The Chylomicronemia Syndrome Is Most Often Multifactorial: A Narrative Review of Causes and Treatment

Inhibitors of apolipoprotein C3, triglyceride levels, and risk of pancreatitis: a systematic review and meta-analysis

In recent years, novel apoC3 inhibitor therapies for the treatment of hypertriglyceridemia have been developed and assessed through phase II and III clinical trials. The objective of this study was to perform an updated meta-analysis on the impact of new apoC3 inhibitor drugs on triglyceride and apoC3 levels, as well as on the incidence of pancreatitis. We conducted a meta-analysis of randomized, placebo-controlled studies assessing the effects of apoC3 inhibitors therapy (antisense oligonucleotides and small interfering RNA) on triglyceride levels, apoC3 levels, and the occurrence of acute pancreatitis. This meta-analysis was performed according to PRISMA guidelines. The random-effects model was performed. Nine randomized clinical trials (n = 717 patients) were considered eligible for this systematic review. ApoC3 inhibitor drugs were consistently associated with decreased triglyceride levels (MD -57.0%; 95% CI -61.9 to -52.1, I2 82%) and lowered apoC3 values (MD -76; 95% CI -80.1 to -71.8, I2 77%) when compared to placebo. Furthermore, the use of apoC3 inhibitor drugs demonstrated a reduction in the risk of acute pancreatitis (OR 0.11; 95% CI 0.04 to 0.27, I2 0%). The present updated meta-analysis of randomized clinical trials demonstrated that the utilization of apoC3 inhibitors in patients with hypertriglyceridemia correlated with reduced apoC3 and triglyceride levels, along with a decreased risk of acute pancreatitis compared to the placebo.

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.

Lipid-lowering in diabetes: An update

Atherosclerotic cardiovascular disease (ASCVD) is accelerated in people with diabetes. Dyslipidemia, hyperglycemia, oxidative stress, and inflammation play a role via a variety of mechanisms operative in the artery wall. In addition, some unique features predispose people with type 1 diabetes to accelerated atherosclerosis. Various organizations have created guidelines that provide advice regarding screening, risk assessment, and roadmaps for treatment to prevent ASCVD in diabetes. Management of dyslipidemia, especially with statins, has proven to be of immense benefit in the prevention of clinical CVD. However, since many patients fail to attain the low levels of low-density lipoproteins (LDL) recommended in these guidelines, supplemental therapy, such as the addition of ezetimibe, bempedoic acid or PCSK9 inhibitors, is often required to reach LDL goals. As a result, the upfront use of combination therapies, particularly a statin plus ezetimibe, is a rational initial approach. The addition to statins of drugs that specifically lower triglyceride levels has not proven beneficial, although the addition of icosapent-ethyl has been shown to be of value, likely by mechanisms independent of triglyceride lowering. Newer treatments in development, including apoC-III and ANGPTL3 inhibitors, seem promising in further reducing apoB-containing lipoproteins.

Genetic and clinical characteristics of patients with lipoprotein lipase deficiency from Slovenia and Pakistan: case series and systematic literature review

Introduction

Hypertriglyceridemia (HTG) is a complex disorder caused by genetic and environmental factors that frequently results from loss-of-function variants in the gene encoding lipoprotein lipase (LPL). Heterozygous patients have a range of symptoms, while homozygous LPL deficiency presents with severe symptoms including acute pancreatitis, xanthomas, and lipemia retinalis.

Methods

We described the clinical characteristics of three Slovenian patients (an 8-year-old female, an 18-year-old man, and a 57-year-old female) and one Pakistani patient (a 59-year-old male) with LPL deficiency. We performed next-generation sequencing (NGS) targeting all coding exons and intron-exon boundaries of the LPL gene, and Sanger sequencing for variant confirmation. In addition, we performed a systematic literature review of all cases with three identified variants and described their clinical characteristics.

Results

Two Slovenian patients with a heterozygous pathogenic variant NM_000237.3:c.984G>T (p.Met328Ile) were diagnosed within the first three years of life and had triglyceride (TG) values of 16 and 20 mmol/L. An asymptomatic Pakistani patient with TG values of 36.8 mmol/L until the age of 44 years, was identified as heterozygous for a pathogenic variant NM_000237.3:c.724G>A (p.Asp242Asn). His TG levels dropped to 12.7 mmol/L on dietary modifications and by using fibrates. A Slovenian patient who first suffered from pancreatitis at the age of 18 years with a TG value of 34 mmol/L was found to be homozygous for NM_000237.3:c.337T>C (p.Trp113Arg).

Conclusions

Patients with LPL deficiency had high TG levels at diagnosis. Homozygous patients had worse outcomes. Good diet and medication compliance can reduce severity.

Carotid intima-medial thickness in patients with severe hypertriglyceridemia

Background and aims

Severe hypertriglyceridemia (HTG), defined as plasma triglyceride (TG) concentration > 10 mmol/L, is relatively uncommon, and its implications for atherosclerotic cardiovascular disease (ASCVD) risk remain somewhat unclear. We evaluated the association between severe HTG and carotid intima-media thickness (IMT), a marker for ASCVD.

Methods

We studied three clinical cohorts: 88 patients with severe HTG (mean TG level 20.6 mmol/L), 271 patients with familial hypercholesterolemia (FH) as a contrast group, and 70 normolipidemic controls. Carotid IMT was measured using standardized ultrasound imaging. Statistical analysis was conducted using one-way analysis of variance (ANOVA) to compare mean IMT values, analysis of covariance (ANCOVA) to adjust for confounding variables, specifically age and sex, as well as Spearman pairwise correlation analysis between variables.

Results

Unadjusted mean carotid IMT was greater in severe HTG and FH groups compared to controls, however, this was no longer significant for severe HTG after adjustment for age and sex. In contrast, adjusted carotid IMT remained significantly different between the FH and control groups.

Conclusions

Our findings suggest that extreme TG elevations in severe HTG patients are not significantly associated with carotid IMT, in contrast to the increased IMT seen in FH patients. These findings add perspective to the complex relationship between severe HTG and ASCVD risk.

Acute pancreatitis risk in multifactorial chylomicronemia syndrome depends on the molecular cause of severe hypertriglyceridemia

BACKGROUND AND AIMS

Multifactorial chylomicronemia syndrome (MCS) is a severe form of hypertriglyceridemia (hyperTG) associated with an increased risk of acute pancreatitis (AP). Severe hyperTG is mainly polygenic in nature, either caused by the presence of heterozygous pathogenic variants (PVs) in TG-related metabolism genes or by accumulation of common variants in hyperTG susceptibility genes. This study aims to determine if the risk of AP is similar amongst MCS patients with different molecular causes of severe hyperTG.

METHODS

This study included 114 MCS patients who underwent genetic testing for PVs in TG-related metabolism genes and 16 single nucleotide polymorphisms (SNPs) in hyperTG susceptibility genes. A weighted TG-polygenic risk score (TG-PRS) was calculated. A TG-PRS score ≥ 90th percentile was used to define a high TG-PRS.

RESULTS

Overall, 66.7% of patients had severe hyperTG of polygenic origin. MCS patients with only a PV and those with both a PV and high TG-PRS were more prone to have maximal TG concentration ≥ 40 mmol/L (OR 5.33 (1.55-18.36); p = 0.008 and OR 5.33 (1.28-22.25); p = 0.02), as well as higher prevalence of AP (OR 3.64 (0.89-14.92); p = 0.07 and OR 11.90 (2.54-55.85); p = 0.002) compared to MCS patients with high TG-PRS alone.

