Continued Treatment With Tirzepatide for Maintenance of Weight Reduction in Adults With Obesity: The SURMOUNT-4 Randomized Clinical Trial.

Importance: The effect of continued treatment with tirzepatide on maintaining initial weight reduction is unknown. Objective: To assess the effect of tirzepatide, with diet and physical activity, on the maintenance of weight reduction. Design, Setting, and Participants: This phase 3, randomized withdrawal clinical trial conducted at 70 sites in 4 countries with a 36-week, open-label tirzepatide lead-in period followed by a 52-week, double-blind, placebo-controlled period included adults with a body mass index greater than or equal to 30 or greater than or equal to 27 and a weight-related complication, excluding diabetes. Interventions: Participants (n = 783) enrolled in an open-label lead-in period received once-weekly subcutaneous maximum tolerated dose (10 or 15 mg) of tirzepatide for 36 weeks. At week 36, a total of 670 participants were randomized (1:1) to continue receiving tirzepatide (n = 335) or switch to placebo (n = 335) for 52 weeks. Main Outcomes and Measures: The primary end point was the mean percent change in weight from week 36 (randomization) to week 88. Key secondary end points included the proportion of participants at week 88 who maintained at least 80% of the weight loss during the lead-in period. Results: Participants (n = 670; mean age, 48 years; 473 [71%] women; mean weight, 107.3 kg) who completed the 36-week lead-in period experienced a mean weight reduction of 20.9%. The mean percent weight change from week 36 to week 88 was -5.5% with tirzepatide vs 14.0% with placebo (difference, -19.4% [95% CI, -21.2% to -17.7%]; P < .001). Overall, 300 participants (89.5%) receiving tirzepatide at 88 weeks maintained at least 80% of the weight loss during the lead-in period compared with 16.6% receiving placebo (P < .001). The overall mean weight reduction from week 0 to 88 was 25.3% for tirzepatide and 9.9% for placebo. The most common adverse events were mostly mild to moderate gastrointestinal events, which occurred more commonly with tirzepatide vs placebo. Conclusions and Relevance: In participants with obesity or overweight, withdrawing tirzepatide led to substantial regain of lost weight, whereas continued treatment maintained and augmented initial weight reduction. Trial Registration: ClinicalTrials.gov Identifier: NCT04660643.

GIP and GLP-2 together improve bone turnover in humans supporting GIPR-GLP-2R co-agonists as future osteoporosis treatment.

The intestinal hormones glucose-dependent insulinotropic polypeptide (GIP) and glucagon-like peptide-2 (GLP-2) are key regulators of postprandial bone turnover in humans. We hypothesized that GIP and GLP-2 co-administration would provide stronger effect on bone turnover than administration of the hormones separately, and tested this using subcutaneous injections of GIP and GLP-2 alone or in combination in humans. Guided by these findings, we designed series of GIPR-GLP-2R co-agonists as template for new osteoporosis treatment. The clinical experiment was a randomized cross-over design including 10 healthy men administered subcutaneous injections of GIP and GLP-2 alone or in combination. The GIPR-GLP-2R co-agonists were characterized in terms of binding and activation profiles on human and rodent GIP and GLP-2 receptors, and their pharmacokinetic (PK) profiles were improved by dipeptidyl peptidase-4 protection and site-directed lipidation. Co-administration of GIP and GLP-2 in humans resulted in an additive reduction in bone resorption superior to each hormone individually. The GIPR-GLP-2R co-agonists, designed by combining regions of importance for cognate receptor activation, obtained similar efficacies as the two native hormones and nanomolar potencies on both human receptors. The PK-improved co-agonists maintained receptor activity along with their prolonged half-lives. Finally, we found that the GIPR-GLP-2R co-agonists optimized toward the human receptors for bone remodeling are not feasible for use in rodent models. The successful development of potent and efficacious GIPR-GLP-2R co-agonists, combined with the improved effect on bone metabolism in humans by co-administration, support these co-agonists as a future osteoporosis treatment.

