Oral Semaglutide: A Review of the First Oral Glucagon-Like Peptide 1 Receptor Agonist

The role of glucagon-like peptide-1/GLP-1R and autophagy in diabetic cardiovascular disease

Diabetes leads to a significantly accelerated incidence of various related macrovascular complications, including peripheral vascular disease and cardiovascular disease (the most common cause of mortality in diabetes), as well as microvascular complications such as kidney disease and retinopathy. Endothelial dysfunction is the main pathogenic event of diabetes-related vascular disease at the earliest stage of vascular injury. Understanding the molecular processes involved in the development of diabetes and its debilitating vascular complications might bring up more effective and specific clinical therapies. Long-acting glucagon-like peptide (GLP)-1 analogs are currently available in treating diabetes with widely established safety and extensively evaluated efficacy. In recent years, autophagy, as a critical lysosome-dependent self-degradative process to maintain homeostasis, has been shown to be involved in the vascular endothelium damage in diabetes. In this review, the GLP-1/GLP-1R system implicated in diabetic endothelial dysfunction and related autophagy mechanism underlying the pathogenesis of diabetic vascular complications are briefly presented. This review also highlights a possible crosstalk between autophagy and the GLP-1/GLP-1R axis in the treatment of diabetic angiopathy.

Hypoglycemic Ability of Sericin-Derived Oligopeptides (SDOs) from Bombyx mori Yellow Silk Cocoons and Their Physiological Effects on Streptozotocin (STZ)-Induced Diabetic Rats

Patients with diabetes require daily medication to maintain blood sugar levels. Nevertheless, the long-term use of antidiabetics can lose efficacy and cause degeneration in some patients. For long-term diabetes care, integrating natural dietary foods and medicine is being considered. This study investigated the impact of SDOs on blood sugar levels and their physiological effects on diabetic rats. We induced diabetes in male Wistar rats with STZ (50 mg/kg) and then administered an oral glucose tolerance test to determine the SDO dosage comparable to glibenclamide. The rats were divided into nine groups: normal, diabetic, and diabetic with insulin (10 U/kg), glibenclamide (0.6 mg/kg), bovine serum albumin (BSA; 200 mg/kg), soy protein isolate (200 mg/kg), or SDOs (50, 100, and 200 mg/kg). Diabetic rats administered SDOs had a higher body weight and serum insulin but a lower blood sugar than diabetic control rats. Biochemical assays indicated lower AST/SGOT, ALT/SGPT, BUN, and triglycerides but higher HDL in the SDO groups. Immunohistochemistry showed that SDOs reduced damaged islet cells, increased beta-cell size, and improved insulin levels while decreasing alpha cell size and glucagon. The vascular effects of SDOs were like those of normal control treatment and insulin treatment in diabetic rats. SDOs, a yellow silk protein, show potential for long-term diabetes care.

Engineering peptide drug therapeutics through chemical conjugation and implication in clinics

The development of peptide drugs has made tremendous progress in the past few decades because of the advancements in modification chemistry and analytical technologies. The novel-designed peptide drugs have been modified through various biochemical methods with improved diagnostic, therapeutic, and drug-delivery strategies. Researchers found it a helping hand to overcome the inherent limitations of peptides and bring continued advancements in their applications. Furthermore, the emergence of peptide-drug conjugates (PDCs)-utilizes target-oriented peptide moieties as a vehicle for cytotoxic payloads via conjugation with cleavable chemical agents, resulting in the key foundation of the new era of targeted peptide drugs. This review summarizes the various classifications of peptide drugs, suitable chemical modification strategies to improve the ADME (adsorption, distribution, metabolism, and excretion) features of peptide drugs, and recent (2015-early 2024) progress/achievements in peptide-based drug delivery systems as well as their fruitful implication in preclinical and clinical studies. Furthermore, we also summarized the brief description of other types of PDCs, including peptide-MOF conjugates and peptide-UCNP conjugates. The principal aim is to provide scattered and diversified knowledge in one place and to help researchers understand the pinching knots in the science of PDC development and progress toward a bright future of novel peptide drugs.

Oral peptide therapeutics for diabetes treatment: State-of-the-art and future perspectives

Diabetes, characterized by hyperglycemia, is a major cause of death and disability worldwide. Peptides, such as insulin and glucagon-like peptide-1 (GLP-1) analogs, have shown promise as treatments for diabetes due to their ability to mimic or enhance insulin's actions in the body. Compared to subcutaneous injection, oral administration of anti-diabetic peptides is a preferred approach. However, biological barriers significantly reduce the efficacy of oral peptide therapeutics. Recent advancements in drug delivery systems and formulation techniques have greatly improved the oral delivery of peptide therapeutics and their efficacy in treating diabetes. This review will highlight (1) the benefits of oral anti-diabetic peptide therapeutics; (2) the biological barriers for oral peptide delivery, including pH and enzyme degradation, intestinal mucosa barrier, and biodistribution barrier; (3) the delivery platforms to overcome these biological barriers. Additionally, the review will discuss the prospects in this field. The information provided in this review will serve as a valuable guide for future developments in oral anti-diabetic peptide therapeutics.

Glucagon-like peptide-1 analogs: Miracle drugs are blooming?

Glucagon-like peptide-1 (GLP-1), secreted by L cells in the small intestine, assumes a central role in managing type 2 diabetes mellitus (T2DM) and obesity. Its influence on insulin secretion and gastric emptying positions it as a therapeutic linchpin. However, the limited applicability of native GLP-1 stems from its short half-life, primarily due to glomerular filtration and the inactivating effect of dipeptidyl peptidase-IV (DPP-IV). To address this, various structural modification strategies have been developed to extend GLP-1's half-life. Despite the commendable efficacy displayed by current GLP-1 receptor agonists, inherent limitations persist. A paradigm shift emerges with the advent of unimolecular multi-agonists, such as the recently introduced tirzepatide, wherein GLP-1 is ingeniously combined with other gastrointestinal hormones. This novel approach has captured the spotlight within the diabetes and obesity research community. This review summarizes the physiological functions of GLP-1, systematically explores diverse structural modifications, delves into the realm of unimolecular multi-agonists, and provides a nuanced portrayal of the developmental prospects that lie ahead for GLP-1 analogs.

Sociodemographic Disparities in Sodium-Glucose Co-Transporter-2 Inhibitors and Glucagon-Like Peptide-1 Receptor Agonists Prescription Patterns Among Patients With Poorly Controlled Diabetes

Introduction Sodium-glucose co-transporter-2 inhibitors (SGLT2Is) and glucagon-like peptide-1 receptor agonists (GLP-1RAs) are novel antihyperglycemic agents that reduce cardiovascular mortality through insulin-independent mechanisms. In this cross-sectional study, we investigated prescription patterns of these drugs and identified inequities in antihyperglycemic utilization. Methods Unique encounters for diabetes care between January 1, 2020, and December 31, 2020, were identified through a systematic query of our healthcare system's database. All patients ≥18 years old with a hemoglobin A1C level of ≥8% were included in the sample. Demographic data, SGLT2I or GLP-1RA prescription status, diabetes-related complications, and mortality were abstracted. Results A total of 2,746 patients were included in the sample. Among these individuals, 670 (24.4%) were prescribed either an SGLT2I or a GLP-1RA (users) and 2,076 (75.6%) were not prescribed either agent (non-users). There were significantly more males than females in the cohort, but there was no significant difference in the sex distribution between users and non-users. Compared to non-users, users were younger (mean age of 65.1 ± 9.4 years versus 66.4 ± 9.9 years, p-value = 0.005), more likely to be non-Hispanic (86.3% versus 13.7%), more likely to live in a middle-income zip code, and have private insurance. The mortality rate was lower among users when compared to non-users, but the difference did not reach statistical significance (2.7% versus 5.5%, p-value = 0.62). SGLT2I use was associated with a 60% lower risk of mortality. Conclusion Ethnicity, median household income, and insurance type influence the likelihood of being prescribed an SGLT2I or a GLP-1RA. Individuals prescribed either agent appear to have better mortality outcomes than those prescribed other medications. Further investigation may reveal underlying causes and potential solutions for disparities in prescription patterns.