CONCLUSIONS

This is the first study to show that MCS caused by a high TG-PRS and a PV is associated with higher risk of AP, similar to what is seen in the monogenic form of severe hyperTG. This suggests that determining the molecular cause of severe hyperTG could be useful to stratify the risk of pancreatitis in MCS.

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.

Therapeutic plasma exchange decreases serum triglyceride level rapidly and reduces early recurrence rate but no advantages in improving outcomes for patients with hyperlipidemic acute pancreatitis: a retrospective propensity score matching analysis based on twenty year's experience

BACKGROUND

Hyperlipidaemic acute pancreatitis (HLAP) has become the most common cause of acute pancreatitis (AP) not due to gallstones or alcohol (Mosztbacher et al, Pancreatology 20:608-616, 2020; Yin et al, Pancreas 46:504-509, 2017). Therapeutic plasma exchange (TPE) has been reported to be effective in reducing serum TG levels which is important in management of HLAP (World J Clin Cases 9:5794-803, 2021). However, studies on TPE are mostly focusing on cases reports, TPE remains poorly evaluated till date and need to be compared with conservative therapy with a well-designed study.

METHODS

A retrospectively cohort study on HLAP patients between January 2003 and July 2023 was conducted. Factors correlated with efficacy of TPE were included in a propensity model to balance the confounding factors and minimize selection bias. Patients with and without TPE were matched 1:2 based on the propensity score to generate the compared groups. Lipid profiles were detected on admission and consecutive 7 days. The triglyceride (TG) level decline rates, percentage of patients to reach the target TG levels, early recurrence rate, local complications and mortality were compared between groups.

RESULTS

A total of 504 HLAP patients were identified. Since TPE was scarcely performed on patients with TG < 11.3 mmol/L, 152 patients with TG level 5.65 to 11.3 mmol/L were excluded while 352 with TG ≧11.3 mmol/L were enrolled. After excluding 25 cases with incomplete data or pregnancy, 327 patients, of whom 109 treated without TPE while 218 treated with TPE, were included in data analysis. One-to-two propensity-score matching generated 78 pairs, 194 patients with well-balanced baseline characteristics. Of 194 patients enrolled after matching done, 78 were treated without while 116 with TPE. In the matched cohort (n = 194), patients treated with TPE had a higher TG decline rate in 48 h than those without TPE (70.00% vs 54.00%, P = 0.001); the early recurrence rates were 8.96% vs 1.83%, p = 0.055. If only SAP patients were analyzed, the early recurrence rates were 14.81% vs 0.00% (p = 0.026) respectively. For patients with CT severity index (CTSI) rechecked within 14 days, early CTSI improment rate were 40.90% vs 31.91%. Local complications checked 6 months after discharge were 44.12% vs 38.30%. Mortality was 1.28% vs 1.72%. No differences were found in early stage CTSI improment rate (P = .589), local complications (P = .451) or motality between two groups.

CONCLUSIONS

TPE reduces TG levels more quickly in 48 h compared with those with conservative treatment, but no difference in the consecutive days. TPE tends to reduce the early recurrence rate comparing with conventional therapy, but TPE has no advantages in improving CTSI in early stage, and no improvement for outcomes including local complications and mortalty.

Triglyceride Clearance in Hypertriglyceridemic Pancreatitis: Time Course and Its Implications for Management

OBJECTIVE

To characterize the time course of triglyceride (Tg) lowering in hypertriglyceridemic (HTg) pancreatitis according to the initial Tg values, causes, and interventions.

METHODS

Patients hospitalized from October 2013 through December of 2018 with a diagnosis of pancreatitis associated with HTg (Tg level, ≥500 mg/dL), in the absence of other causes, were identified by medical record review. Tg lowering was retrospectively assessed for differences in relation to the initial Tg values, use of intravenous insulin, ethanol-associated versus nonethanol-associated causes, and time to Tg values of <500 versus <1000 mg/dL.

RESULTS

Sixty-six cases were identified, and 45 had multiple measurements for time-course evaluation. Those with initial Tg values of <4000 mg/dL achieved Tg levels of <1000 mg/dL in <3 days, whereas 18.8% with higher values took 5-9 days. Insulin therapy was associated with a longer duration of HTg, whereas ethanol was associated with a shorter duration. Tg clearance in ethanol-associated HTg appeared independent of insulin treatment. Time to Tg levels of <500 mg/dL versus <1000 mg/dL was significantly longer when the initial Tg levels were >2000 mg/dL.

CONCLUSION

A threshold of 4000 mg/dL for the initial Tg levels in HTg pancreatitis appears to separate patients who are likely to achieve Tg levels of <1000 mg/dL in <3 versus >3 days, independent of cause or treatment. Insulin therapy is appropriate for patients with hyperglycemia but appears unnecessary for those with isolated ethanol-associated HTg. A threshold Tg level of <1000 mg/dL appears more practical than that of <500 mg/dL for resuming nutritional intake.

RNA Interference Therapy Targeting Apolipoprotein C-III in Hypertriglyceridemia

BACKGROUND: Apolipoprotein C-III (APOC3) inhibits triglyceride clearance by reducing lipoprotein lipase–mediated hydrolysis and hepatocyte uptake of triglyceride-rich lipoproteins. ARO-APOC3, a hepatocyte-targeting RNA interference therapeutic, inhibits APOC3 messenger ribonucleic acid expression, lowering triglyceride levels. The objective of this trial was to assess the safety, pharmacodynamic variables, and pharmacokinetic variables of ARO-APOC3 treatment. METHODS: Healthy participants and adults with hypertriglyceridemia were randomly assigned to receive escalating single (day 1) or repeat (days 1 and 29) doses, respectively, of subcutaneous injections of ARO-APOC3 10, 25, 50, or 100 mg or placebo; they were followed up until day 113. Additional cohorts of healthy participants and adults with chylomicronemia received repeat doses of open-label ARO-APOC3. The primary objective was to evaluate the safety and side effect profile of ARO-APOC3. Key secondary and exploratory objectives included pharmacokinetic variables and changes in serum APOC3, triglyceride, and cholesterol levels. RESULTS: Eighty-eight participants received ARO-APOC3 and 24 participants received placebo across double-blind and open-label cohorts. Treatment-emergent adverse events (AEs) of transient, mild to moderate liver transaminase changes occurred in 10 participants: 1 patient receiving ARO-APOC3 25 mg, 5 patients receiving ARO-APOC3 50 mg, and 4 participants receiving ARO-APOC3 100 mg (1 healthy participant and 3 patients with hypertriglyceridemia). These events were asymptomatic, and transaminase levels returned to near baseline by the end of the trial. No AEs related to thrombocytopenia or platelet declines were reported. In the hypertriglyceridemia cohorts, the day 113 mean changes from baseline in APOC3 at the 10-, 25-, 50-, and 100-mg doses were −62.0%, −81.7%, −90.1%, and −94.4%, respectively, compared with −1.6% with placebo. This corresponded to median changes in triglyceride levels of −65.6%, −69.9%, −81.2%, and −81.0% compared with −2.8% with placebo. CONCLUSIONS: In this small trial of short duration, ARO-APOC3 was associated with few AEs and reduced serum levels of APOC3 and triglycerides in healthy participants and patients with hypertriglyceridemia. (Funded by Arrowhead Pharmaceuticals, Inc.; ClinicalTrials.gov number, NCT03783377.)

