, the L10 and L11 leucine insertion, which can lower and raise low-density lipoprotein cholesterol (LDL-C) levels respectively. TG levels fluctuated concomitantly between the two children, were especially high following the migration from a country to another, and were reduced under a low-fat diet. This case is crucial to raise public awareness on the risks of consanguineous marriages to decrease the emergence of inherited autosomal recessive diseases. It also highlights the importance of the early diagnosis and management of these diseases to prevent serious complications, such as recurrent pancreatitis in the case of familial hyperchylomicronemia.

Efficacy and safety of the apolipoprotein C-III inhibitor Volanesorsen: a systematic evaluation and meta-analysis

PURPOSE

Familial celiac disease syndrome (FCS) is a form of hypertriglyceridemia (HTG) caused by the accumulation of celiac particles. Currently, volanesorsen is considered to be used to treat patients with FCS and HTG to improve symptoms. To evaluate the effect of volanesorsen on lipid metabolism in patients with FCS, we performed a systematic evaluation and meta-analysis.

METHODS

A systematic search of PubMed, Embase, ClinicalTrials.gov, and the Cochrane Library was conducted, and the bibliographies of original articles were checked manually. The quality of the studies was assessed using the Cochrane Risk of Bias tool.

RESULTS

Four randomized, controlled trials involving 246 patients were analyzed in this study. Patients treated with volanesorsen showed (MD = -78.85%; 95% CI = -96.04 to -61.65, P = 0.67, I² = 0%) decrease in TG and (MD = -80.08%; 95% CI = -90.02 to -71.54, P = 0.25, I² = 29%) decrease in ApoC-III levels compared to patients in the placebo group showing a significant decrease. In addition, HDL-C increased (MD = 46.01% 95% CI = 41.03 to 50.99, P = 0.41, I² = 0%), NHDL-C decreased (MD = -32.12%; 95% CI = -44.39 to -19.85, P = 0.11, I² = 55%), VLDL-C decreased (MD = -65.88%; 95% CI = -83.97 to -47.79, P = 0.71, I² = 0%), apo A1 increased (MD = 13.12%; 95% CI = 7.83 to 18.40, P = 0.72, I² = 0%), and apoB increased (MD = 7.94 %; 95% CI = -1.90 to 17.78, P = 0.54, I² = 0%) all suggest that volanesorsen has an overall FCS with a therapeutic effect. However, LDL-C increased (MD = 99.59%; 95% CI = 69.19 to 130.00, P = 0.61, I² = 0%) and apo B48 decreased (MD = 82.89%; 95% CI = -100.88 to -64.91, P = 0.42, I² = 0%), showing an inverse effect, suggesting that volanesorsen's did not target all proteins of lipid metabolism.

New Therapies for Primary Hyperlipidemia

Primary hyperlipidemias include a heterogeneous set of monogenic and polygenic conditions characterized by a strong family aggregation, severe forms of hypercholesterolemia and/or hypertriglyceridemia, appearance early on life, and a high risk of cardiovascular events and/or recurrent pancreatitis. In real life, a small proportion of the primary hyperlipidemia cases is recognized and treated properly. Our goal is to present an update of current and upcoming therapies for patients with primary hyperlipidemia. Recently, new lipid-lowering medications have obtained authorization from the U.S. Food and Drug Administration and the European Medicines Agency. These drugs target metabolic pathways, including (adenosine 5'-triphosphates)-citrate lyase (bempedoic acid), proprotein convertase subtilisin/kexin 9 (inclisiran), apolipoprotein CIII (volanesorsen), and angiopoietin-like 3 (volanesorsen), that have additive effects with the actions of the currently available therapies (i.e., statins, ezetimibe or fibrates). We discuss the potential clinical indications for the novel medications. To conclude, the addition of these new medications to the therapeutic options for primary hyperlipidemia patients may increase the likelihood of achieving the treatment targets. Also, it could be a safer alternative for patients with side effects for the currently available drugs.

