Glucagon-like peptide-1 analogs: Miracle drugs are blooming?

Glucagon-like peptide-1 (GLP-1), secreted by L cells in the small intestine, assumes a central role in managing type 2 diabetes mellitus (T2DM) and obesity. Its influence on insulin secretion and gastric emptying positions it as a therapeutic linchpin. However, the limited applicability of native GLP-1 stems from its short half-life, primarily due to glomerular filtration and the inactivating effect of dipeptidyl peptidase-IV (DPP-IV). To address this, various structural modification strategies have been developed to extend GLP-1's half-life. Despite the commendable efficacy displayed by current GLP-1 receptor agonists, inherent limitations persist. A paradigm shift emerges with the advent of unimolecular multi-agonists, such as the recently introduced tirzepatide, wherein GLP-1 is ingeniously combined with other gastrointestinal hormones. This novel approach has captured the spotlight within the diabetes and obesity research community. This review summarizes the physiological functions of GLP-1, systematically explores diverse structural modifications, delves into the realm of unimolecular multi-agonists, and provides a nuanced portrayal of the developmental prospects that lie ahead for GLP-1 analogs.

A long-acting GDF15 analog causes robust, sustained weight loss and reduction of food intake in an obese nonhuman primate model

Growth Differentiation Factor-15 (GDF15) is a circulating polypeptide linked to cellular stress and metabolic adaptation. GDF15's half-life is ~3 h and activates the glial cell line-derived neurotrophic factor family receptor alpha-like (GFRAL) receptor expressed in the area postrema. To characterize sustained GFRAL agonism on food intake (FI) and body weight (BW), we tested a half-life extended analog of GDF15 (Compound H [CpdH]) suitable for reduced dosing frequency in obese cynomolgus monkeys. Animals were chronically treated once weekly (q.w.) with CpdH or long-acting GLP-1 analog dulaglutide. Mechanism-based longitudinal exposure-response modeling characterized effects of CpdH and dulaglutide on FI and BW. The novel model accounts for both acute, exposure-dependent effects reducing FI and compensatory changes in energy expenditure (EE) and FI occurring over time with weight loss. CpdH had linear, dose-proportional pharmacokinetics (terminal half-life ~8 days) and treatment caused exposure-dependent reductions in FI and BW. The 1.6 mg/kg CpdH reduced mean FI by 57.5% at 1 week and sustained FI reductions of 31.5% from weeks 9-12, resulting in peak reduction in BW of 16 ± 5%. Dulaglutide had more modest effects on FI and peak BW loss was 3.8 ± 4.0%. Longitudinal modeling of both the FI and BW profiles suggested reductions in BW observed with both CpdH and dulaglutide were fully explained by exposure-dependent reductions in FI without increase in EE. Upon verification of the pharmacokinetic/pharmacodynamic relationship established in monkeys and humans for dulaglutide, we predicted that CpdH could reach double digit BW loss in humans. In summary, a long-acting GDF15 analog led to sustained reductions in FI in overweight monkeys and holds potential for effective clinical obesity pharmacotherapy.

Design of a Dual Agonist of Exendin-4 and FGF21 as a Potential Treatment for Type 2 Diabetes Mellitus and Obesity

Background

Fibroblast growth factor 21 (FGF21) is a metabolic, endocrine hormone regulating insulin sensitivity, energy expenditure, and lipid metabolism. It has significant potential as a therapeutic drug for treating type 2 diabetes and obesity. However, the clinical efficacy of FGF21 analogs is limited due to their instability and short half-life. Glucagon-like peptide 1 (GLP-1) receptor agonists have been recognized as effective medications for type 2 diabetes mellitus and obesity over the past two decades.

Methods

This study designed a new long-acting dual-agonist, exendin-4/FGF21, utilizing albumin-binding-designed ankyrin repeat proteins (DARPins) as carriers. The purified fusion proteins were subcutaneously injected into mice for pharmacokinetic and biological activity studies.

