Once-weekly GLP-1 agonists: How do they differ from exenatide and liraglutide?

Comparative effects of glucagon-like peptide-1 receptors agonists, 4-dipeptidyl peptidase inhibitors, and metformin on metabolic syndrome

AIMS

To assess the comparative effects of glucagon-like peptide-1 receptor agonists (GLP-1RA), 4-dipeptidyl peptidase inhibitors (DPP-4I), and metformin treatment during one year on metabolic syndrome (MetS) components and severity in MetS patients.

METHODS

Prospective study (n = 6165 adults) within the frame of PREDIMED-Plus trial. The major end-point was changes on MetS components and severity after one- year treatment of GLP-1RA, DPP-4I, and metformin. Anthropometric measurements (weight, height and waist circumference), body mass index (BM), and blood pressure were registered. Blood samples were collected after overnight fasting. Plasma glucose, glycosylated hemoglobin (HbA1c), plasma triglycerides and cholesterol were measured. Dietary intakes as well as physical activity were assessed through validated questionnaires.

RESULTS

MetS parameters improved through time. The treated groups improved glycaemia compared with untreated (glycaemia ∆ untreated: -1.7 mg/dL(± 13.5); ∆ metformin: - 2.5(± 23.9) mg/dL; ∆ DPP-4I: - 4.5(± 42.6); mg/dL ∆ GLP-1RA: - 4.3(± 50.9) mg/dL; and HbA1c: ∆ untreated: 0.0(± 0.3) %; ∆ metformin: - 0.1(± 0.7) %; ∆ DPP-4I: - 0.1(± 1.0) %; ∆ GLP-1RA: - 0.2(± 1.2) %. Participants decreased BMI and waist circumference. GLP-1RA and DPP-4I participants registered the lowest decrease in BMI (∆ untreated: -0.8(± 1.6) kg/m²; ∆ metformin: - 0.8(± 1.5) kg/m²; ∆ DPP-4I: - 0.6(± 1.3) kg/m²; ∆ GLP-1RA: - 0.5(± 1.2) kg/m². and their waist circumference (∆ untreated: -2.8(± 5.2) cm; ∆ metformin: - 2.6(± 15.2) cm; ∆ DPP-4I: - 2.1(± 4.8) cm; ∆ GLP-1RA: - 2.4(± 4.1) cm.

CONCLUSION

In patients with MetS and healthy lifestyle intervention, those treated with GLP-1RA and DPP-4I obtained better glycemic profile. Anthropometric improvements were modest.

Glucagon-like peptide-1 receptor agonists in type 2 diabetes treatment: are they all the same?

Glucagon-like peptide-1 (GLP-1) receptor agonists (RAs) are an important class of drugs with a well-established efficacy and safety profile in patients with type 2 diabetes mellitus. Agents in this class are derived from either exendin-4 (a compound present in Gila monster venom) or modifications of human GLP-1 active fragment. Differences among these drugs in duration of action (ie, short-acting vs long-acting), effects on glycaemic control and weight loss, immunogenicity, tolerability profiles, and administration routes offer physicians several options when selecting the most appropriate agent for individual patients. Patient preference is also an important consideration. The aim of this review is to discuss the differences between and similarities of GLP-1 RAs currently approved for clinical use, focusing particularly on the properties characterising the single short-acting and long-acting GLP-1 RAs rather than on their individual efficacy and safety profiles. The primary pharmacodynamic difference between short-acting (ie, exenatide twice daily and lixisenatide) and long-acting (ie, albiglutide, dulaglutide, exenatide once weekly, liraglutide, and semaglutide) GLP-1 RAs is that short-acting agents primarily delay gastric emptying (lowering postprandial glucose) and long-acting agents affect both fasting glucose (via enhanced glucose-dependent insulin secretion and reduced glucagon secretion in the fasting state) and postprandial glucose (via enhanced postprandial insulin secretion and inhibition of glucagon secretion). Other advantages of long-acting GLP-1 RAs include smaller fluctuations in plasma drug concentrations, improved gastrointestinal tolerability profiles, and simpler, more convenient administration schedules (once daily for liraglutide and once weekly for albiglutide, dulaglutide, the long-acting exenatide formulation, and semaglutide), which might improve treatment adherence and persistence.

Structure-based stabilization of insulin as a therapeutic protein assembly via enhanced aromatic-aromatic interactions

Key contributions to protein structure and stability are provided by weakly polar interactions, which arise from asymmetric electronic distributions within amino acids and peptide bonds. Of particular interest are aromatic side chains whose directional π-systems commonly stabilize protein interiors and interfaces. Here, we consider aromatic-aromatic interactions within a model protein assembly: the dimer interface of insulin. Semi-classical simulations of aromatic-aromatic interactions at this interface suggested that substitution of residue TyrB26 by Trp would preserve native structure while enhancing dimerization (and hence hexamer stability). The crystal structure of a [TrpB26]insulin analog (determined as a T3Rf3 zinc hexamer at a resolution of 2.25 Å) was observed to be essentially identical to that of WT insulin. Remarkably and yet in general accordance with theoretical expectations, spectroscopic studies demonstrated a 150-fold increase in the in vitro lifetime of the variant hexamer, a critical pharmacokinetic parameter influencing design of long-acting formulations. Functional studies in diabetic rats indeed revealed prolonged action following subcutaneous injection. The potency of the TrpB26-modified analog was equal to or greater than an unmodified control. Thus, exploiting a general quantum-chemical feature of protein structure and stability, our results exemplify a mechanism-based approach to the optimization of a therapeutic protein assembly.

Glucagon-like peptide-1 exerts anti-inflammatory effects on mouse colon smooth muscle cells through the cyclic adenosine monophosphate/nuclear factor-κB pathway in vitro

Background

Intestinal smooth muscle cells (SMCs) undergo substantial morphological, phenotypic, and contractile changes during inflammatory bowel disease (IBD). SMCs act as a source and target for different inflammatory mediators, however their role in IBD pathogenesis is usually overlooked. Glucagon-like peptide-1 (GLP-1) is an incretin hormone reported to exert multiple anti-inflammatory effects in different tissues including the gastrointestinal tract through various mechanisms.