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.

A Case of Type V Hyperlipoproteinemia Resistant to Insulin Treatment

Type V hyperlipoproteinemia or multifactorial chylomicronemia syndrome is a rare lipid disorder triggered mainly by uncontrolled diabetes, obesity, poor diet, or particular medications. It is associated with an increased risk of acute pancreatitis and accelerated coronary artery disease which may manifest in younger age groups. We present a case of a 42-year-old male who presented to the emergency department (ED) complaining of a non-healing hand injury. Upon laboratory workup, the patient was found to have an elevated total cholesterol (TC) of 1129 mg/dL, very low levels of high-density lipoprotein (HDL) and triglycerides (TG) > 4000 mg/dL with an inability to calculate low-density lipoprotein (LDL). Lipoprotein electrophoresis revealed an actual TG level of > 7000 mg/dL, increased chylomicrons, normal B and pre-B-lipoproteins, and increased L-lipoproteins with an elevated Apolipoprotein B. Despite these derangements, the patient did not exhibit any abdominal complaints, demonstrating a normal lipase level. The physical exam was indicative of bilateral arcus senilis and obesity. Insulin drip was initiated along with intravenous (IV) hydration and it required 12 days to bring triglycerides down to less than 1000 mg/dL. The total cholesterol was also seen to be down trending to around 500 mg/dL and the HDL improved to 22 mg/dL. We present this case as a unique presentation of asymptomatic chylomicronemia resistant to insulin treatment with an elevated ApoB but with no evidence of pancreatitis or coronary artery disease.

Nutrition interventions for adults with dyslipidemia: A Clinical Perspective from the National Lipid Association

Lifestyle habits can have a profound impact on atherosclerotic cardiovascular disease (ASCVD) risk. The National Lipid Association previously published recommendations for lifestyle therapies to manage dyslipidemia. This Clinical Perspective provides an update with a focus on nutrition interventions for the three most common dyslipidemias in adults: 1) low-density lipoprotein cholesterol (LDL-C) elevation; 2) triglyceride (TG) elevation, including severe hypertriglyceridemia with chylomicronemia; and 3) combined dyslipidemia, with elevations in both LDL-C and TG levels. Lowering LDL-C and non-high-density lipoprotein cholesterol are the primary objectives for reducing ASCVD risk. With severe TG elevation (≥500 mg/dL), the primary objective is to prevent pancreatitis and ASCVD risk reduction is secondary. Nutrition interventions that lower LDL-C levels include reducing cholesterol-raising fatty acids and dietary cholesterol, as well as increasing intakes of unsaturated fatty acids, plant proteins, viscous fibers, and reducing adiposity for patients with overweight or obesity. Selected dietary supplements may be employed as dietary adjuncts. Nutrition interventions for all patients with elevated TG levels include restricting intakes of alcohol, added sugars, and refined starches. Additional lifestyle factors that reduce TG levels are participating in daily physical activity and reducing adiposity in patients with overweight or obesity. For patients with severe hypertriglyceridemia, an individualized approach is essential. Nutrition interventions for addressing concurrent elevations in LDL-C and TG include a combination of the strategies described for lowering LDL-C and TG. A multidisciplinary approach is recommended to facilitate success in making and sustaining dietary changes and the assistance of a registered dietitian nutritionist is highly recommended.

Volanesorsen and triglyceride levels in familial chylomicronemia syndrome: Long-term efficacy and safety data from patients in an open-label extension trial

BACKGROUND

Familial chylomicronemia syndrome (FCS) is a rare, autosomal recessive genetic disorder characterized by a marked increase in plasma triglyceride (TG) levels and recurrent episodes of pancreatitis. The response to conventional TG-lowering therapies is suboptimal. Volanesorsen, an antisense oligonucleotide that targets hepatic apoC-III mRNA, has been shown to significantly reduce TGs in patients with FCS.

OBJECTIVE

To further evaluate the safety and efficacy of extended treatment with volanesorsen in patients with FCS.

METHODS

This phase 3 open-label extension study evaluated the efficacy and safety of extended treatment with volanesorsen in three groups of patients with FCS: Those who had previously received volanesorsen or placebo in the APPROACH and COMPASS studies, and treatment-naive patients not participating in either study. Key endpoints included change in fasting TG and other lipid measurements, and safety over 52 weeks.

RESULTS

Volanesorsen treatment resulted in sustained reductions in plasma TG levels in previously treated patients from the APPROACH and COMPASS studies. Volanesorsen-treated patients from the three populations studied had mean decreases in fasting plasma TGs from index study baseline to months 3, 6, 12 and 24 as follows: decreases of 48%, 55%, 50%, and 50%, respectively (APPROACH); decreases of 65%, 43%, 42%, and 66%, respectively (COMPASS); and decreases of 60%, 51%, 47%, and 46%, respectively (treatment-naive). Common adverse events were injection site reactions and platelet count decrease, consistent with previous studies.

CONCLUSION

Extended open-label treatment with volanesorsen in patients with FCS resulted in sustained reductions of plasma TG levels and safety consistent with the index studies.

Correlation between chylomicronemia diagnosis scores and post-heparin lipoprotein lipase activity

INTRODUCTION

Sustained chylomicronemia is a defect in post-prandial triglyceride management characterized by severe hypertriglyceridemia (triglyceride > 10 mmol/L) due to functional or genetic defects in lipoprotein lipase (LPL)-mediated triglyceride-rich lipoprotein lipolysis. Familial chylomicronemia syndrome (FCS) is a rare mendelian form of chylomicronemia caused by loss-of-function variants in LPL or LPL-related genes. Most individuals with chylomicronemia however present multifactorial chylomicronemia (MCS), in which LPL bio-availability and activity are variable. FCS and MCS differ in terms of clinical characteristics and risk of disease, and diagnosis scoring systems have been proposed to accurately distinguish FCS from MCS.

OBJECTIVE

The aim of this study was to assess the strength of the relationship between plasma post-heparin LPL activity and two published chylomicronemia diagnosis scoring systems.

DESIGN AND METHODS

Post-heparin plasma LPL activity was measured using colorimetric assays in a sample of 29 subjects with sustained chylomicronemia (20 FCS and 9 MCS). Chylomicronemia diagnosis scores were obtained for all subjects using the scoring system A (model A), which integrates apolipoprotein B and free glycerol, a surrogate marker of triglyceride hydrolysis, and the scoring system B (model B). Correlation analyses were conducted to estimate the linear relationship between LPL activity and the two diagnosis scoring systems.

RESULTS

There was a significant (p < 0.001) difference in post-heparin LPL activity between FCS and MCS. Both scoring systems significantly correlated with post-heparin LPL activity (model A: r_s = -0.64, p < 0.001; model B: r_s = -0.54, p = 0.002).

CONCLUSIONS

These result suggest that chylomicronemia diagnosis scoring systems correlate with LPL activity and adequately contribute to distinguish FCS from MCS.

