Effects of Metreleptin in Pediatric Patients With Lipodystrophy

Analysis of disease characteristics of a large patient cohort with congenital generalized lipodystrophy from the Middle East and North Africa

BACKGROUND

Congenital generalized lipodystrophy (CGL) is a rare inherited disease characterized by a near-total absence of adipose tissue and is associated with organ system abnormalities and severe metabolic complications. Here, we have analyzed the disease characteristics of the largest CGL cohort from the Middle East and North Africa (MENA) who have not received lipodystrophy-specific treatment.

METHODS

CGL was diagnosed clinically by treating physicians through physical assessment and supported by genetic analysis, fat loss patterns, family history, and the presence of parental consanguinity. Data were obtained at the time of patient diagnosis and during leptin-replacement naïve follow-up visits as permitted by available medical records.

RESULTS

Data from 43 patients with CGL (37 females, 86%) were collected from centers located in eight countries. The mean (median, range) age at diagnosis was 5.1 (1.0, at birth-37) years. Genetic analysis of the overall cohort showed that CGL1 (n = 14, 33%) and CGL2 (n = 18, 42%) were the predominant CGL subtypes followed by CGL4 (n = 10, 23%); a genetic diagnosis was unavailable for one patient (2%). There was a high prevalence of parental consanguinity (93%) and family history (67%) of lipodystrophy, with 64% (n = 25/39) and 51% (n = 20/39) of patients presenting with acromegaloid features and acanthosis nigricans, respectively. Eighty-one percent (n = 35/43) of patients had at least one organ abnormality; the most frequently affected organs were the liver (70%, n = 30/43), the cardiovascular system (37%, n = 16/43) and the spleen (33%, n = 14/43). Thirteen out of 28 (46%) patients had HbA1c > 5.7% and 20/33 (61%) had triglyceride levels > 2.26 mmol/L (200 mg/dl). Generally, patients diagnosed in adolescence or later had a greater severity of metabolic disease versus those diagnosed during childhood; however, metabolic and organ system abnormalities were observed in a subset of patients diagnosed before or at 1 year of age.

CONCLUSIONS

This analysis suggests that in addition to the early onset of fat loss, family history and high consanguinity enable the identification of young patients with CGL in the MENA region. In patients with CGL who have not received lipodystrophy-specific treatment, severe metabolic disease and organ abnormalities can develop by late childhood and worsen with age.

Body Fat Distribution Contributes to Defining the Relationship between Insulin Resistance and Obesity in Human Diseases

The risk for metabolic and cardiovascular complications of obesity is defined by body fat distribution rather than global adiposity. Unlike subcutaneous fat, visceral fat (including hepatic steatosis) reflects insulin resistance and predicts type 2 diabetes and cardiovascular disease. In humans, available evidence indicates that the ability to store triglycerides in the subcutaneous adipose tissue reflects enhanced insulin sensitivity. Prospective studies document an association between larger subcutaneous fat mass at baseline and reduced incidence of impaired glucose tolerance. Case-control studies reveal an association between genetic predisposition to insulin resistance and a lower amount of subcutaneous adipose tissue. Human peroxisome proliferator-activated receptorgamma (PPAR-γ) promotes subcutaneous adipocyte differentiation and subcutaneous fat deposition, improving insulin resistance and reducing visceral fat. Thiazolidinediones reproduce the effects of PPAR-γ activation and therefore increase the amount of subcutaneous fat while enhancing insulin sensitivity and reducing visceral fat. Partial or virtually complete lack of adipose tissue (lipodystrophy) is associated with insulin resistance and its clinical manifestations, including essential hypertension, hypertriglyceridemia, reduced HDL-c, type 2 diabetes, cardiovascular disease, and kidney disease. Patients with Prader Willi syndrome manifest severe subcutaneous obesity without insulin resistance. The impaired ability to accumulate fat in the subcutaneous adipose tissue may be due to deficient triglyceride synthesis, inadequate formation of lipid droplets, or defective adipocyte differentiation. Lean and obese humans develop insulin resistance when the capacity to store fat in the subcutaneous adipose tissue is exhausted and deposition of triglycerides is no longer attainable at that location. Existing adipocytes become large and reflect the presence of insulin resistance.

A new mutation in the CAVIN1/PTRF gene in two siblings with congenital generalized lipodystrophy type 4: case reports and review of the literature

Lipodystrophy syndromes are characterized by a progressive metabolic impairment secondary to adipose tissue dysfunction and may have a genetic background. Congenital generalized lipodystrophy type 4 (CGL4) is an extremely rare subtype, caused by mutations in the polymerase I and transcript release factor (PTRF) gene. It encodes for a cytoplasmatic protein called caveolae-associated protein 1 (Cavin-1), which, together with caveolin 1, is responsible for the biogenesis of caveolae, being a master regulator of adipose tissue expandability. Cavin-1 is expressed in several tissues, including muscles, thus resulting, when dysfunctional, in a clinical phenotype characterized by the absence of adipose tissue and muscular dystrophy. We herein describe the clinical phenotypes of two siblings in their early childhood, with a phenotype characterized by a generalized reduction of subcutaneous fat, muscular hypertrophy, distinct facial features, myopathy, and atlantoaxial instability. One of the siblings developed paroxysmal supraventricular tachycardia leading to cardiac arrest at 3 months of age. Height and BMI were normal. Blood tests showed elevated CK, a mild increase in liver enzymes and triglycerides levels, and undetectable leptin and adiponectin concentrations. Fasting glucose and HbA1c were normal, while Homeostatic Model Assessment for Insulin Resistance (HOMA-IR) was mildly elevated. Both patients were hyperphagic and had cravings for foods rich in fats and sugars. Genetic testing revealed a novel pathogenic mutation of the CAVIN1/PTRF gene (NM_012232 exon1:c T21A:p.Y7X) at the homozygous state. The diagnosis of lipodystrophy can be challenging, often requiring a multidisciplinary approach, given the pleiotropic effect, involving several tissues. The coexistence of generalized lack of fat, myopathy with elevated CK levels, arrhythmias, gastrointestinal dysmotility, and skeletal abnormalities should prompt the suspicion for the diagnosis of CGL4, although phenotypic variability may occur.