Aim

The aim of this research is to explore the effect of GLP-1 analog exendin-4 on the expression and secretion of inflammatory markers from mouse colon smooth muscle cells (CSMCs) after stimulation with lipopolysaccharide (LPS).

Materials and methods

Freshly isolated CSMCs from male BALB/c mice were cultured in DMEM and treated with vehicle, LPS (1 μg/mL), LPS+exendin-4 (50 nM), or LPS+exendin-4 (100 nM) for 24 h. Expression of inflammatory cytokines was then evaluated by antibody array membrane.

Results

CSMCs showed basal expression of several cytokines which was enhanced with the induction of inflammation by LPS. However, exendin-4 (50 and 100 nM) significantly (p<0.05) reduced the expression of multiple cytokines including tumor necrosis factor-α (TNF-α), interleukin-1α (IL-1α), T cell activation gene-3 (TCA-3), stromal cell-derived factor-1 (SDF-1), and macrophage colony stimulating factor (M-CSF). To confirm these results, expression of these cytokines was further assessed by enzyme-linked immunosorbent assay and real-time polymerase chain reaction and similar results were also observed. Moreover, secretion of TNF-α and IL1-α into the conditioned media was significantly downregulated by exendin-4 when compared to LPS-treated cells. Furthermore, LPS increased NF-κB phosphorylation, while exendin-4 significantly reduced levels of NF-κB phosphorylation.

Conclusion

These data indicate that GLP-1 analogs can exert significant anti-inflammatory effects on CSMCs and can potentially be used as an adjunct treatment for inflammatory bowel conditions.

Health state utilities associated with attributes of weekly injection devices for treatment of type 2 diabetes

Background

Glucagon-like peptide-1 (GLP-1) receptor agonists are often recommended as part of combination therapy for type 2 diabetes when oral medication does not result in sufficient glycemic control. Several GLP-1 receptor agonists are available as weekly injections. These medications vary in their injection delivery systems, and these differences could impact quality of life and treatment preference. The purpose of this study was to estimate utilities associated with attributes of injection delivery systems for weekly GLP-1 therapies.

Methods

Participants with type 2 diabetes in the UK valued health states in time trade-off interviews. The health states (drafted based on literature, device instructions for use, and clinician interviews) had identical descriptions of type 2 diabetes, but differed in description of the treatment process. One health state described oral treatment, while six others described oral treatment plus a weekly injection. The injection health states varied in three aspects of the treatment administration process: requirements for reconstituting the medication (i.e., mixing the medication prior to the injection), waiting during medication preparation, and needle handling. Every participant valued all seven health states.

Results

A total of 209 participants completed interviews (57.4% male; mean age = 60.4y). The mean utility of the oral treatment health state was 0.89. All injection health states had significantly (p < 0.01) lower utilities ranging from 0.86 to 0.88. Differences among health state utilities suggest that each administration requirement had a small but measureable disutility: -0.004 (reconstitution), -0.004 (needle handling), -0.010 (reconstitution, needle handling), and -0.020 (reconstitution, waiting, needle handling).

Conclusions

Findings suggest it is feasible to use the TTO method to quantify preferences among injection treatment processes. It may be useful to incorporate these utility differences into cost-utility models comparing weekly injectable treatments for patients with type 2 diabetes.

Recent Advances in GLP-1 Receptor Agonists for Use in Diabetes Mellitus

Preclinical Research Mimetics of Glucagon-like peptide 1 (GLP-1) represent a useful alternative or complementary treatment choice to insulin in the treatment of diabetes mellitus. The lack of hypoglycemia as a side effect when GLP-1 receptor agonists are used along with the tendency of these therapeutic agents to prevent or even reduce weight gain makes them valuable targets in therapy development. However, native GLP-1 and many of its early analogues have very short half-lives, requiring repeated treatment to maintain therapeutic levels. As all current treatments are injected subcutaneously, a large focus has been made on trying to extend the half-lives of GLP-1 analogues while retaining bioactivity. Most success in this regard has been achieved with the use of peptide-protein fusions, which are not as well suited for oral administration. However, recent work focused on the development of non-fusion peptides with increased half-lives that may be more appropriate for oral administration. This minireview discusses the structural characteristics of past and present analogues as well as the recent work conducted toward developing novel GLP-1 receptor agonists. Drug Dev Res 78 : 292-299, 2017. © 2017 Wiley Periodicals, Inc.

Beneficial effect of lixisenatide after 76 weeks of treatment in patients with type 2 diabetes mellitus: A meta-analysis from the GetGoal programme

AIMS

To evaluate the long-term efficacy and safety of lixisenatide, a short-acting, prandial glucagon-like peptide-1 receptor agonists (GLP-1 RA) as add-on therapy in type 2 diabetes mellitus.

METHODS

A meta-analysis of 76-week results of 5 placebo-controlled clinical trials from the GetGoal programme was performed, including 3000 inadequately controlled adult diabetic patients where lixisenatide 20 µg once-daily was administered in combination with metformin (GetGoal-M and GetGoal-F1), sulphonylurea ± metformin (GetGoal-S), basal insulin ± metformin (GetGoal-L) or pioglitazone ± metformin (GetGoal-P).

RESULTS

A significant reduction in HbA1c at 76 weeks was observed in the intervention arm compared to placebo (LSM difference: -0.41%, 95%CI: -0.51, -0.32, P < .00001). Compared to placebo, lixisenatide induced a larger decrease in fasting plasma glucose (LSM difference -0.49 mmol/L, 95% CI -0.71, -0.27, P < .0001) and postprandial glucose excursion after a standard test meal (LSM difference -3.29 mmol/L, 95% CI -4.17, -2.42, P < .00001). A bodyweight reduction was observed in the lixisenatide arm (LSM difference -0.40 kg, 95%CI: -0.8, -0.01, P = .05). The risk of hypoglycaemia was slightly higher with lixisenatide vs placebo (risk difference +0.02, 95% CI: 0, 0.04, P = .04). The most commonly observed non-severe adverse events were nausea and vomiting, which after week 16 and week 8, were steadily <4% and <1% in the lixisenatide arm, respectively.

