A GIPR antagonist conjugated to GLP-1 analogues promotes weight loss with improved metabolic parameters in preclinical and phase 1 settings

Specific loss of GIPR signaling in GABAergic neurons enhances GLP-1R agonist-induced body weight loss

OBJECTIVES

Dual incretin agonists are among the most effective pharmaceutical treatments for obesity and type 2 diabetes to date. Such therapeutics can target two receptors, such as the glucagon-like peptide-1 (GLP-1) receptor and the glucose-dependent insulinotropic polypeptide (GIP) receptor in the case of tirzepatide, to improve glycemia and reduce body weight. Regarding body weight effects, GIPR signaling is thought to involve at least two relevant mechanisms: the enhancement of food intake reduction and the attenuation of aversive effects caused by GLP-1R agonists. Although it is known that dual GLP-1R-GIPR agonism produces greater weight loss than GLP-1R agonism alone, the precise mechanism is unknown.

METHODS

To address this question, we used mice lacking GIPR in the whole body, GABAergic neurons, or glutamatergic neurons. These mice were given various combinations of GLP-1R and GIPR agonist drugs with subsequent food intake and conditioned taste aversion measurements.

RESULTS

A GIPR knockout in either the whole body or selectively in inhibitory GABAergic neurons protects against diet-induced obesity, whereas a knockout in excitatory glutamatergic neurons had a negligible effect. Furthermore, we found that GIPR in GABAergic neurons is essential for the enhanced weight loss efficacy of dual incretin agonism, yet, surprisingly, its removal enhances the effect of GLP-1R agonism alone. Finally, GIPR knockout in GABAergic neurons prevents the anti-aversive effects of GIPR agonism.

CONCLUSIONS

Our findings are consistent with GIPR research at large in that both enhancement and removal of GIPR signaling are metabolically beneficial. Notably, however, our findings suggest that future obesity therapies designed to modulate GIPR signaling, whether by agonism or antagonism, would be best targeted towards GABAergic neurons.

Multifunctional incretin peptides in therapies for type 2 diabetes, obesity and associated co-morbidities

Recent studies with peptide-based incretin therapies have focussed mainly on the glucagon-like peptide-1 (GLP-1) receptor agonist semaglutide and the dual agonist tirzepatide that engages receptors for GLP-1 and glucose-dependent insulinotropic polypeptide (GIP). Randomised clinical trials and 'real-world' studies have confirmed the marked glucose-lowering and weight-lowering efficacy of these agents across diverse populations. These include different ethnic groups, young and elderly individuals with and without diabetes and/or overweight or obesity. Recent studies have also confirmed protections against the development and progression of cardiovascular and renal diseases that are additive to the benefits conferred by improved control of blood glucose and body weight. Emerging evidence suggests that incretin therapies could additionally ameliorate fatty liver disease, chronic inflammation, sleep apnea and possibly degenerative bone disorders and cognitive decline. New incretin-based peptide therapies in development include a long-acting glucagon receptor agonist (LY3324954), dual GLP-1/glucagon receptor agonists (survodutide, pemvidutide, mazdutide, G49), triple GLP-1/GIP/glucagon receptor agonists (retatrutide, efocipegtrutide), a combination of semaglutide with the amylin analogue cagrilintide (CagriSema), a unimolecular GLP-1/amylin receptor dual agonist (amycretin), and a GIP receptor antibody with GLP-1 receptor agonism (MariTide). The creation of multi-targeting incretin-based synthetic peptides provides opportunities for improved management of type 2 diabetes and obesity as well as new therapeutic approaches to an expanding list of associated co-morbidities. The aim of the review is to acquaint the reader with developments in the field from 2023 to the present (February 2025).

Glucose-dependent insulinotropic polypeptide (GIP)

BACKGROUND

Glucose-dependent insulinotropic polypeptide (GIP) was the first incretin identified and plays an essential role in the maintenance of glucose tolerance in healthy humans. Until recently GIP had not been developed as a therapeutic and thus has been overshadowed by the other incretin, glucagon-like peptide 1 (GLP-1), which is the basis for several successful drugs to treat diabetes and obesity. However, there has been a rekindling of interest in GIP biology in recent years, in great part due to pharmacology demonstrating that both GIPR agonism and antagonism may be beneficial in treating obesity and diabetes. This apparent paradox has reinvigorated the field, led to new lines of investigation, and deeper understanding of GIP.

SCOPE OF REVIEW

In this review, we provide a detailed overview on the multifaceted nature of GIP biology and discuss the therapeutic implications of GIPR signal modification on various diseases.

MAJOR CONCLUSIONS

Following its classification as an incretin hormone, GIP has emerged as a pleiotropic hormone with a variety of metabolic effects outside the endocrine pancreas. The numerous beneficial effects of GIPR signal modification render the peptide an interesting candidate for the development of pharmacotherapies to treat obesity, diabetes, drug-induced nausea and both bone and neurodegenerative disorders.

Advances in incretin therapies for targeting cardiovascular disease in diabetes

The global prevalence of obesity is skyrocketing at an alarming rate, with recent data estimating that one-in-eight people are now living with the disease. Obesity is a chronic metabolic disorder that shares underlying pathophysiology with other metabolically-linked diseases such as type 2 diabetes mellitus, cardiovascular disease and diabetic cardiomyopathy. There is a distinct correlation between type 2 diabetes status and the likelihood of heart failure. Of note, there is an apparent sexual dimorphism, with women disproportionately affected with respect to the degree of severity of the cardiac phenotype of diabetic cardiomyopathy that results from diabetes. The current pharmacotherapies available for the attenuation of hyperglycaemia in type 2 diabetes are not always effective, and have varying degrees of efficacy in the setting of heart failure. Insulin can worsen heart failure prognosis whereas metformin, sodium-glucose cotransporter 2 inhibitors (SGLT2i) and more recently, glucagon-like peptide-1 receptor agonists (GLP-1RAs), have demonstrated cardioprotection with their administration. This review will highlight the advancement of incretin therapies for individuals with diabetes and heart failure and explore newly-reported evidence of the clinical usefulness of GLP-1R agonists in this distinct phenotype of heart failure.

Evolving Role of Double and Triple Therapy With GLP-1 Receptor Agonists in Obesity and Cardiovascular Disease

Glucagon-like peptide 1 receptor agonists (GLP-1RAs) have emerged as a transformative class of therapies, expanding their clinical utility far beyond glycemic control. Initially developed for the treatment of diabetes, these agents are now recognised as potent therapies for managing overweight and obesity, atherosclerosis, and heart failure. This review explores the evolution of GLP-1RA-based therapies, with a focus on novel advances such as dual GLP-1 and glucose-dependent insulinotropic polypeptide (GIP) receptor agonists ("double G") and triple receptor agonists incorporating glucagon modulation ("triple G"). We also provide an overview of completed and ongoing clinical trials investigating the role of GLP-1RAs in atherosclerosis and heart failure. These developments underscore the expanding therapeutic landscape of GLP-1RAs and their growing significance in cardiometabolic medicine.

GIPR agonism and antagonism decrease body weight and food intake via different mechanisms in male mice

Agonists and antagonists of the glucose-dependent insulinotropic polypeptide receptor (GIPR) enhance body weight loss induced by glucagon-like peptide-1 receptor (GLP-1R) agonism. However, while GIPR agonism decreases body weight and food intake in a GLP-1R-independent manner via GABAergic GIPR+ neurons, it remains unclear whether GIPR antagonism affects energy metabolism via a similar mechanism. Here we show that the body weight and food intake effects of GIPR antagonism are eliminated in mice with global loss of either Gipr or Glp-1r but are preserved in mice with loss of Gipr in either GABAergic neurons of the central nervous system or peripherin-expressing neurons of the peripheral nervous system. Single-nucleus RNA-sequencing shows opposing effects of GIPR agonism and antagonism in the dorsal vagal complex, with antagonism, but not agonism, closely resembling GLP-1R signalling. Additionally, GIPR antagonism and GLP-1R agonism both regulate genes implicated in synaptic plasticity. Collectively, we show that GIPR agonism and antagonism decrease body weight via different mechanisms, with GIPR antagonism, unlike agonism, depending on functional GLP-1R signalling.

