Robust Reductions of Excess Weight and Hyperphagia by Beloranib in Rat Models of Genetic and Hypothalamic Obesity

Reductions of food intake and body weight in diet-induced obese rats following chronic treatment with a monomeric peptide multiagonist

INTRODUCTION

While therapies based on endogenous gut peptides such as glucagon-like peptide-1 (GLP-1) receptor agonists (GLP-1RAs) have been compelling therapeutic agents for obesity and type 2 diabetes (T2D), only a few have achieved long-term weight loss and all have shown significant side-effects, including nausea/malaise and gastrointestinal ailments.

OBJECTIVE

As the pathophysiology of obesity is driven by dysregulation of multiple, inter-related, pathways, we tested a novel peptide targeting multiple receptors of complementary neurocircuits regulating the controls of energy balance.

METHODS

Response to daily injections of GEP44, a GLP-1R and neuropeptide Y1R and Y2R receptor (Y1R/Y2R) triple agonist was tested vs. the GLP-1R agonist liraglutide (LIRA) in diet-induced obese (DIO) male and female rats. Glucose tolerance tests after intraperitoneal injection of glucose (IPGTT) were performed at baseline and after 14-d of treatment in GEP44 treated rats. Other metabolic parameters were assessed in blood at the end of a 28-d intervention.

RESULTS

Upon conclusion at 28-d, body weight reduction compared to vehicle was -15.6%/-11.9% in response to GEP44, vs. -9.7%/-5.1% after LIRA, males, and females, respectively. Significant reductions of cumulative food intake occurred over 28-d in female rats treated with GEP44 (-30%; p < 0.0001), vs. LIRA (-10%), and in male rats GEP44 (-39%; p < 0.0001), vs. LIRA (-20%; p = 0.003). In IPGTTs, a similar stimulation glucose induced insulin secretion was noted in rats treated with GEP44 and LIRA.

CONCLUSION

The strong reductions of body weight in response to long-term applications of the triple agonist GEP44 confirms the therapeutic potential of targeting multiple receptors for achieving more robust and potentially more sustained improvement of energy balance.

Treatment of hypothalamic obesity in people with hypothalamic injury: new drugs are on the horizon

Hypothalamic obesity (HO) is a complex and rare disorder affecting multiple regulatory pathways of energy intake and expenditure in the brain as well as the regulation of the autonomic nervous system and peripheral hormonal signaling. It can be related to monogenic obesity syndromes which often affect the central leptin-melanocortin pathways or due to injury of the hypothalamus from pituitary and hypothalamic tumors, such as craniopharyngioma, surgery, trauma, or radiation to the hypothalamus. Traditional treatments of obesity, such as lifestyle intervention and specific diets, are still a therapeutic cornerstone, but often fail to result in meaningful and sustained reduction of body mass index. This review will give an update on pharmacotherapies of HO related to hypothalamic injury. Recent obesity drug developments are promising for successful obesity intervention outcomes.

Treatment of Acquired Hypothalamic Obesity: Now and the Future

The hypothalamus is the centre of neuroendocrine regulation of energy homeostasis and appetite. Maldevelopment of, or damage to, the key hypothalamic nuclei disrupts the coordinated balance between energy intake and expenditure leading, to rapid and excessive weight gain. Hypothalamic obesity is compounded by a disruption of the hypothalamic-pituitary axis, sleep disruption, visual compromise, and neurological and vascular sequalae. Amongst suprasellar tumors, craniopharyngioma is the most common cause of acquired hypothalamic obesity, either directly or following surgical or radiotherapeutic intervention. At present, therapy is limited to strategies to manage obesity but with a modest and variable impact. Current approaches include optimizing pituitary hormone replacement, calorie restriction, increased energy expenditure through physical activity, behavioral interventions, pharmacotherapy and bariatric surgery. Current pharmacotherapeutic approaches include stimulants that increase energy consumption, anti-diabetic agents, hypothalamic-pituitary substitution therapy, octreotide, and methionine aminopeptidase 2 (MetAP2) inhibitors. Some pharmacological studies of hypothalamic obesity report weight loss or stabilization but reported intervention periods are short, and others report no effect. The impact of bariatric surgery on weight loss in hypothalamic obesity again is variable. Novel or combined approaches to manage hypothalamic obesity are thus required to achieve credible and sustained weight loss. Identifying etiological factors contributing hypothalamic obesity may lead to multi-faceted interventions targeting hyperphagia, insulin resistance, decreased energy expenditure, sleep disturbance, hypopituitarism and psychosocial morbidity. Placebo-controlled trials using current single, or combination therapies are required to determine the impact of therapeutic agents. A well-defined approach to defining the location of hypothalamic damage may support the use of future targeted therapies. Intranasal oxytocin is currently being investigated as an anorexogenic agent. Novel agents including those targeting pro-opimelanocortin-C and AgRP/NPY expressing neurons and the MC4 receptor may result in better outcomes. This article discusses the current challenges in the management of hypothalamic obesity in children and young people and future therapeutic approaches to increasing weight loss and quality of life in these patients.