CONCLUSIONS

Lixisenatide, a once-daily prandial GLP-1 RA, provides long-term glycaemic control, a sustained beneficial effect on weight and with a good safety profile.

Adverse effects of incretin-based therapies on major cardiovascular and arrhythmia events: meta-analysis of randomized trials

BACKGROUND

Recent cardiovascular outcome trials of incretin-based therapies (IBT) in type 2 diabetes have not demonstrated either benefit or harm in terms of major adverse cardiovascular events (MACE). Earlier meta-analyses showed conflicting results but were limited in methodology. We aimed to perform an updated meta-analysis of all available incretin therapies on the incidence of MACE plus arrhythmia and heart failure.

METHODS

We identified studies published through November 2014 by searching electronic databases and reference lists. We included RCTs in which the intervention group received incretin-based therapies and the control group received placebo or standard treatment; enrolled >100 participants in each group; interventions lasted >24 weeks; and reported data on one or more primary major adverse cardiovascular events endpoints plus terms for arrhythmia and heart failure. We used the Peto method for each CV event for individual IBT treatment.

RESULTS

In this meta-analysis of 100 RCTs involving 54,758 incretin-based therapies users and 48,175 controls, exenatide was associated with increased risk of arrhythmia (OR 2.83; 95% CI, 1.06-7.57); saxagliptin was associated with an increased risk of heart failure (OR 1.23; 95% CI, 1.03-1.46), and sitagliptin was associated with a significantly decreased risk of all cause death compared to active controls (OR 0.39, 95% CI 0.18-0.82).

CONCLUSIONS

In type 2 diabetes, exenatide may increase the risk of arrhythmia, and sitagliptin may reduce the risk of all cause death; however, the subgroup of patients most likely to experience harm or benefit is unclear. Copyright © 2016 John Wiley & Sons, Ltd.

Pharmacology and therapeutic implications of current drugs for type 2 diabetes mellitus

Type 2 diabetes mellitus (T2DM) is a global epidemic that poses a major challenge to health-care systems. Improving metabolic control to approach normal glycaemia (where practical) greatly benefits long-term prognoses and justifies early, effective, sustained and safety-conscious intervention. Improvements in the understanding of the complex pathogenesis of T2DM have underpinned the development of glucose-lowering therapies with complementary mechanisms of action, which have expanded treatment options and facilitated individualized management strategies. Over the past decade, several new classes of glucose-lowering agents have been licensed, including glucagon-like peptide 1 receptor (GLP-1R) agonists, dipeptidyl peptidase 4 (DPP-4) inhibitors and sodium/glucose cotransporter 2 (SGLT2) inhibitors. These agents can be used individually or in combination with well-established treatments such as biguanides, sulfonylureas and thiazolidinediones. Although novel agents have potential advantages including low risk of hypoglycaemia and help with weight control, long-term safety has yet to be established. In this Review, we assess the pharmacokinetics, pharmacodynamics and safety profiles, including cardiovascular safety, of currently available therapies for management of hyperglycaemia in patients with T2DM within the context of disease pathogenesis and natural history. In addition, we briefly describe treatment algorithms for patients with T2DM and lessons from present therapies to inform the development of future therapies.

GLP-1 receptor agonists: Nonglycemic clinical effects in weight loss and beyond

OBJECTIVE

Glucagon-like peptide-1 (GLP-1) receptor agonists are indicated for treatment of type 2 diabetes since they mimic the actions of native GLP-1 on pancreatic islet cells, stimulating insulin release, while inhibiting glucagon release, in a glucose-dependent manner. The observation of weight loss has led to exploration of their potential as antiobesity agents, with liraglutide 3.0 mg day(-1) approved for weight management in the US on December 23, 2014, and in the EU on March 23, 2015. This review examines the potential nonglycemic effects of GLP-1 receptor agonists.

METHODS

A literature search was conducted to identify preclinical and clinical evidence on nonglycemic effects of GLP-1 receptor agonists.

RESULTS

GLP-1 receptors are distributed widely in a number of tissues in humans, and their effects are not limited to the well-recognized effects on glycemia. Nonglycemic effects include weight loss, which is perhaps the most widely recognized nonglycemic effect. In addition, effects on the cardiovascular, neurologic, and renal systems and on taste perception may occur independently of weight loss.

CONCLUSIONS

GLP-1 receptor agonists may provide other nonglycemic clinical effects besides weight loss. Understanding these effects is important for prescribers in using GLP-1 receptor agonists for diabetic patients, but also if approved for chronic weight management.

Albiglutide does not impair the counter-regulatory hormone response to hypoglycaemia: a randomized, double-blind, placebo-controlled, stepped glucose clamp study in subjects with type 2 diabetes mellitus

AIM

To determine if the glucagon-like peptide-1 (GLP-1) receptor agonist albiglutide, once weekly, impairs counter-regulatory responses during hypoglycaemia.

METHODS

We conducted a randomized, double-blind, parallel, placebo-controlled study in subjects with type 2 diabetes mellitus. A single dose of albiglutide 50 mg (n = 22) or placebo (n = 22) was administered on day 1. Glucose was clamped on day 4 (to coincide with the approximate albiglutide maximum plasma concentration) at 9.0, 5.0, 4.0, 3.3 and 2.8 mmol/l (162, 90, 72, 59.4 and 50.4 mg/dl), with a post-clamp recovery period to 3.9 mmol/l (70 mg/dl). Hormone measurements were made at each plateau and adverse events (AEs) were recorded.

