Investigation and management of hypertriglyceridaemia

Development and Clinical Applications of Antisense Oligonucleotide Gapmers

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

Primary Hypertriglyceridemia: A Look Back on the Clinical Classification and Genetics of the Disease

INTRODUCTION

Hypertriglyceridemia (HTG) is one of the most common metabolic disorders leading to pancreatitis and cardiovascular disease. HTG develops mostly due to impaired metabolism of triglyceride-rich lipoproteins. Although monogenic types of HTG exist, most reported cases are polygenic in nature.

AIM

This review article is focused on the classification of Primary HTG and the genetic factors behind its development with the aim of providing clinicians a useful tool for early detection of the disease in order to administer proper and effective treatment.

DISCUSSION

HTG is often characterized by a complex phenotype resulting from interactions between genetic and environmental factors. In many instances, the complexity, perplexing causes, and classification of HTG make it difficult for clinicians to properly diagnose and manage the disorder. Better availability of information on its pathophysiology, genetic factors involved, environmental causes, and their interactions could help in understanding such complex disorders and could support its effective diagnosis and treatment.

CONCLUSION

The current review has summarized the case definition, epidemiology, pathophysiology, clinical presentation, classification, associated genetic factors, and scope of genetic screening in the diagnosis of primary HTG.

Inherited metabolic disorders and dyslipidaemia

Monogenic dyslipidaemia is a diverse group of multisystem disorders. Patients may present to various specialities from early childhood to late in adult life, and it usually takes longer before the diagnosis is established. Increased awareness of these disorders among clinicians is imperative for early diagnosis. This best practice review provides an overview of primary dyslipidaemias, highlighting their clinical presentation, relevant biochemical and molecular tests. It also addresses the emerging role of genetics in the early diagnosis and prevention of these disorders.

Hypertriglyceridemia-Associated Drug-Induced Acute Pancreatitis

OBJECTIVES

The aim of our study was to investigate the cases of drug-induced acute pancreatitis (DIAP) with hypertriglyceridemia as the mechanism of injury.

METHODS

A MEDLINE search (1963-2018) of the English language literature was performed looking for all human case reports of adults (>18 years old) with hypertriglyceridemia as the mechanism of DIAP. The latest search date was February 28, 2018. Drugs were classified into probability groups based on a classification used by Badalov et al (Clin Gastroenterol Hepatol. 2007;5:648-661).

RESULTS

The search revealed a total of 76 cases in 59 published reports. A total of 25 medications were found to be implicated in DIAP secondary to hypertriglyceridemia mechanism. Most of acute pancreatitis cases were mild or moderately severe with favorable outcomes. In 3 cases involving tamoxifen, pagaspargase, and quetiapine, patient death was the outcome. Plasmapheresis was only used in 9 cases in an effort to decrease triglyceride levels.

CONCLUSIONS

Hypertriglyceridemia-associated DIAP is a rare phenomenon, and the current systematic review provides a summary of drugs that have been implicated in this phenomenon, which allow physicians to be oriented about this adverse effect when these drugs are used.

Acute pancreatitis secondary to oral contraceptive-induced hypertriglyceridemia: a case report

Hypertriglyceridemia is the third most common cause of acute pancreatitis. Among the causes that lead to secondary hypertriglyceridemia, the use of contraceptive agents is the main reason to be assessed in young women. We report a case of a 31-year-old woman who had suffered two acute pancreatitis episodes secondary to hypertriglyceridemia. In the investigation, the previous medical team indicated a genetic screening before ruling out all secondary causes. LPL, apo CII and apo AV genes were negative for mutations. In the first appointment with us, the patient reported the use of a contraceptive agent for about 2 years. She was instructed to discontinue the drug. After one year of follow-up, her serum triglycerides are within the normal range and a copper intrauterine device was the method chosen by the patient for contraception.

Indicators of hypertriglyceridemia from anthropometric measures based on data mining

BACKGROUND

The best indicator for the prediction of hypertriglyceridemia derived from anthropometric measures of body shape remains a matter of debate. The objectives are to determine the strongest predictor of hypertriglyceridemia from anthropometric measures and to investigate whether a combination of measures can improve the prediction accuracy compared with individual measures.

METHODS

A total of 5517 subjects aged 20-90 years participated in this study. The numbers of normal and hypertriglyceridemia subjects were 3022 and 653 females, respectively, and 1306 and 536 males, respectively. We evaluated 33 anthropometric measures for the prediction of hypertriglyceridemia using statistical analysis and data mining.