The longitudinal triglyceride phenotype in heterozygotes with LPL pathogenic variants

BACKGROUND

Biallelic pathogenic variants in lipoprotein lipase (LPL) cause familial chylomicronemia syndrome with severe hypertriglyceridemia (HTG), defined as plasma triglycerides (TG) > 10 mmol/L (> 885 mg/dL). TG levels in individuals with one copy of a pathogenic LPL gene variant is less familiar; some assume that the phenotype is intermediate between homozygotes and controls.

OBJECTIVE

We undertook an evaluation of the longitudinal TG phenotype of individuals heterozygous for pathogenic LPL variants.

METHODS

Medically stable outpatients were evaluated based on having: (1) a single copy of a rare pathogenic LPL variant; and (2) serial fasting TG measurements obtained over > 1.5 years of follow-up.

RESULTS

Fifteen patients with a single pathogenic LPL variant were followed for a mean of 10.3 years (range 1.5 to 30.3 years). TG levels varied widely both within and between patients. One patient had normal TG levels < 2.0 mmol/L (< 175 mg/dL) continuously, while four patients had at least one normal TG level. Most patients fluctuated between mild-to-moderate and severe HTG: five patients had only mild-to-moderate HTG, with TG levels ranging from 2.0 to 9.9 mmol/L (175 to 885 mg/dL), while 6 patients had at least one instance of severe HTG. Of the 203 total TG measurements from these patients, 14.8%, 67.0% and 18.2% were in the normal, mild-to-moderate and severe HTG ranges, respectively.

CONCLUSION

The heterozygous LPL deficient phenotype is highly variable both within and between patients. Heterozygosity confers susceptibility to a wide range of TG phenotypes, with severity likely depending on secondary factors.

A case of hyperchylomicronemia associated with GPIHBP1 autoantibodies and fluctuating thyroid autoimmune disease

Recent studies have reported that patients with autoimmune hyperchylomicronemia caused by glycosylphosphatidylinositol-anchored high-density lipoprotein binding protein 1 (GPIHBP1) autoantibodies are associated with rheumatoid arthritis, systemic lupus erythematosus, Sjogren's syndrome, Hashimoto's thyroiditis, Basedow's disease, and immune thrombocytopenia. We report a rare case of hyperchylomicronemia due to GPIHBP1 autoantibodies and fluctuating thyroid autoimmune disease. A 28-year-old woman, diagnosed with Hashimoto's thyroiditis at 26 years of age, started taking 50 µg/day of levothyroxine sodium. She had an episode of acute pancreatitis at 27 years of age; her serum triglyceride (TG) level was 1291 mg/dL at that time. The patient was referred to our hospital because her hyperchylomicronemia (hypertriglyceridemia) did not improve on treatment with pemafibrate and eicosapentaenoic acid (EPA). Serum total cholesterol and TG levels were 237 mg/dL and 2535 mg/dL, respectively, while plasma pre-heparin lipoprotein lipase (LPL) mass was 15 ng/mL (26.5-105.5 ng/mL). We diagnosed her as Basedow's disease based on autoimmune antibodies and ultrasound examination. Targeted exome sequencing revealed no pathogenic variants in the LPL or GPIHBP1 genes. The serum GPIHBP1 autoantibody level was 686.0 U/mL (<58.4 U/mL) and GPIHBP1 mass was 301.9 pg/mL (570.6-1625.6 pg/mL). The patient showed hyperchylomicronemia during periods of hypothyroidism and hyperthyroidism, whereas GPIHBP1 autoantibodies were positive during episode of hyperchylomicronemia but negative during periods of normal TG levels. Based on these findings, the patient was diagnosed with hyperchylomicronemia due to GPIHBP1 autoantibodies and treated with rituximab. GPIHBP1 autoantibodies remained undetectable and TG levels were controlled at approximately 200 mg/dL.

Genetic Testing for Hypertriglyceridemia in Academic Lipid Clinics: Implications for Precision Medicine-Brief Report

BACKGROUND

Severe hypertriglyceridemia is often caused by variants in genes of triglyceride metabolism. These variants include rare, heterozygous pathogenic variants (PVs), or multiple common, small-effect single nucleotide polymorphisms that can be quantified using a polygenic risk score (PRS). The role of genetic testing to examine PVs and PRS in predicting risk for pancreatitis and severity of hypertriglyceridemia is unknown.

METHODS

We examined the relationship of PVs and PRSs associated with hypertriglyceridemia with the highest recorded plasma triglyceride level and risk for acute pancreatitis in 363 patients from 3 academic lipid clinics who underwent genetic testing (GBinsight's Dyslipidemia Comprehensive Panel). Categories of hypertriglyceridemia included: normal triglyceride (<200 mg/dL), moderate (200-499 mg/dL), severe (500-999 mg/dL), or very severe (≥1000 mg/dL).

RESULTS

PVs and high PRSs were identified in 37 (10%) and 59 (16%) individuals, respectively. Patients with both had increased risk for very severe hypertriglyceridemia compared with those with neither genetic risk factor. Risk for acute pancreatitis was also increased in individuals with both genetic risk factors (odds ratio, 5.1 [P=0.02] after controlling for age, race, sex, body mass index, and highest triglyceride level), but not in individuals with PV or high PRS alone.

CONCLUSIONS

The presence of both PV and high PRS significantly increased risk for very severe hypertriglyceridemia and acute pancreatitis, whereas PV or PRS alone only modestly increased risk. Genetic testing may help identify patients with hypertriglyceridemia who have the greatest risk for developing pancreatitis and may derive the greatest benefit from novel triglyceride-lowering therapies.

Genetic testing in dyslipidaemia: An approach based on clinical experience

We have used DNA sequencing in our lipid clinic for >20 years. Dyslipidaemia is typically ascertained biochemically. For moderate deviations in the lipid profile, the etiology is often a combination of a polygenic susceptibility component plus secondary non-genetic factors. For severe dyslipidaemia, a monogenic etiology is more likely, although a discrete single-gene cause is frequently not found. A severe phenotype can also result from strong polygenic predisposition that is aggravated by secondary factors. A young age of onset plus a family history of dyslipidaemia or atherosclerotic cardiovascular disease can suggest a monogenic etiology. With severe dyslipidaemia, clinical examination focuses on detecting manifestations of monogenic syndromic conditions. For all patients with dyslipidaemia, secondary causes must be ruled out. Here we describe an experience-based practical approach to genetic testing of patients with severe deviations of low-density lipoprotein, triglycerides, high-density lipoprotein and also combined hyperlipidaemia and dysbetalipoproteinemia.

APOC3 Interference for Familial Chylomicronaemia Syndrome

Patients with familial chylomicronaemia syndrome (FCS) have severe hypertriglyceridaemia due to genetically absent lipolytic capacity. They have a poor response to conventional therapies. To reduce the risk of potentially fatal pancreatitis, the management of FCS relies principally on a strict low-fat diet, which is difficult to follow and compromises quality of life. Targeted reduction of apolipoprotein C-III using new anti-APOC3 agents, such as the short interfering RNA ARO-APOC3, represents a promising approach to correct the severe biochemical disturbance in FCS.