MetAP2 inhibitor treatment of high-fat and -fructose-fed dogs: impact on the response to oral glucose ingestion and a hyperinsulinemic hyperglycemic clamp

We examined the methionine aminopeptidase 2 inhibitor fumagillin in dogs consuming a high-fat and -fructose diet (HFFD). In pilot studies (3 dogs that had consumed HFFD for 3 yr), 8 wk of daily treatment with fumagillin reduced food intake 29%, weight 6%, and the glycemic excursion during an oral glucose tolerance test (OGTT) 44%. A second group of dogs consumed the HFFD for 17 wk: pretreatment (weeks 0-4), treatment with fumagillin (FUM; n = 6), or no drug (Control, n = 8) (weeks 4-12), washout period (weeks 12-16), and fumagillin or no drug for 1 wk (week 17). OGTTs were performed at 0, 4, 11, and 16 wk. A hyperinsulinemic hyperglycemic clamp was performed in week 12; 4 chow-fed dogs underwent identical clamps. Kilocalories per day intake during the treatment period was 2,067 ± 50 (Control) versus 1,824 ± 202 (FUM). Body weights (kg) increased 1.9 ± 0.3 vs. 2.7 ± 0.8 (0-4 wk) and 1.2 ± 0.2 vs. -0.02 ± 0.9 (4-12 wk) in Control versus fumagillin. The OGTT glycemic response was 30% greater in Control versus fumagillin at 11 wk. Net hepatic glucose uptake (NHGU; mg·kg^-1·min^-1) in the Chow, Control, and fumagillin dogs was ~1.5 ± 0.6, -0.1 ± 0.1, and 0.3 ± 0.4 (with no portal glucose infusion) and 3.1 ± 0.6, 0.5 ± 0.3, and 1.5 ± 0.5 (portal glucose infusion at 4 mg·kg^-1·min^-1), respectively. Fumagillin improved glucose tolerance and NHGU in HFFD dogs, suggesting methionine aminopeptidase 2 (MetAP2) inhibitors have the potential for improving glycemic control in prediabetes and diabetes.

Obesity medications in development

Introduction: Obesity is compounded by a neurobiology that is resistant to weight loss. Therefore, the development of pharmacotherapies to address the pathology underlying the dysregulation of energy homeostasis is critical.Areas covered: This review examines selected clinical trial evidence for the pharmacologic treatment of obesity and provides an expert opinion on anti-obesity drug development. The article includes the outcomes of anti-obesity medications that have been evaluated in clinical trials but have not yet received approval from the U.S. Food and Drug Administration. The mechanisms of action of glucagon-like peptide-1 agonists and co-agonists, diabetes medications being investigated for weight loss, and medications acting on the central nervous system as well as peripherally are reviewed. A search was conducted on PubMed using the terms 'Obesity AND Medications' restricted to clinical trials reported in English. Using similar terms, a search was also conducted on ClinicalTrials.gov.Expert opinion: The goal of anti-obesity therapy is finding compounds that are effective and have minimal side effects. Combining medications targeting more than one of the redundant mechanisms driving obesity increases efficacy. However, targeting peripheral mechanisms to overcome the trickle-down effects of centrally acting drugs may be the key to success in treating obesity.

Pathophysiology and Individualized Treatment of Hypothalamic Obesity Following Craniopharyngioma and Other Suprasellar Tumors: A Systematic Review

