The effect of exenatide re-exposure on safety and efficacy

Role of Glucagon-Like Peptide-1 (GLP-1) Receptor Agonists in Hypoglycemia

A relatively recent addition to the arsenal of antidiabetic drugs used for the treatment of type 2 diabetes mellitus (T2DM) has been the "incretin mimetics," a group of drugs that work on the glucagon-like peptide-1 (GLP-1) receptor and enhance insulin secretion from the pancreatic β-cells in a glucose-dependent manner, more potently in hyperglycemic conditions, while suppressing glucagon secretion at the same time. Therefore, it was assumed that this class of drugs would have a lower risk of hypoglycemia than insulin secretagogues like sulphonylureas. However, GLP-1 receptor agonists have been proposed to cause hypoglycemia in healthy normoglycemic subjects implying that their action is not as glucose-dependent as once thought. Other studies concluded that they might not induce hypoglycemia and the risk is dependent on other individual factors. However, the FDA announced that the 12 GLP-1 receptor agonists currently available on the market had potential safety signs and evaluated the need for regulatory action. This review provides an overview of the studies that investigated the possible hypoglycemic effect of GLP-1 receptor agonists. In addition, the current review describes other adverse effects of GLP-1 receptor agonist treatment.

Incretin-based therapy for type 2 diabetes mellitus is promising for treating neurodegenerative diseases

Incretin hormones include glucagon-like peptide-1 (GLP-1) and glucose-dependent insulinotropic polypeptide (GIP). Due to their promising action on insulinotropic secretion and improving insulin resistance (IR), incretin-based therapies have become a new class of antidiabetic agents for the treatment of type 2 diabetes mellitus (T2DM). Recently, the links between neurodegenerative diseases and T2DM have been identified in a number of studies, which suggested that shared mechanisms, such as insulin dysregulation or IR, may underlie these conditions. Therefore, the effects of incretins in neurodegenerative diseases have been extensively investigated. Protease-resistant long-lasting GLP-1 mimetics such as lixisenatide, liraglutide, and exenatide not only have demonstrated promising effects for treating neurodegenerative diseases in preclinical studies but also have shown first positive results in Alzheimer's disease (AD) and Parkinson's disease (PD) patients in clinical trials. Furthermore, the effects of other related incretin-based therapies such as GIP agonists, dipeptidyl peptidase-IV (DPP-IV) inhibitors, oxyntomodulin (OXM), dual GLP-1/GIP, and triple GLP-1/GIP/glucagon receptor agonists on neurodegenerative diseases have been tested in preclinical studies. Incretin-based therapies are a promising approach for treating neurodegenerative diseases.

Role of anti-diabetic drugs as therapeutic agents in Alzheimer's disease

Recent data have suggested a strong possible link between Type 2 Diabetes Mellitus and Alzheimer's disease (AD), although exact mechanisms linking the two are still a matter of research and debate. Interestingly, both are diseases with high incidence and prevalence in later years of life. The link appears so strong that some scientists use Alzheimer's and Type 3 Diabetes interchangeably. In depth study of recent data suggests that the anti diabetic drugs not only have possible role in treatment of Alzheimer's but may also arrest the declining cognitive functions associated with it. The present review gives an insight into the possible links, existing therapeutics and clinical trials of anti diabetic drugs in patients suffering from AD primarily or as co-morbidity. It may be concluded that the possible beneficial effects and usefulness of the current anti diabetic drugs in AD cannot be neglected and further research is required to achieve positive results. Currently, several drug trials are in progress to give conclusive evidence based data.

