Dasiglucagon for the Treatment of Congenital Hyperinsulinism: A Randomized Phase 3 Trial in Infants and Children

CONTEXT

Congenital hyperinsulinism (CHI) is characterized by dysregulated insulin secretion causing hypoglycemia and consequent brain damage. Dasiglucagon is a glucagon analogue under investigation to treat CHI.

OBJECTIVE

To evaluate the efficacy and safety of dasiglucagon delivered via continuous subcutaneous infusion to children with CHI and persistent hypoglycemia as add-on to standard of care (SoC).

METHODS

In this open-label trial, patients were randomized 1:1 to SoC or SoC + dasiglucagon (10-70 µg/h) for 4 weeks. In the following 4 weeks, all patients received dasiglucagon + SoC. Hypoglycemia was assessed by self-monitored plasma glucose (SMPG) and blinded continuous glucose monitoring (CGM). Primary endpoint was average number of SMPG-detected hypoglycemia episodes/week (SMPG <3.9 mmol/L) during Weeks 2 to 4.

RESULTS

Thirty-two patients (0.6-10.9 years) were randomly assigned to dasiglucagon + SoC (n = 16) or SoC (n = 16). The rate of SMPG-detected hypoglycemia decreased from baseline in both groups, but with no statistically significant difference during Weeks 2 to 4 (event rate ratio: 0.85 [0.54; 1.36], P = .5028). However, dasiglucagon administration resulted in a 43% reduction in CGM-detected hypoglycemia (<3.9 mmol/L) vs SoC alone during Weeks 2 to 4 (post hoc analysis; event rate ratio: 0.57 [0.39; 0.83], P = .0029). Dasiglucagon enabled reductions (of 37% to 61%) in all other measures of hypoglycemia assessed by CGM vs SoC alone including extent and percent time in hypoglycemia (post hoc analyses). Dasiglucagon appeared safe and well tolerated. Skin and gastrointestinal events were more frequent with dasiglucagon + SoC than SoC only.

CONCLUSION

Clinically meaningful reductions in all CGM-recorded measures of hypoglycemia support using dasiglucagon as a potential treatment for CHI.

Novel Use of Dasiglucagon, a Soluble Glucagon Analog, for the Treatment of Hyperinsulinemic Hypoglycemia Secondary to Suspected Insulinoma: A Case Report

INTRODUCTION

Hyperinsulinemic hypoglycemia is the most common cause of persistent hypoglycemia in children and adults. In adolescents and adults, hyperinsulinemic hypoglycemia is most frequently caused by an insulin-producing tumor.

CASE PRESENTATION

A 17-year-old, previously healthy male presented with recurrent and severe episodes of hypoglycemia. Diagnostic evaluation was consistent with hyperinsulinemic hypoglycemia, and an insulinoma was suspected. Multiple imaging studies and surgical exploration failed to identify a lesion. Over the course of months, the patient was found to be refractory to conventional medical interventions.

CONCLUSION

Upon approval from the US Food and Drug Administration and the Institutional Review Board, the patient was treated with dasiglucagon, a novel soluble glucagon analog, under a single-patient Investigational New Drug. The patient has tolerated the medication and has been able to achieve appropriate glycemic control.

A Comparative Study of Dasiglucagon Ready-to-Use Autoinjector and Glucagon Emergency Kit During Rescue from Simulated Severe Hypoglycemia

Background: Severe hypoglycemic episodes are life-threatening events demanding rapid administration of glucagon by a caregiver or bystander. The glucagon analog dasiglucagon is stable in aqueous formulation and therefore suitable for delivery in a ready-to-use autoinjector, potentially increasing speed and ease of use compared with standard glucagon emergency kits (GEKs). Methods: In an open label, randomized, crossover, comparative device handling study, trained caregivers and untrained bystanders administered the dasiglucagon autoinjector or Eli Lilly GEK to manikins in a simulated emergency hypoglycemia situation. Results: In total, 54 participants were randomized (18 patient-caregiver pairs and 18 bystanders). Overall, 94% of trained caregivers were able to administer the dasiglucagon autoinjector successfully within 15 min, compared with 56% for the GEK (P < 0.05). A greater proportion of trained caregivers and untrained bystanders successfully prepared and administered the dasiglucagon autoinjector within 2 min compared with the GEK (P < 0.005 and P < 0.05, respectively). Time to successful completion was also significantly faster with the dasiglucagon autoinjector than with the GEK (P < 0.005 for both groups). Most study participants preferred the dasiglucagon autoinjector over the GEK (94%, P < 0.001) and rated it as easier (90%, P < 0.001) and less stressful to use (94%, P < 0.001) than the GEK. Conclusion: Dasiglucagon autoinjector was more rapidly and reliably administered, and users reported greater ease of use and usage satisfaction than with the GEK. Thus, dasiglucagon autoinjector has the potential to improve speed and ease of treatment in severe hypoglycemic events, providing a better usage experience for rescuing individuals and enabling faster recovery for patients.

Dasiglucagon demonstrates reduced costs in the treatment of severe hypoglycemia in a budget impact model

BACKGROUND: Approximately 7.3 million people with type 1 or type 2 diabetes (T1D/T2D) are treated with insulin, placing them at higher risk of severe hypoglycemia (SH). SH requires assistance of another individual and often necessitates the prompt administration of intravenous glucose, injectable glucagon, or both. Untreated, SH can progress to unconsciousness, seizures, coma, or death. Before 2018, all glucagon rescue treatments required reconstitution. The complexity of reconstitution is often a barrier to successful administration during a severe hypoglycemic event. Studies suggest successful administration of glucagon emergency kits range from 6%-56% of the time. Second-generation glucagon treatments and glucagon analogs do not require reconstitution and have caregiver administration success rates ranging from 94%-100%. Dasiglucagon is a glucagon analog administered via autoinjector or prefilled syringe and has been shown to result in rapid hypoglycemia recovery. Moreover, the autoinjector can be administered successfully 94% of the time by trained caregivers. Previous evaluation of costs in budget impact models (BIMs) demonstrated the potential for second-generation glucagon treatments to reduce the cost of SH events (SHEs). The current model expands on those findings with a treatment pathway and accompanying assumptions reflecting important aspects of real-world SHE treatment. OBJECTIVE: To evaluate the economic impact of dasiglucagon compared with available glucagon treatments for SHE management, considering direct cost of treatment and health care resource utilization. METHODS: A 1-year BIM with a hypothetical US commercial health plan of 1 million lives was developed with a target population of individuals with diabetes at risk of SHE. The treatment pathway model included initial and secondary treatment attempts, treatment administration success and failure, plasma glucose (PG) recovery within 15 minutes, emergency medical services, emergency department (ED) visits, and hospitalizations. A 1-way sensitivity analysis was conducted to assess the sensitivity of the model to changes in parameter values. RESULTS: In a 1 million-covered lives population, it was estimated that 12,006 SHEs would occur annually. The higher rate of initial treatment success and PG recovery within 15 minutes associated with dasiglucagon treatment resulted in lower total health care costs. Total SHE treatment costs with dasiglucagon were estimated at $13.4 million, compared with $16.7 million for injectable native glucagon, $20.7 million for nasal glucagon, $35.3 million for reconstituted glucagon, and $43.8 million for untreated individuals. Compared with untreated people, the number needed to treat (NNT) with dasiglucagon was 6 individuals to avoid 1 hospitalization. NNT for this same comparison was 59 for injectable native glucagon and 27 for nasal glucagon. CONCLUSIONS: Treatment of SH with dasiglucagon decreased total direct medical costs by reducing health care resource utilization (emergency calls, emergency transports, ED visits, and hospitalizations) and accompanying costs associated with the treatment of SH. DISCLOSURES: This research was funded by Zealand Pharma. Bromley, Hinahara, and Goss are employed by Boston Healthcare Associates, Inc., which received funding from Zealand Pharma for development of the health economic model and the manuscript. Kendall and Hammer are employed by Zealand Pharma. Weinzimer has received consulting fees from Zealand Pharma.

A double-blind, placebo-controlled, single-ascending dose study to evaluate the safety, tolerability, pharmacokinetics, and pharmacodynamics of HM15136, a novel long-acting glucagon analogue, in healthy subjects

AIM

To evaluate the safety and tolerability, pharmacokinetics, and pharmacodynamics of HM15136, a novel long-acting glucagon analogue under development, in healthy males and females presenting with no childbearing potential.

MATERIALS AND METHODS

A randomized, double-blind, placebo-controlled, single-ascending dose study was conducted in 56 subjects who randomly received a single subcutaneous dose of HM15136 or its matching placebo at a ratio of 6:2 at 10, 20, 30, 50, 80, 100, and 120 μg/kg.

RESULTS

All adverse events were mild and transient. Neither serious adverse events nor discontinuation as a result of adverse events occurred. The most frequent adverse drug reaction was nausea (5.3%, only in the 100- and 120-μg/kg groups). HM15136, particularly at doses of 50 μg/kg or higher, increased fasting blood glucose, with a maximum increase and area under the curve of 1.5 mmol/L at day 10 (P = .006) and 166.3 day·mmol/L (P = .022) at the dose of 80 μg/kg, while suppressing the secretion of endogenous glucagon, which continued until day 17. HM15136 also significantly reduced gluconeogenic and ketogenic amino acids. Compensatory changes in endogenous insulin and incretin hormones by HM15136 were not apparent. HM15136 was slowly but steadily absorbed and reached a peak concentration at 46-68 hours after a single subcutaneous injection. HM15136 was eliminated with a terminal phase half-life of 77.1-101.1 hours.

