Bifunctional PEGylated Exenatide-Amylinomimetic Hybrids to Treat Metabolic Disorders: An Example of Long-Acting Dual Hormonal Therapeutics

Peptide hybrids (phybrids) comprising covalently linked peptide hormones can leverage independent biological pathways for additive or synergistic metabolic benefits. PEGylation of biologics offers enhanced stability, duration, and reduced immunogenicity. These two modalities can be combined to produce long-acting therapeutics with dual pharmacology and enhanced efficacy. Compound <b>10</b> is composed of an exenatide (AC2993) analogue, AC3174, and an amylinomimetic, davalintide (AC2307), with an intervening 40 kD PEG moiety. It displayed dose-dependent and prolonged efficacy for glucose control and body weight reduction in rodents with superior <i>in vitro</i> and <i>in vivo</i> activities compared to those of a side-chain PEGylated phybrid <b>6</b>. In diet-induced obese (DIO) rats, the weight-loss efficacy of <b>10</b> was similar to that of a combination of PEG-parents <b>3</b> and <b>4</b>. A single dose of <b>10</b> elicited sustained body weight reduction in DIO rats for at least 21 days. Compound <b>10</b>’s terminal half-life of ∼27 h should translate favorably to weekly dosing in humans

Hepatic gene expression in <i>P</i>. <i>obesus</i> with NASH.

<p>Gene expression of markers of inflammation and fibrosis in livers of <i>P. obesus</i> with NASH, n = 8–9 per group. *p<0.05, **p<0.005.</p

Improved Glucose Control and Reduced Body Weight in Rodents with Dual Mechanism of Action Peptide Hybrids

<div><p>Combination therapy is being increasingly used as a treatment paradigm for metabolic diseases such as diabetes and obesity. In the peptide therapeutics realm, recent work has highlighted the therapeutic potential of chimeric peptides that act on two distinct receptors, thereby harnessing parallel complementary mechanisms to induce additive or synergistic benefit compared to monotherapy. Here, we extend this hypothesis by linking a known anti-diabetic peptide with an anti-obesity peptide into a novel peptide hybrid, which we termed a phybrid. We report on the synthesis and biological activity of two such phybrids (AC164204 and AC164209), comprised of a glucagon-like peptide-1 receptor (GLP1-R) agonist, and exenatide analog, AC3082, covalently linked to a second generation amylin analog, davalintide. Both molecules acted as full agonists at their cognate receptors <i>in vitro</i>, albeit with reduced potency at the calcitonin receptor indicating slightly perturbed amylin agonism. In obese diabetic <i>Lep^ob/Lep</i>^<i>ob</i> mice sustained infusion of AC164204 and AC164209 reduced glucose and glycated haemoglobin (Hb_A1c) equivalently but induced greater weight loss relative to exenatide administration alone. Weight loss was similar to that induced by combined administration of exenatide and davalintide. In diet-induced obese rats, both phybrids dose-dependently reduced food intake and body weight to a greater extent than exenatide or davalintide alone, and equal to co-infusion of exenatide and davalintide. Phybrid-mediated and exenatide + davalintide-mediated weight loss was associated with reduced adiposity and preservation of lean mass. These data are the first to provide <i>in vivo</i> proof-of-concept for multi-pathway targeting in metabolic disease via a peptide hybrid, demonstrating that this approach is as effective as co-administration of individual peptides.</p> </div

Histopathology of NASH in <i>P. obesus</i>.

<p>Masson's trichrome stained livers at ×400 magnification except F (x40). A: Control group with minimal steatosis and no fibrosis, B: Lipid droplets in most cells, and sinusoidal foamy macrophages (arrows), C: Parenchymal inflammation with neutrophils (arrow), D: Strands of pericellular and perisinusoidal collagen (arrows), E: Fibrous expansion of portal tracts, with oval cells/ductular reaction, F: Distorted architecture, with portal septum formation.</p

PCR primer sequences.

<p>PCR primer sequences.</p

Hepatic lipid species in <i>P. obesus</i>.

<p>Thin layer chromatography analysis of hepatic lipid species in <i>P. obesus</i> fed either the standard diet or cholesterol-supplemented diet. Note that this technique is not quantitative, as equal amounts of lipid were analysed in each lane. CE = cholesterol esters, TAG = triacylglycerides, FFA = free fatty acids, PL = phospholipids.</p

Gene expression in livers of <i>P. obesus</i> fed the cholesterol-supplemented diet, expressed as fold difference relative to animals fed the standard diet.

<p>Gene expression in livers of <i>P. obesus</i> fed the cholesterol-supplemented diet, expressed as fold difference relative to animals fed the standard diet.</p

Phybrid compounds reduced 30 min plasma glucose concentrations similar to GLP-1 receptor agonist (AC3082) in non-diabetic mice, and were insulinotropic in Sprague Dawley rats.

<p>(<b>A</b>) Oral glucose tolerance test (OGTT) of AC3082, AC164204 and AC164209 comparing potency and efficacy of both compounds; (<b>B</b>) intravenous glucose tolerance test (IVGTT) showing glucose-dependent insulinotropism of exenatide, AC164204, and AC164209. </p

Phybrid peptides induced greater weight loss compared to single peptide treatment and improved glycemic control similar to GLP-1 receptor agonism in obese diabetic <i>Lep^ob/Lep</i>^<i>ob</i> mice.

<p>(<b>A</b>) Change in HbA1c, (<b>B</b>) change in plasma glucose, (<b>C</b>) total food intake, expressed as a percentage of vehicle, and (<b>D</b>) change in body weight following subcutaneous peptide infusion in leptin-deficient <i>Lep^ob/Lep</i>^<i>ob</i> mice for 28 days. Groups not sharing the same superscript letter were significantly different from each other (p<0.05).</p

Flowchart of phybrid characterization of receptor activity and <i>in</i><i>vivo</i> efficacy.

<p>After synthesis, the ability of the GLP-1 and amylinomimetic portions of the phybrid to activate their appropriate receptors was assessed: activation of cAMP in cells expressing the GLP-1R or the CT receptor. Acute <i>in </i><i>vivo</i> characteristics of GLP-1 and amylin physiology were then assessed: glucose-lowering in mice for GLP-1 activity, insulin secretion in rats for GLP-1 activity and calcium-lowering in rats for amylin activity. In chronic efficacy models to more accurately gauge the ability of the phybrids to render equal or superior metabolic control relative to mono- or dual-therapy we utilized two models: obese, diabetic mice to assess impact on chronic glucose control, and DIO rats to assess impact on food intake, body weight and body composition.</p