Chylomicronemia through a burr hole: A case report

Chylomicronemia has either a monogenic or multifactorial origin. Multifactorial chylomicronemia is the more common form and is due to the interaction of genetic predisposition and secondary factors such as obesity, diabetes, unhealthy diet, and medications. We report a case of a 38-year-old man who was diagnosed with multifactorial chylomicronemia following presentation with a subarachnoid hemorrhage requiring emergency surgery through a burr hole; lactescent cerebrospinal fluid mixed with blood was observed through the burr hole. The serum triglyceride concentration was 52⋅4 mmol/L with a detectable triglyceride concentration in the cerebrospinal fluid. Rapid weight gain leading to obesity and related unfavorable lifestyle factors were identified as key secondary causes of chylomicronemia. Gene testing revealed a homozygous variant in APOA5 and a heterozygous common variant in GPIHBP1. Accompanied with secondary causes, the interactions of gene and environmental conditions contribute to chylomicronemia. With aggressive medical treatment including excess weight loss, healthy diet, cessation of alcohol, and combination of anti-lipemic medications, normal plasma triglyceride levels were achieved.

A protein of capillary endothelial cells, GPIHBP1, is crucial for plasma triglyceride metabolism

GPIHBP1, a protein of capillary endothelial cells (ECs), is a crucial partner for lipoprotein lipase (LPL) in the lipolytic processing of triglyceride-rich lipoproteins. GPIHBP1, which contains a three-fingered cysteine-rich LU (Ly6/uPAR) domain and an intrinsically disordered acidic domain (AD), captures LPL from within the interstitial spaces (where it is secreted by parenchymal cells) and shuttles it across ECs to the capillary lumen. Without GPIHBP1, LPL remains stranded within the interstitial spaces, causing severe hypertriglyceridemia (chylomicronemia). Biophysical studies revealed that GPIHBP1 stabilizes LPL structure and preserves LPL activity. That discovery was the key to crystallizing the GPIHBP1-LPL complex. The crystal structure revealed that GPIHBP1's LU domain binds, largely by hydrophobic contacts, to LPL's C-terminal lipid-binding domain and that the AD is positioned to project across and interact, by electrostatic forces, with a large basic patch spanning LPL's lipid-binding and catalytic domains. We uncovered three functions for GPIHBP1's AD. First, it accelerates the kinetics of LPL binding. Second, it preserves LPL activity by inhibiting unfolding of LPL's catalytic domain. Third, by sheathing LPL's basic patch, the AD makes it possible for LPL to move across ECs to the capillary lumen. Without the AD, GPIHBP1-bound LPL is trapped by persistent interactions between LPL and negatively charged heparan sulfate proteoglycans (HSPGs) on the abluminal surface of ECs. The AD interrupts the HSPG interactions, freeing LPL-GPIHBP1 complexes to move across ECs to the capillary lumen. GPIHBP1 is medically important; GPIHBP1 mutations cause lifelong chylomicronemia, and GPIHBP1 autoantibodies cause some acquired cases of chylomicronemia.

Hypertriglyceridemia

Mild to moderate hypertriglyceridemia usually results from multiple small-effect variants in genes that control triglyceride metabolism. Hypertriglyceridemia is a critical component of the metabolic syndrome but can also occur secondary to several other conditions or drugs. Hypertriglyceridemia frequently is associated with an increased risk of cardiovascular disease (CVD). Statins are the mainstay of CVD prevention in hypertriglyceridemia, but eicosapentaenoic ethyl esters should be added in very-high-risk individuals. Although fibrates lower triglyceride levels, their role in CVD prevention remains unclear. Familial partial lipodystrophy is another relatively rare cause, although its true incidence is unknown.

Identifying Patients with Familial Chylomicronemia Syndrome Using FCS Score-Based Data Mining Methods

Background: There are no exact data about the prevalence of familial chylomicronemia syndrome (FCS) in Central Europe. We aimed to identify FCS patients using either the FCS score proposed by Moulin et al. or with data mining, and assessed the diagnostic applicability of the FCS score. Methods: Analyzing medical records of 1,342,124 patients, the FCS score of each patient was calculated. Based on the data of previously diagnosed FCS patients, we trained machine learning models to identify other features that may improve FCS score calculation. Results: We identified 26 patients with an FCS score of ≥10. From the trained models, boosting tree models and support vector machines performed the best for patient recognition with overall AUC above 0.95, while artificial neural networks accomplished above 0.8, indicating less efficacy. We identified laboratory features that can be considered as additions to the FCS score calculation. Conclusions: The estimated prevalence of FCS was 19.4 per million in our region, which exceeds the prevalence data of other European countries. Analysis of larger regional and country-wide data might increase the number of FCS cases. Although FCS score is an excellent tool in identifying potential FCS patients, consideration of some other features may improve its accuracy.

Safety and efficacy of therapies for chylomicronemia

INTRODUCTION

Primary chylomicronemia is characterized by pathological accumulation of chylomicrons in the plasma causing severe hypertriglyceridemia, typically >10 mmol/L (>875 mg/dL). Patients with the ultra-rare familial chylomicronemia syndrome (FCS) subtype completely lack lipolytic capacity and respond minimally to traditional triglyceride-lowering therapies. The mainstay of treatment is a low-fat diet, which is difficult to follow and compromises quality of life. New therapies are being developed primarily to prevent episodes of life-threatening acute pancreatitis.

AREAS COVERED

Antagonists of apolipoprotein (apo) C-III, such as the antisense oligonucleotide (ASO) volanesorsen, significantly reduce triglyceride levels in chylomicronemia. However, approval of and access to volanesorsen are restricted since a substantial proportion of treated FCS patients developed thrombocytopenia. Newer apo C-III antagonists, namely, the ASO olezarsen (formerly AKCEA-APOCIII-LRx) and short interfering RNA (siRNA) ARO-APOC3, appear to show efficacy with less risk of thrombocytopenia. Potential utility of antagonists of angiopoietin-like protein 3 (ANGPTL3) such as evinacumab and the siRNA ARO-ANG3 in subtypes of chylomicronemia remains to be defined.

EXPERT OPINION

Emerging pharmacologic therapies for chylomicronemia show promise, particularly apo C-III antagonists. However, these treatments are still investigational. Further study of their efficacy and safety in patients with both rare FCS and more common multifactorial chylomicronemia is needed.

Elevated plasma triglyceride concentration and risk of adverse clinical outcomes in 1.5 million people: a CALIBER linked electronic health record study

BACKGROUND

Assessing the spectrum of disease risk associated with hypertriglyceridemia is needed to inform potential benefits from emerging triglyceride lowering treatments. We sought to examine the associations between a full range of plasma triglyceride concentration with five clinical outcomes.

METHODS

We used linked data from primary and secondary care for 15 M people, to explore the association between triglyceride concentration and risk of acute pancreatitis, chronic pancreatitis, new onset diabetes, myocardial infarction and all-cause mortality, over a median of 6-7 years follow up.

RESULTS

Triglyceride concentration was available for 1,530,411 individuals (mean age 56·6 ± 15·6 years, 51·4% female), with a median of 1·3 mmol/L (IQR: 0.9.to 1.9). Severe hypertriglyceridemia, defined as > 10 mmol/L, was identified in 3289 (0·21%) individuals including 620 with > 20 mmol/L. In multivariable analyses, a triglyceride concentration > 20 mmol/L was associated with very high risk for acute pancreatitis (Hazard ratio (HR) 13·55 (95% CI 9·15-20·06)); chronic pancreatitis (HR 25·19 (14·91-42·55)); and high risk for diabetes (HR 5·28 (4·51-6·18)) and all-cause mortality (HR 3·62 (2·82-4·65)) when compared to the reference category of ≤ 1·7 mmol/L. An association with myocardial infarction, however, was only observed for more moderate hypertriglyceridaemia between 1.7 and 10 mmol/L. We found a risk interaction with age, with higher risks for all outcomes including mortality among those ≤ 40 years compared to > 40 years.