CONCLUSIONS

A single subcutaneous dose of HM15136 at 10-120 μg/kg was safe and well tolerated. The long half-life of HM15136, coupled with an increase in blood glucose for ~2 weeks, may warrant a weekly dosing regimen.

A glucagon analogue decreases body weight in mice via signalling in the liver

Glucagon receptor agonists show promise as components of next generation metabolic syndrome pharmacotherapies. However, the biology of glucagon action is complex, controversial, and likely context dependent. As such, a better understanding of chronic glucagon receptor (GCGR) agonism is essential to identify and mitigate potential clinical side-effects. Herein we present a novel, long-acting glucagon analogue (GCG104) with high receptor-specificity and potent in vivo action. It has allowed us to make two important observations about the biology of sustained GCGR agonism. First, it causes weight loss in mice by direct receptor signalling at the level of the liver. Second, subtle changes in GCG104-sensitivity, possibly due to interindividual variation, may be sufficient to alter its effects on metabolic parameters. Together, these findings confirm the liver as a principal target for glucagon-mediated weight loss and provide new insights into the biology of glucagon analogues.

Immunogenicity of the Novel Glucagon Analogue Dasiglucagon: Results of a Dedicated Immunogenicity Trial in Type 1 Diabetes

Dasiglucagon is a next-generation glucagon analogue that is stable in aqueous formulation. This dedicated immunogenicity trial to support use as rescue treatment for severe hypoglycemia was conducted to evaluate the immunogenicity of repeated subcutaneous doses of dasiglucagon in subjects with type 1 diabetes. A total of 112 subjects were randomized 1:1 to receive three subcutaneous weekly doses of either 0.6 mg dasiglucagon or 1.0 mg recombinant glucagon (GlucaGen^®) according to a double-blind parallel-group trial design. Subjects were followed for 15 weeks, with a multitiered testing approach planned for assessment of antidrug antibody (ADA) formation. For the primary immunogenicity endpoint, the overall ADA incidence was zero, as no subject demonstrated any treatment-induced or treatment-boosted ADA response at any time point in this trial involving three consecutive weekly doses of trial drug. No injection site reactions were reported for subjects receiving dasiglucagon. There were no unexpected safety findings for the trial.

Dasiglucagon, a next-generation glucagon analogue, for treatment of severe hypoglycaemia via an autoinjector device: Results of a phase 3, randomized, double-blind trial

AIM

To confirm the efficacy and safety of dasiglucagon when administered via an autoinjector device.

MATERIALS AND METHODS

In this double-blind trial, 45 participants with type 1 diabetes were randomized 3:1 to receive a single subcutaneous dose of dasiglucagon 0.6 mg or placebo following controlled induction of hypoglycaemia. The primary endpoint was time to plasma glucose recovery, defined as a plasma glucose increase of 20 mg/dL or higher from baseline without rescue intravenous glucose.

RESULTS

Median (95% CI) observed time to recovery was 10.0 (8.0; 12.0) minutes for dasiglucagon and 35.0 (20.0; -) minutes for placebo (P < .001). Plasma glucose recovery was achieved within 15 minutes by 88% of participants receiving dasiglucagon versus none receiving placebo (P < .01). Site of injection (buttock or deltoid) was not shown to have any effect on time to recovery (P = .84). No serious adverse events occurred. As expected for glucagon treatment, nausea and vomiting were common adverse events in dasiglucagon-treated participants.

CONCLUSIONS

Dasiglucagon provided rapid reversal of hypoglycaemia in adults with type 1 diabetes. Dasiglucagon administration was well tolerated. The aqueous formulation of dasiglucagon in a ready-to-use autoinjector device that can be carried at room temperature may provide a reliable treatment for severe hypoglycaemia.

New Fast Acting Glucagon for Recovery from Hypoglycemia, a Life-Threatening Situation: Nasal Powder and Injected Stable Solutions

The goal of diabetes care is to achieve and maintain good glycemic control over time, so as to prevent or delay the development of micro- and macrovascular complications in type 1 (T1D) and type 2 diabetes (T2D). However, numerous barriers hinder the achievement of this goal, first of all the frequent episodes of hypoglycemia typical in patients treated with insulin as T1D patients, or sulphonylureas as T2D patients. The prevention strategy and treatment of hypoglycemia are important for the well-being of patients with diabetes. Hypoglycemia is strongly associated with an increased risk of cardiovascular disease in diabetic patients, due probably to the release of inflammatory markers and prothrombotic effects triggered by hypoglycemia. Treatment of hypoglycemia is traditionally based on administration of carbohydrates or of glucagon via intramuscular (IM) or subcutaneous injection (SC). The injection of traditional glucagon is cumbersome, such that glucagon is an under-utilized drug. In 1983, it was shown for the first time that intranasal (IN) glucagon increases blood glucose levels in healthy volunteers, and in 1989-1992 that IN glucagon is similar to IM glucagon in resolving hypoglycemia in normal volunteers and in patients with diabetes, both adults and children. IN glucagon was developed in 2010 and continued in 2015; in 2019 IN glucagon obtained approval in the US, Canada, and Europe for severe hypoglycemia in children and adults. In the 2010s, two ready-to-use injectable formulations, a stable non-aqueous glucagon solution and the glucagon analog dasiglucagon, were developed, showing an efficacy similar to traditional glucagon, and approved in the US in 2020 and in 2021, respectively, for severe hypoglycemia in adults and in children. Fast-acting glucagon (nasal administration and injected solutions) appears to represent a major breakthrough in the treatment of severe hypoglycemia in insulin-treated patients with diabetes, both adults and children. It is anticipated that the availability of fast-acting glucagon will expand the use of glucagon, improve overall metabolic control, and prevent hypoglycemia-related complications, in particular cardiovascular complications and cognitive impairment.

α/Sulfono-γ-AApeptide Hybrid Analogues of Glucagon with Enhanced Stability and Prolonged In Vivo Activity

Peptide drugs have the advantages of target specificity and good drugability and have become one of the most increasingly important hotspots in new drug research in biomedical sciences. However, peptide drugs generally have low bioavailability and metabolic stability, and therefore, the modification of existing peptide drugs for the purpose of improving stability and retaining activity is of viable importance. It is known that glucagon is an effective therapy for treating severe hypoglycemia, but its short half-life prevents its wide therapeutic use. Herein, we report that combined unnatural residues and long fatty acid conjugation afford potent α/sulfono-γ-AApeptide hybrid analogues of Glucagon with enhanced stability and prolonged in vivo activity. This strategy could be adopted to develop stabilized analogues of other short-acting bioactive peptides.

Dasiglucagon, a next-generation ready-to-use glucagon analog, for treatment of severe hypoglycemia in children and adolescents with type 1 diabetes: Results of a phase 3, randomized controlled trial

BACKGROUND

Dasiglucagon, a next-generation, ready-to-use aqueous glucagon analog formulation, has been developed to treat severe hypoglycemia in individuals with diabetes.

OBJECTIVE

The aim of this trial was to evaluate the safety and efficacy of dasiglucagon in pediatric individuals with type 1 diabetes (T1DM). Participants were children and adolescents (6-17 years) with T1DM.

METHODS

In this randomized double-blind trial, 42 participants were randomly allocated (2:1:1) to a single subcutaneous (SC) injection of dasiglucagon (0.6 mg), placebo, or reconstituted glucagon (GlucaGen; dosed per label) during insulin-induced hypoglycemia. The primary endpoint was time to plasma glucose (PG) recovery (first PG increase ≥20 mg/dL after treatment initiation without rescue intravenous glucose). The primary comparison was dasiglucagon vs. placebo; glucagon acted as a reference.

RESULTS

The median time (95% confidence interval) to PG recovery following SC injection was 10 min (8-12) for dasiglucagon vs. 30 min (20 to -) for placebo (P < .001); the median time for glucagon was 10 min (8-12), which did not include the time taken to reconstitute the lyophilized powder. PG recovery was achieved in all participants in the dasiglucagon and glucagon groups within 20 min of dosing compared to 2 out of 11 patients (18%) with placebo. The most frequent adverse events were nausea and vomiting, as expected with glucagon treatment.

CONCLUSIONS

Consistent with adult phase 3 trials, dasiglucagon rapidly and effectively restored PG levels following insulin-induced hypoglycemia in children and adolescents with T1DM, with an overall safety profile similar to glucagon.

Dasiglucagon: First Approval

Dasiglucagon (Zegalogue^®) is an antihypoglycaemic agent being developed by Zealand Pharma for the treatment of hypoglycaemia, type 1 diabetes mellitus (T1DM) management and congenital hyperinsulinism. In March 2021, dasiglucagon received its first approval in the USA for the treatment of severe hypoglycaemia in paediatric and adult patients with diabetes aged 6 years and above. Dasiglucagon, a glucagon analogue, is available as a single-dose autoinjector or prefilled syringe for subcutaneous injection. This article summarizes the milestones in the development of dasiglucagon leading to this first approval for hypoglycaemia.