RESULTS

The counter-regulatory hormones glucagon, epinephrine, norepinephrine, growth hormone and cortisol were appropriately suppressed when plasma glucose levels were >4.0 mmol/l (>72 mg/dl), but increased in the albiglutide and placebo groups with glucose levels <3.3 mmol/l (<59.4 mg/dl) in response to hypoglycaemia. The area under the curve geometric mean ratios (albiglutide : placebo), calculated from the clamped plateau of 4.0 mmol/l (72 mg/dl) to the glucose recovery point, were not significantly different for any of the counter-regulatory hormones. When plasma glucose levels were >5.0 mmol/l (>90 mg/dl), albiglutide increased pancreatic β-cell secretion of C-peptide in a glucose-dependent manner to a greater extent than did placebo, and it was suppressed in each group when levels were <4.0 mmol/l (<72 mg/dl). No significant difference between groups was observed in the recovery time to glucose level ≥3.9 mmol/l (≥70 mg/dl). There were no clinically relevant differences in AEs or other safety variables.

CONCLUSIONS

A single 50-mg dose of albiglutide was well tolerated and did not impair the counter-regulatory response to hypoglycaemia. These data provide mechanistic evidence supporting the low intrinsic hypoglycaemic potential of albiglutide.

GLP-1R activation for the treatment of stroke: updating and future perspectives

Stroke is the leading cause of adult disability in Westernized societies with increased incidence along ageing and it represents a major health and economical threat. Inactive lifestyle, smoking, hypertension, atherosclerosis, obesity and diabetes all dramatically increase the risk of stroke. While preventive strategies based on lifestyle changes and risk factor management can delay or decrease the likelihood of having a stroke, post stroke pharmacological strategies aimed at minimizing stroke-induced brain damage are highly needed. Unfortunately, several candidate drugs that have shown significant preclinical neuroprotective efficacy, have failed in clinical trials and no treatment for stroke based on neuroprotection is available today. Glucagon-like peptide 1 (GLP-1) is a peptide originating in the enteroendocrine L-cells of the intestine and secreted upon nutrient ingestion. The activation of the GLP-1R by GLP-1 enhances glucose-dependent insulin secretion, suppresses glucagon secretion and exerts multifarious extrapancreatic effects. Stable GLP-1 analogues and inhibitors of the proteolytic enzyme dipeptidyl peptidase 4 (DPP-4) (which counteract endogenous GLP-1 degradation) have been developed clinically for the treatment of type 2 diabetes. Besides their antidiabetic properties, experimental evidence has shown neurotrophic and neuroprotective effects of GLP-1R agonists and DPP-4 inhibitors in animal models of neurological disorders. Herein, we review recent experimental data on the neuroprotective effects mediated by GLP-1R activation in stroke. Due to the good safety profile of the drugs targeting the GLP-1R, we also discuss the high potential of GLP-1R stimulation in view of developing a safe clinical treatment against stroke based on neuroprotection in both diabetic and non-diabetic patients.

Novel Agents for the Treatment of Type 2 Diabetes

In Brief Impaired insulin secretion, increased hepatic glucose production, and decreased peripheral glucose utilization are the core defects responsible for the development and progression of type 2 diabetes. However, the pathophysiology of this disease also includes adipocyte insulin resistance (increased lipolysis), reduced incretin secretion/sensitivity, increased glucagon secretion, enhanced renal glucose reabsorption, and brain insulin resistance/neurotransmitter dysfunction. Although current diabetes management focuses on lowering blood glucose, the goal of therapy should be to delay disease progression and eventual treatment failure. Recent innovative treatment approaches target the multiple pathophysiological defects present in type 2 diabetes. Optimal management should include early initiation of combination therapy using multiple drugs with different mechanisms of action. This review examines novel therapeutic options that hold particular promise.

GLP-1-Based Strategies: A Physiological Analysis of Differential Mode of Action

DPP4 inhibitors and GLP-1 receptor agonists used in incretin-based strategies treat Type 2 diabetes with different modes of action. The pharmacological blood GLP-1R agonist concentration targets pancreatic and some extrapancreatic GLP-1R, whereas DPP4i favors the physiological activation of the gut-brain-periphery axis that could allow clinicians to adapt the management of Type 2 diabetes, according to the patient's pathophysiological characteristics.

Efficacy and safety of lixisenatide once daily vs. placebo in people with Type 2 diabetes insufficiently controlled on metformin (GetGoal-F1)

AIMS

To assess the efficacy and safety of one- and two-step dose-increase regimens of lixisenatide once daily in participants with Type 2 diabetes mellitus insufficiently controlled with metformin.

METHODS

This was a randomized, double-blind, placebo-controlled, parallel-group, multi-centre study enrolling participants with Type 2 diabetes (n = 484) treated with metformin. Participants were randomized to receive either lixisenatide in a one-step dose increase or a two-step dose increase vs. placebo for 24 weeks, followed by a ≥ 52-week variable double blind period. Primary outcome was HbA1c reduction at week 24.

RESULTS

Lixisenatide one-/two-step once daily significantly improved HbA1c at week 24 compared with placebo (P < 0.0001) and allowed more participants to achieve HbA1c < 53 mmol/mol (< 7.0%) (P ≤ 0.0005). Improvements were observed in fasting plasma glucose (-0.5/-0.6 vs. +0.1 mmol/l; P < 0.001) and body weight (-2.6/-2.7 vs. -1.6 kg; P < 0.005). At week 24, adverse events were reported by 67.7/70.8/65.6% of participants treated with lixisenatide one-/two-step/placebo, respectively--nausea and vomiting being reported most frequently. Symptomatic hypoglycaemia occurred in 1.9/2.5% of participants on one-/two-step lixisenatide and 0.6% with placebo, with no severe episodes. Lixisenatide continued to be efficacious and well tolerated during the variable double-blind extension period of at least 52 weeks.