Safety, pharmacokinetics and pharmacodynamics of HRS-7535, a novel oral small molecule glucagon-like peptide-1 receptor agonist, in healthy participants: A phase 1, randomized, double-blind, placebo-controlled, single- and multiple-ascending dose, and food effect trial

AIM

To assess the safety, tolerability, pharmacokinetics (PKs) and pharmacodynamics of HRS-7535, a novel glucagon-like peptide-1 receptor agonist (GLP-1RA), in healthy participants.

MATERIALS AND METHODS

This phase 1 trial consisted of single-ascending dose (SAD), food effect (FE) and multiple-ascending dose (MAD) parts. In the SAD part, participants were randomized (6:2) to receive HRS-7535 (at doses of 15, 60 and 120 mg; administered orally once daily) or placebo. In the FE part, participants were randomized (8:2) to receive a single dose of 90-mg HRS-7535 or placebo, in both fed and fasted states. In the MAD part, participants were randomized (18:6) to receive daily HRS-7535 (120 mg [30/60/90/120-mg titration scheme]) or placebo for 28 days. The primary endpoints were safety and tolerability.

RESULTS

Nausea and vomiting were the most frequently reported AEs across all three parts. In the SAD part, the median Tmax was 5.98-5.99 hours and the geometric mean t1/2 was 5.28-9.08 hours across the HRS-7535 dosing range. In the MAD part, the median Tmax was 5.98-10.98 hours and the geometric mean t1/2 was 6.48-8.42 hours on day 28 in participants on HRS-7535. PKs were approximately dose-proportional. On day 29 in the MAD part, the mean (percentage) reduction in body weight from baseline was 4.38 kg (6.63%) for participants who received HRS-7535, compared with 0.8 kg (1.18%) for those participants who received a placebo.

CONCLUSIONS

HRS-7535 exhibited a safety and tolerability profile consistent with other GLP-1RAs and showed PKs suitable for once-daily dosing. These findings support further clinical development of HRS-7535 for type 2 diabetes.

Interaction between Permeation Enhancers and Lipid Bilayers

Permeation enhancers (PEs) are a class of molecules that interact with the epithelial membrane and transiently increase its transcellular permeability. Although there have been few clinical trials of PE coformulated drugs, the mechanism of action of PEs remains elusive. In this paper, the interaction between two archetypes of PEs [salcaprozate sodium (SNAC) and sodium caprate (C10)] and membranes is investigated with extensive all-atom molecular dynamics simulations. The simulations show that (1) the association between the neutral PEs and membranes is favored in free energy, (2) the propensity of neutral PE aggregation is larger in aqueous solution than in lipid bilayers, (3) the equilibrium distribution of neutral PEs in membranes is fast, e.g., accessible with unbiased MD simulations, and (4) the micelle of neutral PEs formed in aqueous solution does not rupture the membranes (e.g., not forming pores or breaking up the membrane) under simulation conditions. All results combined, this study indicates that PEs insert into the membranes in an equilibrium or near equilibrium process. This study lays the foundation for future investigations of how PEs impact the free energy of permeation for small molecules.

Peptide-Drug Conjugates: Design, Chemistry, and Drug Delivery System as a Novel Cancer Theranostic

The emergence of peptide-drug conjugates (PDCs) that utilize target-oriented peptide moieties as carriers of cytotoxic payloads, interconnected with various cleavable/noncleavable linkers, resulted in the key-foundation of the new era of targeted therapeutics. They are capable of retaining the integrity of conjugates in the blood circulatory system as well as releasing the drugs at the tumor microenvironment. Other valuable advantages are specificity and selectivity toward targeted-receptors, higher penetration ability, and drug-loading capacity, making them a suitable candidate to play their vital role as promising carrier agents. In this review, we summarized the types of cell-targeting (CTPs) and cell-penetrating peptides (CPPs) that have broad applications in the advancement of targeted drug-delivery systems (DDS). Moreover, the techniques to overcome the limitations of peptide-chemistry for their extensive implementation to construct the PDCs. Besides this, the diversified breakthrough of linker chemistry, and ample knowledge of various cytotoxic payloads used in PDCs in recent years, as well as the mechanism of action of PDCs was critically discussed. The principal aim is to provide scattered and diversified knowledge in one place and to help researchers understand the pinching knots in the science of PDC development, also their progression toward a bright future for PDCs as novel theranostics in clinical practice.

Daily Glucose Profiles after Switching from Injectable to Oral Semaglutide in Patients with Type 2 Diabetes Mellitus

Objective This prospective observational study explored the changes in the daily glycemic profile after switching from injectable to oral semaglutide in patients with type 2 diabetes mellitus. Methods Patients with type 2 diabetes mellitus who were treated with once-weekly 0.5 mg injectable semaglutide and wished to switch to once-daily oral semaglutide participated in this study. Oral semaglutide was initiated at 3 mg and increased to 7 mg a month later, according to the package insert. Before and two months after the switch, participants wore a sensor for continuous glucose monitoring for up to 14 days. We also evaluated the questionnaire-based treatment satisfaction and the preference between the two formulations. Patients Twenty-three patients participated. Results Mean glucose levels significantly increased by 9 mg/dL on average, from 132±20 to 141±27 mg/dL (p=0.047), which was equivalent to a change of 0.2% in the estimated hemoglobin A1c (6.5±0.5% to 6.7±0.7%). The inter-individual variability assessed with standard deviation also significantly increased (p=0.004). The change in treatment satisfaction varied considerably among patients, with no specific trend in the overall population. After trying oral semaglutide, 48% of patients responded that they preferred the oral formulation, while 35% preferred the injectable formulation, and 17% had no preference. Conclusion The mean glucose levels increased by 9 mg/dL on average after switching from once-weekly 0.5 mg injectable semaglutide to once-daily 7 mg oral semaglutide, with an increased inter-individual variability. The change in treatment satisfaction considerably varied among patients.

Why do some glucose-lowering agents improve non-alcoholic fatty liver disease whereas others do not? A narrative review in search of a unifying hypothesis

Non-alcoholic fatty liver disease (NAFLD) and type 2 diabetes (T2D) are metabolic disorders connected by common pathophysiological mechanisms. Since insulin resistance (IR) and metabolic alterations are common to both conditions, almost all glucose-lowering agents which improve IR have also been studied in patients with NAFLD. Some have shown great efficacy, others none. Thus, the mechanisms behind the efficacy of these drugs in improving hepatic steatosis, steatohepatitis, and eventually fibrosis remain controversial. Glycaemic control improves T2D, but probably has limited effects on NAFLD, as all glucose-lowering agents ameliorate glucose control but only a few improve NAFLD features. In contrast, drugs that either improve adipose tissue function, reduce lipid ingestion, or increase lipid oxidation are particularly effective in NAFLD. We therefore hypothesise that improved free fatty acid metabolism may be the unifying mechanism behind the efficacy of some glucose-lowering agents on NAFLD and may represent the key to NAFLD treatment.

Oral semaglutide improves body composition and preserves lean mass in patients with type 2 diabetes: a 26-week prospective real-life study

Background

Oral semaglutide is the first glucagon-like peptide-1 receptor agonist (GLP-1RA) designed for oral administration; it offers a promising opportunity to facilitate an early approach to Type 2 Diabetes (T2D). The study aimed to evaluate, in a real-life setting, the effects of oral semaglutide on the body composition of patients with T2D after 26 weeks of therapy.

Methods

Thirty-two patients with T2D were evaluated at baseline (T0) and after three (T3) and six (T6) months of therapy with oral semaglutide. At each time point, body composition was assessed using a phase sensitive bioimpedance analyzer. Clinical, anthropometric and laboratory parameters, and the main biometric surrogates of liver steatosis and fibrosis, were also analyzed and compared.

Results

A significant and early reduction in anthropometric and glucometabolic parameters, alanine aminotransferase, Fatty Liver Index, and Fat Mass was observed. Visceral Adipose Tissue (VAT) decreased, while Fat Free Mass and Skeletal Muscle Mass (SMM) were preserved during therapy, resulting in a beneficial increase in the SMM/VAT ratio. Finally, an overall improvement in body fluid distribution was observed.

