Clinical review of the efficacy and safety of oral semaglutide in patients with type 2 diabetes considered for injectable GLP-1 receptor agonist therapy or currently on insulin therapy

Potential of Nuclear Imaging Techniques to Study the Oral Delivery of Peptides

Peptides are small biomolecules known to stimulate or inhibit important functions in the human body. The clinical use of peptides by oral delivery, however, is very limited due to their sensitive structure and physiological barriers present in the gastrointestinal tract. These barriers can be overcome with chemical and mechanical approaches protease inhibitors, permeation enhancers, and polymeric encapsulation. Studying the success of these approaches pre-clinically with imaging techniques such as fluorescence imaging (IVIS) and optical microscopy is difficult due to the lack of in-depth penetration. In comparison, nuclear imaging provides a better platform to observe the gastrointestinal transit and quantitative distribution of radiolabeled peptides. This review provides a brief background on the oral delivery of peptides and states examples from the literature on how nuclear imaging can help to observe and analyze the gastrointestinal transit of oral peptides. The review connects the fields of peptide delivery and nuclear medicine in an interdisciplinary way to potentially overcome the challenges faced during the study of oral peptide formulations.

Semaglutide for the treatment of type 2 Diabetes Mellitus: A systematic review and network meta-analysis of safety and efficacy outcomes

BACKGROUND AND AIMS

To assess the safety and efficacy of semaglutide compared with placebo and other anti-hyperglycaemic agents in type 2 diabetes (T2DM).

METHODS

We searched PubMed, Scopus, Web of Science, and Cochrane library for relevant randomized controlled trials (RCTs). A network meta-analysis was conducted to compare different doses, durations, and interventions in T2DM. We presented results as mean difference (MD) or relative risk (RR) and 95% confidence interval (CI).

RESULTS

Twenty-six included RCTs studied different doses of subcutaneous (SC) and oral semaglutide, tirzepatide, liraglutide, sitagliptin, canagliflozin, and empagliflozin compared with placebo. Tirzepatide showed the highest efficacy, however, it was comparable to semaglutide. SC semaglutide 1 mg once-weekly showed higher reduction in HbA_1c (MD = -1.72, 95% CI [-2.32; -1.12]), and fasting blood glucose (MD = -1.93, 95% CI [-2.81; -1.04]) versus placebo at 30 weeks and other timepoints. Adverse events (ADs) were comparable to placebo with oral and SC semaglutide, oral sitagliptin, SC liraglutide, and oral empagliflozin at most timepoints. However, SC semaglutide 0.8 mg and tirzepatide 10 mg groups had the highest gastrointestinal adverse events.

CONCLUSION

Tirzepatide, oral and SC semaglutide has a favourable efficacy in treating T2DM. The adverse events were comparable to placebo; however, gastrointestinal adverse events were highly recorded in tirzepatide, oral and SC semaglutide groups.

Structural basis of peptidomimetic agonism revealed by small- molecule GLP-1R agonists Boc5 and WB4-24

Glucagon-like peptide-1 receptor (GLP-1R) agonists are efficacious in the treatment of type 2 diabetes and obesity. While most clinically used agents require subcutaneous injection, Boc5, as the first orthosteric nonpeptidic agonist of GLP-1R, suffers from poor oral bioavailability that hinders its therapeutic development. The cryoelectron microscopy structures of Boc5 and its closely related analog WB4-24 presented here reveal a binding pocket located deeper in the transmembrane domain for nonpeptidic GLP-1R agonists. Molecular interaction with this site may facilitate a broad spectrum of in vivo agonistic activities, in addition to that with the upper helical bundles presumably responsible for biased signaling. These findings deepen our understanding of peptidomimetic agonism at GLP-1R and may help design better drug leads against this important target.

Glucagon-like peptide-1 receptor (GLP-1R) agonists are effective in treating type 2 diabetes and obesity with proven cardiovascular benefits. However, most of these agonists are peptides and require subcutaneous injection except for orally available semaglutide. Boc5 was identified as the first orthosteric nonpeptidic agonist of GLP-1R that mimics a broad spectrum of bioactivities of GLP-1 in vitro and in vivo. Here, we report the cryoelectron microscopy structures of Boc5 and its analog WB4-24 in complex with the human GLP-1R and G_s protein. Bound to the extracellular domain, extracellular loop 2, and transmembrane (TM) helices 1, 2, 3, and 7, one arm of both compounds was inserted deeply into the bottom of the orthosteric binding pocket that is usually accessible by peptidic agonists, thereby partially overlapping with the residues A8 to D15 in GLP-1. The other three arms, meanwhile, extended to the TM1-TM7, TM1-TM2, and TM2-TM3 clefts, showing an interaction feature substantially similar to the previously known small-molecule agonist LY3502970. Such a unique binding mode creates a distinct conformation that confers both peptidomimetic agonism and biased signaling induced by nonpeptidic modulators at GLP-1R. Further, the conformational difference between Boc5 and WB4-24, two closed related compounds, provides a structural framework for fine-tuning of pharmacological efficacy in the development of future small-molecule therapeutics targeting GLP-1R.

Glucagon-Like Peptide 1 Receptor Agonists – Potential Game Changers in the Treatment of Glaucoma?