CONCLUSIONS

Lixisenatide one- or two-step dose-increase regimens significantly improved glycaemic control and decreased body weight over 24 weeks and during a long-term extension period without increasing hypoglycaemia. The study confirmed that tolerability in the one-step group was at least similar to the two-step dose increase, with nausea/vomiting and hypoglycaemia frequency being lower in the one-step regimen.

(Poly)peptide-based therapy for diabetes mellitus: insulins versus incretins

Insulin therapy remains the standard of care for achieving and maintaining adequate glycemic control, especially in hospitalized patients with critical and noncritical illnesses. Insulin therapy is more effective against elevated fasting glycaemia but less in the reduction of postprandial hyperglycaemia. It is associated with a high incidence of hypoglycemia and weight gain. Contrary, GLP-1 mimetic therapy improves postprandial glycaemia without the hypoglycaemia and weight gain associated with aggressive insulin therapy. Moreover, it has the potential to reduce cardiovascular related morbidity. However, its increased immunogenicity and severe gastrointestinal adverse effects present a huge burden on patients. Thus, a right combination of basal insulin which has lowering effect on fasting plasma glucose and GLP-1 mimetic with its lowering effect on postprandial plasma glucose with minimal gastrointestinal adverse effects, seems the right therapy choice from a clinical point of view for some diabetic patients. In this article, we discuss the pros and cons of the use of insulin analogues and GLP-1 mimetics that are associated with the treatment of type 2 diabetes.

Efficacy and safety of lixisenatide once daily versus exenatide twice daily in type 2 diabetes inadequately controlled on metformin: a 24-week, randomized, open-label, active-controlled study (GetGoal-X)

OBJECTIVE

To compare efficacy and safety of lixisenatide once daily versus exenatide twice daily in type 2 diabetes inadequately controlled with metformin.

RESEARCH DESIGN AND METHODS

Adults with diabetes inadequately controlled (HbA1c 7-10%) with metformin were randomized to lixisenatide 20 μg once daily (n=318) or exenatide 10 μg twice daily (n=316) in a 24-week (main period), open-label, parallel-group, multicenter study. The primary objective was a noninferiority assessment of lixisenatide versus exenatide in HbA1c change from baseline to week 24.

RESULTS

Lixisenatide once daily demonstrated noninferiority in HbA1c reduction versus exenatide twice daily. The least squares mean change was -0.79% (mean decrease 7.97 to 7.17%) for lixisenatide versus -0.96% (mean decrease 7.96 to 7.01%) for exenatide, and treatment difference was 0.17% (95% CI, 0.033-0.297), meeting a predefined noninferiority upper CI margin of 0.4%. Responder rate (HbA1c<7.0%) and improvements in fasting plasma glucose were comparable. Both agents induced weight loss (from 94.5 to 91.7 kg and from 96.7 to 92.9 kg with lixisenatide and exenatide, respectively). Incidence of adverse events (AEs) was similar for lixisenatide and exenatide, as was incidence of serious AEs (2.8 and 2.2%, respectively). Discontinuations attributable to AEs occurred in 33 lixisenatide (10.4%) and 41 exenatide (13.0%) patients. In the lixisenatide group, fewer participants experienced symptomatic hypoglycemia (2.5 vs. 7.9%; P<0.05), with fewer gastrointestinal events (especially nausea; 24.5 vs. 35.1%; P<0.05).

CONCLUSIONS

Add-on lixisenatide once daily in type 2 diabetes inadequately controlled with metformin demonstrated noninferior improvements in HbA1c, with slightly lower mean weight loss, lower incidence of hypoglycemia, and better gastrointestinal tolerability compared with exenatide twice daily.

Efficacy and safety of lixisenatide once-daily morning or evening injections in type 2 diabetes inadequately controlled on metformin (GetGoal-M)

OBJECTIVE

To examine the efficacy and safety of lixisenatide (20 μg once daily, administered before the morning or evening meal) as add-on therapy in patients with type 2 diabetes insufficiently controlled with metformin alone.

RESEARCH DESIGN AND METHODS

This was a 24-week, randomized, double-blind, placebo-controlled study in 680 patients with inadequately controlled type 2 diabetes (HbA1c 7-10% [53-86 mmol/mol]). Patients were randomized to lixisenatide morning (n = 255), lixisenatide evening (n = 255), placebo morning (n = 85), or placebo evening (n = 85) injections.

RESULTS

Lixisenatide morning injection significantly reduced mean HbA1c versus combined placebo (mean change -0.9% [9.8 mmol/mol] vs. -0.4% [4.4 mmol/mol]; least squares [LS] mean difference vs. placebo -0.5% [5.5 mmol/mol], P < 0.0001). HbA1c was significantly reduced by lixisenatide evening injection (mean change -0.8% [8.7 mmol/mol] vs. -0.4% [4.4 mmol/mol]; LS mean difference -0.4% [4.4 mmol/mol], P < 0.0001). Lixisenatide morning injection significantly reduced 2-h postprandial glucose versus morning placebo (mean change -5.9 vs. -1.4 mmol/L; LS mean difference -4.5 mmol/L, P < 0.0001). LS mean difference in fasting plasma glucose was significant in both morning (-0.9 mmol/L, P < 0.0001) and evening (-0.6 mmol/L, P = 0.0046) groups versus placebo. Mean body weight decreased to a similar extent in all groups. Rates of adverse events were 69.4% in both lixisenatide groups and 60.0% in the placebo group. Rates for nausea and vomiting were 22.7 and 9.4% for lixisenatide morning and 21.2 and 13.3% for lixisenatide evening versus 7.6 and 2.9% for placebo, respectively. Symptomatic hypoglycemia occurred in 6, 13, and 1 patient for lixisenatide morning, evening, and placebo, respectively, with no severe episodes.

CONCLUSIONS

In patients with type 2 diabetes inadequately controlled on metformin, lixisenatide 20 μg once daily administered in the morning or evening significantly improved glycemic control, with a pronounced postprandial effect, and was well tolerated.