Adverse Effects of GLP-1 Receptor Agonists

Glucagon-like peptide-1 (GLP-1) receptor agonists are a class of injective anti-diabetic drugs that improve glycemic control and many other atherosclerosis-related parameters in patients with type 2 diabetes (T2D). However, the use of this relatively new class of drugs may be associated with certain adverse effects. Concerns have been expressed regarding the effects of these drugs on pancreatic and thyroid tissue, since animal studies and analyses of drug databases indicate an association of GLP-1 receptor agonists with pancreatitis, pancreatic cancer, and thyroid cancer. However, several meta-analyses failed to confirm a cause-effect relation between GLP-1 receptor agonists and the development of these adverse effects. One benefit of GLP-1 receptor agonists is that they do not cause hypoglycemia when combined with metformin or thiazolidinediones, but the dose of concomitant sulphonylurea or insulin may have to be decreased to reduce the risk of hypoglycemic episodes. On the other hand, several case reports have linked the use of these drugs, mainly exenatide, with the occurrence of acute kidney injury, primarily through hemodynamic derangement due to nausea, vomiting, and diarrhea. The most common symptoms associated with the use of GLP-1 receptor agonists are gastrointestinal symptoms, mainly nausea. Other common adverse effects include injection site reactions, headache, and nasopharyngitis, but these effects do not usually result in discontinuation of the drug. Current evidence shows that GLP-1 receptor agonists have no negative effects on the cardiovascular risk of patients with T2D. Thus, GLP-1 receptor agonists appear to have a favorable safety profile, but ongoing trials will further assess their cardiovascular effects. The aim of this review is to analyze critically the available data regarding adverse events of GLP-1 receptor agonists in different anatomic systems published in Pubmed and Scopus. Whenever possible, certain differences between GLP-1 receptor agonists are described. The review also provides the reader with structured data that compare the rates of the most common adverse effects for each of the various GLP-1 receptor agonists.

Systemic Allergic Reaction to the GLP-1 Receptor Agonist Exenatide

Objective: To report a case of systemic hypersensitivity to the glucagon-like peptide-1 (GLP-1) receptor agonist exenatide used in diabetes care to provide significant information within the context of postmarketing safety surveillance of this new drug class. Case Summary: We report on a 52-year-old male with insufficiently controlled diabetes. GLP-1 agonist treatment was indicated and the patient was started on 5 to 10 µg exenatide (Byetta) twice daily, which had to be stopped after 1 month due to intolerable nausea. One year later, an attempt with 0.6 to 1.8 mg liraglutide (Victoza) once daily was well tolerated but lacked efficacy after a few months. Finally, the patient was started on 2 mg exenatide (Bydureon) once weekly. Concomitant treatment included metformine 1000 mg twice daily and candesartan/hydrochlorothiazide (Blopress Plus) 16/12.5 mg once daily. A few hours after the second injection, local urticaria and disseminated pruritus evolved and after the third injection pruritus, urticaria, and shortness of breath developed, which resolved to antihistamines and corticosteroids. Intradermal tests were positive for Byetta (1:1000) and Bydureon (1:100) (both exenatide), while Victoza (liraglutide) was negative (1:10). Specific immunoglobulin E (IgE) to the drugs was not available for testing. Discussion: An objective causality assessment revealed that the adverse effect to exenatide (Bydureon) was probable (Naranjo probability scale: score of 8). Consistency was established through positive skin tests and the biological explanation that the administration of GLP-1 receptor agonists has been associated with antibody formation. Conclusion: Considering emerging use of GLP-1 receptor agonists, systemic hypersensitivity should be recognized as a risk in clinical practice.

Reshaping diabetes care: the fundamental role of dipeptidyl peptidase-4 inhibitors and glucagon-like peptide-1 receptor agonists in clinical practice

OBJECTIVE

To update clinicians on the most recent safety and efficacy data on current incretin-based strategies for the treatment of type 2 diabetes (T2D).

METHODS

Title searches were conducted in the Pubmed database to identify literature pertaining to the safety and efficacy of glucagon-like peptide-1 receptor agonists (GLP-1RAs) and dipeptidyl peptidase-4 (DPP-4) inhibitors. Product-specific title searches included the terms exenatide, liraglutide, linagliptin, saxagliptin, sitagliptin, and vildagliptin.

RESULTS

The recent literature has introduced us to newer DPP-4 inhibitors and longer-acting GLP-1RAs, updated meta-analyses assessing the safety and efficacy of incretin-based therapies, and studies exploring the use of incretin-based treatments in broader clinical settings such as combination therapy with insulin. Meta-analyses have demonstrated placebo-adjusted glycated hemoglobin (HbA1c) reductions of ~1% with GLP-1RAs and 0.6 to 0.8% with DPP-4 inhibitors and have suggested cardioprotective effects such as reduction of cardiovascular events and improvement of lipid profile. As a class, these agents have consistently demonstrated low risks of hypoglycemia relative to other agents.