CONCLUSIONS

We highlight an exponential association between severe hypertriglyceridaemia and risk of incident acute and chronic pancreatitis, new diabetes, and mortality, especially at younger ages, but not for myocardial infarction for which only moderate hypertriglyceridemia conferred risk.

Approach to the Patient With Moderate Hypertriglyceridemia

Hypertriglyceridemia is a common lipid disorder encountered in clinical practice. Plasma triglycerides are a marker for the concentration of triglycerides carried in chylomicrons and very low-density lipoprotein particles. A fasting triglyceride level <150 mg/dL is accepted widely as the upper limit of normal range. Guidelines for hypertriglyceridemia are variable without a global consensus on classification and goals for triglyceride levels. A general classification of hypertriglyceridemia is mild < 200 mg/dL, moderate = 200 to 500 mg/dL, moderate to severe = 500 to 1000 mg/dL, and severe > 1000 mg/dL. Because moderate hypertriglyceridemia does increase atherosclerotic cardiovascular disease risk, it is important to determine the underlying etiology to guide appropriate and timely management. This article provides stepwise recommendations on the diagnosis and management of moderate hypertriglyceridemia, based on 3 common scenarios encountered in clinical practice. Initial steps in management include evaluating for secondary contributors, especially diabetes mellitus. Based on patient characteristics, appropriate management decisions include lifestyle adjustments aimed at weight loss and decreasing alcohol consumption and use of statin and nonstatin therapies.

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.

Approach to patients with hypertriglyceridemia

Elevated triglyceride levels increase the risk of arteriosclerotic cardiovascular disease (ASCVD) and severely elevated triglyceride levels also increase the risk of triglyceride-induced pancreatitis. Although substantially reducing triglyceride levels will prevent pancreatitis, whether lowering triglycerides per se will reduce CVD risk is unclear. In this review, we outline several principles that will help in deciding who and how to treat patients with elevated triglyceride levels in order to prevent both ASCVD and pancreatitis. Using these principles will help in making decisions regarding the treatment of elevated triglyceride levels.

Case Report: Next-Generation Sequencing Identified a Novel Pair of Compound-Heterozygous Mutations of LPL Gene Causing Lipoprotein Lipase Deficiency

Lipoprotein lipase deficiency (LPLD) is a rare disease characterized by the accumulation of chylomicronemia with early-onset. Common symptoms are abdominal pain, hepatosplenomegaly, eruptive xanthomas and lipemia retinalis. Serious complications include acute pancreatitis. Gene LPL is one of causative factors of LPLD. Here, we report our experience on an asymptomatic 3.5-month-old Chinese girl with only milky blood. Whole-exome sequencing was performed and identified a pair of compound-heterozygous mutations in LPL gene, c.862G&gt;A (p.A288T) and c.461A&gt;G (p.H154R). Both variants are predicted “deleterious” and classified as “likely pathogenic”. This study expanded the LPL mutation spectrum of disease LPLD, thereby offering exhaustive and valuable experience on early diagnosis and proper medication of LPLD.

Volanesorsen: A New Era in the Treatment of Severe Hypertriglyceridemia

Introduction: Familial chylomicronemia syndrome (FCS) is a rare inherited disease, mainly due to lipoprotein lipase (LPL) gene mutations, leading to lipid abnormalities. Volanesorsen, a second-generation 2′-O-methoxyethyl (2′-MOE) chimeric antisense therapeutic oligonucleotide, can decrease plasma apolipoprotein C3 and triglycerides (TG) levels through LPL-independent pathways. The European Medicines Agency has approved volanesorsen as an adjunct to diet in adult FCS patients with an inadequate response to TG-lowering therapy. Areas covered: Available clinical data on volanesorsen efficacy and safety are presented. Furthermore, we discuss the yearly treatment with volanesorsen of a 21-year-old female FCS patient with LPL mutation. Volanesorsen was well-tolerated and decreased patient’s TG levels (from >5000 mg/dL (56 mmol/L) to 350–500 mg/dL (4–5.6 mmol/L)) at 12 months. Lipoprotein apheresis (LA) was stopped and there were no episodes of pancreatitis or abdominal pain. Expert opinion: Severe hypertriglyceridemia can potentially be fatal. Until recently, there was no specific treatment for FCS, apart from hypotriglyceridemic diet, fibrates, omega-3 fatty acids, and LA sessions. Therefore, volanesorsen represents a promising therapeutic solution for these patients. The main side effect of volanesorsen therapy is thrombocytopenia, which should be monitored and treated accordingly. Increasing evidence will further elucidate the clinical implications of volanesorsen use in daily practice.

Causes, clinical findings and therapeutic options in chylomicronemia syndrome, a special form of hypertriglyceridemia

The prevalence of hypertriglyceridemia has been increasing worldwide. Attention is drawn to the fact that the frequency of a special hypertriglyceridemia entity, named chylomicronemia syndrome, is variable among its different forms. The monogenic form, termed familial chylomicronemia syndrome, is rare, occuring in 1 in every 1 million persons. On the other hand, the prevalence of the polygenic form of chylomicronemia syndrome is around 1:600. On the basis of the genetical alterations, other factors, such as obesity, alcohol consumption, uncontrolled diabetes mellitus and certain drugs may significantly contribute to the development of the multifactorial form. In this review, we aimed to highlight the recent findings about the clinical and laboratory features, differential diagnosis, as well as the epidemiology of the monogenic and polygenic forms of chylomicronemias. Regarding the therapy, differentiation between the two types of the chylomicronemia syndrome is essential, as well. Thus, proper treatment options of chylomicronemia and hypertriglyceridemia will be also summarized, emphasizing the newest therapeutic approaches, as novel agents may offer solution for the effective treatment of these conditions.

Continuous insulin therapy versus apheresis in patients with hypertriglyceridemia-associated pancreatitis

BACKGROUND

The optimal treatment modality for lowering the triglyceride level in patients with hypertriglyceridemia (HTG)-associated acute pancreatitis is unknown. We evaluated the efficacy of continuous insulin infusion and apheresis procedures as triglyceride-lowering therapy.

MATERIALS AND METHODS

Clinical, demographic, and laboratory data were retrospectively evaluated for patients with HTG-associated pancreatitis who received continuous insulin infusion or apheresis in a single tertiary center. The endpoints were modality effectiveness and clinical outcomes.

RESULTS

The study included 48 patients (mean age, 40.4 ± 9.9 years). Apheresis and insulin infusion were performed in 19 and 29 patients, respectively, in the first 24 h of hospital admission. Apheresis procedures included therapeutic plasma exchange in 10 patients and double filtration plasmapheresis in nine patients. Baseline mean triglyceride level was higher in the apheresis group. The two groups were similar in terms of other baseline clinical and demographic characteristics. Seventeen patients (58.6%) in the insulin group and nine patients (47.4%) in the apheresis group exhibited Balthazar grades D-E. There was a rapid reduction (78.5%) in triglyceride level after the first session of apheresis. Insulin infusion resulted in a 44.4% reduction in mean triglyceride level in the first 24 h. The durations of fasting and hospital stay, and the rates of respiratory failure and hypotension, were similar between groups. More patients in the apheresis group experienced acute renal failure or altered mental status. Prognosis did not significantly differ between groups.