Recent advances in understanding GLP-1R (glucagon-like peptide-1 receptor) function

Type 2 diabetes is a major global health problem and there is ongoing research for new treatments to manage the disease. The GLP-1R (glucagon-like peptide-1 receptor) controls the physiological response to the incretin peptide, GLP-1, and is currently a major target for the development of therapeutics owing to the broad range of potential beneficial effects in Type 2 diabetes. These include promotion of glucose-dependent insulin secretion, increased insulin biosynthesis, preservation of β-cell mass, improved peripheral insulin sensitivity and promotion of weight loss. Despite this, our understanding of GLP-1R function is still limited, with the desired spectrum of GLP-1R-mediated signalling yet to be determined. We review the current understanding of GLP-1R function, in particular, highlighting recent contributions in the field on allosteric modulation, probe-dependence and ligand-directed signal bias and how these behaviours may influence future drug development.

Efficacy and safety of lixisenatide in the treatment of Type 2 diabetes mellitus: a review of Phase III clinical data

Lixisenatide is a novel glucagon-like peptide-1 receptor agonist developed for the treatment of Type 2 diabetes mellitus (T2DM). In its clinical development program, once-daily lixisenatide has been associated with significant improvements in HbA_1c (change from baseline to week 24: up to -0.92%) and postprandial plasma glucose (PPG; change from baseline to week 24 as add-on to basal insulin: up to -7.96 mmol/l) with beneficial weight effects (change from baseline to week 24: up to -2.0 kg as add-on to oral antidiabetic agents and -1.8 kg as add-on to basal insulin) and a low incidence of severe hypoglycemia (from 0 to 1.2% over 24 weeks). Pharmacodynamic data highlight differences between lixisenatide and other glucagon-like peptide-1 receptor agonists, demonstrating more pronounced effects on PPG than liraglutide, with less frequent dosing and a better tolerability profile than exenatide. Lixisenatide has recently been evaluated in a comprehensive Phase III clinical trial program in patients with T2DM, which included three large-scale studies of once-daily lixisenatide in combination with basal insulin. Lixisenatide has been studied as a monotherapy or oral agent combination, or with insulin. It may become a treatment option for certain patient groups in the near future, including those that are unable to reach target HbA_1c goals despite treatment with basal insulin and a fairly well-controlled fasting plasma glucose, indicating that additional PPG control could be needed. This article reviews clinical data for lixisenatide to date, both as monotherapy and in combination with basal insulin, and discusses the implications of lixisenatide for the management of T2DM.

GLP-1 agonists for type 2 diabetes: pharmacokinetic and toxicological considerations

INTRODUCTION

Within recent years, glucagon-like peptide 1 receptor agonists (GLP-1-RA) have emerged as a new treatment option for type 2 diabetes. The GLP-1-RA are administered subcutaneously and differ substantially in pharmacokinetic profiles.

AREAS COVERED

This review describes the pharmacokinetics and safety aspects of the currently available GLP-1 receptor agonists, liraglutide (based on the structure of native GLP-1), exenatide twice daily and exenatide once weekly (based on exendin-4) in relation to the kinetics and toxicology of native GLP-1. The review is based on electronic literature searches and legal documents in the form of assessment reports from the European Medicines Agency and the United States Food and Drug Administration.

EXPERT OPINION

GLP-1-based therapy combines several unique mechanisms of action and have the potential to gain widespread use in the fight against diabetes and obesity. The difference in chemical structure have strong implications for key pharmacokinetic parameters such as absorption and clearance, and eventually the safety and efficacy of the individual GLP-1-RA. The main safety concerns are pancreatitis and neoplasms, for which there are no identifiable differences in risk between the available agents. Antibody formation and injection site reactions are more frequent with the exendin-4-based compounds. The efficacy with regard to Hb(A1c) reduction is superior with the longer-acting agonists, whereas the shorter-acting GLP-1-RA seems to provide greater postprandial glucose control and lower tolerability as a possible consequence of less induction of tachyphylaxis. The future place of these agents will depend on the added safety and efficacy data in the several ongoing cardiovascular outcome trials.

The neuroprotective effects of GLP-1: possible treatments for cognitive deficits in individuals with mood disorders

Incretins are a group of gastrointestinal hormones detected both peripherally and in the central nervous system (CNS). Recent studies have documented multiple effects of incretins on brain structure and function. Research into the neurological effects of incretins has primarily focused on animal models of neurodegenerative disorders (e.g., Alzheimer's Disease, Huntington's and Parkinson's diseases). Mood disorders (e.g. bipolar disorder (BD), major depressive disorder (MDD)) are associated with similar alterations in brain structure and function, as well as a range of cognitive deficits (e.g. memory, learning, executive function). Brain abnormalities and cognitive deficits are also found in populations with metabolic disorders (e.g., diabetes mellitus Type 2). In addition, individuals with mood disorders often have co-morbid metabolic conditions, thus treatment strategies which can effectively treat both cognitive deficits and metabolic abnormalities represent a possible integrated treatment avenue. In particular, glucagon-like peptide-1 (GLP-1) and its more stable, longer-lasting analogues have been demonstrated to exert neuroprotective and anti-apoptotic effects, reduce beta-amyloid (Aβ) plaque accumulation, modulate long-term potentiation and synaptic plasticity, and promote differentiation of neuronal progenitor cells. In animal models of behaviour, treatment with GLP-1 receptor agonists has been demonstrated to improve measures of cognitive function including learning and memory, as well as reduce depressive behaviour. Available GLP-1 treatments also have a favourable metabolic profile which includes weight loss and reduced risk for hypoglycemia. Systematic evaluation of the effects of GLP-1 treatment in psychiatric populations who evince cognitive deficits represents a promising treatment avenue.