GIPR-Ab/GLP-1 peptide-antibody conjugate requires brain GIPR and GLP-1R for additive weight loss in obese mice

Glucose-dependent insulinotropic polypeptide receptor (GIPR) and glucagon-like peptide 1 receptor (GLP-1R) are expressed in the central nervous system (CNS) and regulate food intake. Here, we demonstrate that a peptide-antibody conjugate that blocks GIPR while simultaneously activating GLP-1R (GIPR-Ab/GLP-1) requires both CNS GIPR and CNS GLP-1R for maximal weight loss in obese, primarily male, mice. Moreover, dulaglutide produces greater weight loss in CNS GIPR knockout (KO) mice, and the weight loss achieved with dulaglutide + GIPR-Ab is attenuated in CNS GIPR KO mice. Wild-type mice treated with GIPR-Ab/GLP-1 and CNS GIPR KO mice exhibit similar changes in gene expression related to tissue remodelling, lipid metabolism and inflammation in white adipose tissue and liver. Moreover, GIPR-Ab/GLP-1 is detected in circumventricular organs in the brain and activates c-FOS in downstream neural substrates involved in appetite regulation. Hence, both CNS GIPR and GLP-1R signalling are required for the full weight loss effect of a GIPR-Ab/GLP-1 peptide-antibody conjugate.

Glucose-dependent insulinotropic peptide and beyond: co-agonist innovations in the treatment of metabolic diseases

Glucose-dependent insulinotropic peptide (GIP), a key incretin hormone, has emerged as a pivotal therapeutic target in metabolic disorders. Historically, its therapeutic potential in type 2 diabetes mellitus (T2DM) has been underestimated owing to GIP resistance and its limited acute effects on glycemic control and body weight regulation. However, emerging evidence has demonstrated that GIP resistance is reversible through sustained glycemic improvement, thereby restoring its physiological effectiveness. With the development of gut hormone co-agonists, the potential of GIP in the treatment of metabolic diseases has been reevaluated. The study of GIP and its co-agonists such as glucagon-like peptide-1 (GLP-1), revealed that its mechanism of action in regulating blood glucose, fat metabolism, and bone metabolism is complex and diverse. A better understanding of GIP evolution can help in designing more effective GIP-based treatment strategies. In this review, we summarize the physiological functions of GIP, systematically explores its diverse structural modifications, delves into the realm of unimolecular multi-agonists, and provides a nuanced portrayal of the developmental prospects of GIP analogs.

GLP-1-based therapies for diabetes, obesity and beyond

Glucagon-like peptide 1 (GLP-1)-based therapies, such as semaglutide and tirzepatide, represent highly effective treatment options for people with type 2 diabetes and obesity, enabling effective control of glucose and weight loss, while reducing cardiovascular and renal morbidity and mortality. The success of these medicines has spurred development of next-generation GLP-1-based drugs, promising greater weight loss, improved tolerability and additional options for the route and frequency of dosing. This Review profiles established and emerging GLP-1-based medicines, discussing optimization of pharmacokinetics and tolerability, engagement of new therapeutically useful pathways and safety aspects. Structurally unique GLP-1-based medicines that achieve substantially greater and rapid weight loss may impact musculoskeletal health, providing a rationale for therapeutics that more selectively target adipose tissue loss while preserving muscle mass and strength. Ongoing clinical trials in peripheral vascular disease, neuropsychiatric and substance use disorders, metabolic liver disease, arthritis, hypertension and neurodegenerative disorders may broaden indications for GLP-1-based therapeutics.

Dual and Triple Gut Peptide Agonists on the Horizon for the Treatment of Type 2 Diabetes and Obesity. An Overview of Preclinical and Clinical Data

PURPOSE OF REVIEW

The development of long-acting incretin receptor agonists represents a significant advance in the fight against the concurrent epidemics of type 2 diabetes mellitus (T2DM) and obesity. The aim of the present review is to examine the cellular processes underlying the actions of these new, highly significant classes of peptide receptor agonists. We further explore the potential actions of multi-agonist drugs as well as the mechanisms through which gut-brain communication can be used to achieve long-term weight loss without negative side effects.

RECENT FINDINGS

Several unimolecular dual-receptor agonists have shown promising clinical efficacy studies when used alone or in conjunction with approved glucose-lowering medications. We also describe the development of incretin-based pharmacotherapy, starting with exendin- 4 and ending with the identification of multi-incretin hormone receptor agonists, which appear to be the next major step in the fight against T2DM and obesity. We discuss the multi-agonists currently in clinical trials and how each new generation of these drugs improves their effectiveness. Since most glucose-dependent insulinotropic polypeptide (GIP) receptor: glucagon-like peptide- 1 receptor (GLP- 1) receptor: glucagon receptor triagonists compete in efficacy with bariatric surgery, the success of these agents in preclinical models and clinical trials suggests a bright future for multi-agonists in the treatment of metabolic diseases. To fully understand how these treatments affect body weight, further research is needed.

The unexpected role of GIP in transforming obesity treatment

Despite sharing incretin activity with glucagon-like peptide 1 (GLP-1), the development of gastric inhibitory polypeptide (GIP)-based drugs has been hindered by the minor effects of native GIP on appetite and body weight and genetic studies associating loss-of-function with reduced obesity. Yet, pharmacologically optimized GIP-based molecules have demonstrated profound weight lowering benefits of GIPR agonism when combined with GLP-1-based therapies, which has re-energized deeper exploration of the molecular mechanisms and downstream signaling of GIPR. Interestingly, both GIPR agonism and antagonism offer metabolic benefits, leading to differing viewpoints on how to target GIPR therapeutically. Here we summarize the emerging evidence about the tissue-specific mechanisms that positions GIP-based therapies as important targets for the next generation of anti-obesity and metabolic therapies.

The C-terminal regions of the GLP-1 and GIP receptors are not the key determinants of their differential arrestin recruitment but modulate the rate of receptor endocytosis

Introduction: Glucagon-like peptide-1 (GLP-1) and glucose-dependent insulinotropic polypeptide (GIP) are important regulators of metabolism and mediate the incretin effect. This glucose-dependent potentiation of insulin secretion is severely impaired in patients with type-2 diabetes mellitus. While pharmacological doses of GLP-1 can overcome this impairment, the same is not true for GIP. The reasons for this are unclear. However, differences in the signalling profiles of the GLP-1 and GIP receptors (GLP-1R and GIPR) may contribute. GLP-1R and GIPR are closely related G protein-coupled receptors but differ in their ability to recruit arrestin, GIPR being relatively poorer. Furthermore, these receptors have been reported to utilize different mechanisms to undergo agonist-induced internalization. Methods: This study aimed to identify the role of the C-terminal region of the two receptors in their differing signalling behaviour using chimeric receptors where the C-terminal tail of one receptor was replaced with that of the other. Results: Replacement of the C-terminal tail had only limited effects on G protein and arrestin recruitment to either receptor. GIP-stimulated internalisation of GIPR occurred at a significantly (P < 0.001) slower rate than GLP-1-stimulated internalisation of GLP-1R. Replacement of the C-terminal tail of GIPR with that of GLP-1R significantly (P < 0.05) increased the internalization rate but not to the rate of wild-type GLP-1R. The reciprocal substitution significantly (P < 0.005) decreased internalization rate. Conclusion: These data show that the C-terminal region of GLP-1R and GIPR is not the critical determinant of their differing ability to recruit arrestin but modulates receptor endocytosis.