A combined activation mechanism for the glucagon receptor

We report on a combined activation mechanism for a class B G-protein-coupled receptor (GPCR), the glucagon receptor. By computing the conformational free-energy landscape associated with the activation of the receptor-agonist complex and comparing it with that obtained with the ternary complex (receptor-agonist-G protein) we show that the agonist stabilizes the receptor in a preactivated complex, which is then fully activated upon binding of the G protein. The proposed mechanism contrasts with the generally assumed GPCR activation mechanism, which proceeds through an opening of the intracellular region allosterically elicited by the binding of the agonist. The mechanism found here is consistent with electron cryo-microscopy structural data and might be general for class B GPCRs. It also helps us to understand the mode of action of the numerous allosteric antagonists of this important drug target.

Low doses of dasiglucagon consistently increase plasma glucose levels from hypoglycaemia and euglycaemia in people with type 1 diabetes mellitus

AIM

To characterize the pharmacokinetic and pharmacodynamic properties of dasiglucagon, a novel, stable and liquid formulated glucagon analogue, during hypoglycaemic and euglycaemic conditions in adult patients with type 1 diabetes mellitus.

RESEARCH DESIGN AND METHODS

In this randomized double-blind trial, 17 patients received four single subcutaneous doses (0.03, 0.08, 0.2 and 0.6 mg) of dasiglucagon (4 mg/mL formulation) under euglycaemic (plasma glucose [PG] 5.6 mmol/L [100 mg/dL]) or hypoglycaemic (PG 3.1-3.7 mmol/L [56-66 mg/dL]) conditions. For comparison, three doses (0.03, 0.08 and 0.2 mg) of a commercial glucagon formulation (Eli Lilly) were investigated at euglycaemia.

RESULTS

Dasiglucagon led to a dose-dependent and rapid increase in PG levels across all doses tested (mean increases 30 minutes post-dosing of 2.2 to 4.4 mmol/L [39-80 mg/dL] from euglycaemia and 1.3 to 5.2 mmol/L [24-94 mg/dL] from hypoglycaemia), which was higher than the rises elicited by similar doses of commercial glucagon (1.7-3.9 mmol/L [30-71 mg/dL]). The median time (range) to an increase in PG of >1.1 mmol/L (20 mg/dL) was <20 (18-19.5) minutes with 0.03 mg dasiglucagon and, with higher doses, the median times ranged from 9 to 15 minutes (commercial glucagon 13-14 minutes). In hypoglycaemia, 0.03 and 0.08 mg dasiglucagon re-established normoglycaemia (PG ≥3.9 mmol/L [70 mg/dL]) within median times of 14 and 10 minutes, respectively. Nausea and vomiting occurred more frequently with dasiglucagon than with commercial glucagon at identical doses which might be attributable to dasiglucagon's higher potency.

CONCLUSION

Dasiglucagon rapidly increased PG at doses of 0.03 to 0.6 mg in a dose-dependent manner and, therefore, is a good candidate for use in dual-hormone artificial pancreas systems.

Glucagon-related peptides from phylogenetically ancient fish reveal new approaches to the development of dual GCGR and GLP1R agonists for type 2 diabetes therapy

The insulinotropic and antihyperglycaemic properties of glucagons from the sea lamprey (Petromyzontiformes), paddlefish (Acipenseriformes) and trout (Teleostei) and oxyntomodulin from dogfish (Elasmobranchii) and ratfish (Holocephali) were compared with those of human glucagon and GLP-1 in mammalian test systems. All fish peptides produced concentration-dependent stimulation of insulin release from BRIN-BD11 rat and 1.1 B4 human clonal β-cells and isolated mouse islets. Paddlefish glucagon was the most potent and effective peptide. The insulinotropic activity of paddlefish glucagon was significantly (P < 0.01) decreased after incubating BRIN-BD11 cells with the GLP1R antagonist, exendin-4(9-39) and the GCGR antagonist [des-His¹,Pro⁴, Glu⁹] glucagon amide but GIPR antagonist, GIP(6-30)Cex-K⁴⁰[palmitate] was without effect. Paddlefish and lamprey glucagons and dogfish oxyntomodulin (10 nmol L^-1) produced significant (P < 0.01) increases in cAMP concentration in Chinese hamster lung (CHL) cells transfected with GLP1R and human embryonic kidney (HEK293) cells transfected with GCGR. The insulinotropic activity of paddlefish glucagon was attenuated in CRISPR/Cas9-engineered GLP1R knock-out INS-1 cells but not in GIPR knock-out cells. Intraperitoneal administration of all fish peptides, except ratfish oxyntomodulin, to mice together with a glucose load produced significant (P < 0.05) decreases in plasma glucose concentrations and paddlefish glucagon produced a greater release of insulin compared with GLP-1. Paddlefish glucagon shares the sequences Glu¹⁵-Glu¹⁶ and Glu²⁴-Trp²⁵-Leu²⁶-Lys²⁷-Asn²⁸-Gly²⁹ with the potent GLP1R agonist, exendin-4 so may be regarded as a naturally occurring, dual-agonist hybrid peptide that may serve as a template design of new drugs for type 2 diabetes therapy.

Dogfish glucagon analogues counter hyperglycaemia and enhance both insulin secretion and action in diet-induced obese diabetic mice

AIMS

To investigate the antidiabetic actions of three dogfish glucagon peptide analogues [known glucagon-like peptide-1 and glucagon receptor co-agonists] after chronic administration in diet-induced high-fat-diet-fed diabetic mice.

MATERIALS AND METHODS

National Institutes of Health Swiss mice were pre-conditioned to a high-fat diet (45% fat) for 100 days, and control mice were fed a normal diet (10% fat). Normal diet control and high-fat-fed control mice received twice-daily intraperitoneal (i.p.) saline injections, while the high-fat-fed treatment groups (n = 8) received twice-daily injections of exendin-4(1-39), [S2a]dogfish glucagon, [S2a]dogfish glucagon exendin-4(31-39) or [S2a]dogfish glucagon-Lys(30) -γ-glutamyl-PAL (25 nmol/kg body weight) for 51 days.

RESULTS

After dogfish glucagon analogue treatment, there was a rapid and sustained decrease in non-fasting blood glucose and an associated insulinotropic effect (analysis of variance, p < .05 to <.001) compared with saline-treated high-fat-fed controls. All peptide treatments significantly improved i.p. and oral glucose tolerance with concomitant increased insulin secretion compared with saline-treated high-fat-fed controls (p <.05 to <.001). After chronic treatment, no receptor desensitization was observed but insulin sensitivity was enhanced for all peptide-treated groups (p < .01 to <.001) except [S2a]dogfish glucagon. Both exendin-4 and [S2a]dogfish glucagon exendin-4(31-39) significantly reduced plasma triglyceride concentrations compared with those found in lean controls (p = .0105 and p = .0048, respectively). Pancreatic insulin content was not affected by peptide treatments but [S2a]dogfish glucagon and [S2a]dogfish glucagon exendin-4(31-39) decreased pancreatic glucagon by 28%-34% (p = .0221 and p = .0075, respectively). The percentage of β-cell area within islets was increased by exendin-4 and peptide analogue treatment groups compared with high-fat-fed controls and the β-cell area decreased (p < .05 to <.01).

CONCLUSIONS

Overall, dogfish glucagon co-agonist analogues had several beneficial metabolic effects, showing therapeutic potential for type 2 diabetes.

Glucagon receptor antagonist and GIP agonist combination for diet-induced obese mice

Ablation of glucagon receptor signaling represents a potential treatment option for type 2 diabetes (T2DM). Additionally, activation of glucose-dependent insulinotropic polypeptide (GIP) receptor signaling also holds therapeutic promise for T2DM. Therefore, this study examined both independent and combined metabolic actions of desHis(1)Pro(4)Glu(9)(Lys(12)PAL)-glucagon (glucagon receptor antagonist) and d-Ala(2)GIP (GIP receptor agonist) in diet-induced obese mice. Glucagon receptor binding has been linked to alpha-helical structure and desHis(1)Pro(4)Glu(9)(Lys(12)PAL)-glucagon displayed enhanced alpha-helical content compared with native glucagon. In clonal pancreatic BRIN-BD11 beta-cells, desHis(1)Pro(4)Glu(9)(Lys(12)PAL)-glucagon was devoid of any insulinotropic or cAMP-generating actions, and did not impede d-Ala(2)GIP-mediated (P<0.01 to P<0.001) effects on insulin and cAMP production. Twice-daily injection of desHis(1)Pro(4)Glu(9)(Lys(12)PAL)-glucagon or d-Ala(2)GIP alone, and in combination, in high-fat-fed mice failed to affect body weight or energy intake. Circulating blood glucose levels were significantly (P<0.05 to P<0.01) decreased by all treatments regimens, with plasma and pancreatic insulin elevated (P<0.05 to P<0.001) in all mice receiving d-Ala(2)GIP. Interestingly, plasma glucagon concentrations were decreased (P<0.05) by sustained glucagon inhibition (day 28), but increased (P<0.05) by d-Ala(2)GIP therapy, with a combined treatment resulting in glucagon concentration similar to saline controls. All treatments improved (P<0.01) intraperitoneal and oral glucose tolerance, and peripheral insulin sensitivity. d-Ala(2)GIP-treated mice showed increased glucose-induced insulin secretion in response to intraperitoneal and oral glucose. Metabolic rate and ambulatory locomotor activity were increased (P<0.05 to P<0.001) in all desHis(1)Pro(4)Glu(9)(Lys(12)PAL)-glucagon-treated mice. These studies highlight the potential of glucagon receptor inhibition alone, and in combination with GIP receptor activation, for T2DM treatment.