Atherosclerosis: Pathogenesis and Key Cellular Processes, Current and Emerging Therapies, Key Challenges, and Future Research Directions

Atherosclerosis is the principal cause of cardiovascular disease that continues to be a substantial drain on healthcare systems, being responsible for about 31% of all global deaths. Atherogenesis is influenced by a range of factors, including oxidative stress, inflammation, hypertension, and hyperlipidemia, and is ultimately driven by the accumulation of low-density lipoprotein cholesterol within the arterial wall of medium and large arteries. Lipoprotein accumulation stimulates the infiltration of immune cells (such as monocytes/macrophages and T-lymphocytes), some of which take up the lipoprotein, leading to the formation of lipid-laden foam cells. Foam cell death results in increased accumulation of dead cells, cellular debris and extracellular cholesterol, forming a lipid-rich necrotic core. Vascular smooth muscle cells from the arterial media also migrate into the intima layer and proliferate, taking up the available lipids to become foam cells and producing extracellular matrix proteins such as collagen and elastin. Plaque progression is characterized by the formation of a fibrous cap composed of extracellular matrix proteins and smooth muscle cells, which acts to stabilize the atherosclerotic plaque. Degradation, thinning, and subsequent rupture of the fibrous cap leads to lumen-occlusive atherothrombosis, most commonly resulting in heart attack or stroke. This chapter describes the pathogenesis of atherosclerosis, current and emerging therapies, key challenges, and future directions of research.

Clinical review on triglycerides

Hypertriglyceridaemia is a common clinical problem. Epidemiologic and genetic studies have established that triglyceride-rich lipoproteins (TRL) and their remnants as important contributors to ASCVD while severe hypertriglyceridaemia raises risk of pancreatitis. While low-density lipoprotein is the primary treatment target for lipid lowering therapy, secondary targets that reflect the contribution of TRL such as apoB and non-HDL-C are recommended in the current guidelines. Reduction of severely elevated triglycerides is important to avert or reduce the risk of pancreatitis. Here we discuss interventions for hypertriglyceridaemia, including diet and lifestyle, established treatments such as fibrates and omega-3 fatty acid preparations and emerging therapies, including various biological agents.

Familial chylomicronemia and multifactorial chylomicronemia

The accumulation of chylomicrons in plasma beyond the postprandial period is a pathological event secondary to the partial or complete lack of activity of lipoprotein lipase that can lead to recurrent episodes of abdominal pain and acute pancreatitis. This article reviews the pathophysiology of this syndrome and the differential characteristics depending on whether it is due to congenital monogenic causes or acquired on a polygenic basis in which multiple factors may inluence.

Development of Antisense Oligonucleotide Gapmers for the Treatment of Dyslipidemia and Lipodystrophy

Although technological advances in molecular genetics over the last few decades have greatly expedited the identification of mutations in many genetic diseases, the translation of the genetic mechanisms into a clinical setting has been quite challenging, with a minimum number of effective treatments available. The advancements in antisense therapy have revolutionized the field of neuromuscular disorders as well as lipid-mediated diseases. With the approval of splice-switching antisense oligonucleotide (AO) therapy for nusinersen and eteplirsen for the treatment of spinal muscular atrophy (SMA) and Duchenne muscular dystrophy (DMD), several modified AOs are now being evaluated in clinical trials for the treatment of a number of disorders. In order to activate RNase H-mediated cleavage of the target mRNA, as well as to increase the binding affinity and specificity, gapmer AOs are designed that have a PS backbone flanked with the modified AOs on both sides. Mipomersen (trade name Kynamro), a 2'-O-methoxyethyl (MOE) gapmer, was approved by the Food and Drug Administration (FDA) for the treatment of homozygous familial hypercholesterolemia (HoFH) in 2013. Volanesorsen, another 20-mer MOE gapmer has shown to be successful in lowering the levels of triglycerides (TGs) in several lipid disorders and has received conditional approval in the European Union for the treatment of Familial chylomicronemia syndrome (FCS) in May 2019 following successful results from phase II/III clinical trials. This chapter focuses on the clinical applications of gapmer AOs for genetic dyslipidemia and lipodystrophy.