The role of GIPR in food intake control

Glucose-dependent insulinotropic polypeptide (GIP) is one of two incretin hormones playing key roles in the control of food intake, nutrient assimilation, insulin secretion and whole-body metabolism. Recent pharmacological advances and clinical trials show that unimolecular co-agonists that target the receptors for the incretins - GIP and glucagon-like peptide 1 (GLP-1) - offer more effective treatment strategies for obesity and type 2 diabetes mellitus (T2D) compared with GLP-1 receptor (GLP1R) agonists alone, suggesting previously underappreciated roles of GIP in regulating food intake and body weight. The mechanisms by which GIP regulates energy balance remain controversial as both agonism and antagonism of the GIP receptor (GIPR) produce weight loss and improve metabolic outcomes in preclinical models. Recent studies have shown that GIPR signalling in the central nervous system (CNS), especially in regions of the brain that regulate energy balance, is essential for its action on appetite regulation. This finding has sparked interest in understanding the mechanisms by which GIP engages brain circuits to reduce food intake and body weight. In this review, we present key knowledge around the actions of GIP on food intake regulation and the potential mechanisms by which GIPR and GIPR/GLP1R agonists may regulate energy balance.

GPCR drug discovery: new agents, targets and indications

G protein-coupled receptors (GPCRs) form one of the largest drug target families, reflecting their involvement in numerous pathophysiological processes. In this Review, we analyse drug discovery trends for the GPCR superfamily, covering compounds, targets and indications that have reached regulatory approval or that are being investigated in clinical trials. We find that there are 516 approved drugs targeting GPCRs, making up 36% of all approved drugs. These drugs act on 121 GPCR targets, one-third of all non-sensory GPCRs. Furthermore, 337 agents targeting 133 GPCRs, including 30 novel targets, are being investigated in clinical trials. Notably, 165 of these agents are approved drugs being tested for additional indications and novel agents are increasingly allosteric modulators and biologics. Remarkably, diabetes and obesity drugs targeting GPCRs had sales of nearly US $30 billion in 2023 and the numbers of clinical trials for GPCR modulators in the metabolic diseases, oncology and immunology areas are increasing strongly. Finally, we highlight the potential of untapped target-disease associations and pathway-biased signalling. Overall, this Review provides an up-to-date reference for the drugged and potentially druggable GPCRome to inform future GPCR drug discovery and development.

A comprehensive spatio-cellular map of the human hypothalamus

The hypothalamus is a brain region that plays a key role in coordinating fundamental biological functions1. However, our understanding of the underlying cellular components and neurocircuitries have, until recently, emerged primarily from rodent studies2,3. Here we combine single-nucleus sequencing of 433,369 human hypothalamic cells with spatial transcriptomics, generating a comprehensive spatio-cellular transcriptional map of the hypothalamus, the 'HYPOMAP'. Although conservation of neuronal cell types between humans and mice, as based on transcriptomic identity, is generally high, there are notable exceptions. Specifically, there are significant disparities in the identity of pro-opiomelanocortin neurons and in the expression levels of G-protein-coupled receptors between the two species that carry direct implications for currently approved obesity treatments. Out of the 452 hypothalamic cell types, we find that 291 neuronal clusters are significantly enriched for expression of body mass index (BMI) genome-wide association study genes. This enrichment is driven by 426 'effector' genes. Rare deleterious variants in six of these (MC4R, PCSK1, POMC, CALCR, BSN and CORO1A) associate with BMI at population level, and CORO1A has not been linked previously to BMI. Thus, HYPOMAP provides a detailed atlas of the human hypothalamus in a spatial context and serves as an important resource to identify new druggable targets for treating a wide range of conditions, including reproductive, circadian and metabolic disorders.

The promise of glucagon-like peptide 1 receptor agonists (GLP-1RA) for the treatment of obesity: a look at phase 2 and 3 pipelines

INTRODUCTION

GLP-1-based therapies have changed the treatment of overweight/obesity. Liraglutide 3.0 mg daily, the first GLP-1 RA approved for treatment of overweight, induced a weight loss of 6-8%, Semaglutide 2.4 mg once weekly improved weight loss to about 12-15%, while the dual GIP/GLP-1 receptor agonist tirzepatide once weekly has induced a weight loss of about 20% in obese people without diabetes.

AREAS COVERED

This review describes results obtained with GLP-1 mono-agonists, GLP-1/GIP dual agonists, GLP-1/glucagon co-agonists, and the triple agonist retatrutide (GIP/GLP-1/glucagon), which have shown beneficial effect both on body weight and steatotic liver disease. A combination of semaglutide (a GLP-1 agonist) and cagrilintide (a long-acting amylin analogue) for weekly administration is currently in phase III development, and so is oral semaglutide and several non-peptide small molecule GLP-1 agonists for oral administration. The adverse events with the GLP-1-based therapies are primarily gastrointestinal and include nausea, vomiting, obstipation, or diarrhea, which often can be mitigated by slow up titration.

EXPERT OPINION

The GLP-1-based therapies will change the treatment of obesity and its comorbidities including steatotic liver disease in the future. Outstanding question is maintenance of the weight loss, possibly pharmacological treatment needs to be life-long.

Long-Acting, Longer-Acting, and Ultralong-Acting Antiobesity Peptides

This perspective describes the current status and future prospects of developing long- to ultralong-acting anti-obesity peptides. First, we discuss the current status of lipidation, PEGylation, and Fc fusion technologies to obtain long-acting peptides administered once weekly, and we critique their proposed use for longer dosing intervals. Next, we describe the approach and current results of using macromolecular peptide prodrugs with preprogrammed releasable linkers to achieve longer-acting peptides that can be administered weekly or monthly. Finally, we posit novel modifications of the latter technology that could provide ultralong half-lives of over one month by advantageously exploiting the clearance rates of released peptides. As examples, we posit that prodrugs of low-clearance GLP-1 agonists derived from peptides already modified by lipidation, PEGylation, and Fc fusion could produce ultralong-acting agonists with dosing intervals reaching 3 to even 6 months.

Disulfide-Directed Multicyclic Peptides with N-Terminally Extendable α-Helices for Recognition and Activation of G Protein-Coupled Receptors

Many peptide hormones adopt long α-helical structures upon interacting with their cognate receptors but often exhibit flexible conformations when unbound. Strategies that can stabilize long α-helices without disrupting their binding to receptors are still lacking, which hinders progress in their biological applications and drug development. Here, we present an approach that combines rational design with library screening to create and identify a unique disulfide-directed multicyclic peptide (DDMP) scaffold, which could effectively stabilize N-terminally extendable α-helices while displaying exceptional efficiency in disulfide pairing and oxidative folding. This DDMP scaffold was then utilized for stabilizing the α-helical structure of glucagon-like peptide-1 (GLP-1), resulting in a potent GLP-1 receptor (GLP-1R) agonist with a significantly improved α-helicity and proteolytic stability. By incorporating external α-helices into the DDMP scaffold, we can effectively preserve the native N-terminal α-helical structures while allowing for extensive evolution of the C-terminal disulfide-rich domain for enhancing target binding, as demonstrated by the generation of the DDMP-stabilized GLP-1 (g1:Ox). The cryo-electron microscopy structure of the g1:Ox-GLP-1R in complex with heterotrimeric Gs reveals the molecular basis for the potent binding between g1:Ox and GLP-1R. Specifically, the DDMP moiety establishes additional interactions with the extracellular domain of GLP-1R, which are absent in the case of GLP-1. Thus, this work offers a novel and effective approach for engineering therapeutic peptides and other peptide α-helices, ensuring that both the N- and C-terminal regions remain essential for target recognition and activation.