GLP-1R and amylin agonism in metabolic disease: complementary mechanisms and future opportunities

The discoveries of the incretin hormone glucagon-like peptide-1 (GLP-1) and the β-cell hormone amylin have translated into hormone-based therapies for diabetes. Both classes of molecules also exhibit weight-lowering effects and have been investigated for their anti-obesity potential. In the present review, we explore the mechanisms underlying the physiological and pharmacological actions of GLP-1 and amylin agonism. Despite their similarities (e.g. both molecular classes slow gastric emptying, decrease glucagon and inhibit food intake), there are important distinctions between the central and/or peripheral pathways that mediate their effects on glycaemia and energy balance. We suggest that understanding the similarities and differences between these molecules holds important implications for the development of novel, combination-based therapies, which are increasingly the norm for diabetes/metabolic disease. Finally, the future of GLP-1- and amylin agonist-based therapeutics is discussed.

Drug development: longer-lived proteins

Protein therapeutics represent a powerful class of clinically approved drugs for the prevention and treatment of various diseases. Once administered, the biological fate of protein therapeutics is governed by the body's various complex biochemical and biophysical clearance mechanisms, several of which may decrease the drug's circulation time and efficiency. In this tutorial review, we introduce the concepts of physiological protein clearance from the body, and describe several chemical modification and protein engineering approaches used to improve the life span of administered protein therapeutics.

Liraglutide: clinical pharmacology and considerations for therapy

Liraglutide is a United States Food and Drug Administration (FDA)-approved glucagon-like peptide-1 (GLP-1) analog that is 97% homologous to native human GLP-1. The additional 16-carbon fatty acid chain causes noncovalent binding to albumin, which slows absorption from the injection site and protects the molecule from degradation by the enzyme dipeptidyl peptidase-4, allowing for protraction of action. Albumin binding and an elimination half-life of 13 hours combine to allow for once-daily dosing. Liraglutide 1.2 and 1.8 mg/day given as monotherapy for up to 52 weeks produced mean reductions in hemoglobin A1c (A1C) of 0.6-1.6%; combination therapy of liraglutide with oral antidiabetic agents demonstrated mean A1C reductions up to 1.5%. The satiety effect of GLP-1 receptor agonists and documented weight loss as great as 3.38 kg in clinical trials may make liraglutide ideal for obese patients with type 2 diabetes mellitus. Like other incretin-based agents, preliminary studies suggest liraglutide may also increase β-cell mass and function. Hypoglycemia is rare with liraglutide and tends to occur when used in combination with sulfonylureas; liraglutide in combination with insulin is not yet FDA approved. The pharmacokinetic parameters of liraglutide are unaffected by age, sex, race, or ethnicity, and no special recommendations for altered dosing of liraglutide need apply to populations with hepatic or renal impairment. Results from clinical trials have not shown an increased risk of medullary thyroid cancer, pancreatitis, or poor cardiovascular outcomes with liraglutide treatment. Ongoing, long-term monitoring studies continue to evaluate the safety of liraglutide treatment in these outcomes.

Clinical Efficacy and Safety of Once-Weekly Glucagon-Like Peptide-1 Agonists in Development for Treatment of Type 2 Diabetes Mellitus in Adults

OBJECTIVE:

To review pharmacologic, pharmacokinetic, efficacy, and safety data of once-weekly glucagon-like peptide-1 (GLP-1) agonists exenatide long-acting release (LAR), albiglutide, and taspoglutide in treatment of type 2 diabetes mellitus (T2DM).

DATA SOURCES:

A MEDLINE search (1966-August 2011) was conducted using the following key words: type 2 diabetes mellitus, glucagon-like peptide-1 agonists once weekly, glucagon-like peptide-1 agonists, exenatide LAR, albiglutide, and taspoglutide.

STUDY SELECTION AND DATA EXTRACTION:

All articles published in English identified from the data sources were evaluated, prioritizing randomized controlled trials with human data. The references of published articles identified were examined for additional studies appropriate for the review.

DATA SYNTHESIS:

Native GLP-1 increases glucose-dependent insulin secretion, decreases glucagon secretion, and slows gastric emptying in healthy individuals, but these effects may be blunted in patients with T2DM. Because native GLP-1 is rapidly degraded by dipeptidyl peptidase-IV, it is not a practical treatment option. Currently, 2 GLP-1 receptor agonists have been approved by the Food and Drug Administration: exenatide twice daily and liraglutide once daily. Several additional GLP-1 agonists, including exenatide LAR, albiglutide, and taspoglutide, are in various stages of clinical trials and have been modified to increase their half-lives. These agents have shown significant improvements in hemoglobin A1c, fasting plasma glucose, and postprandial plasma glucose, as well as improvements in body weight, blood pressure, and lipid parameters. These agents allow for less-frequent dosing schedules, improved glycemic control throughout the day, and improved treatment satisfaction compared to some available agents. GLP-1 agonists have been well tolerated, with the most common adverse effects being gastrointestinal related, which occurred early in therapy but typically resolved after 4-8 weeks. The incidence of hypoglycemia was infrequent and mild during therapy.

CONCLUSIONS:

Once-weekly GLP-1 agonists provide similar glycemic control with weight reduction, as well as overall higher treatment satisfaction for patients because of their ease of use and need for less-frequent dosing compared to some available agents.

Novel GLP-1 receptor agonists for diabetes

INTRODUCTION

GLP-1 receptor agonists have been shown to be effective in the treatment of type 2 diabetes mellitus (T2DM). Although the first GLP-1 receptor agonist, exenatide, was approved in the mid-2000s, other agents with longer durations of action (that do not require twice-daily dosing) are now being developed. Indeed, liraglutide, a once-daily GLP-1 receptor agonist, was approved in 2010, and more recently, a once-weekly formulation of exenatide was approved in 2011. This review considers the mechanism of action of GLP-1 receptor agonists and considers the various agents in this class.

AREAS COVERED

The importance of GLP-1 itself in glycemic control and the use of GLP-1 receptor agonists in T2DM are discussed. An overview of the clinical development of the five GLP-1 receptor agonists (exenatide, liraglutide, lixisenatide, albiglutide and taspoglutide) since 2005 is provided and their mechanisms of action, efficacy in terms of glycemic control and weight loss, and tolerability are reviewed.