Frequency and characteristics of diabetes in lipodystrophies and insulin receptoropathies compared with type 1 and type 2: results from the multicenter DPV registry

OBJECTIVE

To investigate the frequency, treatment, and outcome of patients with diabetes due to severe insulin resistance syndromes (SIRS).

RESEARCH DESIGN AND METHODS

Based on data from the multicenter prospective Diabetes Registry DPV, we analyzed diagnosis, treatment, and outcome of 636,777 patients with diabetes from 1995 to 2022.

RESULTS

Diabetes due to SIRS was documented in 67 cases (62.7% females), 25 (37%) had lipodystrophies (LD) and 42 (63%) had congenital defects of insulin signaling. The relative frequency compared to type 1 diabetes (T1D) was about 1:2300. Median age at diabetes diagnosis in patients with SIRS was 14.8 years (interquartile range (IQR) 12.8-33.8). A total of 38 patients with SIRS (57%) received insulin and 34 (51%) other antidiabetics, mostly metformin. As high as 16% of patients with LD were treated with fibrates. Three out of eight patients with generalized LD (37.5%) were treated with metreleptin and one patient with Rabson-Mendenhall syndrome was treated with recombinant insulin-like growth factor 1. The median glycated hemoglobin level at follow-up was 7.1% (54 mmol/mol). Patients with LD had higher triglycerides than patients with T1D and T2D (P < 0.001 and P = 0.022, respectively), and also significantly higher liver enzymes and lower high-density lipoprotein cholesterol than patients with T1D (P < 0.001). Patients with insulin receptor disorders were significantly less likely to be treated with antihypertensive medication than patients with T2D (P = 0.042), despite having similar levels of hypertension.

CONCLUSIONS

Diabetes due to SIRS is rarely diagnosed and should be suspected in lean children or young adults without classical T1D. Awareness of cardiovascular risk factors in these patients should be raised.

Lipodystrophies in non-insulin-dependent children: Treatment options and results from recombinant human leptin therapy

Lipodystrophy is a general definition containing different pathologies which, except for those observed in insulin-treated subjects falling outside the scope of this paper, are characterized by total or partial lack of body fat, that, according to the amount of missing adipose tissue, are divided in generalized or partial lipodystrophy. These diseases are characterized by leptin deficiency, which often leads to metabolic derangement, causing insulin resistance, dyslipidemia, and increasing cardiovascular risk. In this narrative review, we presentend the clinical presentation of different types of lipodystrophies and metabolic unbalances related to disease in children and adolescents, focusing on the main treatment options and the novel results from recombinant human leptin (metreleptin) therapy. Milestones in the management of lipodystrophy include lifestyle modification as diet and physical activity, paired with hypoglycemic drugs, insulin, hypolipidemic drugs, and other drugs with the aim of treating lipodystrophy complications. Metreleptin has been recently approved for pediatric patients with general lipodystrophy (GL)> 2 years of age and for children with partial lipodystrophy (PL)> 12 years of age not controlled with conventional therapies. New therapeutic strategies are currently being investigated, especially for patients with PL forms, specifically, liver-targeted therapies. Further studies are needed to achieve the most specific and precise treatment possible.

Targeting adipokines in polycystic ovary syndrome and related metabolic disorders: from experimental insights to clinical studies

Polycystic ovary syndrome (PCOS) affects approximately 15% of women of reproductive age worldwide. It is the most prevalent endocrine disorder with marked risks for female infertility, type 2 diabetes mellitus (T2DM), psychiatric disorders and gynecological cancers. Although the pathophysiology of PCOS remains largely elusive, growing evidence suggests a close link with obesity and its related metabolic disorders. As a highly active endocrine cell population, hypertrophic adipocytes in obesity have disturbed production of a vast array of adipokines, biologically active peptides that exert pleiotropic effects on homeostatic regulation of glucose and lipid metabolism. In parallel with their crucial roles in the pathophysiology of obesity-induced metabolic diseases, adipokines have recently been identified as promising targets for novel therapeutic strategies for multiple diseases. Current treatments for PCOS are suboptimal with insufficient alleviation of all symptoms. Novel findings in adipokine-targeted agents may provide important insight into the development of new drugs for PCOS. This Review presents an overview of the current understanding of mechanisms that link PCOS to obesity and highlights emerging evidence of adipose-ovary crosstalk as a pivotal mediator of PCOS pathogenesis. We summarize recent findings of preclinical and clinical studies that reveal the therapeutic potential of adipokine-targeted novel approaches to PCOS and its related metabolic disorders. We also discuss the critical gaps in knowledge that need to be addressed to guide the development of adipokine-based novel therapies for PCOS.

When Sugar Reaches the Liver: Phenotypes of Patients with Diabetes and NAFLD

Type 2 diabetes mellitus (T2DM) and non-alcoholic fatty liver disease (NAFLD) have been traditionally linked to one another. Recent studies suggest that NAFLD may be increasingly common in other types of diabetes such as type 1 diabetes (T1DM) and less frequently ketone-prone and Maturity-onset Diabetes of the Young (MODY) diabetes. In this review, we address the relationship between hyperglycemia and insulin resistance and the onset and progression of NAFLD. In addition, despite the high rate of patients with T2DM and other diabetes phenotypes that can alter liver metabolism and consequently develop steatosis, fibrosis, and cirrhosis, NALFD screening is not still implemented in the daily care routine. Incorporating a clinical algorithm created around a simple, non-invasive, cost-effective model would identify high-risk patients. The principle behind managing these patients is to improve insulin resistance and hyperglycemia states with lifestyle changes, weight loss, and new drug therapies.