Conclusion

Our real-world data confirm the clinical efficacy of oral semaglutide and highlight its ability to improve the nutritional status of patients with T2D.

Discovery of an orally effective double-stapled peptide for reducing ovariectomy-induced bone loss in mice

Stapled peptides with significantly enhanced pharmacological profiles have emerged as promising therapeutic molecules due to their remarkable resistance to proteolysis and performance to penetrate cells. The all-hydrocarbon peptide stapling technique has already widely adopted with great success, yielding numerous potent peptide-based molecules. Based on our prior efforts, we conceived and prepared a double-stapled peptide in this study, termed FRNC-1, which effectively attenuated the bone resorption capacity of mature osteoclasts in vitro through specific inhibition of phosphorylated GSK-3β. The double-stapled peptide FRNC-1 displayed notably improved helical contents and resistance to proteolysis than its linear form. Additionally, FRNC-1 effectively prevented osteoclast activation and improved bone density for ovariectomized (OVX) mice after intravenous injection and importantly, after oral (intragastric) administration. The double-stapled peptide FRNC-1 is the first orally effective peptide that has been validated to date as a therapeutic candidate for postmenopausal osteoporosis (PMOP).

Cost-effectiveness analysis of once-daily oral semaglutide versus placebo and subcutaneous glucagon-like peptide-1 receptor agonists added to insulin in patients with type 2 diabetes in China

Introduction: Oral semaglutide is a glucagon-like peptide-1 receptor agonist (GLP-1 RA) that improves glycated hemoglobin levels and body weight in patients with type 2 diabetes (T2DM). We aim to evaluate the cost-effectiveness of once-daily oral semaglutide in comparison to placebo and injectable GLP-1 RAs in Chinese patients with T2DM inadequately controlled on basal insulin. Methods: The United Kingdom Prospective Diabetes Study Outcomes Model (UKPDS OM2.1) was used to estimate the cost-effectiveness by calculating the incremental cost-effectiveness ratio (ICER). Baseline characteristics of the simulation cohort were obtained from the PIONEER 8 trial. Utility and safety inputs were derived from a network meta-analysis of 12 trials. Direct medical costs were retrieved from published literature and discounted at an annual rate of 5%. We used a willingness-to-pay (WTP) threshold of $36,528.3 per quality-adjusted life-year (QALY) gained. Scenario analysis, and one-way and probabilistic sensitivity analysis were performed. Results: The effectiveness of oral semaglutide was 10.39 QALYs with a total cost of $30,223.10, while placebo provided 10.13 QALYs at a lower total cost of $20,039.19. Oral semaglutide was not cost-effective at an ICER of $39,853.22 and $88,776.61 per QALY compared to placebo and exenatide at the WTP. However, at an annual price of $1,871.9, it was cost-effective compared with dulaglutide, liraglutide, and lixisenatide. The model was most sensitive to the discount rate and annual cost of oral semaglutide. The price of oral semaglutide needed to be reduced to $1,711.03 per year to be cost-effective compared to placebo and other injectable GLP-1 RAs except for exenatide and semaglutide injection. Conclusion: We found that once-daily oral semaglutide, at a comparable price of semaglutide injection, proves to be a cost-effective add-on therapy to insulin for Chinese patients with T2DM, especially when compared to subcutaneous GLP-1 RAs other than injectable semaglutide and exenatide. However, to achieve cost-effectiveness in comparison to placebo, further cost reduction of oral semaglutide is necessary. The estimated annual cost of $1,711.03 for oral semaglutide demonstrates a more cost-effective option than placebo, highlighting its potential value in the management of T2DM.

Oral Semaglutide Induces Loss of Body Fat Mass Without Affecting Muscle Mass in Patients With Type 2 Diabetes

Background

Excessive body fat may be a major cause of insulin resistance and diabetes. But body weight reduction by energy restriction may simultaneously reduce both fat and muscle. Skeletal muscle is an important organ for glucose metabolism regulation, and loss of muscle may deteriorate glucose metabolism. Therefore, it is preferable to predominantly reduce fat without significant loss of muscle with weight loss in patients with type 2 diabetes. Previously, the anti-diabetic agent glucagon-like peptide-1 receptor agonists (GLP-1RAs) liraglutide and semaglutide given by injection were reported to decrease fat with less effect on muscle in diabetic patients. Recently oral semaglutide was developed and was reported to decrease body weight, but the effect on muscle has not been fully evaluated.

Methods

This was a non-interventional retrospective longitudinal study. We evaluated the effect of 24-week treatment with oral semaglutide on body fat and muscle mass in 25 Japanese patients with type 2 diabetes. Laboratory examination and body composition test by bioelectrical impedance analysis (BIA) were performed at baseline, 12 weeks, and 24 weeks, and the effects on glycemic control and body composition were assessed.

Results

Hemoglobin A1c significantly decreased at 12 weeks and further ameliorated at 24 weeks (8.7±0.87% at baseline; 7.6±1.00% at 12 weeks; 7.0±0.80% at 24 weeks; mean ± standard error (SE)). While body fat significantly decreased (28.3 ± 1.52 kg at baseline; 26.8 ± 1.59 kg at 12 weeks; 25.5 ± 1.57 kg at 24 weeks; mean ± SE), whole-body lean mass was not significantly changed (48.1 ± 1.92 kg at baseline; 47.7 ± 1.93 kg at 12 weeks; 47.6 ± 1.89 kg at 24 weeks; mean ± SE). Furthermore, the appendicular skeletal muscle index (SMI) defined as appendicular skeletal muscle mass (ASM)/height squared (units; kg/m2) was also unchanged.

Conclusion

The 24-week treatment with oral semaglutide ameliorated glycemic control with reduction of body fat but not muscle mass in Japanese patients with type 2 diabetes.

The glucagon-like peptide-1 (GLP-1) analogue semaglutide reduces alcohol drinking and modulates central GABA neurotransmission

Growing evidence indicates that the glucagon-like peptide-1 (GLP-1) system is involved in the neurobiology of addictive behaviors, and GLP-1 analogues may be used for the treatment of alcohol use disorder (AUD). Here, we examined the effects of semaglutide, a long-acting GLP-1 analogue, on biobehavioral correlates of alcohol use in rodents. A drinking-in-the-dark procedure was used to test the effects of semaglutide on binge-like drinking in male and female mice. We also tested the effects of semaglutide on binge-like and dependence-induced alcohol drinking in male and female rats, as well as acute effects of semaglutide on spontaneous inhibitory postsynaptic currents (sIPSCs) from central amygdala (CeA) and infralimbic cortex (ILC) neurons. Semaglutide dose-dependently reduced binge-like alcohol drinking in mice; a similar effect was observed on the intake of other caloric/noncaloric solutions. Semaglutide also reduced binge-like and dependence-induced alcohol drinking in rats. Semaglutide increased sIPSC frequency in CeA and ILC neurons from alcohol-naive rats, suggesting enhanced GABA release, but had no overall effect on GABA transmission in alcohol-dependent rats. In conclusion, the GLP-1 analogue semaglutide decreased alcohol intake across different drinking models and species and modulated central GABA neurotransmission, providing support for clinical testing of semaglutide as a potentially novel pharmacotherapy for AUD.

Semaglutide reduces alcohol intake and relapse-like drinking in male and female rats

BACKGROUND

Glucagon-like peptide1 receptor (GLP-1R) agonists have been found to reduce alcohol drinking in rodents and overweight patients with alcohol use disorder (AUD). However, the probability of low semaglutide doses, an agonist with higher potency and affinity for GLP-1R, to attenuate alcohol-related responses in rodents and the underlying neuronal mechanisms is unknown.

METHODS

In the intermittent access model, we examined the ability of semaglutide to decrease alcohol intake and block relapse-like drinking, as well as imaging the binding of fluorescently marked semaglutide to nucleus accumbens (NAc) in both male and female rats. The suppressive effect of semaglutide on alcohol-induced locomotor stimulation and in vivo dopamine release in NAc was tested in male mice. We evaluated effect of semaglutide on the in vivo release of dopamine metabolites (DOPAC and HVA) and gene expression of enzymes metabolising dopamine (MAOA and COMT) in male mice.