CONCLUSION

Incretin-based therapies are characterized by an overall favorable safety profile and weight effect, a low risk of hypoglycemia, and clinically meaningful improvements in HbA1c. Based on an expanding and favorable literature describing their use in various patient populations, the guidelines of the American Association of Clinical Endocrinologists and the recently updated guidelines from the American Diabetes Association assign these agents a central role in the treatment of T2D.

Exenatide extended-release: a once weekly treatment for patients with type 2 diabetes

BACKGROUND

This article reviews the clinical efficacy, safety, and patient outcomes literature on the first once weekly treatment for type 2 diabetes mellitus (T2DM), exenatide extended-release (ER).

METHODS

Relevant literature on exenatide ER and T2DM was identified through PubMed database searches from inception until April 2014.

RESULTS

Exenatide ER is the first medication for the treatment of T2DM dosed on a weekly schedule. Exenatide ER is a glucagon-like peptide-1 (GLP-1) receptor agonist, the third to be approved in the US, and is associated with a low risk of hypoglycemia, may result in weight loss, and has proven to be a safe and effective treatment for T2DM. Exenatide ER reduces A1c levels by decreasing fasting and postprandial hyperglycemia. The most common adverse events are gastrointestinal in nature, which are lesser in frequency than those observed with short-acting exenatide. Exenatide ER has been shown to be more effective than exenatide twice daily and slightly less efficacious than liraglutide. Exenatide ER is useful as monotherapy and in combination with other oral antidiabetic drugs.

CONCLUSION

Once weekly treatment options for diabetes such as exenatide ER have the potential to offer substantial convenience for patients who have high medication burden and poor medication adherence.

Antidiabetic agents: past, present and future

Treatment of diabetes mellitus requires, at a certain stage of its course, drug intervention. This article reviews the properties of available antidiabetic medications and highlights potential targets for developing newer and safer drugs. Antidiabetic agents are grouped in the article as parts I, II and III according to the history of development. Part I groups early developed drugs, during the 20th century, including insulin, sulfonylureas, the metiglinides, insulin sensitizers, biguanides and α-glucosidase inhibitors. Part II groups newer drugs developed during the early part of the 21st century, the past decade, including GLP-1 analogs, DPP-VI inhibitors, amylin analogs and SGLT2 inhibitors. Part III groups potential targets for future design of newer antidiabetic agents with less adverse effects than the currently available antidiabetic drugs.

Clinical relevance of anti-exenatide antibodies: safety, efficacy and cross-reactivity with long-term treatment

AIMS

Antibody formation to therapeutic peptides is common. This analysis characterizes the time-course and cross-reactivity of anti-exenatide antibodies and potential effects on efficacy and safety.

METHODS

Data from intent-to-treat patients in 12 controlled (n = 2225,12-52 weeks) and 5 uncontrolled (n = 1538, up to 3 years) exenatide twice-daily (BID) trials and 4 controlled (n = 653,24-30 weeks) exenatide once weekly (QW) trials with 1 uncontrolled period (n = 128,52 weeks) were analysed.

RESULTS

Mean titres peaked early (6-22 weeks) and subsequently declined. At 30 weeks, 36.7% of exenatide BID patients were antibody-positive; 31.7% exhibited low titres (≤125) and 5.0% had higher titres (≥625). Antibody incidence declined to 16.9% (1.4% higher titre) at 3 years. Similarly, 56.8% of exenatide QW patients were antibody-positive (45.0% low/11.8% higher titre) at 24-30 weeks, declining to 45.4% positive (9.2% higher titre) at 52 weeks. Treatment-emergent anti-exenatide antibodies from a subset of patients tested did not cross-react with human GLP-1 or glucagon. Other than injection-site reactions, adverse event rates in antibody-positive and antibody-negative patients were similar. Efficacy was robust in both antibody-negative and antibody-positive patients (mean HbA1c change: -1.0 and -0.9%, respectively, exenatide BID; -1.6% and -1.3% exenatide QW). No correlation between change in HbA1c and titre was observed for exenatide BID, although mean reductions were attenuated in the small subset of patients (5%) with higher titres. A significant correlation was observed for exenatide QW with no difference between antibody-negative and low-titre patients, but an attenuated mean reduction in the subset of patients (12%) with higher titres.