Dunnigan lipodystrophy syndrome: French National Diagnosis and Care Protocol (PNDS; Protocole National de Diagnostic et de Soins)

Dunnigan syndrome, or Familial Partial Lipodystrophy type 2 (FPLD2; ORPHA 2348), is a rare autosomal dominant disorder due to pathogenic variants of the LMNA gene. The objective of the French National Diagnosis and Care Protocol (PNDS; Protocole National de Diagnostic et de Soins), is to provide health professionals with a guide to optimal management and care of patients with FPLD2, based on a critical literature review and multidisciplinary expert consensus. The PNDS, written by members of the French National Reference Center for Rare Diseases of Insulin Secretion and Insulin Sensitivity (PRISIS), is available on the French Health Authority website (in French). Dunnigan syndrome is characterized by a partial atrophy of the subcutaneous adipose tissue and by an insulin resistance syndrome, associated with a risk of metabolic, cardiovascular and muscular complications. Its prevalence, assessed at 1/100.000 in Europe, is probably considerably underestimated. Thorough clinical examination is key to diagnosis. Biochemical testing frequently shows hyperinsulinemia, abnormal glucose tolerance and hypertriglyceridemia. Elevated hepatic transaminases (hepatic steatosis) and creatine phosphokinase, and hyperandrogenism in women, are common. Molecular analysis of the LMNA gene confirms diagnosis and allows for family investigations. Regular screening and multidisciplinary monitoring of the associated complications are necessary. Diabetes frequently develops from puberty onwards. Hypertriglyceridemia may lead to acute pancreatitis. Early atherosclerosis and cardiomyopathy should be monitored. In women, polycystic ovary syndrome is common. Overall, the management of patients with Dunnigan syndrome requires the collaboration of several health care providers. The attending physician, in conjunction with the national care network, will ensure that the patient receives optimal care through regular follow-up and screening. The various elements of this PNDS are described to provide such a support.

Childhood obesity: A review of current and future management options

Obesity is becoming increasingly prevalent in paediatric populations worldwide. In addition to increasing prevalence, the severity of obesity is also continuing to rise. Taken together, these findings demonstrate a worrying trend and highlight one of the most significant challenges to public health. Childhood obesity affects multiple organs in the body and is associated with both significant morbidity and ultimately premature mortality. The prevalence of complications associated with obesity, including dyslipidaemia, hypertension, fatty liver disease and psychosocial complications are becoming increasingly prevalent within the paediatric populations. Treatment guidelines currently focus on intervention with lifestyle and behavioural modifications, with pharmacotherapy and surgery reserved for patients who are refractory to such treatment. Research into adult obesity has established pharmacological novel therapies, which have been approved and established in clinical practice; however, the research and implementation of such therapies in paediatric populations have been lagging behind. Despite the relative lack of widespread research in comparison to the adult population, newer therapies are being trialled, which should allow a greater availability of treatment options for childhood obesity in the future. This review summarizes the current evidence for the management of obesity in terms of medical and surgical options. Both future therapeutic agents and those which cause weight loss but have an alternative indication are also included and discussed as part of the review. The review summarizes the most recent research for each intervention and demonstrates the potential efficacy and limitations of each treatment option.

Treatment Options for Lipodystrophy in Children

Lipodystrophy includes a heterogeneous group of rare diseases characterized by different amounts of adipose tissue loss and several metabolic complications, including hypertriglyceridemia, steatohepatitis and particularly insulin resistance, that may lead to severe morbidity and, sometimes, mortality. Therefore, therapy for lipodystrophy primarily consists of a conventional approach that involves standard treatments of metabolic abnormalities. Given the evidence of leptin deficiency in lipodystrophy syndromes, leptin replacement therapy has been considered as a treatment option. Long-term studies on the use of therapy with a methionylated analog of human leptin, metreleptin, first on animals and subsequently on human patients, demonstrated enormous improvements of patients' clinical features and metabolic conditions. Recently, metreleptin was approved by Food and Drug Administration (FDA) for the treatment of generalized lipodystrophy and by European Medicines Agency (EMA) for the treatment of both generalized and partial lipodystrophy. However, further research is being conducted for new and different therapeutic agents, especially helpful for the treatment of patients with partial lipodystrophy, as some of them do not have access to metreleptin therapy or show poor response.

Approach to Diagnosing a Pediatric Patient With Severe Insulin Resistance in Low- or Middle-income Countries

Diabetes mellitus (DM) in children is most often caused by impaired insulin secretion (type 1 DM). In some children, the underlying mechanism for DM is increased insulin resistance, which can have different underlying causes. While the majority of these children require insulin dosages less than 2.0 U/kg/day to achieve normoglycemia, higher insulin requirements indicate severe insulin resistance. Considering the therapeutic challenges in patients with severe insulin resistance, early diagnosis of the underlying cause is essential in order to consider targeted therapies and to prevent diabetic complications. Although rare, several disorders can attribute to severe insulin resistance in pediatric patients. Most of these disorders are diagnosed through advanced diagnostic tests, which are not commonly available in low- or middle-income countries. Based on a case of DM with severe insulin resistance in a Surinamese adolescent who was later confirmed to have autosomal recessive congenital generalized lipodystrophy, type 1 (Berardinelli-Seip syndrome), we provide a systematic approach to the differential diagnosis and work-up. We show that a thorough review of medical history and physical examination generally provide sufficient information to diagnose a child with insulin-resistant DM correctly, and, therefore, our approach is especially applicable to low- or middle-income countries.

Effects of metreleptin in patients with lipodystrophy with and without baseline concomitant medication use

OBJECTIVE

To evaluate the effects of metreleptin in distinct subgroups of patients with generalized lipodystrophy (GL) and partial lipodystrophy (PL), using multivariate linear regression modeling to account for the role of patients' baseline usage of concomitant glucose and lipid-lowering medications and other covariates on their outcomes.