RESULTS

In the 20-90-year-old groups, age in women was the variable that exhibited the highest predictive power; however, this was not the case in men in all age groups. Of the anthropometric measures, the waist-to-height ratio (WHtR) was the best predictor of hypertriglyceridemia in women. In men, the rib-to-forehead circumference ratio (RFcR) was the strongest indicator. The use of a combination of measures provides better predictive power compared with individual measures in both women and men. However, in the subgroups of ages 20-50 and 51-90 years, the strongest indicators for hypertriglyceridemia were rib circumference in the 20-50-year-old group and WHtR in the 51-90-year-old group in women and RFcR in the 20-50-year-old group and BMI in the 51-90-year-old group in men.

CONCLUSIONS

Our results demonstrated that the best predictor of hypertriglyceridemia may differ according to gender and age.

Severe hypertriglyceridaemia in Type 2 diabetes mellitus: beneficial effect of continuous insulin infusion

BACKGROUND

Severe hypertriglyceridaemia is a recognized complication of Type 2 diabetes mellitus (T2DM); however, there is no consensus on acute management despite the significant risk of developing associated complications such as acute pancreatitis and hyperviscosity syndrome.

AIM

To identify the association between hyperglycaemia and severe hypertriglyceridaemia in patients with T2DM and assess the effect of continuous insulin infusion therapy on serum triglyceride (TG) concentrations and report any adverse events associated with this therapeutic approach.

DESIGN

Retrospective review of case records.

METHODS

Patients with uncontrolled hyperglycaemia and severe hypertriglyceridaemia (serum TG > 15 mmol/l) treated with continuous intravenous insulin infusion between October 2008 and September 2009 were retrospectively evaluated (n = 15). Details recorded included demographics, admission details, lipid profiles, glycaemic control, serum amylase and adverse events. Patients receiving treatment-dose unfractionated heparin infusion were excluded.

RESULTS

Severe hypertriglyceridaemia is associated with hyperglycaemia in our heterogeneous group of patients with T2DM presenting with new-onset diabetes or established disease on pre-existing insulin or oral hypoglycaemic agents. Administration of continuous exogenous insulin not only achieved normoglycaemia but also dramatically corrected severe hypertriglyceridaemia in all patients (P = 0.001).

CONCLUSION

The administration of continuous insulin in patients with T2DM with severe hypertriglyceridaemia is a simple and safe method of significantly reducing the immediate risk associated with this metabolic complication and should be considered in any T2DM patient presenting with severe hypertriglyceridaemia and hyperglycaemia.

Adipose tissue dysfunction and hypertriglyceridemia: mechanisms and management

Elevated plasma triglyceride levels, as often seen in obese subjects, are independently associated with an increased risk of cardiovascular diseases. By secreting adipokines (such as adiponectin and leptin) and other proteins (such as lipoprotein lipase and cholesteryl ester transferase protein), adipose tissue affects triglyceride metabolism. In obesity, adipocyte hypertrophy leads to many changes in adipocyte function and production of anti- and pro-inflammatory cytokines. Furthermore, free fatty acids are released into the circulation contributing to insulin resistance. Adipose tissue dysfunction will eventually lead to abnormalities in lipid metabolism, such as hypertriglyceridemia (due to increased hepatic very-low-density lipoprotein production and decreased triglyceride hydrolysis), small dense low-density lipoprotein particles, remnant lipoproteins and low high-density lipoprotein cholesterol levels, all associated with a higher risk for the development of cardiovascular diseases. The clinical implications of elevated plasma triglycerides are still a matter of debate. Understanding the pathophysiology of adipose tissue dysfunction in obesity, which is becoming a pandemic condition, is essential for designing appropriate therapeutic interventions. Lifestyle changes are important to improve adipose tissue function in obese patients. Pharmacological interventions to improve adipose tissue function need further evaluation. Although statins are not very potent in reducing plasma triglycerides, they remain the mainstay of therapy for cardiovascular risk reduction in high-risk patients.

Severe hypertriglyceridemia influenced by alcohol (SHIBA)

AIMS

This study was conducted to examine the relationship between triglyceride (TG) levels and a history of excessive drinking in patients with severe hypertriglyceridemia (HT).

METHODS

Alcohol intake as well as other risk factors associated with HT were searched for in case records of 300 patients known to the laboratory to have had a TG level over 11.3 mmol/l.

RESULTS

The majority of severe HT could be attributed to obesity, diabetes mellitus, excessive alcohol consumption or combinations of these. Excessive alcohol intake (over 210 g/week for males; over 140 g/week for females) was recorded for 24% of the total, and for 43% in the highest TG quartile. TG levels were significantly higher in the excessive drinkers (P < 0.001) and in patients with acute pancreatitis (P = 0.001). The incidence of pancreatitis in this cohort was 4% and limited to very high TG levels.