Defective insulin secretion by chronic glucagon receptor activation in glucose intolerant mice

Stimulation of insulin secretion by short-term glucagon receptor (GCGR) activation is well characterized; however, the effect of long-term GCGR activation on β-cell function is not known, but of interest, since hyperglucagonemia occurs early during development of type 2 diabetes. Therefore, we examined whether chronic GCGR activation affects insulin secretion in glucose intolerant mice. To induce chronic GCGR activation, high-fat diet fed mice were continuously (2 weeks) infused with the stable glucagon analog ZP-GA-1 and challenged with oral glucose and intravenous glucose±glucagon-like peptide 1 (GLP1). Islets were isolated to evaluate the insulin secretory response to glucose±GLP1 and their pancreas were collected for immunohistochemical analysis. Two weeks of ZP-GA-1 infusion reduced insulin secretion both after oral and intravenous glucose challenges in vivo and in isolated islets. These inhibitory effects were corrected for by GLP1. Also, we observed increased β-cell area and islet size. We conclude that induction of chronic ZP-GA-1 levels in glucose intolerant mice markedly reduces insulin secretion, and thus, we suggest that chronic activation of the GCGR may contribute to the failure of β-cell function during development of type 2 diabetes.

THE ROLE OF GLUCAGON IN THE PATHOPHYSIOLOGY AND MANAGEMENT OF DIABETES

OBJECTIVE

There is general recognition that insulin and glucagon are the main hormones involved in the pathophysiology of diabetes, but the role of glucagon in diabetes is complex and in some circumstances controversial. The increasing appreciation of the role of glucagon in currently used hypoglycemic agents and the ongoing development of glucagon-targeted therapies underscores glucagon's important contribution in optimizing diabetes management. The current review provides a background on glucagon physiology and pathophysiology and an update for investigators, endocrinologists, and other healthcare providers on glucagon-modulating therapies.

METHODS

A literature review was conducted utilizing published literature in PubMed and AccessMedicine including the years 1922-2015 using the following key words: glucagon, bihormonal, diabetes mellitus, glucagon antagonists, glucagon-targeted therapies.

RESULTS

Glucagon is a counterregulatory hormone that promotes hepatic glucose production, thus preventing hypoglycemia in normal physiology. In patients with diabetes mellitus, glucagon secretion may be unregulated, which contributes to problems with glucose homeostasis. Several of the most effective therapies for diabetes have been found to suppress glucagon secretion or action, which may contribute to their success. Additionally, glucagon-specific targeted therapies, such as glucagon receptor antagonists, are being studied at a basic and clinical level.

CONCLUSION

Glucagon plays an important role in contributing to hyperglycemia in patients with diabetes. Utilizing hypoglycemic agents that decrease glucagon secretion or inhibit glucagon action can help improve glycemic control, making these agents a valuable resource in diabetes therapy.

Two novel glucagon receptor antagonists prove effective therapeutic agents in high-fat-fed and obese diabetic mice

AIMS

To examine the effect of two novel, enzymatically stable, glucagon receptor peptide antagonists, on metabolic control in two mouse models of obesity/diabetes.

METHOD

The effects of twice daily i.p. administration of desHis(1)Pro(4)Glu(9)-glucagon or desHis(1)Pro(4)Glu(9)Lys(12)FA-glucagon for 10 days on metabolic control in high-fat-fed (HFF; 45% fat) and obese diabetic (ob/ob) mice were compared with saline-treated controls.

RESULTS

Neither analogue altered body weight or food intake in either model over 10 days; however, treatment with each peptide restored non-fasting blood glucose towards normal control values in HFF mice. Basal glucose was also reduced (p < 0.01) in desHis(1)Pro(4)Glu(9)Lys(12)FA-glucagon treated ob/ob mice by day 10, coinciding with increases (p < 0.001) in circulating insulin. At the end of the treatment period, both analogues significantly (p < 0.05-0.01) improved oral and i.p. glucose tolerance (p < 0.05) and peripheral insulin sensitivity, increased pancreatic insulin and glucagon content (p < 0.05-0.01) and decreased (p < 0.05) cholesterol levels in HFF mice. Similarly beneficial metabolic effects on oral glucose tolerance (p < 0.01) and pancreatic insulin content (p < 0.05) were observed in ob/ob mice, especially after desHis(1)Pro(4)Glu(9)Lys(12)FA-glucagon treatment. No significant differences in circulating triglycerides or aspects of indirect calorimetry were noted between peptide treatment groups and respective control HFF and ob/ob mice. Finally, glucagon-mediated elevations of glucose and insulin were significantly (p < 0.05-0.01) annulled after 10 days of desHis(1)Pro(4)Glu(9)-glucagon or desHis(1)Pro(4)Glu(9)Lys(12)FA-glucagon treatment in both animal models.

CONCLUSION

These data indicate that peptide-based glucagon receptor antagonists can reverse aspects of genetically and dietary-induced obesity-related diabetes.

Biochemical stabilization of glucagon at alkaline pH

BACKGROUND

For patients with type 1 diabetes mellitus, a bihormonal artificial endocrine pancreas system utilizing glucagon and insulin has been found to stabilize glycemic control. However, commercially available formulations of glucagon cannot currently be used in such systems because of physical instability characterized by aggregation and chemical degradation. Storing glucagon at pH 10 blocks protein aggregation but results in chemical degradation. Reductions in pH minimize chemical degradation, but even small reductions increase protein aggregation. We hypothesized that common pharmaceutical excipients accompanied by a new excipient would inhibit glucagon aggregation at an alkaline pH.

METHODS AND RESULTS

As measured by tryptophan intrinsic fluorescence shift and optical density at 630 nm, protein aggregation was indeed minimized when glucagon was formulated with curcumin and albumin. This formulation also reduced chemical degradation, measured by liquid chromatography with mass spectrometry. Biological activity was retained after aging for 7 days in an in vitro cell-based bioassay and also in Yorkshire swine.

CONCLUSIONS

Based on these findings, a formulation of glucagon stabilized with curcumin, polysorbate-80, l-methionine, and albumin at alkaline pH in glycine buffer may be suitable for extended use in a portable pump in the setting of a bihormonal artificial endocrine pancreas.

A novel DPP IV-resistant C-terminally extended glucagon analogue exhibits weight-lowering and diabetes-protective effects in high-fat-fed mice mediated through glucagon and GLP-1 receptor activation

AIMS/HYPOTHESIS

Modification of the structure of glucagon could provide useful compounds for the potential treatment of obesity-related diabetes.

METHODS

This study evaluated N-acetyl-glucagon, (D-Ser(2))glucagon and an analogue of (D-Ser(2))glucagon with the addition of nine amino acids from the C-terminal of exendin(1-39), namely (D-Ser(2))glucagon-exe.

RESULTS

All analogues were resistant to dipeptidyl peptidase IV degradation. N-Acetyl-glucagon lacked acute insulinotropic effects in BRIN BD11 cells, whereas (D-Ser(2))glucagon and (D-Ser(2))glucagon-exe evoked significant (p < 0.001) insulin release. (D-Ser(2))glucagon-exe stimulated cAMP production (p < 0.001) in glucagon- and GLP-1-receptor (GLP-1R)-transfected cells but not in glucose-dependent insulinotropic polypeptide-receptor-transfected cells. In normal mice, N-acetyl-glucagon and (D-Ser(2))glucagon retained glucagon-like effects of increasing (p < 0.001) plasma glucose and insulin levels. (D-Ser(2))glucagon-exe was devoid of hyperglycaemic actions but substantially (p < 0.001) increased plasma insulin levels. (D-Ser(2))glucagon-exe reduced the glycaemic excursion (p < 0.01) and increased the insulin secretory (p < 0.01) response following a glucose challenge 12 h after administration. Studies in GLP-1R knockout mice confirmed involvement of the GLP-1R pathway in the biological actions of (D-Ser(2))glucagon-exe. Twice-daily administration of (D-Ser(2))glucagon-exe to high-fat-fed mice for 28 days significantly (p < 0.05 to p < 0.001) reduced body weight, energy intake and non-fasting glucose levels, as well as increasing insulin concentrations. Glucose tolerance and insulin sensitivity were significantly (p < 0.01) improved and energy expenditure, O2 consumption and locomotor activity were (p < 0.05 to p < 0.001) augmented. The metabolic benefits were accompanied by increases in pancreatic islet number (p < 0.001) and area (p < 0.05), as well as beta cell area (p < 0.05). Beneficial effects were largely retained for 14 days following cessation of treatment.

CONCLUSIONS/INTERPRETATION

This study emphasises the potential of (D-Ser(2))glucagon-exe for the treatment of obesity-related diabetes.