MATERIALS AND METHODS

A post-hoc statistical analysis of two published single-arm, interventional, phase 2 clinical trials at NIH was conducted. Concomitant medication use was assessed for the clinical trial population using prescription fill data, measured at baseline and the post-one year following metreleptin initiation. Pre-specified co-primary efficacy endpoints measured were change from baseline in HbA1c at month 12, and the percent change from baseline in fasting serum triglycerides (TG) at month 12. Descriptive and statistical analyses were conducted for the overall population, the separate populations with GL and PL, and additional PL subgroups defined by baseline metabolic markers of elevated HbA1c and elevated fasting TG.

RESULTS

As previously reported, improvement in HbA1c and fasting TG from baseline to 12 months on metreleptin were observed in the overall population (mean change -1.57 percentage points and median change -37.9%, respectively) and subgroups. For both HbA1c and TG, baseline levels were significant predictors of changes after metreleptin. After considering baseline characteristics such as disease type, age, sex, and baseline HbA1c, baseline insulin use was not found to be a significant predictor of HbA1c improvement following metreleptin initiation. Similar results were seen for TG levels, with the use of any lipid-lowering medications at baseline not found to be a significant predictor of reductions in fasting TG levels.

CONCLUSIONS

Patients treated with metreleptin experienced statistically significant improvement in metabolic markers of glycemic and hypertriglyceridemic control-e.g. HbA1c and triglyceride levels-across various subgroups after controlling for baseline characteristics and concomitant medication usage.

Metreleptin treatment of non-HIV lipodystrophy syndromes

Lipodystrophy syndromes (LS) constitute a group of rare diseases of the adipose tissue, characterized by a complete or selective deficiency of the fat mass. These disorders are associated with important insulin resistance, cardiovascular and metabolic comorbidities that impact patient's survival and quality of life. Management is challenging and includes diet, physical activity, and specific pharmacological treatment of LS-associated comorbidities. Because of a common pathophysiology involving decreased concentration of the adipokine leptin, efforts have been made to develop therapeutic strategies with leptin replacement therapy. Metreleptin, a recombinant human leptin analogue, has been proposed in hypoleptinemic patients since the beginning of 2000's. The treatment leads to an improvement in metabolic parameters, more important in generalized than in partial LS forms. In this review, the current knowledge about the development of the drug, its outcomes in the treatment of lipodystrophic patients as well as the peculiarities of its use will be presented.

Severe insulin resistance syndromes

Severe insulin resistance syndromes are a heterogeneous group of rare disorders characterized by profound insulin resistance, substantial metabolic abnormalities, and a variety of clinical manifestations and complications. The etiology of these syndromes may be hereditary or acquired, due to defects in insulin potency and action, cellular responsiveness to insulin, and/or aberrations in adipose tissue function or development. Over the past decades, advances in medical technology, particularly in genomic technologies and genetic analyses, have provided insights into the underlying pathophysiological pathways and facilitated the more precise identification of several of these conditions. However, the exact cellular and molecular mechanisms of insulin resistance have not yet been fully elucidated for all syndromes. Moreover, in clinical practice, many of the syndromes are often misdiagnosed or underdiagnosed. The majority of these disorders associate with an increased risk of severe complications and mortality; thus, early identification and personalized clinical management are of the essence. This Review aims to categorize severe insulin resistance syndromes by disease process, including insulin receptor defects, signaling defects, and lipodystrophies. We also highlight several complex syndromes and emphasize the need to identify patients, investigate underlying disease mechanisms, and develop specific treatment regimens.

Effect of Leptin Therapy on Survival in Generalized and Partial Lipodystrophy: A Matched Cohort Analysis

CONTEXT

Data quantifying the impact of metreleptin therapy on survival in non-human immunodeficiency virus (HIV)-related generalized lipodystrophy (GL) and partial lipodystrophy (PL) are unavailable.

OBJECTIVE

This study aimed to estimate the treatment effect of metreleptin on survival in patients with GL and PL.

DESIGN/SETTING/PATIENTS

Demographic and clinical characteristics were used to match metreleptin-treated and metreleptin-naïve patients with GL and PL. Differences in mortality risk were estimated between matched cohorts of metreleptin-treated and metreleptin-naïve patient cohorts using Cox proportional hazard models. Sensitivity analyses assessed the impact of study assumptions and the robustness of results.

OUTCOME MEASURES

This study assessed time-to-mortality and risk of mortality.

RESULTS

The analysis evaluated 103 metreleptin-naïve patients with characteristics matched to 103 metreleptin-treated patients at treatment initiation. Even after matching, some metabolic and organ abnormalities were more prevalent in the metreleptin-treated cohort due to bias toward treating more severely affected patients. A Cox proportional hazards model associated metreleptin therapy with an estimated 65% decrease in mortality risk (hazard ratio [HR] 0.348, 95% confidence interval (CI): 0.134-0.900; P = 0.029) even though the actual number of events were relatively small. Results were robust across a broad range of alternate methodological assumptions. Kaplan-Meier estimates of time-to-mortality for the metreleptin-treated and the matched metreleptin-naïve cohorts were comparable.

CONCLUSIONS

Metreleptin therapy was associated with a reduction in mortality risk in patients with lipodystrophy syndromes despite greater disease severity in treated patients, supporting the view that metreleptin can have a positive disease-modifying impact. Confirmatory studies in additional real-world and clinical datasets are warranted.

GPAT3 deficiency alleviates insulin resistance and hepatic steatosis in a mouse model of severe congenital generalized lipodystrophy

Berardinelli-Seip congenital lipodystrophy type 2 (BSCL2) is the most severe form of human lipodystrophy and is caused by loss-of-function mutations in the BSCL2/seipin gene. Exactly how seipin may regulate adipogenesis remains unclear. A recent study in vitro suggested that seipin may function to inhibit the activity of glycerol-3-phosphate acyltransferases (GPATs), and increased GPAT activity may be responsible for the defective adipogenesis under seipin deficiency. Here we generated Seipin-/-Gpat3-/- mice, which had mild but significant recovery of white adipose tissue mass over Seipin-/- mice. The mass of brown adipose tissue (BAT) of the Seipin-/-Gpat3-/- mice was almost completely restored to normal level. Importantly, the Seipin-/-Gpat3-/- mice showed significant improvement in liver steatosis and insulin sensitivity over Seipin-/- mice, which is attributable to the increased BAT mass and to the enhanced browning of the subcutaneous fat of the Seipin-/-Gpat3-/- mice. Together, our results establish a functional link between seipin and GPAT3 in vivo and suggest that GPAT inhibitors may have beneficial effects on BSCL2 patients.