Obesity and Cardiometabolic Disease: Insights From Genetic Studies

Obesity is a highly prevalent chronic disease and major driver of both atherosclerotic heart disease and heart failure. Obesity is also a heritable neuronal disease with heritability estimates of up to 70%. In this work I review how common genetic variants, usually with small effect sizes, contribute to the risk for developing obesity and cardiometabolic disease in the majority of people and how this can be further modulated by environmental factors. In some individuals, rare genetic variants with large effect sizes can influence the risk of developing obesity, in some cases in a Mendelian manner. I also address how identification of these rare variants has led to fundamental biologic insights into how satiety and reward are biologic processes, has led to more personalized treatments, and has identified potential novel drug treatments. Biologic insights derived from genetic studies of obesity have also improved our understanding of the causal mediators between obesity and cardiovascular disease. A major limitation of studies to date is that they involved mostly people of European ancestry. Studying more diverse populations will improve our understanding of obesity and cardiometabolic disease. Lessons derived from genetic studies make a compelling case for increasing accessibility to therapies that have sustained efficacy in managing obesity and improving health. This increased knowledge must also inform public health initiatives that will reduce the prevalence of obesity in the coming decades.

Cellular senescence: from homeostasis to pathological implications and therapeutic strategies

Cellular aging is a multifactorial and intricately regulated physiological process with profound implications. The interaction between cellular senescence and cancer is complex and multifaceted, senescence can both promote and inhibit tumor progression through various mechanisms. M6A methylation modification regulates the aging process of cells and tissues by modulating senescence-related genes. In this review, we comprehensively discuss the characteristics of cellular senescence, the signaling pathways regulating senescence, the biomarkers of senescence, and the mechanisms of anti-senescence drugs. Notably, this review also delves into the complex interactions between senescence and cancer, emphasizing the dual role of the senescent microenvironment in tumor initiation, progression, and treatment. Finally, we thoroughly explore the function and mechanism of m6A methylation modification in cellular senescence, revealing its critical role in regulating gene expression and maintaining cellular homeostasis. In conclusion, this review provides a comprehensive perspective on the molecular mechanisms and biological significance of cellular senescence and offers new insights for the development of anti-senescence strategies.

Chronic GIPR agonism results in pancreatic islet GIPR functional desensitisation

OBJECTIVES

There is renewed interest in targeting the glucose-dependent insulinotropic polypeptide receptor (GIPR) for treatment of obesity and type 2 diabetes. G-protein coupled receptor desensitisation is suggested to reduce the long-term efficacy of glucagon-like-peptide 1 receptor (GLP-1R) agonists and may similarly affect the efficacy of GIPR agonists. We explored the extent of pancreatic GIPR functional desensitisation with sustained agonist exposure.

METHODS

A long-acting GIPR agonist, GIP108, was used to probe the effect of sustained agonist exposure on cAMP responses in dispersed pancreatic islets using live cell imaging, with rechallenge cAMP responses after prior agonist treatment used to quantify functional desensitisation. Receptor internalisation and β-arrestin-2 activation were investigated in vitro using imaging-based assays. Pancreatic mouse GIPR desensitisation was assessed in vivo via intraperitoneal glucose tolerance testing.

RESULTS

GIP108 treatment led to weight loss and improved glucose homeostasis in mice. Prolonged exposure to GIPR agonists produced homologous functional GIPR desensitisation in isolated islets. GIP108 pre-treatment in vivo also reduced the subsequent anti-hyperglycaemic response to GIP re-challenge. GIPR showed minimal agonist-induced internalisation or β-arrestin-2 activation.

CONCLUSIONS

Although GIP108 chronic treatment improved glucose tolerance, it also resulted in partial desensitisation of the pancreatic islet GIPR. This suggests that ligands with reduced desensitisation tendency might lead to improved in vivo efficacy. Understanding whether pancreatic GIPR desensitisation affects the long-term benefits of GIPR agonists in humans is vital to design effective metabolic pharmacotherapies.

Binding Kinetics, Bias, Receptor Internalization and Effects on Insulin Secretion in vitro and in vivo of a Novel GLP-1R/GIPR Dual Agonist, HISHS-2001

The use of incretin analogues has emerged in recent years as an effective approach to achieve both enhanced insulin secretion and weight loss in type 2 diabetes (T2D) patients. Agonists which bind and stimulate multiple receptors have shown particular promise. However, off target effects, including nausea and diarrhoea, remain a complication of using these agents, and modified versions with optimized pharmacological profiles and/or biased signaling at the cognate receptors are increasingly sought. Here, we describe the synthesis and properties of a molecule which binds to both glucagon-like peptide-1 (GLP-1) and glucose-dependent insulinotropic polypeptide (GIP) receptors (GLP-1R and GIPR) to enhance insulin secretion. HISHS-2001 shows increased affinity at the GLP-1R, as well as a tendency towards reduced internalization and recycling at this receptor versus FDA-approved dual GLP-1R/GIPR agonist tirzepatide. HISHS-2001 also displayed significantly greater bias towards cAMP generation versus β-arrestin 2 recruitment compared to tirzepatide. In contrast, Gαs recruitment was lower versus tirzepatide at the GLP-1R, but higher at the GIPR. Administered to obese hyperglycaemic db/db mice, HISHS-2001 increased circulating insulin whilst lowering body weight and HbA1c with similar efficacy to tirzepatide at substantially lower doses. Thus, HISHS-2001 represents a novel dual receptor agonist with an improved pharmacological profile.

Paradigm shift in obesity treatment: an extensive review of current pipeline agents

Obesity is a multifaceted disease that poses a significant public health challenge. Recent discoveries in understanding the biological pathways that regulate satiety and metabolism have led to a shift in the treatment paradigm for obesity. Thus, the gap between pharmacological and surgical interventions has diminished. The latest approved antiobesity medications help to achieve weight loss comparable to surgery. These GLP-1 analog-based therapies not only cause substantial weight loss but also improve obesity-associated comorbidities. However, there are still unmet needs in obesity care, and treatment options with alternative pathways are necessary. Whether achieved through lifestyle changes or medication, weight loss often leads to muscle mass loss and reduced energy expenditure, resulting in rebound weight gain. Moreover, addressing severe obesity and comorbidities, such as metabolic-associated fatty liver disease (MAFLD), metabolic dysfunction-associated steatohepatitis (MASH), heart failure with preserved ejection fraction, and obstructive sleep apnea, necessitates the development of additional therapeutic strategies. Various antiobesity medications with novel mechanisms of action are currently in the pipeline. Myostatin-activin pathway inhibitors are under development to preserve muscle mass, and combination therapies with glucagon agonists address MAFLD and MASH. Amylin agonists offer a promising alternative to those unable to tolerate GLP-1 analogs. Mitochondrial uncouplers are under investigation for enhancing energy expenditure, NLRP-3 inhibitors for reducing inflammation, and GWAS targets for additional weight loss benefits. Combination therapies, such as dual or triple hormonal receptor agonists, are being developed to maximize weight loss and optimize tolerability. These emerging medications in the clinical trial pipeline show promise for more tolerable and sustainable obesity management.

GLP-1 and the Neurobiology of Eating Control: Recent Advances

Obesity is now considered a chronic relapsing progressive disease, associated with increased all-cause mortality that scales with body weight, affecting more than 1 billion people worldwide. Excess body fat is strongly associated with excess energy intake, and most successful anti-obesity medications (AOMs) counter this positive energy balance through the suppression of eating to drive weight loss. Historically, AOMs have been characterized by modest weight loss and side effects which are compliance-limiting, and in some cases life-threatening. However, the field of obesity pharmacotherapy has now entered a new era of AOMs based on analogues of the gut hormone and neuropeptide glucagon-like peptide-1 (GLP-1). The latest versions of these drugs elicit unprecedented levels of weight loss in clinical trials, which are now starting to be substantiated in real-world usage. Notably, these drugs reduce weight primarily by reducing energy intake, via activation of the GLP-1 receptor on multiple sites of action primarily in the central nervous system, although the most relevant sites of action, and the neural circuits recruited remain contentious. Here we provide a targeted synthesis of recent developments in the field of GLP-1 neurobiology, highlighting studies which have advanced our understanding of how GLP-1 signaling modulates eating, and identify open questions and future challenges we believe still need to be addressed to aid the prevention and/or treatment of obesity.