Characterisation of structurally modified analogues of glucagon as potential glucagon receptor antagonists

Acute in vitro and in vivo biological activities of four novel structural analogues of glucagon were tested. desHis(1)Pro(4)-glucagon, desHis(1)Pro(4)Glu(9)-glucagon, desHis(1)Pro(4)Glu(9)Lys(12)FA-glucagon and desHis(1)Pro(4)Glu(9)Lys(30)FA-glucagon were stable to DPP-4 degradation and dose-dependently inhibited glucagon-mediated cAMP production (p<0.05 to p<0.001). None stimulated insulin secretion in vitro above basal levels, but all inhibited glucagon-induced insulin secretion (p<0.01 to p<0.001). In normal mice all analogues antagonised acute glucagon-mediated elevations of blood glucose (p<0.05 to p<0.001) and blocked corresponding insulinotropic responses. In high-fat fed mice, glucagon-induced increases in plasma insulin (p<0.05 to p<0.001) and glucagon-induced hyperglycaemia were blocked (p<0.05 to p<0.01) by three analogues. In obese diabetic (ob/ob) mice only desHis(1)Pro(4)Glu(9)-glucagon effectively (p<0.05 to p<0.01) inhibited both glucagon-mediated glycaemic and insulinotropic responses. desHis(1)Pro(4)-glucagon and desHis(1)Pro(4)Glu(9)-glucagon were biologically ineffective when administered 8h prior to glucagon, whereas desHis(1)Pro(4)Glu(9)Lys(12)FA-glucagon retained efficacy (p<0.01) for up to 24h. Such peptide-derived glucagon receptor antagonists have potential for type 2 diabetes therapy.

Mechanisms of glucagon degradation at alkaline pH

Glucagon is unstable and undergoes degradation and aggregation in aqueous solution. For this reason, its use in portable pumps for closed loop management of diabetes is limited to very short periods. In this study, we sought to identify the degradation mechanisms and the bioactivity of specific degradation products. We studied degradation in the alkaline range, a range at which aggregation is minimized. Native glucagon and analogs identical to glucagon degradation products were synthesized. To quantify biological activity in glucagon and in the degradation peptides, a protein kinase A-based bioassay was used. Aged, fresh, and modified peptides were analyzed by liquid chromatography with mass spectrometry (LCMS). Oxidation of glucagon at the Met residue was common but did not reduce bioactivity. Deamidation and isomerization were also common and were more prevalent at pH 10 than 9. The biological effects of deamidation and isomerization were unpredictable; deamidation at some sites did not reduce bioactivity. Deamidation of Gln 3, isomerization of Asp 9, and deamidation with isomerization at Asn 28 all caused marked potency loss. Studies with molecular-weight-cutoff membranes and LCMS revealed much greater fibrillation at pH 9 than 10. Further work is necessary to determine formulations of glucagon that minimize degradation and fibrillation.

N -acetyl-GLP-1: a DPP IV-resistant analogue of glucagon-like peptide-1 (GLP-1) with improved effects on pancreatic β-cell-associated gene expression

Glucagon-like peptide-1(7-36)amide (GLP-1) is a key insulinotropic hormone with the reported potential to differentiate non-insulin secreting cells into insulin-secreting cells. The short biological half-life of GLP-1 after cleavage by dipeptidylpeptidase IV (DPP IV) to GLP-1(9-36)amide is a major therapeutic drawback. Several GLP-1 analogues have been developed with improved stability and insulinotropic action. In this study, the N-terminally modified GLP-1 analogue, N-acetyl-GLP-1, was shown to be completely resistant to DPP IV, unlike native GLP-1, which was rapidly degraded. Furthermore, culture of pancreatic ductal ARIP cells for 72 h with N-acetyl-GLP-1 indicated a greater ability to induce pancreatic beta-cell-associated gene expression, including insulin and glucokinase. Further investigation of the effects of stable GLP-1 analogues on beta-cell differentiation is required to assess their potential in diabetic therapy.

Identification of key residues for the binding of glucagon to the N-terminal domain of its receptor: an alanine scan and modeling study

Glucagon plays an essential role in the glycemia maintenance during fasting, but also aggravates hyperglycemia in diabetic patients. A series of analogues of glucagon were synthesized replacing each amino acid of the C-terminal region (residues 15-29) with alanine. The residues affecting the binding to the glucagon receptor are found to be located on one face of the glucagon helix. Several 3-dimensional models of the N-terminal domain of the glucagon receptor in complex with its ligand peptide were built and used to analyze the peptide-receptor interface in terms of the nature of the peptide residues and the interactions they form with the receptor. The models suggest that glucagon keeps its native helical structure upon binding, and that a large part of the interface formed with the receptor is hydrophobic. We find that in the C-terminal region, F22, V23, M27, and D15 are the most important residues for peptide binding. They bury a large portion of their solvent accessible surface area and make numerous interactions with the receptor mainly of the hydrophobic type.

Rescue of a pathogenic mutant human glucagon receptor by pharmacological chaperones

We have previously demonstrated that a homozygous inactivating P86S mutation of the glucagon receptor (GCGR) causes a novel human disease of hyperglucagonemia, pancreatic α-cell hyperplasia, and pancreatic neuroendocrine tumors (Mahvash disease). The mechanisms for the decreased activity of the P86S mutant (P86S) are abnormal receptor localization to the endoplasmic reticulum (ER) and defective interaction with glucagon. To search for targeted therapies for Mahvash disease, we examined whether P86S can be trafficked to the plasma membrane by pharmacological chaperones and whether novel glucagon analogs restore effective receptor interaction. We used enhanced green fluorescent protein-tagged P86S stably expressed in HEK 293 cells to allow fluorescence imaging and western blotting and molecular modeling to design novel glucagon analogs in which alanine 19 was replaced with serine or asparagine. Incubation at 27 °C largely restored normal plasma membrane localization and normal processing of P86S but osmotic chaperones had no effects. The ER stressors thapsigargin and curcumin partially rescued P86S. The lipophilic GCGR antagonist L-168,049 also partially rescued P86S, so did Cpd 13 and 15 to a smaller degree. The rescued P86S led to more glucagon-stimulated cAMP production and was internalized by glucagon. Compared with the native glucagon, the novel glucagon analogs failed to stimulate more cAMP production by P86S. We conclude that the mutant GCGR is partially rescued by several pharmacological chaperones and our data provide proof-of-principle evidence that Mahvash disease can be potentially treated with pharmacological chaperones. The novel glucagon analogs, however, failed to interact with P86S more effectively.

Glucagon-like peptide-1 inhibits insulinotropic effects of oxyntomodulin and glucagon in cattle

Oxyntomodulin (OXM), glucagon, and glucagon-like peptide-1 (GLP-1), peptide hormones derived from the glucagon gene, play an important role in glucose homeostasis. The insulinotropic action of these three homologous peptides has been well documented in monogastric animals. However, information on the relationships among these peptides in insulin-releasing action, specifically in ruminants, is still insufficient. In this regard, we carried out two experiments in cattle. In experiment 1, effects of glucagon and GLP-1 on plasma insulin and glucose were investigated in 10-mo-old Holstein steers (347 ± 8 kg, n = 8) under normoglycemic conditions. Peptides were administered intravenously at dose rates of 0.12, 0.25, 0.50, and 1.25 nmol/kg body weight (BW). In experiment 2, the relationships among OXM, glucagon, and GLP-1 in the insulinotropic and glucoregulatory actions were elucidated in 3-mo-old Holstein steers (94 ± 2 kg, n = 8) using agonist-antagonist strategy. In agonist strategy, these three peptides were administered alone or coadministered at dose rates of 10 μg of OXM/kg BW, 4 μg of glucagon/kg BW, and 2 μg of GLP-1/kg BW. In antagonist strategy, 2 μg of each peptide was administered alone or in combination with 10 μg of [des His1, des Phe6, Glu9] glucagon amide (a glucagon receptor antagonist) or exendin-4 (5-39) amide (a GLP-1 receptor antagonist). Our results showed that OXM, glucagon, and GLP-1 had insulinotropic actions in ruminants under normoglycemic conditions. Our results also showed that the insulin-releasing effects of OXM and glucagon were mediated through both GLP-1 receptors (GLP-1R) and glucagon receptors. These insulinotropic effects of OXM and glucagon through GLP-1R were inhibited by GLP-1. Our findings expand the relationships among OXM, glucagon, and GLP-1 in the insulinotropic and glucoregulatory actions.

Optimization of the native glucagon sequence for medicinal purposes

BACKGROUND

Glucagon is a life-saving medication used in the treatment of hypoglycemia. It possesses poor solubility in aqueous buffers at or near physiological pH values. At low and high pH, at which the peptide can be formulated to concentrations of a milligram or more per milliliter, the chemical integrity of the hormone is limited, as evidenced by the formation of multiple degradation-related peptides. Consequently, the commercial preparation is provided as a lyophilized solid with an acidic diluent and directions for rendering it soluble at the time of use. Any unused material is recommended for disposal immediately after initial use.

METHODS

A set of glucagon analogs was prepared by solid-phase peptide synthesis to explore the identification of a glucagon analog with enhanced solubility and chemical stability at physiological pH. The physical properties of the peptide analogs were studied by solubility determination, high-performance chromatography, and mass spectral analysis. The biochemical properties were determined in engineered human embryonic kidney cell line 293 (HEK293) cells that overexpressed either the human glucagon or glucagon-like peptide-1 (GLP-1) receptors linked to a luciferase reporter gene.