Long-Term Efficacy and Safety of Anti-Obesity Treatment: Where Do We Stand?

PURPOSE OF REVIEW

As a chronic and relapsing disease, obesity impairs metabolism and causes cardiovascular diseases. Although behavioral modification is important for the treatment of obesity, it is difficult to achieve an ideal weight or sustain the process of long-term weight loss. Therefore, the obesity control guidelines strongly recommend lifestyle interventions along with medical treatment for patients who are overweight. There is sufficient evidence supporting that pharmacotherapy in combination with behavior-based interventions can result in significant weight loss and improved cardiometabolism.

RECENT FINDINGS

Recent meta-analyses of new anti-obesity drugs and their weight-loss efficacy have shown that the overall placebo-subtracted weight reduction (%) for at least 12 months ranged from 2.9 to 6.8% for the following drugs: phentermine/topiramate (6.8%), liraglutide (5.4%), naltrexone/bupropion (4.0%), orlistat (2.9%), and lorcaserin (3.1%). However, very recently, on February 13, 2020, the US Food and Drug Administration (FDA) ordered the withdrawal of lorcaserin from markets, as a clinical trial to assess drug safety showed an increased risk of cancer. Currently, the anti-obesity medications that have been approved by the FDA for chronic weight management are orlistat, phentermine/topiramate, naltrexone/bupropion, and liraglutide. However, they are costly and may have adverse effects in some individuals. Therefore, drug therapy should be initiated in obese individuals after weighing its benefits and risks. One of the strategies for long-term obesity control is that anti-obesity medications should be tailored for specific patients depending on their chronic conditions, comorbidities, and preferences.

Effects of Metreleptin on Patient Outcomes and Quality of Life in Generalized and Partial Lipodystrophy

Generalized and partial lipodystrophy are rare and complex diseases with progressive clinical and humanistic burdens stemming from selective absence of subcutaneous adipose tissue, which causes reduced energy storage capacity and a deficiency of adipokines such as leptin. Treatment options were limited before leptin replacement therapy (metreleptin) became available. This retrospective study evaluates both clinical and humanistic consequences of the disease and treatment. Chart data were abstracted from a cohort of metreleptin-treated patients with generalized and partial lipodystrophy (n = 112) treated at the US National Institutes of Health. To quantify the quality-of-life consequences of the lipodystrophy disease attributes recorded in chart data, a discrete choice experiment was completed in 6 countries (US, n = 250; EU, n = 750). Resulting utility decrements were used to estimate the quality-adjusted life-year consequences of changes in lipodystrophy attribute prevalence before and after metreleptin. In addition to metabolic impairment, patients with generalized and partial lipodystrophy experienced a range of lipodystrophy consequences, including liver abnormality (94%), hyperphagia (79%), impaired physical appearance (77%), kidney abnormality (63%), reproductive dysfunction (80% of females of reproductive age), and pancreatitis (39%). Improvement was observed in these attributes following initiation of metreleptin. Quality-adjusted life-year gains associated with 12 months of treatment with metreleptin were estimated at 0.313 for generalized and 0.117 for partial lipodystrophy, reducing the gap in quality of life between untreated lipodystrophy and perfect health by approximately 59% and 31%, respectively. This study demonstrates that metreleptin is associated with meaningful clinical and quality-of-life improvements.

Serum IGF1 and linear growth in children with congenital leptin deficiency before and after leptin substitution

BACKGROUND

Evidence from in vitro and rodent studies suggests that leptin, a key signal of long-term energy reserves, promotes IGF1 synthesis and linear growth. This effect of leptin has not been fully investigated in humans. The aim of our study was to investigate the effect of leptin substitution on growth factors and linear growth in children with congenital leptin deficiency (CLD).

METHODS

In this cohort study we included eight pediatric patients (six males), age 0.9-14.8 years, who were diagnosed with CLD and received leptin substitution at our University Medical Center. We calculated standard deviation scores (SDS) for serum levels of IGF1 and IGFBP3, IGF1/IGFBP3 molar ratio, and height at baseline (T0) and 12 months (T12) after the initiation of substitution with metreleptin.

RESULTS

All patients had severe obesity (BMI-SDS mean ± SD: 4.14 ± 1.51) at T0 and significant BMI-SDS reduction to 2.47 ± 1.05 at T12. At T0, all patients were taller than the mid-parental median, yet had low IGF1 and IGF1/IGFBP3 molar ratios (IGF1-SDS[Formula: see text]_T0: -1.58 ± 0.92, IGF1/IGFBP3 molar ratio-SDS[Formula: see text]_T0: -1.58 ± 0.88). At T12, IGF1-SDS increased significantly (∆_T0-12: 1.63 ± 1.40, p = 0.01), and IGFBP3-SDS and IGF1/IGFBP3 molar ratio-SDS showed a trend toward an increase. In the three children within the childhood growth period (post-infancy, pre-puberty) height-SDS increased (∆height-SDS_T0-12: 0.57 ± 0.06, p = 0.003) despite substantial weight loss.

CONCLUSIONS

These results in CLD patients are contrary to observations in children with idiopathic obesity who typically have above-mean IGF1 levels that decrease with weight loss, and therefore suggest that leptin increases IGF1 levels and promotes linear growth.