An Overview of Existing and Emerging Weight-Loss Drugs to Target Obesity-Related Complications: Insights from Clinical Trials

Obesity requires treatment as it is associated with health problems such as type 2 diabetes, hypertension, dyslipidemia, cardiovascular diseases, and some cancers, which increase mortality rates. Achieving sufficient weight loss to reduce obesity-related diseases requires a variety of interventions, including comprehensive lifestyle modification of diet and exercise, change in behavior, anti-obesity medications, and surgery. To date, anti-obesity agents with various mechanisms of action have been developed, and mostly reduce energy intake, resulting in weight loss of about 5% to 10% compared to baseline. Recently developed drugs and those currently under development have been shown to reduce body weight by more than 10% and are expected to reduce obesity-related complications. This article summarizes existing and emerging anti-obesity medications, with a particular focus on those evaluated in clinical trials.

Emerging pharmacotherapies for obesity: A systematic review

The history of antiobesity pharmacotherapies is marked by disappointments, often entangled with societal pressure promoting weight loss and the prevailing conviction that excess body weight signifies a lack of willpower. However, categories of emerging pharmacotherapies generate hope to reduce obesity rates. This systematic review of phase 2 and phase 3 trials in adults with overweight/obesity investigates the effect of novel weight loss pharmacotherapies, compared to placebo/control or US Food and Drug Administration-approved weight loss medication, through searching Medline, Embase, and ClinicalTrials.gov (2012-2024). We identified 53 phase 3 and phase 2 trials, with 36 emerging antiobesity drugs or combinations thereof and 4 withdrawn or terminated trials. Oral semaglutide 50 mg is the only medication that has completed a phase 3 trial. There are 14 ongoing phase 3 trials on glucagon-like peptide-1 (GLP-1) receptor agonists (RAs) (ecnoglutide, orforglipron, and TG103), GLP-1 RA/amylin agonist (CagriSema), GLP-1/glucagon RAs (mazdutide and survodutide), GLP-1/glucose-dependent insulinotropic polypeptide and glucagon RA (retatrutide), dapagliflozin, and the combination sibutramine/topiramate. Completed phase 2 trials on incretin-based therapies showed a mean percent weight loss of 7.4% to 24.2%. Almost half of the drugs undergoing phase 2 trials are incretin analogs. The obesity drug pipeline is expanding rapidly, with the most promising results reported with incretin analogs. Data on mortality and obesity-related complications, such as cardio-renal-metabolic events, are needed. Moreover, long-term follow-up data on the safety and efficacy of weight maintenance with novel obesity pharmacotherapies, along with studies focused on underrepresented populations, cost-effectiveness assessments, and drug availability, are needed to bridge the care gap for patients with obesity. SIGNIFICANCE STATEMENT: Obesity is the epidemic of the 21st century. Except for the newer injectable medications, drugs with suboptimal efficacy have been available in the clinician's armamentarium for weight management. However, emerging alternatives of novel agents and combinations populate the current obesity therapeutic pipeline. This systematic review identifies the state and mechanism of action of emerging pharmacotherapies undergoing or having completed phase 2 and phase 3 clinical trials. The information provided herein furthers the understanding of obesity management, implying direct clinical implications and stimulating research initiatives.

Characterization of Interchanging Incretin Analogs in Clinical Practice: A Descriptive Report

OBJECTIVE

To characterize the tolerability associated with incretin analog interchanges to equipotent or higher strengths based on an interchange process in an adult outpatient setting.

METHODS

This was a retrospective chart review of adult patients receiving care through a participating family medicine or endocrinology clinic between January 1, 2022, and November 30, 2022 at a major academic medical center. An incretin analog equivalency table and protocol for interchange was created in response to ongoing shortages and need for therapy adjustments to different medications within the same class. Patients were included if a recommended incretin analog interchange was initiated and a tolerability assessment was conducted. Patients were excluded if they did not meet inclusion criteria or if they were unreachable for tolerability assessments for interchanged agents.

RESULTS

There were 156 patients included for characterization and response to tolerability of interchange. It was determined that 96% of patients tolerated the incretin analog interchange. A dose escalation occurred in 58% of patients, 41% were transitioned to an equipotent dose, and a dose decrease was considered in 1 patient. Prior authorizations were required 74% of the time for the new therapy. The most common interchanges were dulaglutide 4.5 mg to tirzepatide 7.5 mg, dulaglutide 4.5 mg to tirzepatide 10 mg, and dulaglutide 3 mg to tirzepatide 7.5 mg. These interchanges made up 37.3% of the total population and were observed to have 93% tolerability. Seven patients did not tolerate incretin analog interchange. Five experienced gastrointestinal effects and 2 experienced injection site reactions. The interchange of incretin analog was estimated to reduce time to maximum dose by a median of 3 months. During this study, no patients experienced interruption of therapy defined as missing a dose of incretin analog.

CONCLUSION

This characterization report demonstrates an effective approach to addressing incretin analog interchanges. A high level of tolerability is evident with the defined interchange process. Future studies should continue to confirm effective and safe interchanges of incretin analogs from outcomes and tolerability reports.

Tirzepatide for overweight and obesity management

INTRODUCTION

Tirzepatide is a once-weekly dual agonist, acting on glucagon-like peptide-1 (GLP-1) and glucose-dependent insulinotropic polypeptide (GIP) receptors. It is approved at the same doses (5, 10 and 15 mg) for both type 2 diabetes (T2D) and chronic weight management.

AREAS COVERED

Following a search in PubMed, clinicaltrials.gov, conference abstracts and Lilly website, we review herein the global phase 3 SURMOUNT program on tirzepatide's safety and efficacy for chronic weight management. Additionally, we discuss findings from the regional SURMOUNT-CN and SURMOUNT-J trials (in East-Asian populations) and the phase 2 SYNERGY-NASH, phase 3 SURMOUNT-OSA and SUMMIT studies on tirzepatide's impact on obesity-related complications. We also explore the clinical implications of SURMOUNT program results, considerations for tirzepatide prescribing for overweight/obesity, ongoing research and evidence gaps.

EXPERT OPINION

Tirzepatide marks a new era in overweight/obesity treatment, enabling many to achieve ≥ 20% weight loss. It is well-tolerated with a safety profile similar to GLP-1 receptor agonists. Tirzepatide also results in clinically important improvements in multiple obesity-related complications including sleep apnea, metabolic-dysfunction associated steatohepatitis, heart failure with preserved ejection fraction and diabetes prevention. Ongoing trials will provide further data on tirzepatide's long-term safety, efficacy (including cardiovascular outcomes) and potential cost-effectiveness for managing overweight/obesity and/or T2D.

Weight Loss Blockbuster Development: A Role for Unimolecular Polypharmacology

Obesity and type 2 diabetes mellitus (T2DM) impact more than 2.5 billion adults worldwide, necessitating innovative therapeutic approaches. Unimolecular polypharmacology, which involves designing single molecules to target multiple receptors or pathways simultaneously, has revolutionized treatment strategies. Blockbuster drugs such as tirzepatide and retatrutide have shown unprecedented success in managing obesity and T2DM, demonstrating superior efficacy compared to conventional single agonists. Tirzepatide, in particular, has garnered tremendous attention for its remarkable effectiveness in promoting weight loss and improving glycemic control, while offering additional cardiovascular and renal benefits. Despite their promises, such therapeutic agents also face challenges that include gastrointestinal side effects, patient compliance issues, and body weight rebound after cessation of the treatment. Nonetheless, the development of these therapies marks a significant leap forward, underscoring the transformative potential of unimolecular polypharmacology in addressing metabolic diseases and paving the way for future innovations in personalized medicine.

