Neoglycolipids for Prolonging the Effects of Peptides: Self-Assembling Glucagon-like Peptide 1 Analogues with Albumin Binding Properties and Potent in Vivo Efficacy.

Novel principles for optimizing the properties of peptide-based drugs are needed in order to leverage their full pharmacological potential. We present the design, synthesis, and evaluation of a library of neoglycolipidated glucagon-like peptide 1 (GLP-1) analogues, which are valuable drug candidates for treatment of type 2 diabetes and obesity. Neoglycolipidation of GLP-1 balanced the lipophilicity, directed formation of soluble oligomers, and mediated albumin binding. Moreover, neoglycolipidation did not compromise bioactivity, as in vitro potency of neoglycolipidated GLP-1 analogues was maintained or even improved compared to native GLP-1. This translated into pronounced in vivo efficacy in terms of both decreased acute food intake and improved glucose homeostasis in mice. Thus, we propose neoglycolipidation as a novel, general method for modulating the properties of therapeutic peptides.

GUB06-046, a novel secretin/glucagon-like peptide 1 co-agonist, decreases food intake, improves glycemic control, and preserves beta cell mass in diabetic mice.

Bariatric surgery is currently the most effective treatment of obesity, which has spurred an interest in developing pharmaceutical mimetics. It is thought that the marked body weight-lowering effects of bariatric surgery involve stimulated secretion of appetite-regulating gut hormones, including glucagon-like peptide 1. We here report that intestinal expression of secretin is markedly upregulated in a rat model of Roux-en-Y gastric bypass, suggesting an additional role of secretin in the beneficial metabolic effects of Roux-en-Y gastric bypass. We therefore developed novel secretin-based peptide co-agonists and identified a lead compound, GUB06-046, that exhibited potent agonism of both the secretin receptor and glucagon-like peptide 1 receptor. Semi-acute administration of GUB06-046 to lean mice significantly decreased cumulative food intake and improved glucose tolerance. Chronic administration of GUB06-046 to diabetic db/db mice for 8 weeks improved glycemic control, as indicated by a 39% decrease in fasting blood glucose and 1.6% reduction of plasma HbA1c levels. Stereological analysis of db/db mice pancreata revealed a 78% increase in beta-cell mass after GUB06-046 treatment, with no impact on exocrine pancreas mass or pancreatic duct epithelial mass. The data demonstrate beneficial effects of GUB06-046 on appetite regulation, glucose homeostasis, and beta-cell mass in db/db mice, without proliferative effects on the exocrine pancreas and the pancreatic duct epithelium. Copyright © 2017 European Peptide Society and John Wiley & Sons, Ltd.

Synthesis and evaluation of novel lipidated neuromedin U analogs with increased stability and effects on food intake.

Neuromedin U (NMU) is a 25 amino acid peptide expressed and secreted in the brain and gastrointestinal tract. Data have shown that peripheral administration of human NMU decreases food intake and body weight and improves glucose tolerance in mice, suggesting that NMU receptors constitute a possible anti-diabetic and anti-obesity drug target. However, the clinical use of native NMU is hampered by a poor pharmacokinetic profile. In the current study, we report in vitro and in vivo data from a series of novel lipidated NMU analogs. In vitro plasma stability studies of native NMU were performed to investigate the proteolytic stability and cleavage sites using LC-MS. Native NMU was found to be rapidly cleaved at the C-terminus between Arg(24) and Asn(25) , followed by cleavage between Arg(16) and Gly(17) . Lipidated NMU analogs were generated using solid-phase peptide synthesis, and in vitro potency was investigated using a human embryonic kidney 293-based inositol phosphate accumulation assay. All lipidated analogs had preserved in vitro activity on both NMU receptors with potency improving as the lipidation site was moved away from the receptor-interacting C-terminal octapeptide segment. In vivo efficacy was assessed in lean mice as reduction in food intake after acute subcutaneous administration of 1, 0.3, 0.1, and 0.03 µmol/kg. These lipidated NMU analogs prolonged the anorectic effect of NMU in a dose-dependent manner. This was likely an effect of improved pharmacokinetic properties because of improved vitro plasma stability. Accordingly, the data demonstrate that lipidated NMU analogs may represent drug candidates for the treatment of obesity.

Half-Life Extension of Biopharmaceuticals using Chemical Methods: Alternatives to PEGylation.

Peptides and proteins constitute a vast pool of excellent drug candidates. Evolution has equipped these molecules with superior drug-like properties such as high specificity and potency. However, native peptides and proteins suffer from an inadequate pharmacokinetic profile, and their outstanding pharmacological potential can only be realized if this issue is addressed during drug development. To overcome this challenge, a variety of half-life extension techniques relying on covalent chemical modification have been developed. These methods include PEGylation, fusion to unstructured polypeptide-based PEG mimetics, conjugation of large polysaccharides, native-like glycosylation, lipidation, fusion to albumin or the Fc domain of IgG, and derivatization with bio-orthogonal moieties that direct self-assembly. This review provides an overview of available conjugation chemistries, biophysical properties, and safety data associated with these concepts. Moreover, the effects of these modifications on peptide and protein pharmacokinetics are demonstrated through key examples.

The DPP4 inhibitor linagliptin delays the onset of diabetes and preserves ß-cell mass in non-obese diabetic mice.

Recent data indicate that dipeptidyl peptidase 4 (DPP4) inhibitors have anti-inflammatory and ß-cell-sparing effects in animal models of type 1 diabetes. To evaluate the effects of the DPP4 inhibitor linagliptin on ß-cell mass and insulinitis, we examined the progression of diabetes (blood glucose >11  mmol/l) in non-obese diabetic (NOD) mice with terminal stereological assessment of cellular pancreatic changes. Female NOD mice were fed a normal chow diet or a diet containing linagliptin 0.083  g/kg chow for 60 days. At study end, the incidence of diabetes in linagliptin-treated mice was reduced by almost 50% compared with vehicle (10 of 31 mice vs 18 of 30 mice, P=0.021). The total islet mass and total ß-cell mass, identified by insulin immunoreactivity, were greater in non-diabetic linagliptin-treated mice compared with non-diabetic vehicle-treated mice (P<0.01 for both) but were greatly reduced in diabetic mice irrespective of treatment. No changes were seen in the α, δ and γ endocrine cell pool. Moreover, the total mass of lymphocyte insulinitis was significantly reduced in linagliptin-treated mice compared with vehicle. The data indicate that linagliptin treatment delays the onset of diabetes in NOD mice by protecting ß-cell mass.