Overview of Atypical Diabetes

Although type 1 diabetes mellitus and, to a lesser extent, type 2 diabetes mellitus, are the prevailing forms of diabetes in youth, atypical forms of diabetes are not uncommon and may require etiology-specific therapies. By some estimates, up to 6.5% of children with diabetes have monogenic forms. Mitochondrial diabetes and cystic fibrosis related diabetes are less common but often noted in the underlying disease. Atypical diabetes should be considered in patients with a known disorder associated with diabetes, aged less than 25 years with nonautoimmune diabetes and without typical characteristics of type 2 diabetes mellitus, and/or with comorbidities associated with atypical diabetes.

Metreleptin for the treatment of progressive encephalopathy with/without lipodystrophy (PELD) in a child with progressive myoclonic epilepsy: a case report

BACKGROUND

A number of genetic syndromes associated with variants in the BSCL2/seipin gene have been identified. Variants that cause skipping of exon 7 are associated with progressive encephalopathy with/without lipodystrophy (PELD), which is characterized by the development of progressive myoclonic epilepsy at a young age, severe progressive neurological impairment, and early death, often in childhood. Because the genetic basis of PELD is similar to that of congenital lipodystrophy type 2, we hypothesized that a patient with PELD may respond to treatments approved for other congenital lipodystrophic syndromes.

CASE PRESENTATION

We describe a 5-year-old boy with an extremely rare phenotype involving severe progressive myoclonic epilepsy who received metreleptin (a recombinant analogue of leptin) to control metabolic abnormalities. At the age of two, he had no subcutaneous adipose tissue, with hypertriglyceridemia, hypertransaminasemia and hepatic steatosis. He also had a moderate psychomotor delay and generalized tonic seizures. At 4 years, he had insulin resistance, hypercholesterolemia, hypertriglyceridemia, mild hepatosplenomegaly and mild hepatic steatosis; he began a hypolipidemic diet. Severe psychomotor delay and myoclonic/myoclonic atonic seizures with absences was evident. At 5 years of age, metreleptin 0.06 mg/kg/day was initiated; after 2 months, the patient's lipid profile improved and insulin resistance resolved. After 1 year of treatment, hepatic steatosis improved and abdominal ultrasound showed only mild hepatomegaly. Seizure frequency decreased but was not eliminated during metreleptin therapy.

CONCLUSIONS

Metreleptin may be used to control metabolic disturbances and may lead to better seizure control in children with PELD.

Current Diagnosis, Treatment and Clinical Challenges in the Management of Lipodystrophy Syndromes in Children and Young People

Lipodystrophy is a heterogeneous group of disorders characterized by lack of body fat in characteristic patterns, which can be genetic or acquired. Lipodystrophy is associated with insulin resistance that can develop in childhood and adolescence, and usually leads to severe metabolic complications. Diabetes mellitus, hypertriglyceridemia, and hepatic steatosis ordinarily develop in these patients, and most girls suffer from menstrual abnormalities. Severe complications develop at a relatively young age, which include episodes of acute pancreatitis, renal failure, cirrhosis, and complex cardiovascular diseases, and all of these are associated with serious morbidity. Treatment of lipodystrophy consists of medical nutritional therapy, exercise, and the use of anti-hyperglycemic and lipid-lowering agents. New treatment modalities, such as metreleptin replacement, promise much in the treatment of metabolic abnormalities secondary to lipodystrophy. Current challenges in the management of lipodystrophy in children and adolescents include, but are not limited to: (1) establishing specialized centers with experience in providing care for lipodystrophy presenting in childhood and adolescence; (2) optimizing algorithms that can provide some guidance for the use of standard and novel therapies to ensure adequate metabolic control and to prevent complications; (3) educating patients and their parents about lipodystrophy management; (4) improving patient adherence to chronic therapies; (5) reducing barriers to access to novel treatments; and (5) improving the quality of life of these patients and their families.

Metabolomic Analysis of the Effects of Leptin Replacement Therapy in Patients with Lipodystrophy

Context and Objective

Leptin treatment has dramatic clinical effects on glucose and lipid metabolism in leptin-deficient patients with lipodystrophy. Further elucidation of metabolic effects of exogenous leptin therapy will shed light on understanding leptin physiology in humans. Our objective was to utilize metabolomic profiling to examine the changes associated with administration of short-term metreleptin therapy in patients with lipodystrophy.

Study Design

We conducted a pre-post-treatment study in 19 patients (75% female) with varying forms of lipodystrophy (congenital generalized lipodystrophy, n = 10; acquired generalized lipodystrophy, n = 1; familial partial lipodystrophy, n = 8) who received daily subcutaneous metreleptin injections for a period of 16 to 23 weeks. A 3-hour oral glucose tolerance test and body composition measurements were conducted before and after the treatment period, and fasting blood samples were used for metabolomic profiling. The study outcome aimed at measuring changes in physiologically relevant metabolites before and after leptin therapy.

Results

Metabolomic analysis revealed changes in pathways involving branched-chain amino acid metabolism, fatty acid oxidation, protein degradation, urea cycle, tryptophan metabolism, nucleotide catabolism, vitamin E, and steroid metabolism. Fold changes in pre- to post-treatment metabolite levels indicated increased breakdown of fatty acids, branched chain amino acids proteins, and nucleic acids.

Conclusions

Leptin replacement therapy has significant effects on important metabolic pathways implicated in patients with lipodystrophy. Continued metabolomic studies may provide further insight into the mechanisms of action of leptin replacement therapy and provide novel biomarkers of lipodystrophy.Abbreviations: 1,5-AG, 1,5-anhydroglucitol; 11βHSD1, 11-β hydroxysteroid dehydrogenase 1; BCAA, branched-chain amino acid; FFA, free fatty acid; GC-MS, gas chromatography mass spectrometry; IDO, indoleamine 2,3-dioxygenase; IFN-γ, interferon-γ; m/z, mass to charge ratio; OGTT, oral glucose tolerance test; TDO, tryptophan 2,3-dioxygenase; TNF-α, tumor necrosis factor-α; UPLC-MS/MS, ultra-performance liquid chromatography-tandem mass spectrometry.