RESULTS

We observed the previously characterized formation of glucagon degradation products upon incubation of the peptide in dilute acid for extended periods or elevated temperature. Lowering the isoelectric point of the hormone through the substitution of asparagine-28 with aspartic acid significantly increased the solubility at physiological pH. Similarly, the C-terminal extension (Cex) of the hormone with an exendin-based, 10-residue, C-terminal sequence yielded a peptide of dramatically enhanced solubility. These two glucagon analogs, D28 and Cex, maintained high potency and selectivity for the glucagon receptor relative to GLP-1 receptor.

CONCLUSIONS

Glucagon presents unique structural challenges to the identification of an analog of high biological activity and selectivity that also possesses sufficient aqueous solubility and stability such that it might be developed as a ready-to-use medicine. The glucagon analogs D28 and Cex demonstrated all of the chemical, physical, and biochemical properties supportive of further study as potential clinical candidates for treatment of hypoglycemia.

In vitro and in vivo evaluation of native glucagon and glucagon analog (MAR-D28) during aging: lack of cytotoxicity and preservation of hyperglycemic effect

BACKGROUND

For automated prevention of hypoglycemia, there is a need for glucagon (or an analog) to be sufficiently stable so that it can be indwelled in a portable pump for at least 3 days. However, under some conditions, solutions of glucagon can form amyloid fibrils. Currently, the usage instructions for commercially available glucagon allow only for its immediate use.

METHODS

In NIH 3T3 fibroblasts, we tested amyloid formation and cytotoxicity of solutions of native glucagon and the glucagon analog MAR-D28 after aging under different conditions for 5 days. In addition, aged native glucagon was subjected to size-exclusion chromatography (SEC). We also studied whether subcutaneous aged Novo Nordisk GlucaGen® would have normal bioactivity in octreotide-treated, anesthetized, nondiabetic pigs.

RESULTS

We found no evidence of cytotoxicity from native glucagon or MAR-D28 (up to 2.5 mg/ml) at a pH of 10 in a glycine solvent. We found a mild cytotoxicity for both compounds in Tris buffer at pH 8.5. A high concentration of the commercial glucagon preparation (GlucaGen) caused marked cytotoxicity, but low pH and/or a high osmolarity probably accounted primarily for this effect. With SEC, the decline in monomeric glucagon over time was much lower when aged in glycine (pH 10) than when aged in Tris (pH 8.5) or in citrate (pH 3). Congo red staining for amyloid was very low with the glycine preparation (pH 10). In the pig studies, the hyperglycemic effect of commercially available glucagon was preserved despite aging conditions associated with marked amyloid formation.

CONCLUSIONS

Under certain conditions, aqueous solutions of glucagon and MAR-D28 are stable for at least 5 days and are thus very likely to be safe in mammals. Glycine buffer at a pH of 10 appears to be optimal for avoiding cytotoxicity and amyloid fibril formation.

Gcg-XTEN: an improved glucagon capable of preventing hypoglycemia without increasing baseline blood glucose

OBJECTIVE

While the majority of current diabetes treatments focus on reducing blood glucose levels, hypoglycemia represents a significant risk associated with insulin treatment. Glucagon plays a major regulatory role in controlling hypoglycemia in vivo, but its short half-life and hyperglycemic effects prevent its therapeutic use for non-acute applications. The goal of this study was to identify a modified form of glucagon suitable for prophylactic treatment of hypoglycemia without increasing baseline blood glucose levels.

METHODOLOGY/PRINCIPAL FINDINGS

Through application of the XTEN technology, we report the construction of a glucagon fusion protein with an extended exposure profile (Gcg-XTEN). The in vivo half-life of the construct was tuned to support nightly dosing through design and testing in cynomolgus monkeys. Efficacy of the construct was assessed in beagle dogs using an insulin challenge to induce hypoglycemia. Dose ranging of Gcg-XTEN in fasted beagle dogs demonstrated that the compound was biologically active with a pharmacodynamic profile consistent with the designed half-life. Prophylactic administration of 0.6 nmol/kg Gcg-XTEN to dogs conferred resistance to a hypoglycemic challenge at 6 hours post-dose without affecting baseline blood glucose levels. Consistent with the designed pharmacokinetic profile, hypoglycemia resistance was not observed at 12 hours post-dose. Importantly, the solubility and stability of the glucagon peptide were also significantly improved by fusion to XTEN.

CONCLUSIONS/SIGNIFICANCE

The data show that Gcg-XTEN is effective in preventing hypoglycemia without the associated hyperglycemia expected for unmodified glucagon. While the plasma clearance of this Gcg-XTEN has been optimized for overnight dosing, specifically for the treatment of nocturnal hypoglycemia, constructs with significantly longer exposure profiles are feasible. Such constructs may have multiple applications such as allowing for more aggressive insulin treatment regimens, treating hypoglycemia due to insulin-secreting tumors, providing synergistic efficacy in combination therapies with long-acting GLP1 analogs, and as an appetite suppressant for treatment of obesity. The improved physical properties of the Gcg-XTEN molecule may also allow for novel delivery systems not currently possible with native glucagon.

Plasma C5 glucose-to-2H2O ratio does not provide an accurate assessment of gluconeogenesis during hyperinsulinemic-euglycemic clamps in either nondiabetic or diabetic humans

OBJECTIVE

Measurement of plasma C2 glucose enrichment is cumbersome. Therefore, the plasma C5 glucose-to-(2)H(2)O rather than the plasma C5-to-C2 glucose ratio commonly has been used to measure gluconeogenesis and glycogenolysis during hyperinsulinemic-euglycemic clamps. The validity of this approach is unknown.

RESEARCH DESIGN AND METHODS

Ten nondiabetic and 10 diabetic subjects ingested (2)H(2)O the evening before study. The following morning, insulin was infused at a rate of 0.6 mU . kg(-1) . min(-1) and glucose was clamped at approximately 5.3 mmol/l for 5 h. Plasma C5 glucose, C2 glucose, and (2)H(2)O enrichments were measured hourly from 2 h onward.

RESULTS

Plasma C2 glucose and plasma (2)H(2)O enrichment were equal in both groups before the clamp, resulting in equivalent estimates of gluconeogenesis and glycogenolysis. In contrast, plasma C2 glucose and plasma C5 glucose enrichments fell throughout the clamp, whereas plasma (2)H(2)O enrichment remained unchanged. Since the C5 glucose concentration and, hence, the C5 glucose-to-(2)H(2)O ratio is influenced by both gluconeogenesis and glucose clearance, whereas the C5-to-C2 glucose ratio is only influenced by gluconeogenesis, the C5 glucose-to-(2)H(2)O ratio overestimated (P < 0.01) gluconeogenesis during the clamp. This resulted in biologically implausible negative (i.e., calculated rates of gluconeogenesis exceeding total endogenous glucose production) rates of glycogenolysis in both the nondiabetic and diabetic subjects.

CONCLUSIONS

Plasma C5 glucose-to-(2)H(2)O ratio does not provide an accurate assessment of gluconeogenesis in nondiabetic or diabetic subjects during a traditional (i.e., 2-3 h) hyperinsulinemic-euglycemic clamp. The conclusions of studies that have used this approach need to be reevaluated.

Design, synthesis and crystallization of a novel glucagon analog as a therapeutic agent

Glucagon and glucagon-like peptide 1 (GLP-1) are drugs or drug candidates for the treatment of metabolic diseases such as diabetes and obesity. The native hormones have pharmacological deficiencies such as short half-life and poor solubility. A novel glucagon receptor agonist named glucagon-Cex has been designed, synthesized and crystallized. This peptide was highly soluble under physiological conditions and crystallized readily. The crystal diffracted X-rays to 2.2 A resolution and the diffraction was consistent with space group P23, with unit-cell parameters a = b = c = 48.20 A, alpha = beta = gamma = 90.0 degrees. The crystals were suitable for a full structural determination to reveal the conformational differences between glucagon-Cex and the native hormone.

Glucagon receptor agonists and antagonists affect the growth of the chick eye: a role for glucagonergic regulation of emmetropization?

PURPOSE

In chicks, plus defocus retards eye growth, thickens the choroid, and activates glucagonergic amacrine cells, probably releasing glucagon. Glucagon receptor antagonists (expected to inhibit compensation to plus defocus) and agonists (expected to block myopia induction by form deprivation) were administered to eyes of chicks, to test the hypothesis that glucagon mediates the induction of changes in eye growth by plus defocus.

METHODS

Seven-day-old (P7) chick eyes were injected intravitreally with peptides at concentrations of approximately 10(-9) to 10(-5) M in 20 microL (injection volume). The glucagon-receptor antagonists [des-His(1),des- Phe(6),Glu(9)]-glucagon-NH(2) (des- Phe(6)-antagonist) and [des-His(1),Glu(9)]-glucagon-NH(2) (Phe(6)-antagonist) were administered daily for 4 to 5 days to plus-defocused eyes. Agonists (porcine glucagon-[1-29] and [Lys(17,18),Glu(21)]-glucagon-NH(2)) were monocularly administered daily for 5 days to form-deprived eyes. The contralateral eye remained open and received saline. After treatment, eyes were refracted, measured, and examined for histologic changes.