Apolipoprotein C-III and cardiovascular diseases: when genetics meet molecular pathologies

Cardiovascular diseases (CVD) have overtaken infectious diseases and are currently the world's top killer. A quite strong linkage between this type of ailments and elevated plasma levels of triglycerides (TG) has been always noticed. Notably, this risk factor is mired in deep confusion, since its role in atherosclerosis is uncertain. One of the explanations that aim to decipher this persistent enigma was provided by apolipoprotein C-III (apoC-III), a small protein historically recognized as an important regulator of TG metabolism. Preeminently, hundreds of studies have been carried out in order to explore the APOC3 genetic background, as well as to establish a correlation between its variants and dyslipidemia-related disorders, pointing to an earnest predictive power for future outcomes. Among several polymorphisms reported within the APOC3, the SstI site in its 3'-untranslated region (3'-UTR) was the most consistently and robustly associated with an increased CVD risk. As more genetic data supporting its importance in cardiovascular events aggregate, it was declared, correspondingly, that apoC-III exerts various atherogenic effects, either by intervening in the function and catabolism of many lipoproteins, or by inducing endothelial inflammation and smooth muscle cells (SMC) proliferation. This review was designed to shed the light on the structural and functional aspects of the APOC3 gene, the existing association between its SstI polymorphism and CVD, and the specific molecular mechanisms that underlie apoC-III pathological implications. In addition, the translation of all these gathered knowledges into preventive and therapeutic benefits will be detailed too.

THE PREVALENCE OF PROBABLE FAMILIAL CHYLOMICRONEMIA SYNDROME IN A SOUTHERN CALIFORNIA POPULATION

OBJECTIVE

To estimate the prevalence of probable familial chylomicronemia syndrome (FCS) in a major Southern California Academic Center as well as to provide a systematic review of past FCS studies and management recommendations.

METHODS

Electronic medical records were queried based on single fasting plasma triglyceride (TG) levels of ≥880 mg/dL and at least 1 episode of acute pancreatitis. After the exclusion of secondary causes (diabetes, alcohol misuse, gallbladder disease, chronic kidney disease, uncontrolled hypothyroidism, estrogen, and drug use) and responses to lipid-lowering treatment, probable patients with FCS were identified. A systematic review of all published literature on the prevalence and management guidelines for FCS was then presented and discussed.

RESULTS

Out of 7 699 288 charts queried, 138 patients with TG levels of ≥880 mg/dL and documented evidence of at least 1 episode of acute pancreatitis were identified. Nine patients did not have any documented secondary causes of chylomicronemia. Four of the 9 patients had >20% decrease in TG levels after lipid-lowering treatment, 2 patients were not responsive to lipid-lowering medication, and data on lipid-lowering medications were missing in 3 patients.

CONCLUSION

Our study estimates the prevalence of probable FCS at a range of 0.26 to 0.66 per million. Using the recommended criteria, probable FCS cases can be identified to allow early diagnosis and management.

Lipid-Lowering Biotechnological Drugs: from Monoclonal Antibodies to Antisense Therapies-a Clinical Perspective

PURPOSE

While low density lipoprotein cholesterol (LDL-C) remains a key contributor of atherosclerotic cardiovascular disease (ASCVD), additional risk factors identified through epidemiological and genetic studies have ushered in a fertile era of drug discovery in lipid-lowering therapy. Unlike contemporary small molecule medications, many of the novel agents are biologics utilizing monoclonal antibody (mAb) or RNA interference (RNAi) technologies. This report aims to review the evidence to date, focusing on completed and ongoing clinical trials and how these new agents will impact clinical practice.

METHODS

We review data from pertinent studies on lipid-lowering biologics in clinical use or have translated to human studies and are undergoing clinical trials.

RESULTS

Several targets affecting lipid metabolism have been identified to be causally associated with ASCVD including proprotein convertase subtilisin/kexin type 9 (PCSK9), angiopoietin-like protein 3 (ANGPTL3), apolipoprotein C3 (APOC3), and lipoprotein (a) (Lp[a]). Biotechnological modalities that have been developed for these targets include mAb, small interfering RNA (siRNA), and anti-sense oligonucleotide (ASO) agents. Agents such as alirocumab and evolocumab have shown efficacy in risk reduction of ASCVD in cardiovascular outcome trials and have been incorporated into evidence-based practice guidelines. Other agents included in this review are in various stages of clinical trials and have shown significant efficacy in the reduction of lipid parameters.