The long-term management of congenital generalized lipodystrophy (Berardinelli-Seip syndrome): the clinical manifestations of Japanese siblings for approximately 20 years

Congenital generalized lipodystrophy (CGL) is a rare autosomal recessive disease that is characterized by loss of subcutaneous and visceral adipose tissues, and associated with dysregulation of glycolipid metabolism. In the present study, we reported the clinical manifestations and treatments of Japanese siblings with CGL caused by BSCL2 gene mutations with a clinical course of approximately 20 yr. Comprehensive management with metreleptin therapy, dietary control with additional medication, and psychosocial counseling in line with the patients’ stages of growth and development were important in achieving long-term metabolic control of this condition.

Leptin Restores Endothelial Function via Endothelial PPARγ-Nox1-Mediated Mechanisms in a Mouse Model of Congenital Generalized Lipodystrophy

Leptin is the current treatment for metabolic disorders associated with acquired and congenital generalized lipodystrophy (CGL). Although excess leptin levels have been associated with vascular inflammation and cardiovascular disease in the context of obesity, the effects of chronic leptin treatment on vascular function remain unknown in CGL. Here, we hypothesized that leptin treatment will improve endothelial function via direct vascular mechanisms. We investigated the cardiovascular consequences of leptin deficiency and supplementation in male gBscl2^-/- (Berardinelli-Seip 2 gene-deficient) mice-a mouse model of CGL. CGL mice exhibited reduced adipose mass and leptin levels, as well as impaired endothelium-dependent relaxation. Blood vessels from CGL mice had increased NADPH Oxidase 1 (Nox1) expression and reactive oxygen species production, and selective Nox1 inhibition restored endothelial function. Remarkably, chronic and acute leptin supplementation restored endothelial function via a PPARγ-dependent mechanism that decreased Nox1 expression and reactive oxygen species production. Selective ablation of leptin receptors in endothelial cells promoted endothelial dysfunction, which was restored by Nox1 inhibition. Lastly, we confirmed in aortic tissue from older patients undergoing cardiac bypass surgery that acute leptin can promote signaling in human blood vessels. In conclusion, in gBscl2^-/- mice, leptin restores endothelial function via peroxisome proliferator activated receptor gamma-dependent decreases in Nox1. Furthermore, we provide the first evidence that vessels from aged patients remain leptin sensitive. These data reveal a new direct role of leptin receptors in the control of vascular homeostasis and present leptin as a potential therapy for the treatment of vascular disease associated with low leptin levels.

Recent advances in understanding lipodystrophy: a focus on lipodystrophy-associated cardiovascular disease and potential effects of leptin therapy on cardiovascular function

Lipodystrophy is a disease characterized by a partial or total absence of adipose tissue leading to severe metabolic derangements including marked insulin resistance, type 2 diabetes, hypertriglyceridemia, and steatohepatitis. Lipodystrophy is also a source of major cardiovascular disorders which, in addition to hepatic failure and infection, contribute to a significant reduction in life expectancy. Metreleptin, the synthetic analog of the adipocyte-derived hormone leptin and current therapy of choice for patients with lipodystrophy, successfully improves metabolic function. However, while leptin has been associated with hypertension, vascular diseases, and inflammation in the context of obesity, it remains unknown whether its daily administration could further impair cardiovascular function in patients with lipodystrophy. The goal of this short review is to describe the cardiovascular phenotype of patients with lipodystrophy, speculate on the etiology of the disorders, and discuss how the use of murine models of lipodystrophy could be beneficial to address the question of the contribution of leptin to lipodystrophy-associated cardiovascular disease.

Leptin and the endocrine control of energy balance

The discovery of leptin changed the view of adipose tissue from that of a passive vessel that stores fat to that of a dynamic endocrine organ that actively regulates behaviour and metabolism. Secreted by adipose tissue, leptin functions as an afferent signal in a negative feedback loop, acting primarily on neurons in the hypothalamus and regulating feeding and many other functions. The leptin endocrine system serves a critical evolutionary function by maintaining the relative constancy of adipose tissue mass, thereby protecting individuals from the risks associated with being too thin (starvation and infertility) or too obese (predation). In this Review, the biology of leptin is summarized, and a conceptual framework is established for studying the pathogenesis of obesity, which, analogously to diabetes, can result from either leptin hyposecretion or leptin resistance. Herein, these two states are distinguished with the terms 'type 1 obesity' and 'type 2 obesity': type 1 obesity describes a subset of obese individuals with low endogenous plasma leptin levels who respond to leptin therapy, whereas type 2 obesity describes most obese individuals, who are leptin resistant but might respond to leptin therapy in combination with other drugs, such as leptin sensitizers.

Fatty liver in lipodystrophy: A review with a focus on therapeutic perspectives of adiponectin and/or leptin replacement

Lipodystrophy is a group of clinically heterogeneous, inherited or acquired, disorders characterized by complete or partial absence of subcutaneous adipose tissue that may occur simultaneously with the pathological, ectopic, accumulation of fat in other regions of the body, including the liver. Fatty liver adds significantly to hepatic and extra-hepatic morbidity in patients with lipodystrophy. Lipodystrophy is strongly associated with severe insulin resistance and related comorbidities, such as hyperglycemia, hyperlipidemia and nonalcoholic fatty liver disease (NAFLD), but other hepatic diseases may co-exist in some types of lipodystrophy, including autoimmune hepatitis in acquired lipodystrophies, or viral hepatitis in human immunodeficiency virus (HIV)-associated lipodystrophy. The aim of this review is to summarize evidence linking lipodystrophy with hepatic disease and to provide a special focus on potential therapeutic perspectives of leptin replacement therapy and adiponectin upregulation in lipodystrophy.