The development of hypothalamic obesity (HO) following craniopharyngioma (CP) and other suprasellar tumors leads to reduced patient quality of life. No treatment algorithms are currently available for management of HO. Depending on which hypothalamic nuclei are destroyed, the pathophysiologic mechanisms and clinical symptoms that contribute to HO differ among patients. Herein, we review the contribution of the hypothalamus to the pathophysiologic mechanisms and symptoms underlying CP-associated HO. Additionally, we performed a systematic search of MEDLINE and Embase to identify all intervention studies for weight management in patients with CP or other suprasellar tumors published until September 2017. The search yielded 1866 publications, of which 40 were included. Of these 40 studies, we identified four modalities for intervention (i.e., lifestyle, dietary, pharmacotherapeutic, or surgical) within six clinical domains (i.e., psychosocial disorders, hyperphagia, sleep disturbances, decreased energy expenditure, hyperinsulinemia, and hypopituitarism). We used the findings from our systematic review, in addition to current knowledge on the pathophysiology of HO, to develop an evidence-based treatment algorithm for patients with HO caused by CP or other suprasellar tumors. Although the individual effects of the HO interventions were modest, beneficial individual effects may be achieved when the pathophysiologic background and correct clinical domain are considered. These two aspects can be combined in an individualized treatment algorithm with a stepwise approach for each clinical domain. Recently elucidated targets for HO intervention were also explored to improve future management of HO for patients with CP and other suprasellar tumors.

Single and multiple dose evaluation of a novel MetAP2 inhibitor: Results of a randomized, double-blind, placebo-controlled clinical trial

AIMS

Methionine aminopeptidase 2 (MetAP2) inhibition has been shown to result in significant weight loss and improved glucose control. This Phase 1 clinical trial assessed the safety and tolerability, pharmacokinetics and preliminary efficacy of a novel MetAP2 inhibitor, ZGN-1061.

METHODS

This clinical trial included a single ascending dose (SAD) phase in healthy subjects (BMI, 23 to <30 kg/m² ) and a multiple ascending dose (MAD) phase in otherwise healthy subjects (BMI, 27 to 40 kg/m² ). SAD phase doses, administered subcutaneously (SC), were 0.2, 0.6, 1.2, 2.4, 3.6 and 4.8 mg and the MAD phase evaluated doses of 0.2, 0.6 and 1.8 mg twice weekly SC for 4 weeks.

RESULTS

The SAD phase included 39 subjects (ZGN-1061, N = 28; placebo, N = 11); 90% were male and BMI was 26.4 kg/m² . ZGN-1061 was well tolerated across all doses, with the most frequent adverse events being mild headache and procedural-related irritation. There were no severe or serious adverse events. All doses of ZGN-1061 were rapidly absorbed and cleared, resulting in short duration of exposure that is anticipated to minimize potential off-drug target risks. The MAD phase included 29 subjects (ZGN-1061, N = 22; placebo, N = 7); 76% were male and BMI was 33.5 kg/m² . Safety observations were consistent with SAD findings. Efficacy measures in the MAD phase indicated trends for weight change (-1.5 kg total ZGN-1061 vs -0.2 kg placebo) and other biomarker changes.

CONCLUSIONS

ZGN-1061 was well tolerated with no safety signals in all doses tested. In addition, the desired pharmacokinetic profile and preliminary efficacy observations with ZGN-1061 support evaluation in larger and longer clinical trials.

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.

Preclinical Efficacy and Safety of the Novel Antidiabetic, Antiobesity MetAP2 Inhibitor ZGN-1061

Methionine aminopeptidase 2 (MetAP2) inhibition is a promising approach to treating diabetes, obesity, and associated metabolic disorders. Beloranib, a MetAP2 inhibitor previously investigated for treatment of Prader-Willi syndrome, was associated with venous thrombotic adverse events likely resulting from drug effects on vascular endothelial cells (ECs). Here, we report the pharmacological characterization of ZGN-1061, a novel MetAP2 inhibitor being investigated for treatment of diabetes and obesity. Four weeks of subcutaneous administration of ZGN-1061 to diet-induced obese (DIO) insulin-resistant mice produced a 25% reduction in body weight, primarily due to reduced fat mass, that was comparable to beloranib. ZGN-1061 also produced improvements in metabolic parameters, including plasma glucose and insulin, and, in HepG2 cells, initiated gene changes similar to beloranib that support observed in vivo pharmacodynamics. In vitro studies in ECs demonstrated that ZGN-1061 effects on EC proliferation and coagulation proteins were greatly attenuated, or absent, relative to beloranib, due to lower intracellular drug concentrations, shorter half-life of inhibitor-bound MetAP2 complex, and reduced cellular enzyme inhibition. In dogs, ZGN-1061 was more rapidly absorbed and cleared, with a shorter half-life than beloranib. Unlike beloranib, ZGN-1061 did not increase coagulation markers in dogs, and ZGN-1061 had a greatly improved safety profile in rats relative to beloranib. In conclusion, ZGN-1061 and beloranib demonstrated similar efficacy in a mouse model of obesity, while ZGN-1061 had a markedly improved safety profile in multiple in vitro and in vivo models. The lower duration of exposure characteristic of ZGN-1061 is expected to provide a meaningfully enhanced clinical safety profile.