Design of Stapled Oxyntomodulin Analogs Containing Functionalized Biphenyl Cross-Linkers

Stapled peptides as potential therapeutics for diabetes and other metabolic diseases

The field of peptide drug research has experienced notable progress, with stapled peptides featuring stabilized α-helical conformation, emerging as a promising field. These peptides offer enhanced stability, cellular permeability, and binding affinity and exhibit potential in the treatment of diabetes and metabolic disorders. Stapled peptides, through the disruption of protein-protein interactions, present varied functionalities encompassing agonism, antagonism, and dual-agonism. This comprehensive review offers insight into the technology of peptide stapling and targeting of crucial molecular pathways associated with glucose metabolism, insulin secretion, and food intake. Additionally, we address the challenges in developing stapled peptides, including concerns pertaining to structural stability, peptide helicity, isomer mixture, and potential side effects.

How to target membrane proteins for degradation: Bringing GPCRs into the TPD fold

We are now in the middle of a so-called "fourth wave" of drug innovation: multispecific medicines aimed at diseases and targets previously thought to be "undruggable"; by inducing proximity between two or more proteins, for example, a target and an effector that do not naturally interact, such modalities have potential far beyond the scope of conventional drugs. In particular, targeted protein degradation (TPD) strategies to destroy disease-associated proteins have emerged as an exciting pipeline in drug discovery. Most efforts are focused on intracellular proteins, whereas membrane proteins have been less thoroughly explored despite the fact that they comprise roughly a quarter of the human proteome with G-protein coupled receptors (GPCRs) notably dysregulated in many diseases. Here, we discuss the opportunities and challenges of developing degraders for membrane proteins with a focus on GPCRs. We provide an overview of different TPD platforms in the context of membrane-tethered targets, and we present recent degradation technologies highlighting their potential application to GPCRs.

Emerging roles of oxyntomodulin-based glucagon-like peptide-1/glucagon co-agonist analogs in diabetes and obesity

Oxyntomodulin (OXM) is an endogenous peptide hormone secreted from the intestines following nutrient ingestion that activates both glucagon-like peptide-1 (GLP-1) and glucagon receptors. OXM is known to exert various effects, including improvement in glucose tolerance, promotion of energy expenditure, acceleration of liver lipolysis, inhibition of food intake, delay of gastric emptying, neuroprotection, and pain relief. The antidiabetic and antiobesity properties have led to the development of biologically active and enzymatically stable OXM-based analogs with proposed therapeutic promise for metabolic diseases. Structural modification of OXM was ongoing to enhance its potency and prolong half-life, and several GLP-1/glucagon dual receptor agonist-based therapies are being explored in clinical trials for the treatment of type 2 diabetes mellitus and its complications. In the present article, we provide a brief overview of the physiology of OXM, focusing on its structural-activity relationship and ongoing clinical development.

Design of Potent and Proteolytically Stable Biaryl-Stapled GLP-1R/GIPR Peptide Dual Agonists

Recent clinical trials have revealed that the chimeric peptide hormones simultaneously activating glucagon-like peptide-1 receptor (GLP-1R) and glucose-dependent insulinotropic polypeptide receptor (GIPR) demonstrate superior efficacy in glycemic control and body weight reduction, better than those activating the GLP-1R alone. However, the linear peptide-based GLP-1R/GIPR dual agonists are susceptible to proteolytic cleavage by common digestive enzymes present in the gastrointestinal tract and thus not suitable for oral administration. Here, we report the design and synthesis of biaryl-stapled peptides, with and without fatty diacid attachment, that showed potent GLP-1R/GIPR dual agonist activities. Compared to a linear peptide dual agonist and semaglutide, the biaryl-stapled peptides displayed drastically improved proteolytic stability against the common digestive enzymes. Furthermore, two stapled peptides showed excellent efficacy in an oral glucose tolerance test in mice, owing to their potent receptor activity in vitro and good pharmacokinetics exposure upon subcutaneous injection. By exploring a more comprehensive set of biaryl staplers, we expect that this stapling method could facilitate the design of the stapled peptide-based dual agonists suitable for oral administration.

Advances in therapeutic peptides targeting G protein-coupled receptors

Dysregulation of peptide-activated pathways causes a range of diseases, fostering the discovery and clinical development of peptide drugs. Many endogenous peptides activate G protein-coupled receptors (GPCRs) - nearly 50 GPCR peptide drugs have been approved to date, most of them for metabolic disease or oncology, and more than 10 potentially first-in-class peptide therapeutics are in the pipeline. The majority of existing peptide therapeutics are agonists, which reflects the currently dominant strategy of modifying the endogenous peptide sequence of ligands for peptide-binding GPCRs. Increasingly, novel strategies are being employed to develop both agonists and antagonists, to both introduce chemical novelty and improve drug-like properties. Pharmacodynamic improvements are evolving to allow biasing ligands to activate specific downstream signalling pathways, in order to optimize efficacy and reduce side effects. In pharmacokinetics, modifications that increase plasma half-life have been revolutionary. Here, we discuss the current status of the peptide drugs targeting GPCRs, with a focus on evolving strategies to improve pharmacokinetic and pharmacodynamic properties.