Novel agonist and antagonist radioligands for the GLP-2 receptor. Useful tools for studies of basic GLP-2 receptor pharmacology.

BACKGROUND: Glucagon-like peptide-2 (GLP-2) is a pro-glucagon-derived hormone secreted from intestinal enteroendocrine L cells with actions on gut and bones. GLP-2(1-33) is cleaved by DPP-4, forming GLP-2(3-33), having low intrinsic activity and competitive antagonism properties at GLP-2 receptors. We created radioligands based on these two molecules. EXPERIMENTAL APPROACH: The methionine in position 10 of GLP-2(1-33) and GLP-2(3-33) was substituted with tyrosine (M10Y) enabling oxidative iodination, creating [125 I]-hGLP-2(1-33,M10Y) and [125 I]-hGLP-2(3-33,M10Y). Both were characterized by competition binding, on-and-off-rate determination and receptor activation. Receptor expression was determined by target-tissue autoradiography and immunohistochemistry. KEY RESULTS: Both M10Y-substituted peptides induced cAMP production via the GLP-2 receptor comparable to the wildtype peptides. GLP-2(3-33,M10Y) maintained the antagonistic properties of GLP-2(3-33). However, hGLP-2(1-33,M10Y) had lower arrestin recruitment than hGLP-2(1-33). High affinities for the hGLP-2 receptor were observed using [125 I]-hGLP-2(1-33,M10Y) and [125 I]-hGLP-2(3-33,M10Y) with KD values of 59.3 and 40.6 nM. The latter (with antagonistic properties) had higher Bmax and faster on and off rates compared to the former (full agonist). Both bound the hGLP-1 receptor with low affinity (Ki of 130 and 330 nM, respectively). Autoradiography in wildtype mice revealed strong labelling of subepithelial myofibroblasts, confirmed by immunohistochemistry using a GLP-2 receptor specific antibody that in turn was confirmed in GLP-2 receptor knock-out mice. CONCLUSION AND IMPLICATIONS: Two new radioligands with different binding kinetics, one a full agonist and the other a weak partial agonist with antagonistic properties were developed and subepithelial myofibroblasts identified as a major site for GLP-2 receptor expression.

The safety of available treatment options for short bowel syndrome and unmet needs.

INTRODUCTION: Short bowel syndrome (SBS) is a rare, highly disabling, life-threatening condition due to extensive intestinal resections, characterized by diarrhea, malabsorption, and malnutrition. SBS is the main cause of intestinal failure (SBS-IF). The primary therapy for SBS-IF is intravenous supplementation (IVS) of nutrients. The pharmacological therapy aims to improve the remnant bowel function, leading to the decrease of IVS requirement. AREAS COVERED: This review provides a safety perspective and discusses unmet clinical needs on pharmacotherapy for SBS, ranging from symptomatic agents traditionally used off-label to manage hypersecretion and diarrhea, to curative drugs with selective intestinotrophic properties. Real-world evidence on symptomatic drugs is lacking. Data on teduglutide - the first-in-class glucagon-like peptide-2 (GLP-2) receptor agonist approved in SBS - are mainly derived from clinical trials, with several unsettled safety issues, including the risk of malignancies. EXPERT OPINION: Defining the long-term safety of drugs used for SBS is a priority; a unified list of commonly used drugs with consolidated proof of effectiveness is needed to harmonize the symptomatic pharmacological approach to SBS. GLP-2 receptor agonists are a promising curative pharmaco-therapeutic approach, although long-term safety and effectiveness deserve further real-world assessment. Pharmacovigilance and global data sharing are crucial to support safe prescribing in SBS.

Site-Specific and Temporal Effects of Apraglutide, a Novel Long-Acting Glucagon-Like Peptide-2 Receptor Agonist, on Intestinal Growth in Mice.