CONCLUSIONS

Low-titre anti-exenatide antibodies were common with exenatide treatment (32% exenatide BID, 45% exenatide QW patients), but had no apparent effect on efficacy. Higher-titre antibodies were less common (5% exenatide BID, 12% exenatide QW) and within that titre group, increasing antibody titre was associated with reduced average efficacy that was statistically significant for exenatide QW. Other than injection-site reactions, anti-exenatide antibodies did not impact the safety of exenatide.

Long-term effects of adding exenatide to a regimen of metformin and/or sulfonylurea in type 2 diabetes: an uncontrolled, open-label trial in Hungary

BACKGROUND

Studies of the glucagon-like peptide-1 receptor agonists (GLP-1RAs) are needed to determine the durability of metabolic response and tolerability associated with long-term treatment.

OBJECTIVE

The present study was conducted to provide long-term data on glycemic control, weight changes, and tolerability of exenatide 10 μg BID treatment in patients with type 2 diabetes mellitus who have failed to achieve glycemic targets with oral antihyperglycemic medication.

METHODS

In this uncontrolled, open-label trial with treatment up to 156 weeks, patients received exenatide 10 μg BID while continuing treatment with metformin and/or a sulfonylurea (SFU). Intent-to-treat (ITT), 52-, 100-, and 132-week completer populations were defined. Metabolic changes were analyzed in the completer and ITT populations; adverse events (AEs) were summarized in the ITT population. Descriptive statistics were used for absolute and change-from-baseline data. Within-treatment comparisons were conducted using the paired t test.

RESULTS

Of 155 patients in the ITT population (mean [SD]: age, 59 [9] years; 56% female; duration of diabetes, 9.1 [5.9] years; weight, 88.8 [16.5] kg; body mass index, 31.9 [4.7] kg/m(2); hemoglobin [Hb] A(1c), 8.7% [1.2%]), 133, 111, and 103 patients completed 52, 100, and 132 weeks of treatment, respectively. In the ITT population, the mean (SE) change in HbA(1c) from baseline to week 132 was -1.0% (0.10%) (P < 0.0001). In patients completing 52, 100, and 132 weeks, HbA(1c) changes from baseline to end point were -1.3% (0.10%), -1.0% (0.12%), and -1.0 (0.13%) (P < 0.0001), with 40% of patients achieving HbA(1c) <7% at 132 weeks. Patients in the ITT and completer populations experienced mean (SE) weight changes of -3.7 (0.39) kg and -3.9 (0.51) kg (P < 0.0001) at week 132. Improved glycemic control and weight loss occurred in 63% of patients in the completer population at week 132. In addition, 38% of completers at week 132 achieved HbA(1c) <7% without weight gain. No relationship was found between the development of antiexenatide antibodies and change in HbA(1c). The most common AEs were gastrointestinal in nature, reported in 46% of patients and leading to discontinuation in 7 cases. Serious AEs were reported in 26% of patients, and 18% withdrew due to a treatment-emergent AE. Of 24% of patients in whom hypoglycemia was reported, 22% were on SFU or metformin + SFU combination, and 2% were on metformin.

CONCLUSIONS

The findings from this open-label, single-arm study characterized the response to exenatide 10 μg BID for up to 132 weeks. Significant, persistent improvements in HbA(1c) and weight were observed in patients receiving exenatide BID, with reported AEs consistent with those from studies of shorter duration. ClinicalTrials.gov identifier: NCT00044668.