CONCLUSION

The development of new biologics targeting lipid risk factors will provide clinicians additional tools to reduce the risk for ASCVD. Important factors to consider will be cost-effectiveness and improving methods to personalize treatments to risk factors.

Antisense drug discovery and development technology considered in a pharmacological context

When coined, the term "antisense" included oligonucleotides of any structure, with any chemical modification and designed to work through any post-RNA hybridization mechanism. However, in practice the term "antisense" has been used to describe single stranded oligonucleotides (ss ASOs) designed to hybridize to RNAswhile the term "siRNA" has come to mean double stranded oligonucleotides designed to activate Ago2. However, the two approaches share many common features. The medicinal chemistry developed for ASOs greatly facilitated the development of siRNA technology and remains the chemical basis for both approaches. Many of challenges faced and solutions achieved share many common features. In fact, because ss ASOs can be designed to activate Ago2, the two approaches intersect at this remarkably important protein. There are also meaningful differences. The pharmacokinetic properties are quite different and thus potential routes of delivery differ. ASOs may be designedto use a variety of post-RNA binding mechanismswhile siRNAs depend solely on the robust activity of Ago2. However, siRNAs and ASOs are both used for therapeutic purposes and both must be and can be understood in a pharmacological context. Thus, the goals of this review are to put ASOs in pharmacological context and compare their behavior as pharmacological agents to the those of siRNAs.

The Diagnosis and Treatment of Hypertriglyceridemia

BACKGROUND

Hypertriglyceridemia affects 15-20% of the adult population and is associated with overweight, metabolic syndrome, and diabetes mellitus. It is often discovered incidentally.

METHODS

This review is based on pertinent publications retrieved by a selective literature search, including current guidelines on hypertriglyceridemia.

RESULTS

Elevated triglyceride (TG) levels are causally linked to cardiovascular disease; TG levels above 1000 mg/dL (11.4 mmol/L) can induce acute pancreatitis. The individual risk of cardiovascular disease and of pancreatitis must be estimated in order to decide whether, and how, hypertriglyceridemia should be treated. Lifestyle modifications (cessation of alcohol consumption, reduced intake of rapidly metabolized carbohydrates), weight loss, and blood sugar control are the most effective ways to lower TG levels. The need to lower the low-density lipoprotein (LDL) concentration must be determined on the basis of the cardiovascular risk, independently of the success of the lifestyle changes. Few patients need specific drug treatment to lower the TG level. Fibrates can lower TG concentrations, but their efficacy in combination with statins has not been clearly shown in endpoint studies. A daily dose of 2-4 g omega-3 fatty acids can also lower TG levels. To date, only a single large-scale randomized, blinded trial has shown the efficacy of 4 g of eicosapentaenoic acid ethyl ester per day in lowering the risk in high-risk patients (number needed to treat = 21). Patients with the very rare purely genetic types of hypertriglyceridemia (familial chylomicronemia syndrome) should be treated in specialized outpatient clinics.

CONCLUSION

Hypertriglyceridemia is causally linked to cardiovascular disease and pancreatitis. Lifestyle modifications play a paramount role in its treatment.

Volanesorsen in the Treatment of Familial Chylomicronemia Syndrome or Hypertriglyceridaemia: Design, Development and Place in Therapy

Severe hypertriglyceridaemia is associated with pancreatitis and chronic pancreatitis-induced diabetes. Familial chylomicronaemia syndrome (FCS) is a rare autosomal recessive disorder of lipid metabolism characterised by high levels of triglycerides (TGs) due to failure of chylomicron clearance. It causes repeated episodes of severe abdominal pain, fatigue and attacks of acute pancreatitis. There are few current options for its long-term management. The only universal long-term therapy is restriction of total dietary fat intake to <10-15% of daily calories (15 to 20g per day). Many patients have been treated with fibrates and statins with a variable response, but many remain susceptible to pancreatitis. Other genetic syndromes associated with hypertriglyceridaemia include familial partial lipodystrophy (FPLD). Targeting apolipoprotein C3 (apoC3) offers the ability to increase clearance of chylomicrons and other triglyceride-rich lipoproteins. Volanesorsen is an antisense oligonucleotide (ASO) inhibitor of apoC3, which reduces TG levels by 70–80% which has been shown also to reduce rates of pancreatitis and improve well-being in FCS and reduce TGs and improve insulin resistance in FPLD. It is now undergoing licensing and payer reviews. Further developments of antisense technology including small interfering RNA therapy to apoC3 as well as other approaches to modulating triglycerides are in development for this rare disorder.