CONCLUSION

Although apheresis treatments are safe and effective, they provided no clear benefit over insulin infusion for HTG-associated pancreatitis.

Chylomicronemia Due to the Rare Hyperlipoproteinemia Type 3 Complicated by a Circulating Monoclonal Protein

The polygenic variety of chylomicronemia occurs in adults in whom factors such as obesity, diabetes, alcoholism, renal disease, and certain drugs can precipitate chylomicronemia. A rare cause of polygenic chylomicronemia is hyperlipoproteinemia type 3 (HLP3). We report on a 54-year-old male who presented with chylomicronemia with triglycerides (TG) >2000 mg/dL. From admission, the ratio of total cholesterol to total triglycerides was not below 0.2 but was closer to 0.5, suggesting that his condition was not classic chylomicronemia. We confirmed that the patient had HLP3 based on his very-low-density lipoprotein cholesterol (VLDL-C)/TG ratio, which was ≥0.3, and lipoprotein electrophoresis showing a broad beta band. Because he was not responsive to initial therapy, we considered an interferent impairing lipolysis and TG reduction. The interferent was an M-protein that may also have falsely elevated both apolipoprotein-B and direct-LDL-C levels. In this case study, we report on a patient with chylomicronemia resulting from HLP3 complicated by a circulating M-protein.

Effects of Alirocumab on Triglyceride Metabolism: A Fat-Tolerance Test and Nuclear Magnetic Resonance Spectroscopy Study

Background: PCSK9 antibodies strongly reduce LDL cholesterol. The effects of PCSK9 antibodies on triglyceride metabolism are less pronounced. The present study aimed to investigate in detail the effects of alirocumab on triglycerides, triglyceride-rich lipoproteins, and lipase regulators. Methods: A total of 24 patients with an indication for treatment with PCSK9 antibodies were recruited. There were two visits at the study site: the first before initiation of treatment with alirocumab and the second after 10 weeks of treatment. Fat-tolerance tests, nuclear magnetic resonance spectroscopy, and enzyme-linked immunosorbent assays were performed to analyze lipid metabolism. Results: A total of 21 participants underwent the first and second investigation. Among these, two participants only received alirocumab twice and 19 patients completed the trial per protocol. All of them had atherosclerotic vascular disease. There was no significant effect of alirocumab treatment on fasting triglycerides, post-prandial triglycerides, or lipoprotein-lipase regulating proteins. Total, large, and small LDL particle concentrations decreased, while the HDL particle concentration increased (all p < 0.001). Mean total circulating PCSK9 markedly increased in response to alirocumab treatment (p < 0.001). Whereas PCSK9 increased more than three-fold in all 19 compliant patients, it remained unchanged in those two patients with two injections only. Conclusion: Significant effects of alirocumab on triglyceride metabolism were not detectable in the ALIROCKS trial. The total circulating PCSK9 concentration might be a useful biomarker to differentiate non-adherence from non-response to PCSK9 antibodies.

Incidence, predictors and patterns of care of patients with very severe hypertriglyceridemia in Ontario, Canada: a population-based cohort study

BACKGROUND

The incidence of severe (S-HTG) and very severe hypertriglyceridemia (VS-HTG) among Canadians is unknown. This study aimed to determine the incidence, characteristics, predictors and care patterns for individuals with VS-HTG.

METHODS

Using linked administrative healthcare databases, a population-based cohort study of Ontario adults was conducted to determine incidence of new onset S-HTG (serum triglycerides (TG) > 10-20 mmol/L) and VS-HTG (TG > 20 mmol/L) between 2010 and 2015. Socio-demographic and clinical characteristics of those with VS-HTG were compared to those who had no measured TG value > 3 mmol/L. Univariable and multivariable logistic regression were used to determine predictors for VS-HTG. Healthcare patterns were evaluated for 2 years following first incidence of TG > 20 mmol/L.

RESULTS

Incidence of S-HTG and VS-HTG in Ontario was 0.16 and 0.027% among 10,766,770 adults ≥18 years and 0.25 and 0.041% among 7,040,865 adults with at least one measured TG, respectively. Predictors of VS-HTG included younger age [odds ratios (OR) 0.64/decade, 95% confidence intervals (CI) 0.62-0.66], male sex (OR 3.83; 95% CI 3.5-4.1), diabetes (OR 5.38; 95% CI 4.93-5.88), hypertension (OR 1.69; 95% CI 1.54-1.86), chronic liver disease (OR 1.71; 95% CI 1.48-1.97), alcohol abuse (OR 2.47; 95% CI 1.90-3.19), obesity (OR 1.49; 95% CI 1.13-1.98), and chronic kidney disease (OR 1.39; 95% CI 1.19-1.63).

CONCLUSION

The 5-year incidence of S-HTG and VS-HTG in Canadian adults was 1 in 400 and 1 in 2500, respectively. Males, those with diabetes, obese individuals and those with alcohol abuse are at highest risk for VS-HTG and may benefit from increased surveillance.

ANGPTL3 and ANGPTL8 in Thai subjects with hyperalphalipoproteinemia and severe hypertriglyceridemia

BACKGROUND

The role of ANGPTL3 and ANGPTL8 in lipid regulation in patients with very high levels of HDL-cholesterol and triglyceride is unknown.

OBJECTIVE

We examined plasma levels of ANGPTL3 and ANGPTL8 in subjects with hyperalphalipoproteinemia (HALP) and in those with severe hypertriglyceridemia (HTG).

METHODS

Plasma ANGPTL3 and ANGPTL8 levels were measured by ELISA in 320 subjects, consisting of HALP subjects with HDL-cholesterol ≥100 mg/dl (n=90) and healthy controls (n=90) and subjects with triglyceride ≥886 mg/dl (n=89) and control subjects (n=51).

RESULTS

The mean plasma ANGPTL3 level was significantly higher in the HALP group compared to that of the controls (297 ± 112 ng/mL vs. 230 ± 100 ng/mL, p<0.001). Similarly, the mean plasma ANGPTL8 level was also higher in the HALP group (30 ± 11 ng/mL vs. 20 ± 8 ng/mL, p<0.001). Both ANGPTL3 and ANGPTL8 levels positively correlated with HDL-cholesterol levels. In the severe HTG group, plasma ANGPTL3 level was significantly higher than those in the control group (223 ± 105 ng/mL vs. 151 ± 60 ng/mL, p<0.001), but not ANGPTL8 (23 ± 20 ng/mL vs. 31 ± 23 ng/mL in controls, p=0.028). Only ANGPTL3, but not ANGPTL8, levels positively correlated with triglyceride levels.

CONCLUSION

Plasma level of ANGPTL3 was increased in both HALP and severe HTG whereas an increase in plasma level of ANGPTL8 was found only in HALP, and not in severe HTG, suggesting that both ANGPTL3 and ANGPTL8 might play distinct roles in lipid regulation on these two extremes of dyslipidemia.