Results

Ex-DARP-FGF21 had a high binding affinity for human serum albumin (HSA) in vitro and a prolonged half-life of 27.6 hours in vivo. Bioactivity results reveal that Ex-DARP-FGF21 significantly reduced blood glucose levels in healthy mice. Moreover, compared to Ex-DARP alone, the Ex-DARP-FGF21 dual agonist displayed enhanced blood glucose lowering bioactivity and superior body weight management in the diet-induced obesity (DIO) mouse model.

Conclusions

These results indicate that the long-acting dual agonist of exendin-4 and FGF21 holds considerable potential as a treatment for type 2 diabetes mellitus (T2DM) and obesity in the future.

Glucagon-Like Peptide-1 Receptor Agonist Use in People Living with Type 2 Diabetes Mellitus and Chronic Kidney Disease: A Narrative Review of the Key Evidence with Practical Considerations

Glucagon-like peptide-1 receptor agonists (GLP-1 RAs) are incretin-mimetic agents that are effective adjuncts in the treatment of diabetes. This class of medications is also associated with promoting weight loss and a low risk of hypoglycemia, and some have been shown to be associated with a significant reduction of major cardiovascular events. Mounting evidence suggests that GLP-1 RAs have benefits beyond reducing blood glucose that include improving kidney function in people living with type 2 diabetes mellitus (T2DM) and chronic kidney disease (CKD), a common microvascular complication of T2DM. Several large clinical studies, the majority of which are cardiovascular outcome trials, indicate that GLP-1 RA therapy is safe and tolerable for people living with T2DM and compromised renal function, and also suggest that GLP-1 RAs may have renoprotective properties. Although evidence from clinical trials has shown GLP-1 RAs to be safe and efficacious in people living with T2DM and renal impairment, their use is uncommon in this patient population. With continuing developments in the field of GLP-1 RA therapy, it is important for physicians to understand the benefits and practical use of GLP-1 RAs, as well as the clinical evidence, in order to achieve positive patient outcomes. Here, we review evidence on GLP-1 RA use in people living with T2DM and CKD and summarize renal outcomes from clinical studies. We provide practical considerations for GLP-1 RA use to provide an added benefit to guide treatment in this high-risk patient population.

Albumin-binding domain extends half-life of glucagon-like peptide-1

Glucagon-like peptide-1 (GLP-1) is considered to be a promising peptide for the treatment of type 2 diabetes mellitus (T2DM). However, the extremely short half-life of GLP-1 limits its clinical application. Albumin-binding domain (ABD) with high affinity for human serum albumin (HSA) has been used widely for half-life extension of therapeutic peptides and proteins. In the present study, novel GLP-1 receptor agonists were designed by genetic fusion of GLP-1 to three kinds of ABDs with different affinities for HSA: GA3, ABD035 and ABDCon. The bioactivities and half-lives of ABD-fusion GLP-1 proteins with different types and lengths of linkers were investigated in vitro and in vivo. The results demonstrated that ABD-fusion GLP-1 proteins could bind to HSA with high affinity. The blood glucose-lowering effect of GLP-1 was significantly improved and sustained by fusion to ABD. Meanwhile, the fusion proteins significantly inhibited food intake, which was beneficial for T2DM and obesity treatment. The half-life of GLP-1 was substantially extended by virtue of ABD. The in vivo results also showed that a longer linker inserted between GLP-1 and ABD resulted in a higher blood glucose-lowering effect. The fusion proteins generated by fusion of GLP-1 to GA3, ABD035 and ABDCon exhibited similar bioactivities and pharmacokinetics in vivo. These findings demonstrate that ABD-fusion GLP-1 proteins retain the bioactivities of natural GLP-1 and can be further developed for T2DM treatment and weight loss. It also indicates that the ABD-fusion strategy can be generally applicable to any peptide or protein, to improve pharmacodynamic and pharmacokinetic properties.