PROMIS® and Neuro-QoLTM measures are valid measures of health-related quality of life among patients with familial chylomicronemia syndrome

Background: FCS significantly affects health-related quality of life (HRQOL). Legacy patient-reported outcome measures are often not sensitive to FCS's impact. NIH PROMIS and Neuro-QoL measures may accurately capture HRQOL in FCS patients. This study assessed a broad range of PROMIS and Neuro-QoL measures covering physical, mental, and social HRQOL to determine their suitability for the FCS population.Methods: Adult FCS patients in the United States (N = 25) were recruited to an online survey study and completed several PROMIS short forms and Neuro-QoL computer adaptive tests.Results: Scores were more than 0.5 standard deviations (SD) worse than the normative mean on 10 of 16 normed measures, and more than 0.75 SDs worse than the normative mean on two measures. Responses at the floor and ceiling were occasionally observed, marginal reliabilities were strong, and significant differences across performance status (ps < 0.05) provided preliminary support for construct validity. The measures correlated with each other strongly and as expected.Conclusion: Results support the ability of PROMIS and Neuro-QoL measures to detect HRQOL impairment among patients with FCS. PROMIS and Neuro-QoL measures captured the functional impact and symptom burden associated with FCS, and the broad range of symptom severity experienced by patients with FCS.

Familial chylomicronemia syndrome: an under-recognized cause of severe hypertriglyceridaemia

Familial chylomicronemia syndrome (FCS) is a rare autosomal recessive disorder of chylomicron metabolism causing severe elevation of triglyceride (TG) levels (>10 mmol L^-1 ). This condition is associated with a significant risk of recurrent acute pancreatitis (AP). AP caused by hypertriglyceridaemia (HTG) has been associated with a worse prognosis and higher mortality rates compared to pancreatitis of other aetiology. Despite its association with poor quality of life and increased lifelong risk of HTG-AP, few healthcare providers are familiar with FCS. Because this condition is under-recognized, the majority of FCS patients are diagnosed after age 20 often after consulting several physicians. Although other forms of severe HTG such as multifactorial chylomicronemia have been associated with high atherosclerotic cardiovascular disease (ASCVD) risk and metabolic abnormalities, ASCVD and metabolic syndrome are not usually observed in FCS patients. Because FCS is a genetic condition, the optimal diagnosis strategy remains genetic testing. The presence of bi-allelic pathogenic mutations in LPL, APOC2, GPIHBP1, APOA5 or LMF1 genes confirms the diagnosis. However, some cases of FCS caused by autoantibodies against LPL or GPIHBP1 proteins have also been reported. Furthermore, a clinical score for the diagnosis of FCS has been proposed but needs further validation. Available treatment options to lower triglycerides such as fibrates or omega-3 fatty acids are not efficacious in FCS patients. Currently, the cornerstone of treatment remains a lifelong very low-fat diet, which prevents the formation of chylomicrons. Finally, inhibitors of apo C-III and ANGPTL3 are in development and may eventually constitute additional treatment options for FCS patients.

Investigational drugs in development for hypertriglyceridemia: a coming-of-age story

Introduction: Elevated triglyceride (TG) level is a prevalent condition in the general population and in patients with cardiovascular (CV) risk even under statin therapy. Severe hypertriglyceridemia (HTG) puts patients at risk for acute pancreatitis. Several TG-lowering drugs failed in clinical trials, but subgroup analyses suggest that high-risk patients, such as those with atherogenic dyslipidemia or diabetes, benefit from TG lowering.Areas covered: We review advances for TG-lowering drugs in clinical development. These include selective PPARα modulators, omega-3 fatty acid formulations that have been approved for severe HTG, and inhibitors of apolipoprotein C-III, angiopoietin-like-3 or microsomal transfer protein. Lessons learned from the success of the phase 3 trial REDUCE-IT with high-dose icosapent ethyl are also reviewed.Expert opinion: We believe that TG-lowering therapies are coming of age as they will allow to treat patients with high CV risk and moderate HTG, including T2D subjects, as well as patients with severe HTG or even homozygous familial hypercholesterolemia, all of which being 'optimally' treated with a statin. More studies on the impact of therapy on quality of life in patients with severe HTG should be conducted with the help of patient registries.