Drugs developed to treat diabetes, liraglutide and lixisenatide, cross the blood brain barrier and enhance neurogenesis

Background

Type 2 diabetes is a risk factor for Alzheimer's disease (AD), most likely linked to an impairment of insulin signalling in the brain. Therefore, drugs that enhance insulin signalling may have therapeutic potential for AD. Liraglutide (Victoza) and exenatide (Byetta) are novel long-lasting analogues of the GLP-1 incretin hormone and are currently available to treat diabetes. They facilitate insulin signalling via the GLP-1 receptor (GLP-1R). Numerous in vitro and in vivo studies have shown that GLP-1 analogues have a range of neuroprotective properties. GLP-1Rs are expressed in the hippocampal area of the brain an important site of adult neurogenesis and maintenance of cognition and memory formation. Therefore, if GLP-1 analogues can cross the blood brain barrier, diffuse through the brain to reach the receptors and most importantly activate them, their neuroprotective effects may be realized.

Results

In the present study we profiled the GLP-1 receptor agonists liraglutide (Victoza) and lixisenatide (Lyxumia). We measured the kinetics of crossing the blood brain barrier (BBB), activation of the GLP-1R by measuring cAMP levels, and physiological effects in the brain on neuronal stem cell proliferation and neurogenesis. Both drugs were able to cross the BBB. Lixisenatide crossed the BBB at all doses tested (2.5, 25, or 250 nmol/kg bw ip.) when measured 30 min post-injection and at 2.5-25 nmol/kg bw ip. 3 h post-injection. Lixisenatide also enhanced neurogenesis in the brain. Liraglutide crossed the BBB at 25 and 250 nmol/kg ip. but no increase was detectable at 2.5 nmol/kg ip. 30 min post-injection, and at 250 nmol/kg ip. at 3 h post-injection. Liraglutide and lixisenatide enhanced cAMP levels in the brain, with lixisenatide being more effective.

Conclusions

Our results suggest that these novel incretin analogues cross the BBB and show physiological activity and neurogenesis in the brain, which may be of use as a treatment of neurodegenerative diseases.

A continued saga of Boc5, the first non-peptidic glucagon-like peptide-1 receptor agonist with in vivo activities

Glucagon-like peptide-1 (GLP-1)-based therapy presents a promising option for treating type 2 diabetes. However, there are several limitations relative to the peptidic GLP-1 mimetics currently on the market or under development. This concern has led to a continued interest in the search for non-peptidic agonists for GLP-1 receptor (GLP-1R). Here, we briefly review the discovery, characterization and current status of a novel class of cyclobutane-derivative-based non-peptidic agonists for GLP-1R, including Boc5 and its newly discovered analogue WB4-24. Although the oral bioavailability of such compounds still poses great challenges, the progress made so far encourages us to identify a truly 'druggable' small molecule agonist for GLP-1R.

Chitosan-based therapeutic nanoparticles for combination gene therapy and gene silencing of in vitro cell lines relevant to type 2 diabetes

Glucagon like peptide 1 (GLP-1), a blood glucose homeostasis modulating incretin, has been proposed for the treatment of type 2 diabetes mellitus (T2DM). However, native GLP-1 pharmacokinetics reveals low bioavailability due to degradation by the ubiquitous dipeptydil peptidase IV (DPP-IV) endoprotease. In this study, the glucosamine-based polymer chitosan was used as a cationic polymer-based in vitro delivery system for GLP-1, DPP-IV resistant GLP-1 analogues and siRNA targeting DPP-IV mRNA. We found chitosans to form spherical nanocomplexes with these nucleic acids, generating two distinct non-overlapping size ranges of 141-283 nm and 68-129 nm for plasmid and siRNA, respectively. The low molecular weight high DDA chitosan 92-10-5 (degree of deacetylation, molecular weight and N:P ratio (DDA-Mn-N:P)) showed the highest plasmid DNA transfection efficiency in HepG2 and Caco-2 cell lines when compared to 80-10-10 and 80-80-5 chitosans. Recombinant native GLP-1 protein levels in media of transfected cells reached 23 ng/L while our DPP-IV resistant analogues resulted in a fivefold increase of GLP-1 protein levels (115 ng/L) relative to native GLP-1, and equivalent to the Lipofectamine positive control. We also found that all chitosan-DPP-IV siRNA nanocomplexes were capable of DPP-IV silencing, with 92-10-5 being significantly more effective in abrogating enzymatic activity of DPP-IV in media of silenced cells, and with no apparent cytotoxicity. These results indicate that specific chitosan formulations may be effectively used for the delivery of plasmid DNA and siRNA in a combination therapy of type 2 diabetes.