Optimizing treatment of cardiovascular risk factors in cerebral small vessel disease using genetics

Cerebral small vessel disease (cSVD) causes lacunar stroke (LS), intracerebral haemorrhage, and is the most common pathology underlying vascular dementia. However, there are few trials examining whether treating conventional cardiovascular risk factors reduce stroke risk in cSVD, as opposed to stroke as a whole. We used Mendelian randomization techniques to investigate which risk factors are causally related to cSVD and to evaluate whether specific drugs may be beneficial in cSVD prevention. We identified genetic proxies for blood pressure traits, lipids, glycaemic markers, anthropometry measures, smoking, alcohol consumption, and physical activity from large-scale genome-wide association studies of European ancestry. We also selected genetic variants as proxies for drug target perturbation in hypertension, dyslipidaemia, hyperglycaemia, and obesity. Mendelian randomization was performed to assess their associations with LS from the GIGASTROKE Consortium (n = 6811) and in a sensitivity analysis in a cohort of patients with MRI-confirmed LS (n = 3306). We also investigated associations with three neuroimaging features of cSVD, namely, white matter hyperintensities (n = 55 291), fractional anisotropy (n = 36 460), and mean diffusivity (n = 36 012). Genetic predisposition to higher systolic and diastolic blood pressure was associated with LS and cSVD imaging markers. Genetically predicted liability to diabetes, obesity, smoking, higher triglyceride levels, and the ratio of triglycerides to high density lipoprotein (HDL) also showed detrimental associations with LS risk, while genetic predisposition to higher HDL concentrations and moderate-to-vigorous physical activity showed protective associations. Genetically proxied blood pressure-lowering through calcium channel blockers (CCBs) was associated with cSVD imaging markers, while genetically proxied HDL-raising through Cholesteryl Ester Transfer Protein (CETP) inhibitors, triglyceride-lowering through lipoprotein lipase (LPL), and weight-lowering through gastric inhibitory polypeptide receptor (GIPR) were associated with lower risk of LS. Our findings highlight the importance of some conventional cardiovascular risk factors, including blood pressure and BMI, in cSVD, but not other e.g. LDL. The findings further demonstrate the potential beneficial effects of CCBs on cSVD imaging markers and CETP inhibitors, LPL enhancement, and GIPR obesity-targeted drugs on LS. They provide useful information for initiating future clinical trials examining secondary prevention strategies in cSVD.

GLP-1 receptor agonists in patients with chronic kidney disease and either overweight or obesity

Glucagon-like peptide-1 receptor agonists (GLP-1 RAs) have emerged as game-changers across the cardiovascular-kidney-metabolic (CKM) spectrum: overweight/obesity, type 2 diabetes mellitus (T2DM) and associated chronic kidney disease (CKD) and cardiovascular disease (CVD). Liraglutide, semaglutide and tirzepatide are European Medicines Agency approved to improve metabolic control in T2DM and to decrease weight in persons with obesity [body mass index (BMI) ≥30 kg/m2] or with overweight (BMI ≥27 kg/m2) associated with weight-related comorbidities such as hypertension, dyslipidaemia, CVD and others. Additionally, liraglutide and semaglutide are approved to reduce CVD risk in patients with CVD and T2DM. Semaglutide is also approved to reduce CVD risk in patients with CVD and either obesity or overweight and in phase 3 clinical trials showed kidney and cardiovascular protection in patients with T2DM and albuminuric CKD (FLOW trial) as well as in persons without diabetes that had CVD and overweight/obesity (SELECT trial). Thus, nephrologists should consider prescribing GLP-1 RAs to improve metabolic control, reduce CVD risk or improve kidney outcomes in three scenarios: patients with overweight and a related comorbid condition such as hypertension, dyslipidaemia or CVD, patients with obesity and patients with T2DM. This review addresses the promising landscape of GLP-1 RAs to treat persons with overweight or obesity, with or without T2DM, within the context of CKD, assessing their safety and impact on weight, metabolic control, blood pressure and kidney and cardiovascular outcomes, as part of a holistic patient-centred approach to preserve CKM health.

Obstructive sleep apnea and obesity: A review of epidemiology, pathophysiology and the effect of weight-loss treatments

Despite the commonly-accepted paradigm that patients with obstructive sleep apnea (OSA) also invariably have obesity, OSA prevalence extends beyond obesity. This necessitates a reevaluation of screening strategies, biomarkers of increased OSA risk, and heightened awareness among healthcare providers about the array of OSA treatments for diverse adult populations. While obesity contributes importantly to OSA pathogenesis, there is substantial evidence that non-anatomical factors also play a crucial role, especially in patients who do not have obesity. In recent years, notwithstanding the recognition of diverse contributors to OSA pathogenesis, research has frequently focused on weight reduction to address OSA. Insights from past experiences with bariatric surgery in OSA serve as a lens to anticipate potential outcomes of emerging anti-obesity pharmacotherapies. Pharmacological alternatives, particularly incretin agonists, exhibit promise in weight reduction and OSA improvement, but encounter obstacles such as potential side effects and high costs. With this comprehensive narrative review, we delve into the complex epidemiological and pathophysiological connections between OSA and obesity. Additionally, we emphasize the importance of a multifaceted approach to OSA treatment, recognizing that while weight management is crucial, there is a need for comprehensive strategies that go beyond traditional weight-centric perspectives.

Müller T. Why are we still in need for novel anti-obesity medications?

From the pioneering moment in 1987 when the insulinotropic effect of glucagon-like peptide 1 (GLP-1) was first demonstrated in humans, to today's pharmaceutical gold rush for GLP-1-based treatments of obesity, the journey of GLP-1 pharmacology has been nothing short of extraordinary. The sequential conceptual developments of long-acting GLP-1 receptor (GLP-1R) mono-agonists, GLP-1R/glucose-dependent insulinotropic polypeptide receptor (GIPR) dual-agonists, and GLP-1R/GIPR/glucagon receptor (GcgR) triple agonists, have led to profound body weight-lowering capacities, with benefits that extend past obesity and towards obesity-associated diseases. The GLP-1R/GIPR dual-agonist tirzepatide has demonstrated a remarkable 23% body weight reduction in individuals with obesity over 72 weeks, eclipsing the average result achieved by certain types of bariatric surgery. Meanwhile, the GLP-1R/GIPR/GcgR triple-agonist retatrutide achieves similar body weight loss (∼25%) in just two-thirds of the time, potentially surpassing the efficacy of Roux-en-Y gastric bypass. These remarkable achievements rightfully raise the question whether and why there is still need for novel anti-obesity medications (AOMs) in the future.

Recent achievements and future directions of anti-obesity medications

Pharmacological management of obesity long suffered from a reputation of a 'Mission Impossible,' with inefficient weight loss and/or unacceptable tolerability. However, the tide has turned with recent progress in biochemical engineering and the development of long-acting agonists at the receptor for glucagon-like peptide-1 (GLP-1), and with unimolecular peptides that simultaneously possess activity at the receptors for GLP-1, the glucose-dependent insulinotropic polypeptide (GIP) and glucagon. Some of these novel therapeutics not only improve body weight and glycemic control in individuals with obesity and type 2 diabetes with hitherto unmet efficacy and tolerable safety, but also exhibit potential therapeutic value in diverse areas such as neurodegenerative diseases, fatty liver disease, dyslipidemia, atherosclerosis, and cardiovascular diseases. In this review, we highlight recent advances in incretin-based therapies and discuss their pharmacological potential within and beyond the treatment of obesity and diabetes, as well as their limitations in use, side effects, and underlying molecular mechanisms.