Practical definitions of severe versus familial hypercholesterolaemia and hypertriglyceridaemia for adult clinical practice

Diagnostic scoring systems for familial hypercholesterolaemia and familial chylomicronaemia syndrome often cannot differentiate between adults who have extreme dyslipidaemia based on a simple monogenic cause versus people with a more complex cause involving polygenic factors and an environmental component. This more complex group of patients carries a substantial risk of atherosclerotic cardiovascular disease in the case of marked hypercholesterolaemia and pancreatitis in the case of marked hypertriglyceridaemia. Complications are mainly a function of the degree of disturbance in lipid metabolism resulting in elevated lipid levels, so the added value of knowing the precise genetic cause in clinical decision making is unclear and does not lead to clinically meaningful benefit. We propose that for severe elevations of plasma low density lipoprotein cholesterol or triglyceride, the primary factor driving intervention should be the biochemical perturbation rather than the clinical risk score. This underscores the importance of expanding the definition of severe dyslipidaemias and to not rely solely on clinical scoring systems to identify individuals who would benefit from appropriate treatment approaches. We advocate for the use of simple, practical, clinical, and largely biochemically based definitions for severe hypercholesterolaemia (eg, LDL cholesterol >5 mmol/L) and severe hypertriglyceridaemia (triglyceride >10 mmol/L), which complement current definitions of familial hypercholesterolaemia and familial chylomicronaemia syndrome. Irrespective of the precise genetic cause, individuals diagnosed with severe hypercholesterolaemia and severe hypertriglyceridaemia require intensive therapy, including special consideration for new effective but more expensive therapies.

Differentiating Familial Chylomicronemia Syndrome From Multifactorial Severe Hypertriglyceridemia by Clinical Profiles

Context

Differentiation between familial chylomicronemia syndrome (FCS, type 1 hyperlipoproteinemia), a rare metabolic disorder, and the more common multifactorial severe hypertriglyceridemia (sHTG, type 5 hyperlipoproteinemia) is challenging because of their overlapping symptoms but important in patient management.

Objective

To assess whether readily obtainable clinical information beyond triglycerides can effectively diagnose and differentiate patients with FCS from those with sHTG, based on well-curated data from two intervention studies of these conditions.

Methods

The analysis included 154 patients from two phase 3 clinical trials of patients with sHTG, one cohort with genetically confirmed FCS (n = 49) and one with multifactorial sHTG (n = 105). Logistic regression analyses were performed to determine the ability of variables (patient demographics, medical history, and baseline lipids, individually or in sets) to differentiate the patient populations. Receiver operating characteristics were used to determine the variable sets with the highest accuracy (percentage of times actual values matched predicted) and optimal sensitivity and specificity.

Results

The primary model diagnosed 45 of 49 patients with FCS and 99 of 105 patients with sHTG correctly. Optimal sensitivity for all available parameters (n = 17) was 91.8%, optimal specificity was 94.3%, and accuracy was 93.5%. Fasting low-density lipoprotein cholesterol (LDL-C) provided the highest individual predictability. However, a three-variable set of ultracentrifugally measured LDL-C, body mass index, and pancreatitis history differentiated the diseases with a near similar accuracy of 91.0%, and adding high-density lipoprotein cholesterol and very low-density lipoprotein cholesterol for a five-variable set provided a small incremental increase in accuracy (92.2%).

Conclusions

In the absence of genetic testing, hypertriglyceridemic patients with FCS and sHTG can be differentiated with a high degree of accuracy by analyzing readily obtainable clinical information.

