Long-Acting GLP-1 Analogue in V-Shaped Conformation by Terminal Polylysine Modifications

Design and evaluation of GLP-1 receptor G-protein biased agonist with prolonged efficacy on diabetes

AIM

Glucagon-like peptide-1 receptor agonists (GLP-1RAs) have emerged as potent drug development target for treating diabetes and obesity. Here, we designed and evaluated novel long-acting GLP-1R G protein biased agonist with potent clinical application.

MAIN METHODS

GLP-1R G-protein biased sequences were screened via a high-throughput autocrine-based strategy and then fused to Exendin (9-39). These fusion peptides were further performed with site-specific modification. Surface plasmon resonance (SPR) measurements, GLP-1R activation potencies and plasma stability tests were applied to screen optimal candidate. Acute and chronic hypoglycemic and insulinotropic activities of selected agent were evaluated in diabetic and obese rodent animals.

MAIN FINDINGS

AX09 exert highest binding affinities for GLP-1R extracellular domain (GLP-1R ECD). Further in vitro plasma stability and GLP-1R activation assays demonstrated better potency of AX18. Acute pharmacodynamic evaluation of AX18 demonstrated the promising insulinotropic and hypoglycemic activities which were exhibited in a dose-dependent manner. Prolonged hypoglycemic efficacies of AX18 were also observed in both hypoglycemic duration test and multiple oral glucose tolerance tests (OGTTs) in the diabetic mice. Further pharmacokinetic test in cynomolgus monkeys exhibited that the half-life of AX18 was more than 6 days. Once weekly treatment of AX18 in diabetic mice for 8-week achieved significantly improved %HbA1C, insulin resistance, glucose tolerance, β-cells and diabetic retinal injury. Chronic treatment of AX18 in diet-induced obese (DIO) mice also exhibited beneficial efficacies on %HbA1C, inflammation-related factors lowering, and weight gains.

CONCLUSION

AX18, as a novel GLP-1R G protein biased agonist, exhibited potency for treating diabetes mellitus and its complications.

Novel mono-PEGylated dimeric GLP-1 conjugate with enhanced receptor activation and prolonged anti-diabetes efficacies

AIMS

To design and evaluate novel mono-PEGylated dimeric GLP-1 conjugate with enhanced GLP-1 receptor activation and prolonged anti-diabetes efficacies.

MAIN METHODS

All these novel GLP-1 conjugates were produced by using solid-phase synthesis method and further specific cysteine-maleimide modification. In vitro GLP-1R activation assay was performed in CHO cells stably expressing human GLP-1 receptor. The binding affinity for human serum albumin (HSA) in vitro was also conducted using surface plasmon resonance measurement. Subsequently, selected GLP-1 conjugate was subjected to evaluate the acute and chronic efficacies in vivo.

KEY FINDINGS

Four novel glucagon-like peptide-1 (GLP-1) conjugates, termed DIG-1 to DIG-4, were designed and prepared with high purity. Moreover, DIG-1(PEG-5 kDa) and DIG-2 (PEG-10 kDa) exerted ~3-fold and ~2-fold higher potencies of GLP-1R activation than native GLP-1, respectively, and both obviously higher than the DIG-3 (PEG-10 kDa) and DIG-4 (PEG-30 kDa). Then DIG-2 exhibited better in vivo glucose-stabilizing and insulinotropic efficacies than DIG-1 by using multiple oral glucose tests (OGTTs) in SD rats. Furthermore, prolonged glucose-lowering ability of DIG-2 exhibited in hypoglycemic duration test and multiple OGTTs in diabetic db/db mice. Pharmacokinetic data of DIG-2 in cynomolgus monkeys revealed a half-life of ~97.2 h and ~120.4 h after a single subcutaneous (s.c.) administration at doses of 100 and 150 nmol/kg, respectively. Chronic treatment of DIG-2 in db/db mice for consecutive 8-week significantly ameliorate the diabetic symptoms including deteriorative % hemoglobin A1C (HbA1C), glucose tolerance and pancreatic function.

SIGNIFICANCE

DIG-2, as a novel mono-PEGylated dimeric GLP-1 conjugate, holds enhanced receptor activation and prolonged anti-diabetes efficacies.