FINDINGS

In male and female rats, acute and repeated semaglutide administration reduced alcohol intake and prevented relapse-like drinking. Moreover, fluorescently labelled semaglutide was detected in NAc of alcohol-drinking male and female rats. Further, semaglutide attenuated the ability of alcohol to cause hyperlocomotion and to elevate dopamine in NAc in male mice. As further shown in male mice, semaglutide enhanced DOPAC and HVA in NAc when alcohol was onboard and increased the gene expression of COMT and MAOA.

INTERPRETATION

Altogether, this indicates that semaglutide reduces alcohol drinking behaviours, possibly via a reduction in alcohol-induced reward and NAc dependent mechanisms. As semaglutide also decreased body weight of alcohol-drinking rats of both sexes, upcoming clinical studies should test the plausibility that semaglutide reduces alcohol intake and body weight in overweight AUD patients.

FUNDING

Swedish Research Council (2019-01676), LUA/ALF (723941) from the Sahlgrenska University Hospital and the Swedish brain foundation.

The Oral Delivery System of Modified GLP-1 by Probiotics for T2DM

The glucagon-like peptide-1 (GLP-1) is a peptide with incretin activity and plays an important role in glycemic control as well as the improvement of insulin resistance in type 2 diabetes mellitus (T2DM). However, the short half-life of the native GLP-1 in circulation poses difficulties for clinical practice. To improve the proteolytic stability and delivery properties of GLP-1, a protease-resistant modified GLP-1 (mGLP-1) was constructed with added arginine to ensure the structural integrity of the released mGLP-1 in vivo. The model probiotic Lactobacillus plantarum WCFS1 was chosen as the oral delivery vehicle with controllable endogenous genetic tools driven for mGLP-1 secretory constitutive expression. The feasibility of our design was explored in db/db mice which showed an improvement in diabetic symptoms related to decreased pancreatic glucagon, elevated pancreatic β-cell proportion, and increased insulin sensitivity. In conclusion, this study provides a novel strategy for the oral delivery of mGLP-1 and further probiotic transformation.

Characterizing interspecies differences in gastric fluid properties to improve understanding of in vivo oral drug formulation performance

An in-depth understanding of the properties of gastric fluid(s) prior to an in vivo pharmacokinetic investigation can vastly improve predictions of in vivo performance. Previously, properties of animal and human gastric fluids have been characterized with varying methods. Unfortunately, characterization has often not been thorough, and some properties, such as density and viscosity, have not been reported. Here, human, porcine and canine gastric fluids were harvested and characterized for pH, viscosity, surface tension, density, and osmolarity. We found that the variability of pH and surface tension between dogs was significantly higher than the variability between pigs, and, furthermore, gastric fluids collected from the same canine species (beagles) housed in two different countries (Denmark and China) had surprisingly different pH values. Next, an in vitro dissolution study in diluted gastric fluids from each species was performed using minitablets containing ibuprofen. Human gastric fluids and porcine gastric fluids showed similar dissolution profiles and corroborated well with biorelevant human Fasted State Simulated Gastric Fluid (FaSSGF). In contrast, differences in canine gastric fluids caused highly variable dissolution results. We systematically compared our findings to those in the literature and based on this evaluation, propose obtaining aspirates from the animals used for in vivo studies to ensure knowledge on the fluid properties affecting the performance of the formulated drug in question.

Non-Covalent Albumin Ligands in FDA-Approved Therapeutic Peptides and Proteins

An increasing number of drugs that consist of a therapeutic peptide or protein linked to an albumin-binding structure are being approved. In this perspective, the pharmacokinetic data of currently marketed drugs of this type will be presented. Acylation with fatty acids or fatty α,ω-dicarboxylic acids has been used successfully to prepare long-acting analogs of insulin, GLP-1, and other peptides but not of larger proteins. With a tetrazole-sulfonylamide fatty acid bioisostere, it has now been possible to prepare a long-acting analog of human growth hormone (191 amino acids), which is suitable for once-weekly administration.

The Safety Profile of Sodium-Glucose Cotransporter-2 Inhibitors and Glucagon-like Peptide 1 Receptor Agonists in the Standard of Care Treatment of Type 2 Diabetes Mellitus

AIM

We evaluated the safety of sodium-glucose cotransporter-2 inhibitors (SGLT2i) and glucagon-like peptide 1 receptor agonists (GLP-1 RAs) for their use with other glucose-lowering drugs and drugs for the treatment of type 2 diabetes mellitus (T2DM), in a standard-of-care regimen with maximum tolerated doses, and, respectively, when compared with metformin.

METHODS

We conducted a retrospective, observational study on 405 patients that were seen in the outpatient clinic of the N Paulescu National Institute for Diabetes Mellitus, Bucharest, Romania, in 2019. Their demographics, metabolic parameters, and medication safety were evaluated at three follow-up visits, from baseline, six months, and twelve months.

RESULTS

Both SGLT-2is and GLP-1 RAs are safe regarding creatinine, eGFR, urea, GOT, and GPT upon the comparison of the data from the six- and twelve-month visits with the initial visit, and also the twelve-month visit with the six-month visit. Moreover, when comparing SGLT-2is and GLP-1 RAs with metformin, there are safety data only for urea.

CONCLUSIONS

In this retrospective analysis, both SGLT-2is and GLP-1 RAs, when used in conjunction with other glucose-lowering, blood-pressure-lowering, and lipid-lowering medications, appeared to be safe for the management of T2DM.

Is the steady-state concentration, duration of action, or molecular weight of GLP-1RA associated with cardiovascular and renal outcomes in type 2 diabetes?

IMPORTANCE

Disparities were found in the cardiovascular and renal outcomes among different glucagon-like peptide 1 receptor agonist (GLP-1RA) subtypes. However, whether the characteristics of GLP-1RA itself are associated with these disparities remains unclear.

OBJECTIVE

To assess the association between the steady-state concentration, duration of action, or molecular weight of GLP-1RA and the risks of cardiovascular and renal outcomes in patients with type 2 diabetes (T2D).

DATA SOURCES

PubMed, MEDLINE, EMBASE, Cochrane and Clinicaltrial.gov from inception to April 2022.

STUDY SELECTION

Randomized controlled trials (RCTs) investigating GLP-1RAs in patients with T2D were included.

DATA EXTRACTION AND SYNTHESIS

Literature screening and data extraction were performed independently by 2 researchers. The outcomes were computed as odds ratio (OR) and its 95% confidence interval (CI). Subgroup analyses were conducted according to steady-state concentration, duration of action and molecular weight of GLP-1RAs.

MAIN OUTCOMES AND MEASURES

Primary outcomes were major adverse cardiovascular events (MACE), composite renal outcome and all-cause mortality.

RESULTS

In all, 61 RCTs were included. When compared with non-GLP-1RA agents, GLP-1RAs with high steady-state concentration were associated with greater risk reduction in MACE (p for subgroup difference = 0.01) and the composite renal outcome (p for subgroup difference = 0.008) in patients with T2D. Greater risk reductions in MACE between GLP-1RA users versus non-GLP-RA users were observed in long acting stratum when compared with short acting stratum (p for subgroup difference = 0.04) in patients with T2D. The molecular weight of GLP-1RAs was not associated with the risk of cardiovascular and renal outcomes.

CONCLUSIONS AND RELEVANCE

GLP-1RAs with high steady-state concentrations might be associated with greater risk reductions in cardiovascular and renal outcomes in patients with T2D. Long acting GLP-1RAs might outperform short acting ones in reducing the risk of cardiovascular outcomes. These findings provided new insights for guiding the clinical applications of GLP-1RAs in patients with T2D.