Glaucoma is a common ocular neurodegenerative disease characterized by the progressive loss of retinal ganglion cells and their axons. It is the most common cause of irreversible blindness. With an increasing number of glaucoma patients and disease progression despite treatment, it is paramount to develop new and effective therapeutics. Emerging new candidates are the receptor agonists of the incretin hormone glucagon-like-peptide-1 (GLP-1), originally used for the treatment of diabetes. GLP-1 receptor (GLP-1R) agonists have shown neuroprotective effects in preclinical and clinical studies on neurodegenerative diseases in both the brain (e.g., Alzheimer’s disease, Parkinson’s disease, stroke and diabetic neuropathy) and the eye (e.g., diabetic retinopathy and AMD). However, there are currently very few studies investigating the protective effects of GLP-1R agonists in the treatment of specifically glaucoma. Based on a literature search on PubMed, the Cochrane Library, and ClinicalTrials.gov, this review aims to summarize current clinical literature on GLP-1 receptor agonists in the treatment of neurodegenerative diseases to elucidate their potential in future anti-glaucomatous treatment strategies.

Meeting the Challenge of Virtual Diabetes Care: A Consensus Viewpoint on the Positioning and Value of Oral Semaglutide in Routine Clinical Practice

While glucagon-like peptide-1 receptor agonists (GLP-1 RAs), such as semaglutide, are among the most effective drugs for treating people with type 2 diabetes (T2D), they are clinically under-utilised. Until recently, the only route for semaglutide administration was via subcutaneous injection. However, an oral formulation of semaglutide was recently licensed, with the potential to address therapy inertia and increase patient adherence to treatment, which is essential in controlling blood glucose and reducing complications. The availability of oral semaglutide provides a new option for both clinicians and patients who are reluctant to use an injectable agent. This has been of particular importance in addressing the challenge of virtual diabetes care during the COVID-19 pandemic, circumventing the logistical problems that are often associated with subcutaneous medication administration. However, there remains limited awareness of the clinical and economic value of oral semaglutide in routine clinical practice. In this article, we present our consensus opinion on the role of oral semaglutide in routine clinical practice and discuss its value in reducing the burden of delivering diabetes care in the post-COVID-19 pandemic period of chronic disease management.

Molecular insights into ago-allosteric modulation of the human glucagon-like peptide-1 receptor

The glucagon-like peptide-1 (GLP-1) receptor is a validated drug target for metabolic disorders. Ago-allosteric modulators are capable of acting both as agonists on their own and as efficacy enhancers of orthosteric ligands. However, the molecular details of ago-allosterism remain elusive. Here, we report three cryo-electron microscopy structures of GLP-1R bound to (i) compound 2 (an ago-allosteric modulator); (ii) compound 2 and GLP-1; and (iii) compound 2 and LY3502970 (a small molecule agonist), all in complex with heterotrimeric G_s. The structures reveal that compound 2 is covalently bonded to C347 at the cytoplasmic end of TM6 and triggers its outward movement in cooperation with the ECD whose N terminus penetrates into the GLP-1 binding site. This allows compound 2 to execute positive allosteric modulation through enhancement of both agonist binding and G protein coupling. Our findings offer insights into the structural basis of ago-allosterism at GLP-1R and may aid the design of better therapeutics.

The glucagon-like peptide-1 (GLP-1) receptor is a key regulator of glucose homeostasis and a drug target for type 2 diabetes but available GLP-1R agonists are suboptimal due to several side-effects. Here authors report the cryo-EM structure of GLP-1R bound to an ago-allosteric modulator in complex with heterotrimeric G_s which offers insights into the molecular details of ago-allosterism.

Integrating oral semaglutide into clinical practice in primary care: for whom, when, and how?

Oral semaglutide is the first US Food and Drug Administration-approved oral glucagon-like peptide-1 receptor agonist (GLP-1RA) for the treatment of type 2 diabetes (T2D). Prior articles within this supplement reviewed the PIONEER trial program, which demonstrated that oral semaglutide reduced glycated hemoglobin and body weight when given to patients with uncontrolled T2D on various background therapies, and had a safety profile consistent with subcutaneous GLP-1RAs. This article provides guidance on integrating oral semaglutide into clinical practice in primary care. Patient populations with T2D who may gain benefit from oral semaglutide include those with inadequate glycemic control taking one or more oral glucose-lowering medication (e.g. after metformin), patients for whom weight loss would be beneficial, patients at risk of hypoglycemia, those who would historically have been considered for treatment with a subcutaneous GLP-1RA, and those receiving basal insulin who require treatment intensification. Like other GLP-1RAs, oral semaglutide is contraindicated in those with personal/family history of medullary thyroid carcinoma, and in those with multiple endocrine neoplasia syndrome type 2, as noted in a boxed warning in the prescribing information. Oral semaglutide has not been studied in those with a history of pancreatitis, is not recommended in patients with suspected/confirmed pancreatitis, and is not indicated in type 1 diabetes. When initiating oral semaglutide, gradual dose escalation is recommended to minimize the risk of gastrointestinal adverse events. As food and excess liquid reduce oral semaglutide absorption, patients should swallow the tablet with up to 4 fl oz/120 mL of water on an empty stomach upon waking, and should wait at least 30 minutes before eating, drinking, or taking other oral medications. Those managing patients should be aware of the potential impact of these dosing conditions on concomitant medications. When counseling patients, it is important to discuss these administration instructions, realistic therapeutic expectations, and strategies for mitigation of gastrointestinal events. Oral semaglutide provides a new option for add-on to initial T2D therapy (or later in the treatment paradigm), with the potential to enable more patients to benefit from the improvements in glycemic control, reductions in body weight, and low risk of hypoglycemia afforded by GLP-1RAs.