Long-acting glucagon-like peptide-2 receptor (GLP-2R) agonists are well-established to increase intestinal growth in rodents and, most notably, humans with short bowel syndrome. Most of the trophic effects of GLP-2R agonists are reported to be mediated through increased growth of the crypt-villus axis, resulting in enhanced mucosal mass and improved intestinal function. The present study examined the effects of apraglutide, a novel GLP-2R agonist, on the growth of the small intestine and colon after 3, 7, and 10 weeks of treatment in male and female mice. Apraglutide (3 mg/kg; three times per week) significantly increased small intestinal weight (P < 0.001) and length (P < 0.001) after 3 weeks of administration, with a further increase in effectiveness after 10 weeks (P < 0.01). Crypt depth and villus height were both markedly increased after 3 weeks of apraglutide administration (P < 0.001) but did not show any further increase with duration of treatment, whereas crypt number and intestinal circumference were increased after 7 and 10 weeks (P < 0.01) but not after 3 weeks of apraglutide treatment. Both the weight and the length of the colon were also enhanced by apraglutide treatment for 3 weeks (P < 0.001), and these effects were maintained but did not improve further with continued apraglutide administration. The results of this study demonstrate that the novel, long-acting GLP-2R agonist, apraglutide, demonstrates an unexpected marked ability to increase intestinal length as well as exert time- and location-dependent specificity in its intestinotrophic actions. SIGNIFICANCE STATEMENT: The novel long-acting glucagon-like peptide 2 receptor agonist, apraglutide, enhances intestinal weight as well as intestinal length in a time- and site-dependent fashion.

Pharmacological Characterization of Apraglutide, a Novel Long-Acting Peptidic Glucagon-Like Peptide-2 Agonist, for the Treatment of Short Bowel Syndrome.

Glucagon-like peptide-2 (GLP-2) agonists have therapeutic potential in clinical indications in which the integrity or absorptive function of the intestinal mucosa is compromised, such as in short bowel syndrome (SBS). Native hGLP-2, a 33-amino acid peptide secreted from the small intestine, contributes to nutritional absorption but has a very short half-life because of enzymatic cleavage and renal clearance and thus is of limited therapeutic value. The GLP-2 analog teduglutide (Revestive/Gattex; Shire Inc.) has been approved for use in SBS since 2012 but has a once-daily injection regimen. Pharmacokinetic (PK) and pharmacodynamic studies confirm that apraglutide, a novel GLP-2 analog, has very low clearance, long elimination half-life, and high plasma protein binding compared with GLP-2 analogs teduglutide and glepaglutide. Apraglutide and teduglutide retain potency and selectivity at the GLP-2 receptor comparable to native hGLP-2, whereas glepaglutide was less potent and less selective. In rat intravenous PK studies, hGLP-2, teduglutide, glepaglutide, and apraglutide had clearances of 25, 9.9, 2.8, and 0.27 ml/kg per minute, respectively, and elimination half-lives of 6.4, 19, 16, and 159 minutes, respectively. The unique PK profile of apraglutide administered via intravenous and subcutaneous routes was confirmed in monkey and minipig and translated into significantly greater in vivo pharmacodynamic activity, measured as small intestinal growth in rats. Apraglutide showed greater intestinotrophic activity than the other peptides when administered at less-frequent dosing intervals because of its prolonged half-life. We postulate that apraglutide offers several advantages over existing GLP-2 analogs and is an excellent candidate for the treatment of gastrointestinal diseases, such as SBS. SIGNIFICANCE STATEMENT: Apraglutide is a potent and selective GLP-2 agonist with an extremely low clearance and prolonged elimination half-life, which differentiates it from teduglutide (the only approved GLP-2 agonist). The enhanced pharmacokinetics of apraglutide will benefit patients by enabling a reduced dosing frequency and removing the need for daily injections.