Recent Advances in Half-life Extension Strategies for Therapeutic Peptides and Proteins

Peptides and proteins are two classes of molecules with attractive possibilities for therapeutic applications. However, the bottleneck for the therapeutic application of many peptides and proteins is their short halflives in vivo, typically just a few minutes to hours. Half-life extension strategies have been extensively studied and many of them have been proven to be effective in the generation of long-acting therapeutics with improved pharmacokinetic and pharmacodynamic properties. In this review, we summarize the recent advances in half-life extension strategies, illustrate their potential applications and give some examples, highlighting the strategies that have been used in approved drugs and for drugs in clinical trials. Meanwhile, several novel strategies that are still in the process of discovery or at a preclinical stage are also introduced. In these strategies, the two most frequently used half-life extension methods are the reduction in the rate of renal clearance or the exploitation of the recycling mechanism of FcRn by binding to the albumin or IgG-Fc. Here, we discuss half-life extension strategies of recombinant therapeutic protein via genetic fusion, rather than chemical conjugation such as PEGylation. With the rapid development of genetic engineering and protein engineering, novel strategies for half-life extension have been emerged consistently. Some of these will be evaluated in clinical trials and may become viable alternatives to current strategies for making next-generation biodrugs.

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.

C-terminal site-specific PEGylated Exendin-4 analog: A long-acting glucagon like Peptide-1 receptor agonist, on glycemic control and beta cell function in diabetic db/db mice

PEG modification is a common clinical strategy for prolonging the half-life of therapeutic proteins or polypeptides. In a previous work, we have successfully synthesized PEG-modified Exendin-4 (PE) by conjugating a 20 kDa PEG to the C-terminal of Exendin-4. Then, we introduced an integrative characterization for PE to evaluate its hypoglycemic activity and pharmacokinetic properties. The normoglycemic efficacies and therapeutic activity of PE were investigated in db/db mice. The hypoglycemic time after single administration of PE on db/db mice was prolonged from 8.4 h to 54.9 h. In multiple treatment with PE, the fasting blood glucose in various PE dosages (50, 150, and 250 nmol/kg) were remarkably reduced, and the glycosylated hemoglobin level was decreased to 2.0%. When the in vivo single- and multiple-dose pharmacokinetics of PE were examined in Sprague-Dawley rats, the half-life was prolonged to 31.7 h, and no accumulation effect was observed. Overall, this study provided a novel promising therapeutic approach to improving glucose-controlling ability and extending half-life without accumulation in vivo for long-acting treatment of type-2 diabetes.

Improved glycemic control with once-weekly dulaglutide in addition to insulin therapy in type 2 diabetes mellitus patients on hemodialysis evaluated by continuous glucose monitoring

AIMS

To evaluate the efficacy and safety of adding once-weekly dulaglutide to insulin therapy in type 2 diabetes mellitus (T2DM) patients on hemodialysis.

METHODS

Fifteen insulin-treated T2DM patients on hemodialysis were enrolled. Continuous glucose monitoring was performed before (1st hospitalization) and after the fifth dulaglutide administration (2nd hospitalization). The insulin dose was reduced after the first administration of dulaglutide (1st hospitalization day 6). Parameters of glycemic control were compared on 1st hospitalization days 4-5, 2nd hospitalization days 3-4, and days 6-7.

RESULTS

The median total daily insulin dose was reduced significantly from 12 (12-25) to 0 (0-12) U (p < 0.0001) after treatment with dulaglutide. Mean glucose level on 2nd hospitalization days 3-4 significantly decreased and that on days 6-7 tended to decrease compared with that on 1st hospitalization days 4-5 (median, 8.2 to 6.7 mmol/L, P = 0.006 and 8.2 to 6.9 mmol/L, P = 0.053, respectively). %CV of glucose levels decreased significantly after dulaglutide administration (28.1 to 19.8, P = 0.003 and 28.1 to 21.0, P = 0.019). However, the incidence of hypoglycemia remained unchanged.

CONCLUSIONS

Dulaglutide may improve glycemic control and excursion and allow total daily insulin to be reduced without increasing the risk of hypoglycemia in T2DM patients on hemodialysis.

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.

Pharmacological management of type 2 diabetes: what's new in 2017?