RESULTS

The Phe(6)-antagonist at 10(-5) M (in the syringe) inhibited changes in both refractive error and axial length compensation induced by +7-D lens wear; however, des-Phe(6)-antagonist (10(-5) M) had weak, inconsistent effects and did not antagonize the action of exogenous glucagon. Glucagon prevented ocular elongation and myopia and induced choroidal thickening in form-deprived eyes. [Lys(17,18),Glu(21)]-glucagon-NH(2) had little effect at 10(-7) M, but at 10(-6) to 10(-5) M altered rod structure and inhibited eye growth.

CONCLUSIONS

Exogenous glucagon inhibited the growth of form-deprived eyes, whereas Phe(6)-antagonist inhibited compensation to plus defocus, as might be expected if glucagon is an endogenous mediator of emmetropization. The reason for the failure of des-Phe(6)-antagonist to counteract the effects of exogenous glucagon requires further investigation.

Proglucagon-derived peptides: mechanisms of action and therapeutic potential

Glucagon is used for the treatment of hypoglycemia, and glucagon receptor antagonists are under development for the treatment of type 2 diabetes. Moreover, glucagon-like peptide (GLP)-1 and GLP-2 receptor agonists appear to be promising therapies for the treatment of type 2 diabetes and intestinal disorders, respectively. This review discusses the physiological, pharmacological, and therapeutic actions of the proglucagon-derived peptides, with an emphasis on clinical relevance of the peptides for the treatment of human disease.

Effects of liraglutide (NN2211), a long-acting GLP-1 analogue, on glycaemic control and bodyweight in subjects with Type 2 diabetes

AIMS

Liraglutide (NN2211) is a long-acting GLP-1 analogue, with a pharmacokinetic profile suitable for once-daily administration. This multicentre, double-blind, parallel-group, double-dummy study explored the dose-response relationship of liraglutide effects on bodyweight and glycaemic control in subjects with Type 2 diabetes.

METHODS

Subjects (BMI 27-42 kg/m(2)) with Type 2 diabetes who were previously treated with an OAD (oral anti-diabetic drug) monotherapy (69% with metformin), and had HbA(1c) < or = 10% were enrolled. After a 4-week metformin run-in period, 210 subjects (27-73 years, 60% female) were randomised to receive liraglutide (0.045-0.75 mg) once daily or continued on metformin 1000 mg b.d. for 12 weeks.

RESULTS

Mean baseline values for the six treatment groups ranged from 6.8 to 7.5% for HbA(1c), and 8.06-9.44 mmol/l (145-170 mg/dl) for fasting plasma glucose. After 12-week treatment, a weight change of -0.05 to -1.9% was observed for the six treatment groups. Mean HbA(1c) changes from baseline for 0.045, 0.225, 0.45, 0.6, 0.75 mg liraglutide and metformin were +1.28%, +0.86%, +0.22%, +0.16%, +0.30% and +0.09%, respectively. No significant differences in HbA(1c) were observed between liraglutide and metformin groups at the three highest liraglutide dose levels (0.45, 0.6 and 0.75 mg). The lowest two liraglutide doses (0.045 mg and 0.225 mg) were not sufficient to maintain the fasting plasma glucose values achieved by metformin. No major hypoglycaemic episodes were reported. Episodes of nausea and/or vomiting were reported by 11 patients (6.3%) receiving liraglutide and three (8.8%) receiving metformin.

CONCLUSIONS

Once-daily liraglutide improved glycaemic control and weight, in a comparable degree to metformin. Liraglutide appeared to be safe and generally well tolerated. Higher doses of liraglutide merit study in future clinical trials.

Treatment of type 2 diabetes mellitus with agonists of the GLP-1 receptor or DPP-IV inhibitors

Glucagon-like peptide-1 (GLP-1) is a peptide hormone from the gut that stimulates insulin secretion and protects beta-cells, inhibits glucagon secretion and gastric emptying, and reduces appetite and food intake. In agreement with these actions, it has been shown to be highly effective in the treatment of Type 2 diabetes, causing marked improvements in glycaemic profile, insulin sensitivity and beta-cell performance, as well as weight reduction. The hormone is metabolised rapidly by the enzyme dipeptidyl peptidase IV (DPP-IV) and, therefore, cannot be easily used clinically. Instead, resistant analogues of the hormone (or agonists of the GLP-1 receptor) are in development, along with DPP-IV inhibitors, which have been demonstrated to protect the endogenous hormone and enhance its activity. Agonists include both albumin-bound analogues of GLP-1 and exendin-4, a lizard peptide. Clinical studies with exendin have been carried out for > 6 months and have indicated efficacy in patients inadequately treated with oral antidiabetic agents. Orally active DPP-IV inhibitors, suitable for once-daily administration, have demonstrated similar efficacy. Diabetes therapy, based on GLP-1 receptor activation, therefore, appears very promising.

The long-acting glucagon-like peptide-1 analogue, liraglutide, inhibits beta-cell apoptosis in vitro

We here show that GLP-1 and the long-acting GLP-1 analogue, liraglutide, interfere with diabetes-associated apoptotic processes in the beta-cell. Studies using primary neonatal rat islets showed that native GLP-1 and liraglutide inhibited both cytokine- and free fatty acid-induced apoptosis in a dose-dependent manner. The anti-apoptotic effect of liraglutide was mediated by the GLP-1 receptor as the specific GLP-1 receptor antagonist, exendin(9-39), blocked the effects. The adenylate cyclase activator, forskolin, had an anti-apoptotic effect similar to those of GLP-1 and liraglutide indicating that the effect was cAMP-mediated. Blocking the PI3 kinase pathway using wortmannin but not the MAP kinase pathways by PD98059 inhibited the effects of liraglutide. In conclusion, GLP-1 receptor activation has anti-apoptotic effect on both cytokine, and free fatty acid-induced apoptosis in primary islet-cells, thus suggesting that the long-acting GLP-1 analogue, liraglutide, may be useful for retaining beta-cell mass in both type 1 and type 2 diabetic patients.

Hepatic glucagon receptor binding and glucose-lowering in vivo by peptidyl and non-peptidyl glucagon receptor antagonists

Glucagon receptor antagonists have been actively pursued as potential therapeutics for the treatment of type 2 diabetes. Peptidyl and non-peptidyl glucagon receptor antagonists have been shown to block glucagon-induced blood glucose elevation in both animals and humans. How the antagonists and the glucagon receptor interact in vivo has not been reported and is the subject of the current study. Using (125)I-labeled glucagon as a radiotracer, we developed an in vivo glucagon receptor occupancy assay in mice expressing a human glucagon receptor in place of the endogenous mouse glucagon receptor (hGCGR mice). Using this assay, we first showed that the glucagon receptor is expressed predominantly in liver, to a much lesser extent in kidney, and is below detection in several other tissues/organs in the mice. We subsequently showed that, at 2 mg/kg body weight (mg/pk) dosed intraperitoneally (i.p.), peptidyl glucagon receptor antagonist des-His-glucagon binds to approximately 78% of the hepatic glucagon receptor and blocks an exogenous glucagon-induced blood glucose elevation in the mice. Finally, we also showed that, at 10 and 30 mg/kg dosed orally (p.o.), compound A, a non-peptidyl small molecule glucagon receptor antagonist, occupied 65-70% of the hepatic glucagon receptor, and significantly diminished exogenous glucagon-induced blood glucose elevation in the mice. At 3 mg/kg, however, compound A occupied only approximately 39% of the hepatic glucagon receptor and did not affect exogenous glucagon-induced blood glucose elevation in the mice. Taken together, the results confirmed previous reports that glucagon receptors are present predominantly in the liver, and provide the first direct evidence that peptidyl and non-peptidyl glucagon receptor antagonists bind to the hepatic glucagon receptor in vivo, and that at least 60% receptor occupancy correlates with the glucose lowering efficacy by the antagonists in vivo.

[Targeting--a new way to identify unknown tumor markers in blood vessels]

The expression of specific molecules on the surface of vascular endothelial cells in tumours might be a key to anticancer therapy with angiostatic drugs. A new method to find these molecules on tumour vessels, targeting, is presented here. Some of these tumour-specific molecules have been identified by means of so called phage libraries. They are gene-manipulated phages, where the surface is decorated with randomly generated short peptides. After intravenous injection a few of the peptides, expressed on the surface of the phage, attach to complementary structures on the endothelial cell, as a ligand attaches to its receptor. Through biopsies and immunohistochemistry the phage can be isolated and identified. The part of the DNA of the phage that codes for the peptide-sequence of importance is sequenced. This seeking for such vessel-addresses can in the future be used for diagnostic purposes and also for local tumour-treatment. It is envisioned that cytotoxic drugs can be coupled to peptides on nanoparticles and act locally, in order to minimize toxic systemic side effects.