SNAC for Enhanced Oral Bioavailability: An Updated Review

The delivery of proteins and peptides via an oral route poses numerous challenges to improve the oral bioavailability and patient compliance. To overcome these challenges, as well as to improve the permeation of proteins and peptides via intestinal mucosa, several chemicals have been studied such as surfactants, fatty acids, bile salts, pH modifiers, and chelating agents, amongst these medium chain fatty acid like C10 (sodium caprate) and Sodium N-[8-(2-hydroxybenzoyl) amino] caprylate (SNAC) and its derivatives that have been well studied from a clinical perspective. This current review enumerates the challenges involved in protein and peptide delivery via the oral route, i.e., non-invasive routes of protein and peptide administration. This review also covers the chemistry behind SNAC and toxicity as well as mechanisms to enhance the oral delivery of clinically proven molecules like simaglutide and other small molecules under clinical development, as well as other permeation enhancers for efficient delivery of proteins and peptides.

The correlations between steady-state concentration, duration of action and molecular weight of GLP-1RAs and their efficacy and gastrointestinal side effects in patients with type 2 diabetes mellitus: a systematic review and meta-analysis

BACKGROUND

To assess the influence of steady-state concentration, duration of action and molecular weight of glucagon-like peptide-1 receptor (GLP-1RA) on efficacy and gastrointestinal (GI) side effects in patients with type 2 diabetes mellitus (T2DM).

METHODS

PubMed, EMBASE, the Cochrane Center Register of Controlled Trials for Studies and Clinicaltrial.gov were searched from inception to April 2022. Randomized controlled trials (RCTs) comparing GLP-1RA versus non-GLP-1RA agents in patients with T2DM were included. Sensitivity analyses on steady-state concentration, duration of action and molecular weight of GLP-1RA were conducted.

RESULTS

113 RCTs were included. Greater HbA1c reduction between GLP-1RA users versus non-GLP-1RA users was observed in the high-steady-state-concentration stratum and long-acting stratum compared with the low-steady-state-concentration stratum (P_{subgroup difference} = 0.0004) and short-acting stratum (P_{subgroup difference}<0.0001). The risk of GI adverse events in GLP-1RA users versus non-GLP-1RA users was decreased in the high-steady-state-concentration stratum, long-acting stratum and heavy-molecular-weight stratum compared with low-steady-state-concentration stratum (P_{subgroup difference}<0.0001), short-acting stratum (P_{subgroup difference} = 0.002) and light-molecular-weight stratum (P_{subgroup difference} = 0.0008).

CONCLUSION

GLP-1RA with high steady-state concentration and long duration of action showed better hypoglycemic effect. GLP-1RA with high steady-state concentration, long duration of action and heavy molecular weight was associated with lower risk of GI adverse events.

Delivering on the promise of protein degraders

Over the past 3 years, the first bivalent protein degraders intentionally designed for targeted protein degradation (TPD) have advanced to clinical trials, with an initial focus on established targets. Most of these clinical candidates are designed for oral administration, and many discovery efforts appear to be similarly focused. As we look towards the future, we propose that an oral-centric discovery paradigm will overly constrain the chemical designs that are considered and limit the potential to drug novel targets. In this Perspective, we summarize the current state of the bivalent degrader modality and propose three categories of degrader designs, based on their likely route of administration and requirement for drug delivery technologies. We then describe a vision for how parenteral drug delivery, implemented early in research and supported by pharmacokinetic-pharmacodynamic modelling, can enable exploration of a broader drug design space, expand the scope of accessible targets and deliver on the promise of protein degraders as a therapeutic modality.

Gut Molecules in Cardiometabolic Diseases: The Mechanisms behind the Story

Atherosclerotic cardiovascular disease is the most common cause of morbidity and mortality worldwide. Diabetes mellitus increases cardiovascular risk. Heart failure and atrial fibrillation are associated comorbidities that share the main cardiovascular risk factors. The use of incretin-based therapies promoted the idea that activation of alternative signaling pathways is effective in reducing the risk of atherosclerosis and heart failure. Gut-derived molecules, gut hormones, and gut microbiota metabolites showed both positive and detrimental effects in cardiometabolic disorders. Although inflammation plays a key role in cardiometabolic disorders, additional intracellular signaling pathways are involved and could explain the observed effects. Revealing the involved molecular mechanisms could provide novel therapeutic strategies and a better understanding of the relationship between the gut, metabolic syndrome, and cardiovascular diseases.

Advancements, challenges and future perspectives on peptide-based drugs: Focus on antimicrobial peptides

Among other health related issues, the rising concerns on drug resistance led to look for alternative pharmaceutical drugs that are effective both against infectious and noninfectious diseases. Antimicrobial peptides (AMPs) emerged as potential therapeutic molecule with wide range of applications. With their limitations, AMPs have gained reputable attentions in research as well as in the pharmaceutical industry. This review highlighted the historical background, research trends, technological advancements, challenges, and future perspectives in the development and applications of peptide drugs. Some vital questions related with the need for pharmaceutical production, factors for the slow and steady journey, the importance of oral bioavailability, and the drug resistance possibilities of AMPs were raised and addressed accordingly. Therefore, the current study is believed to provide a profound understanding in the past and current scenarios and future directions on the therapeutic impacts of peptide drugs.

New Frontiers in Obesity Treatment: GLP-1 and Nascent Nutrient-Stimulated Hormone-Based Therapeutics

Nearly half of Americans are projected to have obesity by 2030, underscoring the pressing need for effective treatments. Glucagon-like peptide 1 receptor agonists (GLP-1 RAs) represent the first agents in a rapidly evolving, highly promising landscape of nascent hormone-based obesity therapeutics. With the understanding of the neurobiology of obesity rapidly expanding, these emerging entero-endocrine and endo-pancreatic agents combined or coformulated with GLP-1 RAs herald a new era of targeted, mechanism-based treatment of obesity. This article reviews GLP-1 RAs in the treatment of obesity and previews the imminent future of nutrient-stimulated hormone-based anti-obesity therapeutics.

Evaluation in pig of an intestinal administration device for oral peptide delivery

The bioavailability of peptides co-delivered with permeation enhancers following oral administration remains low and highly variable. Two factors that may contribute to this are the dilution of the permeation enhancer in the intestinal fluid, as well as spreading of the released permeation enhancer and peptide in the lumen by intestinal motility. In this work we evaluated an Intestinal Administration Device (IAD) designed to reduce the luminal dilution of drug and permeation enhancer, and to minimize movement of the dosage form in the intestinal lumen. To achieve this, the IAD utilizes an expanding design that holds immediate release mini tablets and places these in contact with the intestinal epithelium, where unidirectional drug release can occur. The expanding conformation limits movement of the IAD in the intestinal tract, thereby enabling drug release at a single focal point in the intestine. A pig model was selected to study the ability of the IAD to promote intestinal absorption of the peptide MEDI7219 formulated together with the permeation enhancer sodium caprate. We compared the IAD to intestinally administered enteric coated capsules and an intestinally administered solution. The IAD restricted movement of the immediate release tablets in the small intestine and histological evaluation of the mucosa indicated that high concentrations of sodium caprate were achieved. Despite significant effect of the permeation enhancer on the integrity of the intestinal epithelium, the bioavailability of MEDI7219 was of the same order of magnitude as that achieved with the solution and enteric coated capsule formulations (2.5-3.8%). The variability in plasma concentrations of MEDI7219 were however lower when delivered using the IAD as compared to the solution and enteric coated capsule formulations. This suggests that dosage forms that can limit intestinal dilution and control the position of drug release can be a way to reduce the absorptive variability of peptides delivered with permeation enhancers but do not offer significant benefits in terms of increasing bioavailability.

Targeting appetite and satiety in diabetes and obesity, via G protein-coupled receptors

Type 2 diabetes and obesity have reached pandemic proportions throughout the world, so much so that the World Health Organisation coined the term "Globesity" to help encapsulate the magnitude of the problem. G protein-coupled receptors (GPCRs) are highly tractable drug targets due to their wide involvement in all aspects of physiology and pathophysiology, indeed, GPCRs are the targets of approximately 30% of the currently approved drugs. GPCRs are also broadly involved in key physiologies that underlie type 2 diabetes and obesity including feeding reward, appetite and satiety, regulation of blood glucose levels, energy homeostasis and adipose function. Despite this, only two GPCRs are the target of approved pharmaceuticals for treatment of type 2 diabetes and obesity. In this review we discuss the role of these, and select other candidate GPCRs, involved in various facets of type 2 diabetic or obese pathophysiology, how they might be targeted and the potential reasons why pharmaceuticals against these targets have not progressed to clinical use. Finally, we provide a perspective on the current development pipeline of anti-obesity drugs that target GPCRs.