INTRODUCTION

Novelties in the management of type 2 diabetes are dominated by the commercialisation of new glucose-lowering agents, which offer alternatives to older antidiabetic medications, and by the publication of several prospective placebo-controlled outcome trials, which demonstrated not only cardiovascular safety but also cardiovascular and renal protection with some new medications. Areas covered: Updates regarding the use of glucose-lowering agents are discussed from a clinical point of view. Some new viewpoints concern older antidiabetic agents such as metformin, sulfonylureas and glitazones whose benefit-risk balance has been revisited, especially in high risk patients. The recent data regarding DPP-4 inhibitors (gliptins) focused on the safety profile of this pharmacological class, including in patients with impaired renal function. The highlight concerns the cardiovascular (and renal) protection by some GLP-1 receptor agonists (liraglutide, semaglutide) and SGLT2 inhibitors (empagliflozin, canagliflozin) in patients with high cardiovascular risk. Finally, efficacy and safety of new combinations and advances in insulin therapy will be briefly discussed. Expert commentary: The recent data from randomized controlled trials, meta-analyses and observational real-life studies should trigger a revision of the algorithm for the treatment of hyperglycemia in type 2 diabetes, especially in patients with high cardiovascular and/or renal risk.

DMT efficiently inhibits hepatic gluconeogenesis by regulating the Gαq signaling pathway

Type 2 diabetes mellitus (T2DM) is a chronic metabolic disease with complicated pathogenesis and targeting gluconeogenesis inhibition is a promising strategy for anti-diabetic drug discovery. G protein-coupled receptors (GPCRs) are classified as distinct families by heterotrimeric G proteins, primarily including Gαs, Gαi and Gαq. Gαs-coupled GPCRs function potently in the regulation of hepatic gluconeogenesis by activating cyclic adenosine monophosphate (cAMP)/protein kinase A (PKA) pathway and Gαi-coupled GPCRs exhibit inhibitory effect on adenylyl cyclase and reduce intracellular cAMP level. However, little is known about the regulation of Gαq-coupled GPCRs in hepatic gluconeogenesis. Here, small-molecule 2-(2,4-dimethoxy-3-methylphenyl)-7-(thiophen-2-yl)-9-(trifluoromethyl)-2,3-dihydropyrido[3',2':4,5]thieno[3,2-d]pyrimidin-4(1H)-one (DMT) was determined to suppress hepatic glucose production and reduce mRNA levels of gluconeogenic genes. Treatment of DMT in db/db mice decreased fasting blood glucose and hemoglobin A1C (HbA1c) levels, while improved glucose tolerance and pyruvate tolerance. Mechanism study demonstrated that DMT-inhibited gluconeogenesis by regulating the Gαq/phospholipase C (PLC)/inositol-1,4,5-triphosphate receptor (IP3R)-mediated calcium (Ca²⁺)/calmodulin (CaM)/phosphatidylinositol-4,5-bisphosphate 3-kinase (PI3K)/protein kinase B (AKT)/forkhead box protein O1 (FOXO1) signaling pathway. To our knowledge, DMT might be the first reported small molecule able to suppress hepatic gluconeogenesis by regulating Gαq signaling, and our current work has also highlighted the potential of DMT in the treatment of T2DM.

The albumin-exendin-4 recombinant protein E2HSA improves glycemic control and β-cell function in spontaneous diabetic KKAy mice

BACKGROUND

E2HSA is a genetic fusion protein that consists of two tandem exendin-4 molecules that are covalently bonded to recombinant human serum albumin via a peptide linker. Previous studies have demonstrated that E2HSA significantly decreased blood glucose levels, improved β-cell function and promoted β-cell proliferation in diabetic db/dB mice. This study aimed to evaluate the benefits of E2HSA on glucose and lipid metabolism in a spontaneous diabetes animal model, KKAy mice.

METHODS

E2HSA was acutely administered at doses of 1, 3 and 9 mg/kg by subcutaneous injection in diabetic KKAy mice with exendin-4 (2 μg/kg) as a positive reference, and then the non-fasting blood glucose and food intake levels were dynamically monitored. In addition, different doses of E2HSA were injected once daily, as well as with exendin-4 twice daily, for 7 weeks to evaluate the effect on glucose and lipid metabolism, as well as the body weight, food and water intake.