Unlocking gut-liver-brain axis communication metabolites: energy metabolism, immunity and barriers

The interaction between the gut-microbiota-derived metabolites and brain has long been recognized in both health and disease. The liver, as the primary metabolic organ for nutrients in animals or humans, plays an indispensable role in signal transduction. Therefore, in recent years, Researcher have proposed the Gut-Liver-Brain Axis (GLBA) as a supplement to the Gut-Brain Axis. The GLBA plays a crucial role in numerous physiological and pathological mechanisms through a complex interplay of signaling pathways. However, gaps remain in our knowledge regarding the developmental and functional influences of the GLBA communication pathway. The gut microbial metabolites serve as communication agents between these three distant organs, functioning prominently within the GLBA. In this review, we provide a comprehensive overview of the current understanding of the GLBA, focusing on signaling molecules role in animal and human health and disease. In this review paper elucidate its mechanisms of communication, explore its implications for immune, and energy metabolism in animal and human, and highlight future research directions. Understanding the intricate communication pathways of the GLBA holds promise for creating innovative treatment approaches for a wide range of immune and metabolic conditions.

The limitation of lipidation: Conversion of semaglutide from once-weekly to once-monthly dosing

The objective of this work was to develop a long-acting form of the lipidated peptide semaglutide that can be administered to humans once-monthly. Semaglutide was attached to hydrogel microspheres by a cleavable linker with an expected in vivo release half-life of about 1 mo. After a single subcutaneous dose, the pharmacokinetic parameters of released semaglutide and bodyweight loss were determined in mice, and results were used to estimate the dosing and pharmacokinetics of the released semaglutide in humans. The in vivo half-life of released semaglutide was ~36 d, and a single dose in diet-induced obese mice resulted in a lean-sparing body weight loss of 20% over 1 mo, statistically the same as semaglutide dosed twice daily. Simulations indicated the microsphere-semaglutide would permit once-monthly administration in humans; moreover, it could maintain the therapeutic minimum concentration (Cmin) of once-weekly semaglutide with only 75% of the once-weekly maximum concentration (Cmax), a feature that could reduce adverse side effects or allow higher dosing. The same approach should enable the conversion of other lipidated peptides from once-weekly to once-monthly administration.

Future Medications for Obesity and Clinical Implications

Semaglutide and tirzepatide have recently been approved for obesity and found to achieve ≥15% weight loss in clinical trials. These drugs have been referred to as second-generation medications because the unprecedented degree of weight loss they afford is sufficient to treat or prevent a broad array of obesity complications and related diseases. Many other medications are in development based on the actions of nutrient-regulated hormones (NRHs), including mono-, dual-, and triple-receptor agonists/antagonists for glucagon-like peptide 1, glucose-dependent insulinotropic polypeptide, amylin, peptide tyrosine-tyrosine, and glucagon. Clinical trial evidence is accumulating that these medications ameliorate multiple biomechanical, metabolic, and vascular complications of obesity. These tools enable a comprehensive complications-centric approach to care within the contextual framework of the diagnostic term adiposity-based chronic disease (ABCD). The potential to reduce patient suffering and the huge social burden of ABCD is profound. The current era of drug development based on NRHs could represent a landmark in the history of medicine provided that societies ensure access to these medications for the patients who need them.

Obesity and Asthma: Implementing a Treatable Trait Care Model

Recognition of obesity as a treatable trait of asthma, impacting its development, clinical presentation and management, is gaining widespread acceptance. Obesity is a significant risk factor and disease modifier for asthma, complicating treatment. Epidemiological evidence highlights that obese asthma correlates with poorer disease control, increased severity and persistence, compromised lung function and reduced quality of life. Various mechanisms contribute to the physiological and clinical complexities observed in individuals with obesity and asthma. These encompass different immune responses, including Type IVb, where T helper 2 cells are pivotal and driven by cytokines like interleukins 4, 5, 9 and 13, and Type IVc, characterised by T helper 17 cells and Type 3 innate lymphoid cells producing interleukin 17, which recruits neutrophils. Additionally, Type V involves immune response dysregulation with significant activation of T helper 1, 2 and 17 responses. Finally, Type VI is recognised as metabolic-induced immune dysregulation associated with obesity. Body mass index (BMI) stands out as a biomarker of a treatable trait in asthma, readily identifiable and targetable, with significant implications for disease management. There exists a notable gap in treatment options for individuals with obese asthma, where asthma management guidelines lack specificity. For example, there is currently no evidence supporting the use of incretin mimetics to improve asthma outcomes in asthmatic individuals without Type 2 diabetes mellitus (T2DM). In this review, we advocate for integrating BMI into asthma care models by establishing clear target BMI goals, promoting sustainable weight loss via healthy dietary choices and physical activity and implementing regular reassessment and referral as necessary.

Efficacy and Safety of GLP-1 Medicines for Type 2 Diabetes and Obesity

The development of glucagon-like peptide 1 receptor agonists (GLP-1RA) for type 2 diabetes and obesity was followed by data establishing the cardiorenal benefits of GLP-1RA in select patient populations. In ongoing trials investigators are interrogating the efficacy of these agents for new indications, including metabolic liver disease, peripheral artery disease, Parkinson disease, and Alzheimer disease. The success of GLP-1-based medicines has spurred the development of new molecular entities and combinations with unique pharmacokinetic and pharmacodynamic profiles, exemplified by tirzepatide, a GIP-GLP-1 receptor coagonist. Simultaneously, investigational molecules such as maritide block the GIP and activate the GLP-1 receptor, whereas retatrutide and survodutide enable simultaneous activation of the glucagon and GLP-1 receptors. Here I highlight evidence establishing the efficacy of GLP-1-based medicines, while discussing data that inform safety, focusing on muscle strength, bone density and fractures, exercise capacity, gastrointestinal motility, retained gastric contents and anesthesia, pancreatic and biliary tract disorders, and the risk of cancer. Rapid progress in development of highly efficacious GLP-1 medicines, and anticipated differentiation of newer agents in subsets of metabolic disorders, will provide greater opportunities for use of personalized medicine approaches to improve the health of people living with cardiometabolic disorders.

GLP-1 Agonism for Kidney Transplant Recipients: A Narrative Review of Current Evidence and Future Directions Across the Research Spectrum

Purpose of Review

Diabetes is the most common cause of kidney disease in individuals that receive a kidney transplant, and those without pre-existing diabetes are at greater risk of developing diabetes following kidney transplant. A class of diabetes treatment medications called glucagon-like peptide-1 receptor agonists (GLP-1RA) has seen recent widespread use for people with diabetes or obesity, with efficacy for improved glycemic control, weight loss, and reduced risk of cardiovascular events. Given these benefits, and indications for use that often co-occur in kidney transplant recipients, use of GLP-1RAs warrants consideration in this population. Therefore, we sought to review the current literature to better understand the mechanisms of action, clinical application, and person-centred considerations of GLP-1RAs in kidney transplant recipients.

Sources of Information

Original articles were identified between December 2023 and July 2024 from electronic databases including the Ovid MEDLINE database, PubMed, and Google Scholar using terms "kidney transplant," "GLP-1," "glucagon-like peptide-1 receptor agonist," and "diabetes."

Methods

A comprehensive review of the literature was conducted to explore the relationship between GLP-1RAs and kidney transplant recipients. We reviewed the current state of evidence across the research disciplines of basic or fundamental science, clinical and health services research, and person-centred equity science, and highlighted important knowledge gaps that offer opportunities for future research.

Key Findings

Numerous clinical studies have demonstrated the benefit of GLP-1RAs in people with and without diabetic kidney disease, including decreased risk of cardiovascular events. However, there is a paucity of high-quality randomized controlled trials and observational studies analyzing use of GLP-1RAs in kidney transplant recipients. Evidence of benefit in this population is therefore limited to small studies or inferred from research conducted in nontransplant populations. Growing evidence from preclinical and clinical studies may elucidate renoprotective mechanisms of GLP-1RAs and remove barriers to application of these drugs in the transplant recipient population. Individuals who are female, non-white, have lower socioeconomic status, and live in rural communities are at greater risk of diabetes and have lower uptake of GLP-1RAs. There is a need for clinical trials across diverse kidney transplant populations to estimate the efficacy of GLP-1RAs on important health outcomes.

Limitations

The search strategy for this narrative review may not have been sensitive to identify all relevant articles. Our search was limited to English language articles.