The role of oral semaglutide in managing type 2 diabetes in Indian clinical settings: Addressing the unmet needs

AIMS

Despite their established benefits, glucagon-like peptide-1 receptor agonists (GLP-1 RAs) remain underutilized for type 2 diabetes mellitus (T2DM) management, which indicates that subcutaneous injection is an unfavorable mode of delivery from the patient's perspective. This review summarizes existing challenges related to medication adherence and the use of antihyperglycemia injectables, revisits the established safety and efficacy of oral semaglutide, and explores its features and considerations for use among the Indian T2DM population.

METHODS

We performed a literature search using MEDLINE and the National Institutes of Health Clinical Trials Registry from July 1, 2016, to July 1, 2021, to identify publications on oral semaglutide approval, T2DM treatment guidelines, and clinical evidence for oral drug formulation.

RESULTS

Oral semaglutide is the first oral GLP-1 RA approved for T2DM patients based on phase 3, randomized PIONEER trials. The multitargeted action of this drug offers glycemic control, weight control, and cardiovascular, renal, and additional benefits, including patient convenience and enhanced medication adherence. In addition to achieving glycemic control, the cost of semaglutide is reported to be lower than other GLP-1 RA in the West, thus potentially mitigating the economic burden that appears to be high among the Indian population.

CONCLUSIONS

Currently, there is no data available on oral semaglutide in Indian clinical settings. However, significant improvements in glycemic control, cardiac and renal benefits, as well as weight loss across clinical trials should encourage clinicians to prioritize oral semaglutide over other antidiabetic agents.

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.

The Role of Glp-1 Receptor Agonists in Insulin Resistance with Concomitant Obesity Treatment in Polycystic Ovary Syndrome

Insulin resistance is documented in clamp studies in 75% of women with polycystic ovary syndrome (PCOS). Although it is not included in the diagnostic criteria of PCOS, there is a crucial role of this metabolic impairment, which along with hormonal abnormalities, increase each other in a vicious circle of PCOS pathogenesis. Insulin resistance in this group of patients results from defects at the molecular level, including impaired insulin receptor-related signaling pathways enhanced by obesity and its features: Excess visceral fat, chronic inflammation, and reactive oxygen species. While lifestyle intervention has a first-line role in the prevention and management of excess weight in PCOS, the role of anti-obesity pharmacological agents in achieving and maintaining weight loss is being increasingly recognized. Glucagon-like peptide-1 receptor agonists (GLP1-RAs) not only act by reducing body weight but also can affect the mechanisms involved in insulin resistance, like an increasing expression of glucose transporters in insulin-dependent tissues, decreasing inflammation, reducing oxidative stress, and modulating lipid metabolism. They also tend to improve fertility either by increasing LH surge in hypothalamus-pituitary inhibition due to estrogen excess connected with obesity or decreasing too high LH levels accompanying hyperinsulinemia. GLP1-RAs seem promising for effective treatment of obese PCOS patients, acting on one of the primary causes of PCOS at the molecular level.

Knowledge Domain and Emerging Trends of Glucagon-Like Peptide 1 Receptor Agonists in Cardiovascular Research: A Bibliometric Analysis

BACKGROUND

Patients with type 2 diabetes (T2DM) are more likely to have cardiovascular disease (CVD). Glucose-lowering drugs with cardiovascular benefits represented by Glucagon-like peptide 1 receptor agonists (GLP1RAs) were discovered and gained more and more attention.

METHODS

Data from 1985 to the 2021 were downloaded in the Web of Science Core Collection (WoSCC) database. CiteSpaceV was used for bibliometric analysis to find research hotspots and frontiers.

RESULTS

The 2088 papers were published by 74 countries (regions), 876 institutions, and 2203 authors. The annual publications increased over time from 2005 to 2020. DIABETES OBESITY METABOLISM published the most papers. The USA and China were the top 2 productive nations. The leading institution was the University of Copenhagen, and the most productive researcher was John B Buse. The most cited paper is "Liraglutide and Cardiovascular Outcomes in Type 2 Diabetes" (by Marso SP, 2016). The research hotspots include the effects of GLP1RA on cardiovascular outcomes, efficacy, complicated metabolic abnormalities, protective mechanisms, and other novel anti-diabetic drugs for cardiovascular protection. Research frontiers include cardiovascular studies on semaglutide, as well as the most prominent research approach in the field-placebo-controlled trial.

CONCLUSION

Numerous countries, institutions, and authors have focused on GLP1RA in cardiovascular research and a great deal of literature has been published. Five research hotspots and two frontiers illustrate the current status and emerging trends of GLP1RA in cardiovascular research. The cardiovascular effects and clinical efficacy of GLP1RA are a current hot topic that is rapidly evolving and of high research value.

Open-Label, Phase I, Pharmacokinetic Studies in Healthy Chinese Subjects to Evaluate the Bioequivalence and Food Effect of a Novel Formulation of Abiraterone Acetate Tablets

Purpose

Abiraterone acetate tablets (I)(N-AbA) is a novel tablet co-formulated with the absorption enhancer sodium N-(8-[2-hydroxybenzoyl] amino) caprylate (SNAC). This study aimed to compare the pharmacokinetics, bioequivalence, safety, and food effects of N-AbA with the reference ZYTIGA^® (R-AbA) in healthy Chinese male subjects.

Patients and Methods

This study was conducted in three parts. Part I was an open, dose-escalation trial conducted in 16 Chinese healthy males; Part II was a randomized, open-label, 2 × 4 crossover, single-dose bioequivalence trial conducted in 36 subjects; Part III was a randomized, 3 × 3 crossover trial conducted on 24 volunteers to investigate the effect of food on the pharmacokinetics of N-AbA.

Results

The exposure (AUC_0-∞) and maximum concentration (C_max) of abiraterone and excipient SNAC were linear in the range of 75–450 mg dose. The bioavailability of N-AbA 300 mg was equivalent to that of R-AbA 1000 mg. The drug exposure of prednisone and prednisolone was not affected by SNAC co-administration. The C_max of orally administered abiraterone as R-AbA in a modified fed state was 5.9 times and AUC_0-∞ was 4.3 times, respectively, higher than those in of orally administered abiraterone as N-AbA in a high-fat diet. The C_max and AUC_0-∞ of orally administered abiraterone as N-AbA on a high-fat diet were 2.2 times and 2 times, respectively, higher than those on a fasting state. All adverse events reported in the three parts of the study were grade 1 or 2, and no serious adverse events were reported.

Conclusion

These three Phase I trials showed that N-AbA and excipient SNAC had excellent linear pharmacokinetic characteristics. A single dose of N-AbA 300 mg was bioequivalent to R-AbA 1000 mg in healthy subjects under fasting conditions. Meanwhile, SNAC had no effect on the pharmacokinetics of prednisone and prednisolone. The effect of food on N-AbA was significantly lower than that on R-AbA.