RESULTS

Single injection of E2HSA decreased non-fasting blood glucose and food intake levels in a dose-dependent manner for 4 days and 2 days, respectively. Repeated injections with E2HSA significantly decreased variations in blood glucose levels with a reduction of HbA1c levels by 1.6% at a 9 mg/kg dose, simultaneously increased fasting blood insulin levels, inhibited fasting blood glucagon levels, improved the impaired oral glucose tolerance and enhanced glucose infusion rate, which is the gold standard for evaluating β-cell function. Moreover, repeated injections with E2HSA also ameliorated the dyslipidemia and reduced body weight, food and water intake in diabetic KKAy mice.

CONCLUSIONS

E2HSA significantly reduced blood glucose levels over a prolonged duration, enhanced β-cell function, and ameliorated dyslipidemia and obesity in diabetic KKAy mice. Thus, E2HSA may be a new candidate for the treatment of type 2 diabetes.

Investigational glucagon-like peptide-1 agonists for the treatment of obesity

INTRODUCTION

Obesity is a worldwide problem predisposing to type 2 diabetes mellitus (T2DM), hypertension, cardiovascular disease, cancer and other comorbidities. Lifestyle modification is the first line intervention but adjunctive pharmacotherapy is often required. The GLP-1 receptor agonists (GLP-1RAs) were developed primarily for T2DM and they also reduce body weight. Liraglutide was approved for the treatment of obesity and other GLP-1RAs are likely to be suitable for this indication.

AREAS COVERED

This review describes the GLP-1RAs that have been approved for the treatment of T2DM as potential candidates for the treatment of obesity and the new agents currently under development which may have advantages in patient adherence.

EXPERT OPINION

The GLP-1RAs offer a welcome addition to obesity pharmacotherapy. They appear to be free of serious adverse effects although uncertainty remains about possible risks of pancreatitis and neoplasms. However, they have frequent gastrointestinal side effects, particularly nausea, which limits their tolerability. Cardiovascular outcome studies in T2DM support their use and this is likely to increase in both T2DM and obesity. Other GLP-1RAs which can be given by subcutaneous injection once weekly or less frequently or by oral administration would have advantages especially if nausea is less frequent than with liraglutide.

Lixisenatide improves glycemic outcomes of Japanese patients with type 2 diabetes: a meta-analysis

BACKGROUND

The GetGoal-L-Asia and -S trials were multi-center trials conducted in 4 and 16 countries, respectively including Japan that evaluated the efficacy and safety of lixisenatide add-on treatment vs. placebo among patients with type 2 diabetes. The aims of this study were to determine the efficacy and safety of lixisenatide add-on treatment among Japanese patient groups.

METHODS

All Japanese intent-to-treat patients with baseline and endpoint HbA1c measurements were included in the meta-analyses. Subgroup analyses were carried out for patients with low (<8 %) and high (≥8 %) baseline HbA1c levels, low (<25 kg/m(2)) and high (≥25 kg/m(2)) baseline body mass index (BMI), short (<10 years) and long (≥10 years) durations of diabetes, and for those <65 and ≥65 years of age.

RESULTS

The overall study population of Japanese type 2 diabetes patients included 143 patients (mean age: 59.0 years; 35 % female) treated with lixisenatide and 136 patients treated with placebo (mean age: 57.8 years; 32 % female). Among the subgroups, lixisenatide treatment vs. placebo was associated with greater change in HbA1c (Low HbA1c -0.80 %, p < 0.0001; High HbA1c -1.19 %, p < 0.0001; low BMI -0.88 %, p < 0.0001; high BMI -1.28 %, p < 0.0001; short diabetes duration -1.28 %, p < 0.0001; long diabetes duration -0.93 %, p < 0.0001; <65 years: -1.00 %, p < 0.0001; ≥65 years -1.24 %, p < 0.0001). Additionally, among the subgroups, lixisenatide treatment vs. placebo was associated with greater change in post-prandial glucose.

CONCLUSIONS

For Japanese type 2 diabetes patients lixisenatide may be an efficacious and safe add-on therapy leading to improved glycemic outcomes. GetGoal-L-Asia NCT01169779 GetGoal-S NCT00713830.