CONCLUSION

Excessive alcohol consumption was recorded in a quarter of patients with severe HT. Patients with the combination of obesity, diabetes and alcohol excess are prone to develop extremely high TG values.

Nonfasting triglycerides and risk of cardiovascular death in men and women from the Norwegian Counties Study

The association between nonfasting triglycerides and cardiovascular disease (CVD) has recently been actualized. The aim of the present study was to investigate nonfasting triglycerides as a predictor of CVD mortality in men and women. A total of 86,261 participants in the Norwegian Counties Study 1974–2007, initially aged 20–50 years and free of CVD were included. We estimated hazard ratios (HRs) for deaths from CVD, ischemic heart disease (IHD), stroke and all causes by level of nonfasting triglycerides. Mean follow-up was 27.0 years. A total of 9,528 men died (3,620 from CVD, 2,408 IHD, 543 stroke), and totally 5,267 women died (1,296 CVD, 626 IHD, 360 stroke). After adjustment for CVD risk factors other than HDL-cholesterol, the HRs (95% CI) per 1 mmol/l increase in nonfasting triglycerides were 1.16 (1.13–1.20), 1.20 (1.14–1.27), 1.26 (1.19–1.34) and 1.09 (0.96–1.23) for all cause mortality, CVD, IHD, and stroke mortality in women. Corresponding figures in men were 1.03 (1.01–1.04), 1.03 (1.00–1.05), 1.03 (1.00–1.06) and 0.99 (0.92–1.07). In a subsample where HDL-cholesterol was measured (n = 40,144), the association between CVD mortality and triglycerides observed in women disappeared after adjustment for HDL-cholesterol. In a model including the Framingham CHD risk score the effect of triglycerides disappeared in both men and women. In conclusion, nonfasting triglycerides were associated with increased risk of CVD death for both women and men. Adjustment for major cardiovascular risk factors, however, attenuated the effect. Nonfasting triglycerides added no predictive information on CVD mortality beyond the Framingham CHD risk score in men and women.

Management of hypertriglyceridemia in the diabetic patient

The hypertriglyceridemia of diabetes can be classified into mild to moderate (triglycerides between 150-499 mg/dL) and severe hypertriglyceridemia (triglycerides > or =500 mg/dL). As in any other individuals with hypertriglyceridemia, secondary causes need to be excluded. The management of severe hypertriglyceridemia (chylomicronemia syndrome) includes aggressive reduction of triglycerides with intravenous insulin, fibrates, omega-3 fatty acids, and/or niacin therapy to avert the risk of pancreatitis. In patients with mild to moderate hypertriglyceridemia, the treatment of choice is statin therapy to achieve the low-density lipoprotein (LDL) and non-high-density lipoprotein (HDL) target goals. The evidence base would favor niacin therapy in combination with statin therapy to achieve the goals pertaining to LDL cholesterol and non-HDL cholesterol. The data about the combination of fibrate therapy with statin therapy are disappointing.

Review of the clinical development of alipogene tiparvovec gene therapy for lipoprotein lipase deficiency

Alipogene tiparvovec (AAV1-LPL(S447X)) gene therapy is developed to prevent complications and decrease the clinical morbidity of lipoprotein lipase deficiency (LPLD). LPLD is an autosomal recessive disease associated with severe hypertriglyceridemia (hyperTG), severe chylomicronaemia, and low HDL. Acute pancreatitis, the most frequent serious clinical LPLD complication, is a complex and heterogeneous inflammatory condition having many causes including hyperTG and chylomicronaemia. In many patients, low fat diet and currently available lipid lowering drugs are ineffective to prevent hyperTG or pancreatitis in LPLD. The clinical development program of alipogene tiparvovec includes observational studies as well as phase I/II and II/III clinical trials. Pooled data are collected on safety and efficacy issues, including the incidence of pancreatitis.

Rheologic reflection in hypertriglyceridemia-induced pancreatitis

Triglyceride levels greater than 1,000 mg/dL may cause severe pancreatitis, and there is mounting evidence for the use of plasmapheresis to remove triglycerides for the treatment of triglyceride-induced pancreatitis. The failure of continuous venovenous hemodialysis (CVVHD) due to severe lipemia, necessitating plasmapheresis in the early phase of severe acute hypertriglyceridemia-induced pancreatitis, is reported. We suggest that in the setting of hypertriglyceridemia-induced pancreatitis with urgent indication for dialysis, plasmapheresis be initiated prior to CVVHD to prevent rheologic failure.