Oral delivery of therapeutic peptides and proteins: Technology landscape of lipid-based nanocarriers

The oral administration of therapeutic peptides and proteins is favoured from a patient and commercial point of view. In order to reach the systemic circulation after oral administration, these drugs have to overcome numerous barriers including the enzymatic, sulfhydryl, mucus and epithelial barrier. The development of oral formulations for therapeutic peptides and proteins is therefore necessary. Among the most promising formulation approaches are lipid-based nanocarriers such as oil-in-water nanoemulsions, self-emulsifying drug delivery systems (SEDDS), solid lipid nanoparticles (SLN), nanostructured lipid carriers (NLC), liposomes and micelles. As the lipophilic character of therapeutic peptides and proteins can be tremendously increased such as by the formation of hydrophobic ion pairs (HIP) with hydrophobic counter ions, they can be incorporated in the lipophilic phase of these carriers. Since gastrointestinal (GI) peptidases as well as sulfhydryl compounds such as glutathione and dietary proteins are too hydrophilic to enter the lipophilic phase of these carriers, the incorporated therapeutic peptide or protein is protected towards enzymatic degradation as well as unintended thiol/disulfide exchange reactions. Stability of lipid-based nanocarriers towards lipases can be provided by the use to excipients that are not or just poorly degraded by these enzymes. Nanocarriers with a size <200 nm and a mucoinert surface such as PEG or zwitterionic surfaces exhibit high mucus permeating properties. Having reached the underlying absorption membrane, lipid-based nanocarriers enable paracellular and lymphatic drug uptake, induce endocytosis and transcytosis or simply fuse with the cell membrane releasing their payload into the systemic circulation. Numerous in vivo studies provide evidence for the potential of these delivery systems. Within this review we provide an overview about the different barriers for oral peptide and protein delivery, highlight the progress made on lipid-based nanocarriers in order to overcome them and discuss strengths and weaknesses of these delivery systems in comparison to other technologies.

Therapeutic peptides: current applications and future directions

Peptide drug development has made great progress in the last decade thanks to new production, modification, and analytic technologies. Peptides have been produced and modified using both chemical and biological methods, together with novel design and delivery strategies, which have helped to overcome the inherent drawbacks of peptides and have allowed the continued advancement of this field. A wide variety of natural and modified peptides have been obtained and studied, covering multiple therapeutic areas. This review summarizes the efforts and achievements in peptide drug discovery, production, and modification, and their current applications. We also discuss the value and challenges associated with future developments in therapeutic peptides.

In Silico-Based Experiments on Mechanistic Interactions between Several Intestinal Permeation Enhancers with a Lipid Bilayer Model

Oral administration of drugs is generally considered convenient and patient-friendly. However, oral administration of biological drugs exhibits low oral bioavailability (BA) due to enzymatic degradation and low intestinal absorption. A possible approach to circumvent the low BA of oral peptide drugs is to coformulate the drugs with permeation enhancers (PEs). PEs have been studied since the 1960s and are molecules that enhance the absorption of hydrophilic molecules with low permeability over the gastrointestinal epithelium. In this study, we investigated the impact of six PEs on the structural properties of a model membrane using molecular dynamics (MD) simulations. The PEs included were the sodium salts of the medium chain fatty acids laurate, caprate, and caprylate and the caprylate derivative SNAC─all with a negative charge─and neutral caprate and neutral sucrose monolaurate. Our results indicated that the PEs, once incorporated into the membrane, could induce membrane leakiness in a concentration-dependent manner. Our simulations suggest that a PE concentration of at least 70-100 mM is needed to strongly affect transcellular permeability. The increased aggregation propensity seen for neutral PEs might provide a molecular-level mechanism for the membrane disruptions seen at higher concentrations in vivo. The ability for neutral PEs to flip-flop across the lipid bilayer is also suggestive of possible intracellular modes of action other than increasing membrane fluidity. Taken together, our results indicate that MD simulations are useful for gaining insights relevant to the design of oral dosage forms based around permeability enhancer molecules.

The current significance and prospects for the use of dual receptor agonism GLP-1/Glucagon

The therapeutic arsenal for treating type 2 diabetes mellitus (T2DM) has been enriched recently with the inclusion of type 1 glucagon-like peptide (GLP-1). GLP-1 receptor agonists (RA) secondarily reduce appetite, decrease gastric emptying, and reduce body weight. This effect has been used to treat overweight/obesity, especially with comorbidities associated with T2DM. However, the first formulations and adverse effects gradually gave way to new formulations with fewer unpleasant effects and a more extended period of action (weekly subcutaneous administration and even oral administration), which improved the acceptance and adherence to the treatment. Therefore, titration of GLP-1RA should be done gradually. Furthermore, when side effects are consistent and intolerable after weeks/months of titration, a lower dose or a combination of antidiabetic therapies should be implemented, avoiding treatment interruption. The effort to produce increasingly powerful molecules with fewer side effects is the driving force behind the pharmaceutical industry. The unimolecular dual agonism GLP-1RA plus glucagon receptor agonism (GRA) represents an updated pharmacological indication for controlling blood glucose levels in treating T2DM and its comorbidities, showing better effects with less adverse impact than mono GLP-1RA. There are currently different proposals in this way by different laboratories. Nevertheless, the experimental results are promising and show that soon, we will have the contribution of new drugs for the treatment of T2DM.

Safety, tolerability, pharmacodynamics, and pharmacokinetics of CJC-1134-PC in healthy Chinese subjects and type-2 diabetic subjects

BACKGROUND

Glucagon-like peptide-1 (GLP-1) mimetics are widely used for treating type 2 diabetes (T2D) with pleiotropic effects on heart and kidneys. The safety/tolerability and pharmacokinetics/pharmacodynamics ((PK/PD) of CJC-1134-PC (a long-acting GLP-1) were investigated in Chinese.

METHOD

Two randomized, double-blind, placebo-controlled phase I studies were conducted. Study A: 30 healthy subjects received (subcutaneously injected) a single dose (2 mg) or titrate doses (2 + 3 and 2 + 3 + 4 mg at weekly intervals) of CJC-1134-PC. Study B: 49 T2D subjects received 10 weekly doses (1, 2, 3, and 4 mg).

RESULT

CJC-1134-PC was well tolerated with gastrointestinal (GI) side effects. Higher doses increased the adverse events risk. CJC-1134-PC was steadily absorbed, with maximum plasma concentrations(C_max) occurring at 36-72 h and 48 h after administration in healthy and T2D subjects, respectively. The steady-state exposures in T2D subjects increased more than the dose-proportionality(1-3 mg). The mean t_1/2 ranged from 111.6 to 127.6 h. After four- five weeks of targeting doses, steady state was reached in T2D subjects with apparent accumulation effect. At week 11 for T2D subjects, HbA1c mean baseline change was significantly different than that of the placebo, and the fasting plasma glucose (FPG) was not significantly altered.

CONCLUSION

The safety and PK/PD profiles of weekly CJC-1134-PC doses support Phase II studies with guidance on optimal-dose selection. Clinical trial registration: ChiCTR-IPC-15007190.

A Series of Novel, Highly Potent, and Orally Bioavailable Next-Generation Tricyclic Peptide PCSK9 Inhibitors

Proprotein convertase subtilisin-like/kexin type 9 (PCSK9) is a key regulator of plasma LDL-cholesterol (LDL-C) and a clinically validated target for the treatment of hypercholesterolemia and coronary artery disease. Starting from second-generation lead structures such as 2, we were able to refine these structures to obtain extremely potent bi- and tricyclic PCSK9 inhibitor peptides. Optimized molecules such as 44 demonstrated sufficient oral bioavailability to maintain therapeutic levels in rats and cynomolgus monkeys after dosing with an enabled formulation. We demonstrated target engagement and LDL lowering in cynomolgus monkeys essentially identical to those observed with the clinically approved, parenterally dosed antibodies. These molecules represent the first report of highly potent and orally bioavailable macrocyclic peptide PCSK9 inhibitors with overall profiles favorable for potential development as once-daily oral lipid-lowering agents. In this manuscript, we detail the design criteria and multiparameter optimization of this novel series of PCSK9 inhibitors.

Development of an orally delivered GLP-1 receptor agonist through peptide engineering and drug delivery to treat chronic disease

Peptide therapeutics are increasingly used in the treatment of disease, but their administration by injection reduces patient compliance and convenience, especially for chronic diseases. Thus, oral administration of a peptide therapeutic represents a significant advance in medicine, but is challenged by gastrointestinal instability and ineffective uptake into the circulation. Here, we have used glucagon-like peptide-1 (GLP-1) as a model peptide therapeutic for treating obesity-linked type 2 diabetes, a common chronic disease. We describe a comprehensive multidisciplinary approach leading to the development of MEDI7219, a GLP-1 receptor agonist (GLP-1RA) specifically engineered for oral delivery. Sites of protease/peptidase vulnerabilities in GLP-1 were removed by amino acid substitution and the peptide backbone was bis-lipidated to promote MEDI7219 reversible plasma protein binding without affecting potency. A combination of sodium chenodeoxycholate and propyl gallate was used to enhance bioavailability of MEDI7219 at the site of maximal gastrointestinal absorption, targeted by enteric-coated tablets. This synergistic approach resulted in MEDI7219 bioavailability of ~ 6% in dogs receiving oral tablets. In a dog model of obesity and insulin resistance, MEDI7219 oral tablets significantly decreased food intake, body weight and glucose excursions, validating the approach. This novel approach to the development of MEDI7219 provides a template for the development of other oral peptide therapeutics.

