Treatment of Type 2 diabetes mellitus based on glucagon-like peptide-1

An imbalanced GLP-1R/GIPR co-agonist peptide with a site-specific N-terminal PEGylation to maximize metabolic benefits

Glycemic and body weight control gained from GLP-1R agonists remains an unmet need for diabetes and obesity treatment, leading to the development of GLP-1R/GIPR co-agonists. An imbalance in GLP-1R/GIPR agonism may extensively maximize the glucose- and weight-lowering effects. Hence, we prepared a potent and imbalanced GLP-1R/GIPR co-agonist, and refined its action time through a site-specific N-terminal PEGylation strategy. The pharmacological efficacy of these resulting long-acting co-agonists was interrogated both in vitro and in vivo. The results showed that peptide 1 possessed potent and imbalanced receptor-stimulating potency favoring GIP activity, but its hypoglycemic action was disrupted probably resulting from its short half-life. After PEGylation to improve the pharmacokinetics, the pharmacological effects were amplified compared to native peptide 1. Among the resulting derivatives, D-5K exhibited significant glycemic, HbA1c, body-weight, and food-intake control, outperforming GLP-1R mono-agonists. Based on its excellent pharmacological profiles, D-5K may hold the great therapeutic potential for diabetes and obesity treatment.

Site-specific N-terminal PEGylation-based controlled release of biotherapeutics: An application for GLP-1 delivery to improve pharmacokinetics and prolong hypoglycemic effects

PEGylation is a well-established technology for half-life extension in drug delivery. In this study, we aimed to develop a site-specific N-terminal PEGylation for biotherapeutics to achieve controlled release, using GLP-1 as a model. An additional threonine was introduced at N-terminal GLP-1. Followed by periodate oxidation, hydrazide-based PEGylation was achieved in a site-selective manner under reductive condition. Two homogenous monovalent mPEG_5k-GLP-1 (peptide 4) and mPEG_20k-GLP-1 (peptide 5) were successfully constructed. After PEGylation, the degradation by DPP-IV and rat plasma was obviously reduced. Their pharmacokinetic performances were enhanced at the expense of impaired GLP-1R stimulating potency, and their hypoglycemic effects were improved in different degrees. Compared with conventional strategies, this approach is devoid of the restriction and alteration of native peptide sequences, and can produce utterly homogenous conjugates with excellent selectivity and efficiency. It provides a practical controlled release approach for peptides by site-specific modification to achieve better pharmacological and therapeutic properties.

Rational design of a GLP-1/GIP/Gcg receptor triagonist to correct hyperglycemia, obesity and diabetic nephropathy in rodent animals

AIMS

To design and screen a potent GLP-1/GIP/Gcg receptors triagonist with therapeutic potential in rodent animals with diabetes and obesity.

MAIN METHODS

First, we obtained a 12-mer dual GIP/Gcg receptor agonist from a large combinatorial peptide library via high-throughput screening technique and then fused to the Exendin (9-39) to generate a potent GLP-1/GIP/Gcg triagonist. Further site fatty chain modification was performed to improve the druggability via enhancing in vivo stability and cyclic half-life. In vitro signaling and functional assays in cell lines expressing each receptor and in vivo efficacy evaluation in rodent model animals with hyperglycemia and obesity were all carefully performed.

KEY FINDINGS

We screened and obtained a potent GLP-1/GIP/Gcg triagonist, termed XFL0, which promotes in vitro GLP-1, GIP, Gcg receptor activation comparable to native GLP-1, GIP and glucagon, respectively. Site-specific fatty acid modification significantly enhanced plasma stability of XFL0 and exhibited no obvious impact on receptor activation. The selected XFL0 conjugates termed XFL6, showed glucose-dependent insulin secretion and improved glucose tolerance by acting on all GLP-1, GIP and Gcg receptors in gene-deficient mice of which the effects were all significantly greater than any single receptor agonist. After chronic treatment in rodent animals with diabetes and obesity, XFL6 potently decreased body weight and food intake, ameliorated the hyperglycemia and hemoglobin A1c levels as well as the lipid metabolism and diabetic nephropathy related disorders.

SIGNIFICANCE

XFL6, as a novel GLP-1/GIP/Gcg receptor triagonist, held potential to deliver outstanding improvement in correcting hyperglycemia, obesity and diabetic nephropathy.

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.