Diagnosis and treatment of lipodystrophy: a step-by-step approach

AIM

Lipodystrophy syndromes are rare heterogeneous disorders characterized by deficiency of adipose tissue, usually a decrease in leptin levels and, frequently, severe metabolic abnormalities including diabetes mellitus and dyslipidemia.

PURPOSE

To describe the clinical presentation of known types of lipodystrophy, and suggest specific steps to recognize, diagnose and treat lipodystrophy in the clinical setting.

METHODS

Based on literature and in our own experience, we propose a stepwise approach for diagnosis of the different subtypes of rare lipodystrophy syndromes, describing its more frequent co-morbidities and establishing the therapeutical approach.

RESULTS

Lipodystrophy is classified as genetic or acquired and by the distribution of fat loss, which can be generalized or partial. Genes associated with many congenital forms of lipodystrophy have been identified that may assist in diagnosis. Because of its rarity and heterogeneity, lipodystrophy may frequently be unrecognized or misdiagnosed, which is concerning because it is progressive and its complications are potentially life threatening. A basic diagnostic algorithm is proposed. Effective management of lipodystrophy includes lifestyle changes and aggressive, evidence-based treatment of comorbidities. Leptin replacement therapy (metreleptin) has been found to improve metabolic parameters in many patients with lipodystrophy. Metreleptin is approved in the United States as replacement therapy to treat the complications of leptin deficiency in patients with congenital or acquired generalized lipodystrophy and has been submitted for approval in Europe.

CONCLUSIONS

Here, we describe the clinical presentation of known types of lipodystrophy, present an algorithm for differential diagnosis of lipodystrophy, and suggest specific steps to recognize and diagnose lipodystrophy in the clinical setting.

Update on Therapeutic Options in Lipodystrophy

PURPOSE OF REVIEW

The purpose of this review is to summarize the therapeutic approach for lipodystrophy syndromes with conventional treatment options and metreleptin therapy in detail and to point out the current investigational treatments in development.

RECENT FINDINGS

The observation of leptin deficiency in patients with lipodystrophy and the potential of leptin replacement to rescue metabolic abnormalities in animal models of lipodystrophy were followed by the first clinical study of leptin therapy in patients with severe lipodystrophy. This and several other long-term studies demonstrated important benefits of recombinant human leptin (metreleptin) to treat metabolic abnormalities of lipodystrophy. These studies ultimately led to the recent FDA approval of metreleptin for the treatment of generalized lipodystrophy and EMA approval for both generalized and partial lipodystrophy. Additional research efforts in progress focus on novel treatment options, predominantly for patients with partial lipodystrophy. Current treatment of generalized lipodystrophy includes metreleptin replacement as an adjunct to diet and standard treatment approach for metabolic consequences of lipodystrophy. Beyond metreleptin, a number of different compounds and treatment modalities are being studied for the treatment of partial lipodystrophy.

Acquired generalised lipodystrophy and type 1 diabetes mellitus in a child: a rare and implacable association

Lipodystrophy syndromes are frequently associated with marked degree of insulin resistance and lipoatrophic diabetes. Although acquired generalised lipodystrophy (AGL) has been known to be associated with various autoimmune disorders, type 1 diabetes mellitus (T1DM) is very rarely reported to occur with AGL. Combination of AGL and T1DM can lead to a totally different phenotype with very difficult-to-treat diabetes and progressive complications of both the conditions. We report a case of AGL with T1DM with poor diabetes control despite high doses of insulin, metformin and pioglitazone. Our case further progressed to develop complication of retroperitoneal fibrosis, not hitherto reported with AGL.

Future Pharmacotherapy for Obesity: New Anti-obesity Drugs on the Horizon

PURPOSE OF REVIEW

Obesity is a global health crisis with detrimental effects on all organ systems leading to worsening disease state and rising costs of care. Persons with obesity failing lifestyle therapies need to be escalated to appropriate pharmacological treatment modalities, medical devices, and/or bariatric surgery if criteria are met and more aggressive intervention is needed. The progression of severe obesity in the patient population coupled with related co-morbidities necessitates the development of novel therapies for the treatment of obesity. This development is preceded by increased understanding of the underpinnings of energy regulation and neurohormonal pathways involved in energy homeostasis.

RECENT FINDINGS

Though there are approved anti-obesity drugs available in the USA, newer drugs are now in the pipeline for development given the urgent need. This review focuses on anti-obesity drugs in the pipeline including centrally acting agents (setmelanotide, neuropeptide Y antagonist [velneperit], zonisamide-bupropion [Empatic], cannabinoid type-1 receptor blockers), gut hormones and incretin targets (new glucagon-like-peptide-1 [GLP-1] analogues [semaglutide and oral equivalents], amylin mimetics [davalintide, dual amylin and calcitonin receptor agonists], dual action GLP-1/glucagon receptor agonists [oxyntomodulin], triple agonists [tri-agonist 1706], peptide YY, leptin analogues [combination pramlintide-metreleptin]), and other novel targets (methionine aminopeptidase 2 inhibitor [beloranib], lipase inhibitor [cetilistat], triple monoamine reuptake inhibitor [tesofensine], fibroblast growth factor 21), including anti-obesity vaccines (ghrelin, somatostatin, adenovirus36). With these new drugs in development, anti-obesity therapeutics have potential to vastly expand allowing better treatment options and personalized approach to obesity care.

Leptin and chronic kidney diseases

Chronic kidney diseases (CKD), a common outcome of various kidney diseases, cause a series of refractory complications, which lead to great economic burdens on patients. The clinical outcomes of CKD depend on various factors, including metabolic disorders. Leptin, a peptide hormone, produced in adipose tissues, plays an important role in regulating food consumption and energy expenditure. Leptin also influences the immune system and hematopoiesis. Increased leptin status is observed in CKD, leptin deficiency attenuates the immune response in nephritis. Conversely, leptin inhibits the development of obesity, which is closely associated glomerular disorder. Now, the precise role of leptin in CKD remains elusive. This review will give an integrated understanding of the potential role of leptin and its interactions with other signal molecules in CKD.