Common pitfalls in drug target Mendelian randomization and how to avoid them

BACKGROUND

Drug target Mendelian randomization describes the use of genetic variants as instrumental variables for studying the effects of pharmacological agents. The paradigm can be used to inform on all aspects of drug development and has become increasingly popular over the last decade, particularly given the time- and cost-efficiency with which it can be performed even before commencing clinical studies.

MAIN BODY

In this review, we describe the recent emergence of drug target Mendelian randomization, its common pitfalls, how best to address them, as well as potential future directions. Throughout, we offer advice based on our experiences on how to approach these types of studies, which we hope will be useful for both practitioners and those translating the findings from such work.

CONCLUSIONS

Drug target Mendelian randomization is nuanced and requires a combination of biological, statistical, genetic, epidemiological, clinical, and pharmaceutical expertise to be utilized to its full potential. Unfortunately, these skillsets are relatively infrequently combined in any given study.

Assessing the therapeutic and toxicological profile of novel GLP-1 receptor agonists for type 2 diabetes

INTRODUCTION

GLP-1 receptor agonists provide multiple benefits for patients with type 2 diabetes. Nonetheless, there are also several significant adverse effects associated with these agents. A thorough understanding of both therapeutic and toxicological profiles of GLP-1 receptor agonists is crucial for appropriate utilization of this medication class. A literature search of PubMed and ClinicalTrials.gov was carried out to inform discussion on the topic.

AREAS COVERED

This review article discusses the key advantages and disadvantages derived from the use of GLP-1 receptor agonists in the treatment of type 2 diabetes. Landmark trials which helped characterize the cardiovascular and renal benefits of GLP-1 receptor agonists are highlighted. We also discuss key studies still in progress and new formulations under investigation.

EXPERT OPINION

GLP-1 receptor agonists provide glycemic and complication-risk reduction benefits for individuals with type 2 diabetes. Current data suggests there is a lot of potential for further applications, even outside of type 2 diabetes management. It would be of particular interest to see the range of benefits conferred from GLP-1 receptor agonists in individuals without type 2 diabetes. Broader application of these medications could be expected given the ongoing development of new oral formulations and combination agents.

Peptibodies: Bridging the gap between peptides and antibodies

Peptides are a very critical class of pharmaceutical compounds that can control several signaling pathways and thereby affect many physiological and biochemical processes. Previous research suggests that both peptides and antibodies may serve as potent tools for research, diagnostics, vaccination, and therapeutics across diverse domains. The distinct attributes of peptides, like their profound tissue penetration, efficient cellular internalization, reduced immunogenicity, and adaptability to chemical modification, underscore their significance in biomedical applications. However, they also possess drawbacks such as lower affinity, poor absorption, low stability to proteolytic digestion, and rapid clearance. The advent of peptibodies is a significant advance that improves the limitations of both peptides and antibodies. Peptibodies, or Peptide-Fc fusions, represent a promising therapeutic modality comprising biologically active peptides fused to an Fc domain. The stability and efficacy of the peptide are enhanced by this fusion strategy, which overcomes some of the inherent limitations. Many peptibodies have been developed to treat conditions like cancer, diabetes, and lupus. Romiplostim and Dulaglutide are the only ones approved by the EMA and FDA, respectively. Given the growing significance of peptibodies in the pharmaceutical landscape, this investigation aims to explain key aspects encompassing the intrinsic properties of peptides, the intricacies of peptibody production, and their potential therapeutic applications.

GLP-1 physiology in obesity and development of incretin-based drugs for chronic weight management

The introduction of the highly potent incretin receptor agonists semaglutide and tirzepatide has marked a new era in the treatment of type 2 diabetes and obesity. With normalisation of glycated haemoglobin levels and weight losses around 15-25%, therapeutic goals that were previously unrealistic are now within reach, and clinical trials have documented that these effects are associated with reduced risk of cardiovascular events and premature mortality. Here, I review this remarkable development from the earliest observations of glucose lowering and modest weight losses with native glucagon-like peptide (GLP)-1 and short acting compounds, to the recent development of highly active formulations and new molecules. I will classify these agents as GLP-1-based therapies in the understanding that these compounds or combinations may have actions on other receptors as well. The physiology of GLP-1 is discussed as well as its mechanisms of actions in obesity, in particular, the role of sensory afferents and GLP-1 receptors in the brain. I provide details regarding the development of GLP-1 receptor agonists for anti-obesity therapy and discuss the possible mechanism behind their beneficial effects on adverse cardiovascular events. Finally, I highlight new pharmacological developments, including oral agents, and discuss important questions regarding maintenance therapy.

AT-7687, a novel GIPR peptide antagonist, combined with a GLP-1 agonist, leads to enhanced weight loss and metabolic improvements in cynomolgus monkeys

OBJECTIVES

Obesity represents a global health crisis with significant patient burdens and healthcare costs. Despite the advances with glucagon-like peptide-1 (GLP-1) receptor agonists in treating obesity, unmet needs remain. This study characterizes a novel glucose-dependent insulinotropic polypeptide receptor (GIPR) peptide antagonist, AT-7687, evaluating its potential to enhance obesity treatment.

METHODS

We assessed the in vitro potency and pharmacokinetics of AT-7687, alongside its therapeutic effects when administered subcutaneously (SC) alone and in combination with liraglutide to high-fat-diet-fed obese non-human primates (NHP). The study spanned a 42-day treatment period and a 15-day washout period.

RESULTS

AT-7687 demonstrated a subnanomolar cAMP antagonistic potency (pKB of 9.5) in HEK-293 cells and a 27.4 h half-life in NHPs. It effectively maintained weight stability in obese monkeys, whereas placebo recipients had an 8.6% weight increase by day 42 (P = 0.01). Monotherapy with liraglutide resulted in a 12.4% weight reduction compared to placebo (P = 0.03) and combining AT-7687 with liraglutide led to a 16.3% weight reduction (P = 0.0002). The combination therapy significantly improved metabolic markers, reducing insulin levels by 52% (P = 0.008), glucose by 30% (P = 0.02), triglycerides by 39% (P = 0.05), total cholesterol by 29% (P = 0.03), and LDL cholesterol by 48% (P = 0.003) compared to placebo. AT-7687 treatment was well tolerated and not associated with any side effects.

CONCLUSIONS

This study underscores the potential of AT-7687 as a promising addition to current obesity treatments.

Antidiabetic Treatment and Prevention of Ischemic Stroke: A Systematic Review

Background: Diabetes mellitus (DM) is a prevalent disease in the general population and also a well-established risk factor for the development of ischemic stroke. Patients who have been diagnosed with diabetes have a 20% higher risk for developing ischemic stroke in comparison to non-diabetic individuals. The aim of the current systematic review is to provide the latest evidence regarding the association between antidiabetic treatment and the prevention of ischemic stroke. Methods: A comprehensive search in scientific literature databases PUBMED, COCHRANE, and SCOPUS was conducted. The studies that were deemed as eligible for this review were those that examined the clinical benefits of therapeutic strategies in terms of preventing ischemic strokes. Results: A total of 32 studies met the established selection criteria. The included studies showed that pioglitazone treatment significantly reduced the risk for recurrent stroke in patients with DM. Furthermore, in the context of primary prevention, the improvement in glycemic control after treatment with the glucagon-like peptide-1 receptor agonists (GLP-1RA) semaglutide and dulaglutide was associated with a reduction in the risk of ischemic stroke in diabetic subjects. Metformin monotherapy may reduce stroke risk, while dipeptidyl peptidase 4 inhibitors, sodium-glucose co-transporter 2 inhibitors, and insulin do not seem to affect the incidence of stroke. Conclusions: The findings of the present systematic review suggest that pioglitazone and GLP-1RA may decrease the risk of stroke. Further studies are needed to provide additional data regarding the preventive effect of novel antidiabetic drugs, such as dual glucose-dependent insulinotropic polypeptide/GLP-1RA agents, on stroke.