Cardiovascular outcomes after initiating GLP-1 receptor agonist or basal insulin for the routine treatment of type 2 diabetes: a region-wide retrospective study

Aim

We aimed to compare cardiovascular outcomes of patients with type 2 diabetes (T2D) who initiated GLP-1 receptor agonists (GLP-1RA) or basal insulin (BI) under routine care.

Methods

We accessed the administrative claims database of the Veneto Region (Italy) to identify new users of GLP-1RA or BI in 2014–2018. Propensity score matching (PSM) was implemented to obtain two cohorts of patients with superimposable characteristics. The primary endpoint was the 3-point major adverse cardiovascular events (3P-MACE). Secondary endpoints included 3P-MACE components, hospitalization for heart failure, revascularizations, and adverse events.

Results

From a background population of 5,242,201 citizens, 330,193 were identified as having diabetes. PSM produced two very well matched cohorts of 4063 patients each, who initiated GLP-1RA or BI after an average of 2.5 other diabetes drug classes. Patients were 63-year-old and only 15% had a baseline history of cardiovascular disease. During a median follow-up of 24 months in the intention-to-treat analysis, 3P-MACE occurred less frequently in the GLP-1RA cohort (HR versus BI 0.59; 95% CI 0.50–0.71; p < 0.001). All secondary cardiovascular endpoints were also significantly in favor of GLP-1RA. Results were confirmed in the as-treated approach and in several stratified analyses. According to the E-value, confounding by unmeasured variables were unlikely to entirely explain between-group differences in cardiovascular outcomes.

Conclusions

Patients with T2D who initiated a GLP-1RA experienced far better cardiovascular outcomes than did matched patients who initiated a BI in the same healthcare system. These finding supports prioritization of GLP-1RA as the first injectable regimen for the management of T2D.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12933-021-01414-3.

The combined effect of permeation enhancement and proteolysis inhibition on the systemic exposure of orally administrated peptides: Salcaprozate sodium, soybean trypsin inhibitor, and teriparatide study in pigs

Oral delivery of peptides and proteins is hindered by their rapid proteolysis in the gastrointestinal tract and their inability to permeate biological membranes. Various drug delivery approaches are being investigated and implemented to overcome these obstacles. In the discussed study conducted in pigs, an investigation was undertaken to assess the effect of combination of a permeation enhancer – salcaprozate sodium, and a proteolysis inhibitor – soybean trypsin inhibitor, on the systemic exposure of the peptide teriparatide, following intraduodenal administration. Results demonstrate that this combination achieves significantly higher Cmax and AUC (~10- and ~20-fold respectively) compared to each of these methodologies on their own. It was thus concluded that an appropriate combination of different technological approaches may considerably contribute to an efficient oral delivery of biological macromolecules.

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Soybean trypsin inhibitor (SBTI) protects hPTH(1–34) from proteolysis in the intestine.

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SNAC/SBTI combination significantly raises plasma exposure of oral hPTH(1–34).

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Oral formulation hPTH(1–34)/SNAC/SBTI befits the PK profile for osteoporosis treatment.

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Endoscopic intraduodenal delivery in pigs enables investigation of absorption mechanisms.

Phytochemicals modulate pancreatic islet β cell function through glucagon-like peptide-1-related mechanisms

Glucagon-like peptide-1 (GLP-1) receptor-based therapies have been developed and extensively applied in clinical practice. GLP-1 plays an important role in improving glycemic homeostasis by stimulating insulin biosynthesis and secretion, suppressing glucagon activity, delaying gastric emptying, and reducing appetite and food ingestion. Furthermore, GLP-1 has positive effects on β-cell function by promoting β-cell proliferation and neogenesis while simultaneously reducing apoptosis. Here, we summarize possible mechanisms of action of GLP-1 upon pancreatic islets as well as describe phytochemicals that modulate pancreatic islet β cell function through glucagon-like peptide-1-related mechanisms. Together, this information provides potential lead compound candidates against diabetes that function as GLP-1 receptor-based pharmacotherapy.

Targeted oral peptide delivery using multi-unit particulates: Drug and permeation enhancer layering approach

Oral delivery of peptides is a challenge due to their instability and their limited transport and absorption characteristics within the gastrointestinal tract. In this work, we used layering techniques in a fluidized bed dryer to create a configuration in which the active peptide, permeation enhancers, and polymers are coated to control the release of the peptide. Formulations were developed to disintegrate at pH values of 5.5 and 7.0. In addition, sustained-release or mucoadhesive polymers were coated to trigger release at a desired site in the gastrointestinal tract. Dissolution studies with a USP Type I (basket) apparatus confirmed the duration of release. Pharmacokinetic studies were performed in beagle dogs to evaluate bioavailability. A high-disintegration pH was found to be advantageous in enhancing bioavailability.

TNFSF14-Derived Molecules as a Novel Treatment for Obesity and Type 2 Diabetes

Obesity is one of the most prevalent metabolic diseases in the Western world and correlates directly with glucose intolerance and insulin resistance, often culminating in Type 2 Diabetes (T2D). Importantly, our team has recently shown that the TNF superfamily (TNFSF) member protein, TNFSF14, has been reported to protect against high fat diet induced obesity and pre-diabetes. We hypothesized that mimics of TNFSF14 may therefore be valuable as anti-diabetic agents. In this study, we use in silico approaches to identify key regions of TNFSF14 responsible for binding to the Herpes virus entry mediator and Lymphotoxin β receptor. In vitro evaluation of a selection of optimised peptides identified six potentially therapeutic TNFSF14 peptides. We report that these peptides increased insulin and fatty acid oxidation signalling in skeletal muscle cells. We then selected one of these promising peptides to determine the efficacy to promote metabolic benefits in vivo. Importantly, the TNFSF14 peptide 7 reduced high fat diet-induced glucose intolerance, insulin resistance and hyperinsulinemia in a mouse model of obesity. In addition, we highlight that the TNFSF14 peptide 7 resulted in a marked reduction in liver steatosis and a concomitant increase in phospho-AMPK signalling. We conclude that TNFSF14-derived molecules positively regulate glucose homeostasis and lipid metabolism and may therefore open a completely novel therapeutic pathway for treating obesity and T2D.

Oral semaglutide in the management of type 2 DM: Clinical status and comparative analysis

BACKGROUND

In the incretin system, Glucagon-like peptide-1 (GLP-1) is a hormone that inhibits the release of glucagon and regulates glucose-dependent insulin secretion. In type 2 diabetes, correcting the impaired incretin system using GLP-1 agonist is a well-defined therapeutic strategy.

OBJECTIVES

This review article aims to discuss the mechanism of action, key regulatory events, clinical trials for glycaemic control and comparative analysis of semaglutide with the second-line antidiabetic drugs.

DESCRIPTION

Semaglutide is a glucagon-like peptide 1 (GLP 1) receptor agonist with enhanced glycaemic control in diabetes patients. In 2019, USFDA approved the first oral GLP-1 receptor agonist, semaglutide to be administered as a once-daily tablet. Further, recent studies highlight the ability of semaglutide to improve the glycaemic control in obese patients with a reduction in body weight. Still, in clinical practice, in type 2 DM treatment paradigm the impact of oral semaglutide remains unidentified. This review article discusses the mechanism of action, pharmacodynamics, key regulatory events, and clinical trials regarding glycaemic control.

CONCLUSION

The review highlights the comparative analysis of semaglutide with the existing second-line drugs for the management of type 2 diabetes mellitus by stressing on its benefits and adverse events.