Large triglyceride-rich lipoproteins in hypertriglyceridemia are associated with the severity of acute pancreatitis in experimental mice

Hypertriglyceridemia severity is linked to acute pancreatitis prognosis, but it remains unknown why a portion of severe hypertriglyceridemia patients do not develop severe acute pancreatitis. To investigate whether hypertriglyceridemia subtypes affect acute pancreatitis progression, we analyzed two genetically modified hypertriglyceridemia mouse models—namely, glycosylphosphatidylinositol high-density lipoprotein binding protein 1 knockout (Gpihbp1−/−) and apolipoprotein C3 transgenic (ApoC3-tg) mice. Acute pancreatitis was induced by 10 intraperitoneal caerulein injections. Biochemical assays and pathological analysis were performed for the severity evaluation of acute pancreatitis. Plasma triglyceride-rich lipoproteins (TRLs), including chylomicrons and very low-density lipoprotein (VLDL), were collected via ultracentrifugation to evaluate their cytotoxic effects on primary pancreatic acinar cells (PACs). We found that the particle sizes of Gpihbp1−/− TRLs were larger than ApoC3-tg TRLs. Severe pancreatic injury with large areas of pancreatic necrosis in the entire lobule was induced in Gpihbp1−/− mice when plasma triglyceride levels were greater than 2000 mg/dL. However, ApoC3-tg mice with the same triglyceride levels did not develop large areas of pancreatic necrosis, even upon the administration of poloxamer 407 to further increase triglyceride levels. Meanwhile, in the acute pancreatitis model, free fatty acids (FFAs) in the pancreas of Gpihbp1−/− mice were greater than in ApoC3-tg mice. TRLs from Gpihbp1−/− mice released more FFAs and were more toxic to PACs than those from ApoC3-tg mice. Chylomicrons from patients showed the same effects on PACs as TRLs from Gpihbp1−/− mice. Gpihbp1−/− mice with triglyceride levels below 2000 mg/dL had milder pancreatic injury and less incidence of pancreatic necrosis than those with triglyceride levels above 2000 mg/dL, similar to Gpihbp1−/−mice with triglyceride levels above 2000 mg/dL but with fenofibrate administration. These findings demonstrated that hypertriglyceridemia subtypes with large TRL particles could affect acute pancreatitis progression and that chylomicrons showed more cytotoxicity than VLDL by releasing more FFAs.

A new dawn for managing dyslipidemias: The era of rna-based therapies

The high occurrence of atherosclerotic cardiovascular disease (ASCVD) events is still a major public health issue. Although a major determinant of ASCVD event reduction is the absolute change of low-density lipoprotein-cholesterol (LDL-C), considerable residual risk remains and new therapeutic options are required, in particular, to address triglyceride-rich lipoproteins and lipoprotein(a) [Lp(a)]. In the era of Genome Wide Association Studies and Mendelian Randomization analyses aimed at increasing the understanding of the pathophysiology of ASCVD, RNA-based therapies may offer more effective treatment options. The advantage of oligonucleotide-based treatments is that drug candidates are targeted at highly specific regions of RNA that code for proteins that in turn regulate lipid and lipoprotein metabolism. For LDL-C lowering, the use of inclisiran - a silencing RNA that inhibits proprotein convertase subtilisin/kexin type 9 (PCSK9) synthesis - has the advantage that a single s.c. injection lowers LDL-C for up to 6 months. In familial hypercholesterolemia, the use of the antisense oligonucleotide (ASO) mipomersen, targeting apolipoprotein (apoB) to reduce LDL-C, has been a valuable therapeutic approach, despite unquestionable safety concerns. The availability of specific ASOs lowering Lp(a) levels will allow rigorous testing of the Lp(a) hypothesis; by dramatically reducing plasma triglyceride levels, Volanesorsen (APOC3) and angiopoietin-like 3 (ANGPTL3)-LRx will further clarify the causality of triglyceride-rich lipoproteins in ASCVD. The rapid progress to date heralds a new dawn in therapeutic lipidology, but outcome, safety and cost-effectiveness studies are required to establish the role of these new agents in clinical practice.