Efficacy and Safety of Long-Acting Glucagon-Like Peptide-1 Receptor Agonists Compared with Exenatide Twice Daily and Sitagliptin in Type 2 Diabetes Mellitus: A Systematic Review and Meta-Analysis

Background:

Long-acting glucagon-like peptide-1 receptor agonists (LA-GLP-1RAs) may deliver additional therapeutic benefits over other available incretin-based therapies.

Objective:

To pool results of randomized controlled trials comparing the efficacy and safely of maximum dose LA-GLP-1RAs (liraglutide, exenatide once weekly) with exenatide twice daily and dipeptidyl-peptidase-IV inhibitors in patients with type 2 diabetes.

Methods:

We searched PubMed, Cochrane Central Register of Controlled Trials and Database of Systematic Reviews, EMBASE (all from inception-December 2010), and abstracts presented at the American Diabetes Association Scientific Sessions in 2009 and 2010 to identify English-language reports of studies of at least 24 weeks' duration. The primary endpoint was mean change in hemoglobin A1c (A1C) from baseline to study endpoint. Weighted mean differences or odds ratios and their 95% confidence intervals for each outcome relative to control were calculated as appropriate.

Results:

A1C was reduced favoring LA-GLP-1RAs compared with exenatide twice daily and sitagliptin (weighted mean difference [WMD] –0.47% [95% CI –0.69 to –0.25] and WMD –0.60% [95% CI –0.75 to –0.45], respectively). Odds ratios greater than 1 favored LA-GLP-1RAs for reaching the A1C target goal of less than 7%. Fasting plasma glucose (FPG) was reduced and favored the LA-GLP-1RA–based regimens. Exenatide demonstrated significantly greater reductions in postprandial glucose (PPG) after the morning and evening meals, compared with LA-GLP-1RAs. Body weight was reduced similarly between LA-GLP-1RAs and exenatide, but favored LA-GLP-1RAs in the sitagliptin comparator trials. LA-GLP-1RA therapy was not associated with severe hypoglycemia or acute pancreatitis. Compared with exenatide twice daily, vomiting was reduced significantly with LA-GLP-1RAs (OR 0.55; 95% CI 0.34 to 0.89); there was a trend toward decreased nausea (OR 0.58; 95% CI 0.32 to 1.06) and no difference in the incidence of diarrhea (OR 1.03; 95% CI 0.67 to 1.58).

Conclusions:

Compared with other incretin-based therapies, LA-GLP-1RAs produce greater improvement in A1C and FPG. They provide lesser effect on PPG, similar reduction in body weight, and result in a potentially favorable adverse event profile compared with exenatide twice daily.

Emerging treatment options for type 2 diabetes

Type 2 diabetes mellitus (T2DM) is rapidly increasing in prevalence and is a major public health problem. It is a progressive disease which commonly requires multiple pharmacotherapy. Current options for treatment may have undesirable side effects (particularly weight gain and hypoglycaemia) and contraindications, and little effect on disease progression. Incretin based therapy is one of several newer therapies to improve glycaemia and is available in two different forms, dipeptidyl peptidase-4 (DPP-4) inhibitors and glucagon-like peptide-1 (GLP-1) agonists. Use of these agents results in a 'glucose-dependant' increase in insulin secretion and glucagon suppression resulting in improved glycaemia with low incidence of hypoglycaemia. DPP-4 inhibitors are oral drugs which are weight neutral, while GLP-1 agonists are injected subcutaneously and help promote weight loss while improving glycaemia. GLP-1 agonists have also been shown to increase beta cell mass in rat models. Bariatric surgery is another option for the obese patient with T2DM, with blood glucose normalizing in over half of the patients following surgery. Other therapies in development for the treatment of T2DM include sodium-glucose transporter 2 (SGLT-2) inhibitors, glucagon receptor antagonists, glucokinase activators and sirtuins. In this article, we will review the various existing and emerging treatment options for T2DM.