Drug discovery approaches targeting the incretin pathway

Incretin pathway plays an important role in the development of diabetes medications. Interventions in DPP-4 and GLP-1 receptor have shown remarkable efficacy in experimental and clinical studies and imperatively become one of the most promising therapeutic approaches in the T2DM drug discovery pipeline. Herein, we analyzed the actionmechanismsof DPP-4 and GLP-1 receptor targeting the incretin pathway in T2DM treatment. We gave an insight into the structural requirements for the potent DPP-4 inhibitors and revealed a classification of DPP-4 inhibitors by stressing on the binding modes of these ligands to the enzyme. We then reviewed the drug discovery strategies for the development of peptide and non-peptide GLP-1 receptor agonists (GLP-1 RAs). Furthermore, the drug design strategies for DPP-4 inhibitors and GLP-1R agonists were detailed accurately. This review might provide an efficient evidence for the highly potent and selective DPP-4 inhibitors and the GLP-1 RAs, as novel medicines for patients suffering from T2DM.

Novel nonapeptide GLP (28-36) amide derivatives with improved hypoglycemic and body weight lowering effects

Glucagon-like peptide-1 (GLP-1) has emerged as a major therapeutic target for the treatment of type 2 diabetes. The nonapeptide GLP-1 (28-36) amide is one of the biological C-terminal products of GLP-1 modified by the neutral endopeptidase (NEP) 24.11 with limited hypoglycemic activity. In this study, we focused on the modification of GLP-1 (28-36) amide for the first time and synthesized a series of GLP-1 (28-36) amide analogues. Results of biological activity evaluation in INS-1 cell, STZ-induced diabetic and diet induced obesity (DIO) mice indicated that S3 as a promising candidate to treat type 2 diabetes and obesity.

Revisiting amino acids and peptides as anti-glycation agents

The importance of controlling or preventing protein glycation cannot be overstated and is of prime importance in the treatment of diabetes and associated complications including Alzheimer's disease, cataracts, atherosclerosis, kidney aliments among others. In this respect, simple molecules such as amino acids and peptides hold much promise both in terms of ease and scale-up of synthesis as well as in relation to negligible/low associated toxicity. In view of this, a comprehensive account of literature reports is presented, that documents the anti-glycation activity of natural and non-natural amino acids and peptides. This review also discusses the chemical reactions involved in glycation and the formation of advanced glycation end-products (AGEs) and possible/probable intervention sites and mechanism of action of the reported amino acids/peptides. This aspect of amino acids/peptides adds to their growing importance in medicinal and therapeutic applications.

Nanoparticles induced by embedding self-assembling cassette into glucagon-like peptide 1 for improving in vivo stability

The multiple physiologic characteristics of glucagon-like peptide 1 (GLP-1) make it a promising drug candidate for treating type 2 diabetes mellitus. However, the half-life of GLP-1 is short as a result of degradation by dipeptidyl peptidase IV and renal clearance. Stabilizing GLP-1 is therefore critical for its use in drug development. Self-assembling peptides are a class of peptides that undergo spontaneous assembly into ordered nanostructures. Recently, studies of self-assembling peptides as drug carriers have increased because of their enhanced stability. In the present study, GLP-1 was modified to incorporate the structural characteristics of self-assembling peptides aiming to generate a self-assembling GLP-1 derivative. Receptor binding capacity and insulinotropic effects were measured to investigate the physiologic functions of GLP-1, along with morphologic approaches to observe supramolecular formation on self-assembly at the nano scale. Finally, blood glucose regulation and body weight were monitored after administration of selected derivatives. Our findings revealed that cadyglp1e and cadyglp1m both exhibited improved stability even though different nanoshapes were observed for these two self-assembling peptides. Both cadyglp1e and cadyglp1m retained glucoregulatory activity after insulin stimulation and were potent drug candidates for long-acting GLP-1 derivatives to treat type 2 diabetes mellitus. Our findings support the feasibility of introducing self-assembly functions into peptides with poor stabilities, such as GLP-1.-Li, Y., Cui, T., Kong, X., Yi, X., Kong, D., Zhang, J., Liu, C., Gong, M. Nanoparticles induced by embedding self-assembling cassette into glucagon-like peptide 1 for improving in vivo stability.

Xenopus-derived glucagon-like peptide-1 and polyethylene-glycosylated glucagon-like peptide-1 receptor agonists: long-acting hypoglycaemic and insulinotropic activities with potential therapeutic utilities

BACKGROUND AND PURPOSE

Incretin-based therapies based on glucagon-like peptide-1 (GLP-1) receptor agonists are effective treatments of type 2 diabetes. Abundant research has focused on the development of long-acting GLP-1 receptor agonists. However, all GLP-1 receptor agonists in clinical use or development are based on human or Gila GLP-1. We have identified a potent GLP-1 receptor agonist, xGLP-1B, based on Xenopus GLP-1.