Volanesorsen for treatment of familial chylomicronemia syndrome

INTRODUCTION

Familial chylomicronemia syndrome (FCS) is a rare subtype of severe hypertriglyceridemia that affects ~1 in 100, 000 to 1,000,000 individuals. The major risk to health is acute pancreatitis. FCS is defined by biallelic loss-of-function mutations in one of five canonical genes that encode proteins critical to lipolysis of large triglyceride-rich lipoprotein particles. Unlike the vast majority of patients with severe hypertriglyceridemia, FCS patients lack any lipolytic capacity and are thus resistant to standard medications.

AREAS COVERED

This review focuses on a mechanism that effectively reduces elevated triglyceride levels in FCS, namely interference of synthesis of apolipoprotein (apo) C-III. Volanesorsen is an antisense RNA drug administered subcutaneously that knocks down apo C-III, resulting in dramatic reductions in triglyceride levels both in FCS patients and in the wider population of subjects with severe hypertriglyceridemia.

EXPERT OPINION

Volanesorsen is a highly effective treatment to reduce elevated triglycerides in FCS patients, providing proof-of-concept of the validity of targeting apo C-III. However, off target effects of volanesorsen, including thrombocytopenia, may ultimately limit its use. Nonetheless, building on the knowledge derived from the volanesorsen experience, there is intensified interest in promising newer agents that also target apo C-III but have technical modifications that limit potential off target adverse effects.

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.

Treatment of chylomicronemia

Fasting chylomicronaemia appears in type V (multifactorial chylomicronaemia syndrome, MCS), and in type I (familial chylomicronaemia syndrome, FCS). MCS needs to be treated as in any general hypertriglyceridaemia: low-calorie diet, avoid sugar and alcohol, reduce body weight, control of diabetes and, in some cases, common lipid lowering-drugs, such as fibrates or omega-3 fatty acids. For type I HLP, FCS, patients should adhere to a strict very low fat diet, usually less than 15-20 g per day. In spite of this, many patients with FCS suffer from recurrent abdominal pain and/or acute pancreatitis. Volanesorsen, an antisense oligonucleotide against apolipoprotein C-III, is the only drug approved to control the disease. As shown in the APPROACH study, the administration of volanesorsen at a weekly dose of 285 mg induced at three month a reduction of triglycerides of 77% (primary end-point) and a reduction of 1712 mg/dL from the baseline. Among patient receiving volanesorsen, 77% reached a fasting triglyceride value below 750 mg/dL. The most frequent side effects were a skin reaction at injection site and low platelet levels, which should be monitored.

Familial hypertriglyceridemia/polygenic hypertrigliceridemia

For decades, familial hypertriglyceridemia (HTG) has been considered a specific entity characterized by an increase in VLDL particles and an autosomal dominant inheritance pattern. In the genomics era, it has been proven that familial HTG, although it could be grouped in families, had a polygenic inheritance in which the phenotype would be determined by concomitant environmental factors. Hence its inclusion in the group of polygenic HTGs. Clinically, they are characterized by moderate HTG, with the consequent increase in cardiovascular risk, and in rare cases, by severe HTG with risk of acute pancreatitis. Treatment will be based on controlling environmental factors, implementing hygienic-dietetic measures and sometimes drugs, to reduce cardiovascular risk in moderate HTGs and acute pancreatitis risk in severe HTGs.

Novel PPARG mutation in multiple family members with chylomicronemia

Chylomicronemia is characterized by severe hypertriglyceridemia when chylomicrons persist in plasma despite a fasting state. The recessive monogenic form is due to homozygous or compound heterozygous loss-of-function mutations in the LPL gene or genes involved in the assembly, transport, or function of LPL, including APOC2, APOA5, GP1HBP1, and LMF1. The multifactorial form of chylomicronemia is due to both common small-effect variants and rare heterozygous large-effect variants in genes in which mutations are associated secondarily with hypertriglyceridemia. The combined inheritance of these variants increases susceptibility to chylomicronemia, and the number of hypertriglyceridemia-associated alleles carried by an individual represents a genetic or polygenic triglyceride risk score. Among these genes associated with hypertriglyceridemia is PPARG. PPARγ is a nuclear transcription factor encoded by the PPARG gene expressed predominantly in adipocytes that is involved in glucose, lipid, and adipose tissue metabolism. Known rare mutations and common polymorphisms in the PPARG genes are associated with a broad range of clinical phenotypes, including hypertriglyceridemia. Here, we present multiple family members with a novel heterozygous PPARG mutation that has not been previously reported.

Antisense technology: an overview and prospectus

Antisense technology is now beginning to deliver on its promise to treat diseases by targeting RNA. Nine single-stranded antisense oligonucleotide (ASO) drugs representing four chemical classes, two mechanisms of action and four routes of administration have been approved for commercial use, including the first RNA-targeted drug to be a major commercial success, nusinersen. Although all the approved drugs are for use in patients with rare diseases, many of the ASOs in late- and middle-stage clinical development are intended to treat patients with very common diseases. ASOs in development are showing substantial improvements in potency and performance based on advances in medicinal chemistry, understanding of molecular mechanisms and targeted delivery. Moreover, the ASOs in development include additional mechanisms of action and routes of administration such as aerosol and oral formulations. Here, we describe the key technological advances that have enabled this progress and discuss recent clinical trials that illustrate the impact of these advances on the performance of ASOs in a wide range of therapeutic applications. We also consider strategic issues such as target selection and provide perspectives on the future of the field.

10-Year Comparative Follow-up of Familial versus Multifactorial Chylomicronemia Syndromes

CONTEXT

The relative incidence of acute pancreatitis, ischemic cardiovascular disease, and diabetes in hyperchylomicronemic patients exhibiting familial chylomicronemia syndrome (FCS) or multifactorial chylomicronemia syndrome (MCS) is unknown.

OBJECTIVE

The objective was to study the occurrence of these events in FCS and MCS patients compared with the general population.

METHODS

Twenty-nine FCS and 124 MCS patients, with genetic diagnosis, in 4 lipid clinics were matched with 413 controls. Individual hospital data linked to the national claims database were collected between 2006 and 2016. The occurrence of complications was retrospectively assessed before follow-up and during a median follow-up time of 9.8 years, for 1500 patient years of follow-up.

RESULTS

Patients with FCS were younger than those with MCS (34.3 ± 13.6 vs 45.2 ± 12.6 years, P < 0.01). During the study period, 58.6% of the FCS patients versus 19.4% of the MCS patients had at least 1 episode of acute hypertriglyceridemic pancreatitis (AHP) (hazard ratio [HR] = 3.6; P < 0.01). Conversely, the ischemic risk was lower in FCS than in MCS (HR = 0.3; P = 0.05). The risk of venous thrombosis was similar in both groups. The incidence of diabetes was high in both groups compared with matched controls (odds ratio [OR] = 22.8; P < 0.01 in FCS and OR = 30.3; P < 0.01 in MCS).

CONCLUSION

The incidence of AHP was much higher in FCS than in MCS patients, whereas the incidence of ischemic cardiovascular events was found to be increased in MCS versus FCS patients and a representative matched control group. Differences in both triglyceride-rich lipoproteins metabolism and comorbidities in MCS versus FCS drive the occurrence of different patterns of complications.