EXPERT OPINION

GLP-1 receptor agonists result in clinically meaningful weight loss in addition to their beneficial effects on glucose homeostasis. These agents provide substantial clinical benefits for patients compared with sulfonylureas or DPP-4 inhibitors and will, therefore, become one of the major therapeutic choices for patients with T2DM.

Incretin therapy--present and future

Although newer treatments for type 2 diabetes (T2D) patients have produced continual improvements in outcome, a large and growing population with prediabetes remains under-treated. In the last few years, incretin-based therapies have become an important treatment option for patients with T2D. There are two classes of incretin agents: the dipeptidyl peptidase-4 (DPP-4) inhibitors and the glucagon like peptide 1 (GLP-1) receptor agonists. The ultimate goal of agents within both of these classes is to increase GLP-1 signaling, which results in augmented glucose-induced insulin secretion, inhibition of glucagon secretion, and decreased appetite. This should result in improved regulation of glucose homeostasis. GLP-1 receptor agonists enable patients to achieve significant weight loss. In contrast, DPP-4 inhibitors result in a less dramatic increase in GLP-1 levels; therefore, they are weight neutral. Incretin therapies are currently recommended for use early in the treatment algorithm for T2D patients whose disease is not manageable by diet and exercise alone, but the potential for these agents may be farther reaching. Current studies are evaluating the potential benefits of combining incretin therapies with basal insulin to provide continuous glucose control before and after meals. In addition, these agents may be promising for patients with prediabetes since they effectively reduce glycosylated hemoglobin levels and fasting plasma glucose levels, enable weight control, and have the potential to preserve β-cell function. Clearly, all of these properties are desirable for patients with prediabetes.

Management of type 2 diabetes: new and future developments in treatment

The increasing prevalence, variable pathogenesis, progressive natural history, and complications of type 2 diabetes emphasise the urgent need for new treatment strategies. Longacting (eg, once weekly) agonists of the glucagon-like-peptide-1 receptor are advanced in development, and they improve prandial insulin secretion, reduce excess glucagon production, and promote satiety. Trials of inhibitors of dipeptidyl peptidase 4, which enhance the effect of endogenous incretin hormones, are also nearing completion. Novel approaches to glycaemic regulation include use of inhibitors of the sodium-glucose cotransporter 2, which increase renal glucose elimination, and inhibitors of 11β-hydroxysteroid dehydrogenase 1, which reduce the glucocorticoid effects in liver and fat. Insulin-releasing glucokinase activators and pancreatic-G-protein-coupled fatty-acid-receptor agonists, glucagon-receptor antagonists, and metabolic inhibitors of hepatic glucose output are being assessed. Early proof of principle has been shown for compounds that enhance and partly mimic insulin action and replicate some effects of bariatric surgery.

Lixisenatide for type 2 diabetes mellitus

INTRODUCTION

Type 2 diabetes mellitus (T2DM) is an increasing health problem worldwide. Glucagon-like peptide-1 (GLP-1) receptor agonists are an expanding drug class that target several of the pathophysiological traits of T2DM. Lixisenatide is a GLP-1 receptor agonist in development for once-daily treatment of T2DM.

AREAS COVERED

Pharmacological, preclinical and clinical evidence demonstrating the applicability of lixisenatide for the treatment of T2DM are reviewed. Available data and pending clinical development are summarized, critically appraised and compared to competitor drugs. The most relevant papers and meeting abstracts published up to November 2010 are used as sources for this review.

EXPERT OPINION

Efficacy and safety in T2DM are demonstrated with lixisenatide in monotherapy and in combination with metformin. However, limited data with the intended once-daily 20 μg subcutaneous dosing necessitate further evaluation of lixisenatide as add-on to various antidiabetic treatments. It remains to be established whether the slightly differing chemical properties compared to other GLP-1 receptor agonists including a rather short duration of action will be a disadvantage or maybe even an advantage, for example, when combined with long-acting insulin.

Glucagon-like peptide-1 (GLP-1) receptor agonists: Differentiating the new medications

INTRODUCTION

Glucagon-like peptide-1 (GLP-1) has been the focus of considerable research activity in the treatment of type 2 diabetes mellitus (T2DM) because the incretin effect is significantly reduced or absent in individuals with T2DM. Thus, pharmacologic efforts to develop medications that mimic the actions of GLP-1 have become a target for improving or reversing chronic hyperglycemia. Two GLP-1 receptor agonists are commercially available: exenatide twice daily (b.i.d.) and liraglutide once daily (q.d.). Targeted and individualized intensification of diabetes management can best be accomplished with a thorough understanding of these new medications.

METHODS

Information was gathered through a search of MEDLINE and PubMed for GLP-1 and glycemic management in patients with type 2 diabetes.

RESULTS

Activation of the GLP-1 receptors on the β-cells results in enhanced levels of insulin biosynthesis, β-cell proliferation, resistance to β-cell apoptosis, and enhanced β-cell survival in both humans and rodents; yet, the risk of hypoglycemia is minimized because insulin production and exocytosis occurs in a glucose-dependent manner. The efficacy and safety of the two commercially available GLP-1 receptor agonists, liraglutide and exenatide, in managing postprandial glycemia have been well documented in numerous clinical trials, in which reductions in glycosylated hemoglobin (HbA1c) levels of -0.79% to -1.12% have been demonstrated. Weight reduction/maintenance and improvements in blood pressure and lipidemia have also been reported.

CONCLUSION

Because GLP-1 receptor agonists work in a glucose-dependent manner, they are likely to reduce hyperglycemia safely, without a marked fluctuation toward hypoglycemia. In the process of acutely restoring β-cell function, GLP-1 agonists may allow patients to achieve HbA(1c) <7% without experiencing weight gain or hypoglycemia. The ability of GLP-1 receptor agonists to improve blood pressure and postprandial lipidemia in the context of weight neutrality or weight loss may have the potential to ameliorate some of the cardiovascular risks observed in patients with T2DM.