EXPERIMENTAL APPROACH

To further modify the structure of xGLP-1B, alanine scanning was performed to study the structure -activity relationship of xGLP-1B. Two strategies were then employed to improve bioactivity. First, the C-terminal tail of lixisenatide was appended to cysteine-altered xGLP-1B analogues. Second, polyethylene glycol (PEG) chains with different molecular weights were conjugated with the peptides, giving a series of PEGylated conjugates. Comprehensive bioactivity studies of these conjugates were performed in vitro and in vivo.

RESULTS

From the in vitro receptor activation potency and in vivo acute hypoglycaemic activities of conjugates 25 -36, 33 was identified as the best candidate for further biological assessments. Conjugate 33 exhibited prominent hypoglycaemic and insulinotropic activities, as well as improved pharmacokinetic profiles in vivo. The prolonged antidiabetic duration of 33 was further confirmed by pre-oral glucose tolerance tests (OGTT) and multiple OGTT. Furthermore, chronic treatment of db/db mice with 33 ameliorated non-fasting blood glucose and insulin levels, reduced HbA1c values and normalized their impaired glucose tolerance. Importantly, no in vivo toxicity was observed in mice treated with 33.

CONCLUSIONS AND IMPLICATIONS

Peptide 33 is a promising long-acting type 2 diabetes therapeutic deserving further investigation.

A novel glucagon-like peptide-1/glucagon receptor dual agonist exhibits weight-lowering and diabetes-protective effects

Glucagon has plenty of effects via a specific glucagon receptor(GCGR) like elevating the blood glucose, improving fatty acids metabolism, energy expenditure and increasing lipolysis in adipose tissue. The most important role of glucagon is to regulate the blood glucose, but the emergent possibilities of hyperglycaemia is exist. Glucagon could also slightly activate glucagon-like peptide-1 receptor(GLP-1R), which lead to blood glucose lowering effect. This study aims to erase the likelihood of hyperglycaemia and to remain the inherent catabolic effects through improving GLP-1R activation and deteriorating GCGR activation so as to lower the bodyweight and show diabetes-protective effects. Firstly, twelve cysteine modified GLP-1/GCGR dual agonists were synthesized (1-12). Then, the GLP-1R/GCGR mediated activation and biological activity in normal ICR mice were comprehensively performed. Compounds substituted by cysteine at positions 22, 23 and 25 in glucagon were observed to be better regulators of the body weight and blood glucose. To prolong the half-lives of derivatives, various fatty side chain maleimides were modified to optimal glucagon analogues. Laurate maleimide conjugate 4d was the most potent. Administration of 1000 nmol/kg 4d once every two days for a month normalized adiposity and glucose tolerance in diet-induced obese (DIO) mice. Improvements in plasma metabolic parameters including insulin, leptin, and adiponectin were observed. These studies suggest that compound 4d behaves well in lowering body weight and maintaining energy expenditure without a chance of hyperglycaemia, 4d has strong clinical potential as an efficient GLP-1/GCGR agonist in the prevention and treatment of obesity and dyslipidemia.

Novel application of hydrophobin in medical science: a drug carrier for improving serum stability

Multiple physiological properties of glucagon-like peptide-1 (GLP-1) ensure that it is a promising drug candidate for the treatment of type 2 diabetes. However, the in vivo half-life of GLP-1 is short because of rapid degradation by dipeptidyl peptidase-IV (DPP-IV) and renal clearance. The poor serum stability of GLP-1 has significantly limited its clinical utility, although many studies are focused on extending the serum stability of this molecule. Hydrophobin, a self-assembling protein, was first applied as drug carrier to stabilize GLP-1 against protease degradation by forming a cavity. The glucose tolerance test clarified that the complex retained blood glucose clearance activity for 72 hours suggesting that this complex might be utilized as a drug candidate administered every 2–3 days. Additionally, it was found that the mutagenesis of hydrophobin preferred a unique pH condition for self-assembly. These findings suggested that hydrophobin might be a powerful tool as a drug carrier or a pH sensitive drug-release compound. The novel pharmaceutical applications of hydrophobin might result in future widespread interest in hydrophobin.