Volanesorsen and Triglyceride Levels in Familial Chylomicronemia Syndrome

BACKGROUND

Familial chylomicronemia syndrome is a rare genetic disorder that is caused by loss of lipoprotein lipase activity and characterized by chylomicronemia and recurrent episodes of pancreatitis. There are no effective therapies. In an open-label study of three patients with this syndrome, antisense-mediated inhibition of hepatic APOC3 mRNA with volanesorsen led to decreased plasma apolipoprotein C-III and triglyceride levels.

METHODS

We conducted a phase 3, double-blind, randomized 52-week trial to evaluate the safety and effectiveness of volanesorsen in 66 patients with familial chylomicronemia syndrome. Patients were randomly assigned, in a 1:1 ratio, to receive volanesorsen or placebo. The primary end point was the percentage change in fasting triglyceride levels from baseline to 3 months.

RESULTS

Patients receiving volanesorsen had a decrease in mean plasma apolipoprotein C-III levels from baseline of 25.7 mg per deciliter, corresponding to an 84% decrease at 3 months, whereas patients receiving placebo had an increase in mean plasma apolipoprotein C-III levels from baseline of 1.9 mg per deciliter, corresponding to a 6.1% increase (P<0.001). Patients receiving volanesorsen had a 77% decrease in mean triglyceride levels, corresponding to a mean decrease of 1712 mg per deciliter (19.3 mmol per liter) (95% confidence interval [CI], 1330 to 2094 mg per deciliter [15.0 to 23.6 mmol per liter]), whereas patients receiving placebo had an 18% increase in mean triglyceride levels, corresponding to an increase of 92.0 mg per deciliter (1.0 mmol per liter) (95% CI, -301.0 to 486 mg per deciliter [-3.4 to 5.5 mmol per liter]) (P<0.001). At 3 months, 77% of the patients in the volanesorsen group, as compared with 10% of patients in the placebo group, had triglyceride levels of less than 750 mg per deciliter (8.5 mmol per liter). A total of 20 of 33 patients who received volanesorsen had injection-site reactions, whereas none of the patients who received placebo had such reactions. No patients in the placebo group had platelet counts below 100,000 per microliter, whereas 15 of 33 patients in the volanesorsen group had such levels, including 2 who had levels below 25,000 per microliter. No patient had platelet counts below 50,000 per microliter after enhanced platelet-monitoring began.

CONCLUSIONS

Volanesorsen lowered triglyceride levels to less than 750 mg per deciliter in 77% of patients with familial chylomicronemia syndrome. Thrombocytopenia and injection-site reactions were common adverse events. (Funded by Ionis Pharmaceuticals and Akcea Therapeutics; APPROACH Clinical Trials.gov number, NCT02211209.).

Emerging Evidence that ApoC-III Inhibitors Provide Novel Options to Reduce the Residual CVD

Purpose of Review

Apolipoprotein C-III (apoC-III) is known to inhibit lipoprotein lipase (LPL) and function as an important regulator of triglyceride metabolism. In addition, apoC-III has also more recently been identified as an important risk factor for cardiovascular disease. This review summarizes the mechanisms by which apoC-III induces hypertriglyceridemia and promotes atherogenesis, as well as the findings from recent clinical trials using novel strategies for lowering apoC-III.

Recent Findings

Genetic studies have identified subjects with heterozygote loss-of-function (LOF) mutations in APOC3, the gene coding for apoC-III. Clinical characterization of these individuals shows that the LOF variants associate with a low-risk lipoprotein profile, in particular reduced plasma triglycerides. Recent results also show that complete deficiency of apoC-III is not a lethal mutation and is associated with very rapid lipolysis of plasma triglyceride-rich lipoproteins (TRL). Ongoing trials based on emerging gene-silencing technologies show that intervention markedly lowers apoC-III levels and, consequently, plasma triglyceride. Unexpectedly, the evidence points to apoC-III not only inhibiting LPL activity but also suppressing removal of TRLs by LPL-independent pathways.

Summary

Available data clearly show that apoC-III is an important cardiovascular risk factor and that lifelong deficiency of apoC-III is cardioprotective. Novel therapies have been developed, and results from recent clinical trials indicate that effective reduction of plasma triglycerides by inhibition of apoC-III might be a promising strategy in management of severe hypertriglyceridemia and, more generally, a novel approach to CHD prevention in those with elevated plasma triglyceride.