Peptide dynamic fingerprints: a tool for investigating the role of conformational flexibility for GLP-1 analogs affinity

Glucagon-like peptide-1 (GLP-1) is a 30-residue peptide implicated in short-term appetite regulation. Its analogs are presumed to be potential drugs against obesity and non-insulin dependent diabetes mellitus (NIDDM or type 2 diabetes). This study examined how the dynamic fingerprints can be used for establishing dynamics-activity relationships in a series of peptides for which the mechanism of action is unknown and in which mutations can cause an increase or decrease in biological activity. The 3D autocorrelation method was used to generate maps of both active and inactive analogs. As the active conformation of GLP-1 is not yet clearly defined, the dynamic fingerprints of peptides in an aqueous environment were compared to explain the high affinity of the peptide for its receptor. The suggestion that the peptide could bind to the receptor in a folded conformation has been examined. In the case of the GLP-1 analogs, it was shown that the folding tendency cannot be directly related to affinity values and the results do not favor a folded active conformation model of GLP-1.

Incretin Mimetics as Emerging Treatments for Type 2 Diabetes

OBJECTIVE:

To review the physiology, pharmacology, and clinical efficacy of glucagon-like peptide (GLP-1) and the incretin mimetics exenatide and liraglutide in clinical studies.

DATA SOURCES:

Primary literature obtained via MEDLINE (1966–April 2004) and International Pharmaceutical Abstracts (1970–April 2004) searches; abstracts obtained from meeting sources and manufacturers.

STUDY SELECTION AND DATA EXTRACTION:

All English-language studies and abstracts evaluating GLP-1, exenatide, and liraglutide in the treatment of patients with type 2 diabetes were reviewed. Data from animal studies were also included if human data were not available. Primary and review articles related to the physiology, development, and evaluation of GLP-1s were reviewed.

DATA SYNTHESIS:

GLP-1, exenatide (exendin-4, AC2993), and liraglutide (NN2211) are incretin mimetics that have been shown in human studies to be an effective treatment to improve glycemic control in patients with type 2 diabetes. Mechanisms by which these compounds improve glycemic control include enhancing glucose-dependent pancreatic secretion of insulin in response to nutrient intake, inhibiting glucagon secretion, delaying gastric emptying, and promoting early satiety. GLP-1 has been shown to promote pancreatic progenitor cell differentiation and improve β-cell function and lifespan. Reported adverse effects of exenatide and liraglutide include nausea, vomiting, and transient headache, as well as increased risk of hypoglycemia when used with sulfonylureas.

CONCLUSIONS:

Clinical studies show that GLP-1, exenatide, and liraglutide improve glycemic control for patients with type 2 diabetes through unique mechanisms not available with current pharmaceutical products. Ongoing Phase III studies will help to further position these compounds as treatment options for patients with type 2 diabetes.

The effect of liraglutide, a long-acting glucagon-like peptide 1 derivative, on glycemic control, body composition, and 24-h energy expenditure in patients with type 2 diabetes

OBJECTIVE

Glucagon-like peptide (GLP)-1 is a gut hormone that exerts incretin effects and suppresses food intake in humans, but its therapeutic use is limited due to its short half-life. This was a randomized, double-blind, parallel-group, placebo-controlled trial investigating the effect of the long-acting GLP-1 derivative liraglutide (NN2211) on glycemic control, body weight, body composition, and 24-h energy expenditure in obese subjects with type 2 diabetes.

RESEARCH DESIGN AND METHODS

Thirty-three patients (mean +/- SD) aged 60.0 +/- 9.5 years, with HbA(1c) 7.5 +/- 1.2% and BMI 36.6 +/- 4.1 kg/m(2), were randomized to treatment with a single daily subcutaneous dose of 0.6 mg liraglutide (n = 21) or placebo (n = 12) for 8 weeks. In addition to weight and glycemic parameters, body composition was assessed by dual-energy X-ray absorptiometry (DEXA) scanning and 24-h energy expenditure in a respiratory chamber.

RESULTS

After 8 weeks, liraglutide reduced fasting serum glucose (liraglutide, -1.90 mmol/l, and placebo, 0.27 mmol/l; P = 0.002) and HbA(1c) (liraglutide, -0.33%, and placebo, 0.47%; P = 0.028) compared with placebo. No change in body weight was detected (liraglutide, -0.7 kg, and placebo, -0.9 kg; P = 0.756). There was a nonsignificant trend toward a decrease in total fat mass (liraglutide, -0.98%, and placebo, -0.12%; P = 0.088) and toward an increase in lean body mass (liraglutide, 1.02%, and placebo, 0.23%; P = 0.118) in the liraglutide group compared with the placebo group. Twenty-four-hour energy expenditure was unaffected by the treatment (liraglutide, -12.6 kJ/h, and placebo, -13.7 kJ/h; P = 0.799).

CONCLUSIONS

Eight weeks of 0.6-mg liraglutide treatment significantly improved glycemic control without increasing weight in subjects with type 2 diabetes compared with those on placebo. No influence on 24-h energy expenditure was detected.

Improved glycemic control with no weight increase in patients with type 2 diabetes after once-daily treatment with the long-acting glucagon-like peptide 1 analog liraglutide (NN2211): a 12-week, double-blind, randomized, controlled trial

OBJECTIVE

Liraglutide is a long-acting glucagon-like peptide 1 analog designed for once daily injection. This study assessed the efficacy and safety of liraglutide after 12 weeks of treatment in type 2 diabetic patients.

RESEARCH DESIGN AND METHODS

A double-blind, randomized, parallel-group, placebo-controlled trial with an open-label comparator arm was conducted among 193 outpatients with type 2 diabetes. The mean age was 56.6 years and the mean HbA(1c) was 7.6% across the treatment groups. Patients were randomly assigned to one of five fixed-dosage groups of liraglutide (0.045, 0.225, 0.45, 0.60, or 0.75 mg), placebo, or open-label sulfonylurea (glimepiride, 1-4 mg). The primary end point was HbA(1c) after 12 weeks; secondary end points were fasting serum glucose, fasting C-peptide, fasting glucagon, fasting insulin, beta-cell function, body weight, adverse events, and hypoglycemic episodes.

RESULTS

A total of 190 patients were included in the intention-to-treat (ITT) analysis. HbA(1c) decreased in all but the lowest liraglutide dosage group. In the 0.75-mg liraglutide group, HbA(1c) decreased by 0.75 percentage points (P < 0.0001) and fasting glucose decreased by 1.8 mmol/l (P = 0.0003) compared with placebo. Improvement in glycemic control was evident after 1 week. Body weight decreased by 1.2 kg in the 0.45-mg liraglutide group (P = 0.0184) compared with placebo. The proinsulin-to-insulin ratio decreased in the 0.75-mg liraglutide group (-0.18; P = 0.0244) compared with placebo. Patients treated with glimepiride had decreased HbA(1c) and fasting glucose, but slightly increased body weight. No safety issues were raised for liraglutide; observed adverse events were mild and transient.

CONCLUSIONS

A once-daily dose of liraglutide provides efficacious glycemic control and is not associated with weight gain. Adverse events with the drug are mild and transient, and the risk of hypoglycemia is negligible.

One week's treatment with the long-acting glucagon-like peptide 1 derivative liraglutide (NN2211) markedly improves 24-h glycemia and alpha- and beta-cell function and reduces endogenous glucose release in patients with type 2 diabetes

Glucagon-like peptide 1 (GLP-1) is potentially a very attractive agent for treating type 2 diabetes. We explored the effect of short-term (1 week) treatment with a GLP-1 derivative, liraglutide (NN2211), on 24-h dynamics in glycemia and circulating free fatty acids, islet cell hormone profiles, and gastric emptying during meals using acetaminophen. Furthermore, fasting endogenous glucose release and gluconeogenesis (3-(3)H-glucose infusion and (2)H(2)O ingestion, respectively) were determined, and aspects of pancreatic islet cell function were elucidated on the subsequent day using homeostasis model assessment and first- and second-phase insulin response during a hyperglycemic clamp (plasma glucose approximately 16 mmol/l), and, finally, on top of hyperglycemia, an arginine stimulation test was performed. For accomplishing this, 13 patients with type 2 diabetes were examined in a double-blind, placebo-controlled crossover design. Liraglutide (6 micro g/kg) was administered subcutaneously once daily. Liraglutide significantly reduced the 24-h area under the curve for glucose (P = 0.01) and glucagon (P = 0.04), whereas the area under the curve for circulating free fatty acids was unaltered. Twenty-four-hour insulin secretion rates as assessed by deconvolution of serum C-peptide concentrations were unchanged, indicating a relative increase. Gastric emptying was not influenced at the dose of liraglutide used. Fasting endogenous glucose release was decreased (P = 0.04) as a result of a reduced glycogenolysis (P = 0.01), whereas gluconeogenesis was unaltered. First-phase insulin response and the insulin response to an arginine stimulation test with the presence of hyperglycemia were markedly increased (P < 0.001), whereas the proinsulin/insulin ratio fell (P = 0.001). The disposition index (peak insulin concentration after intravenous bolus of glucose multiplied by insulin sensitivity as assessed by homeostasis model assessment) almost doubled during liraglutide treatment (P < 0.01). Both during hyperglycemia per se and after arginine exposure, the glucagon responses were reduced during liraglutide administration (P < 0.01 and P = 0.01). Thus, 1 week's treatment with a single daily dose of the GLP-1 derivative liraglutide, operating through several different mechanisms including an ameliorated pancreatic islet cell function in individuals with type 2 diabetes, improves glycemic control throughout 24 h of daily living, i.e., prandial and nocturnal periods. This study further emphasizes GLP-1 and its derivatives as a promising novel concept for treatment of type 2 diabetes.