GLP-2 Acutely Prevents Endotoxin-Related Increased Intestinal Paracellular Permeability in Rats.

BACKGROUND: Circulating endotoxin (lipopolysaccharide, LPS) increases the gut paracellular permeability. We hypothesized that glucagon-like peptide-2 (GLP-2) acutely reduces LPS-related increased intestinal paracellular permeability by a mechanism unrelated to its intestinotrophic effect. METHODS: We assessed small intestinal paracellular permeability in vivo by measuring the appearance of intraduodenally perfused FITC-dextran 4000 (FD4) into the portal vein (PV) in rats 1-24 h after LPS treatment (5 mg/kg, ip). We also examined the effect of a stable GLP-2 analog teduglutide (TDG) on FD4 permeability. RESULTS: FD4 movement into the PV was increased 6 h, but not 1 or 3 h after LPS treatment, with increased PV GLP-2 levels and increased mRNA expressions of proinflammatory cytokines and proglucagon in the ileal mucosa. Co-treatment with a GLP-2 receptor antagonist enhanced PV FD4 concentrations. PV FD4 concentrations 24 h after LPS were higher than FD4 concentrations 6 h after LPS, reduced by exogenous GLP-2 treatment given 6 or 12 h after LPS treatment. FD4 uptake measured 6 h after LPS was reduced by TDG 3 or 6 h after LPS treatment. TDG-associated reduced FD4 uptake was reversed by the VPAC1 antagonist PG97-269 or L-NAME, not by EGF or IGF1 receptor inhibitors. CONCLUSIONS: Systemic LPS releases endogenous GLP-2, reducing LPS-related increased permeability. The therapeutic window of exogenous GLP-2 administration is at minimum within 6-12 h after LPS treatment. Exogenous GLP-2 treatment is of value in the prevention of increased paracellular permeability associated with endotoxemia.

Recent Developments in Therapeutic Peptides for the Glucagon-like Peptide 1 and 2 Receptors.

Glucagon-like peptide 1 (GLP-1) and glucagon-like peptide 2 (GLP-2) are proglucagon derived peptides that are released from gut endocrine cells in response to nutrient intake. These molecules are rapidly inactivated by the action of dipeptidyl peptidase IV (DPP-4) which limits their use as therapeutic agents. The recent emergence of three-dimensional structures of GPCRs such as GLP-1R and glucagon receptor has helped to drive the rational design of innovative peptide molecules that hold promise as novel peptide therapeutics. One emerging area is the discovery of multifunctional molecules that act at two or more pharmacological systems to enhance therapeutic efficacy. In addition, drug discovery efforts are also focusing on strategies to improve patient convenience through alternative routes of peptide delivery. These novel strategies highlight the broad utility of peptide-based therapeutics in human disease settings where unmet needs still exist.

Metabolic and gut microbiome changes following GLP-1 or dual GLP-1/GLP-2 receptor agonist treatment in diet-induced obese mice.

Enteroendocrine L-cell derived peptide hormones, notably glucagon-like peptide-1 (GLP-1) and glucagon-like peptide-2 (GLP-2), have become important targets in the treatment of type 2 diabetes, obesity and intestinal diseases. As gut microbial imbalances and maladaptive host responses have been implicated in the pathology of obesity and diabetes, this study aimed to determine the effects of pharmacologically stimulated GLP-1 and GLP-2 receptor function on the gut microbiome composition in diet-induced obese (DIO) mice. DIO mice received treatment with a selective GLP-1 receptor agonist (liraglutide, 0.2 mg/kg, BID) or dual GLP-1/GLP-2 receptor agonist (GUB09-145, 0.04 mg/kg, BID) for 4 weeks. Both compounds suppressed caloric intake, promoted a marked weight loss, improved glucose tolerance and reduced plasma cholesterol levels. 16S rDNA sequencing and deep-sequencing shotgun metagenomics was applied for comprehensive within-subject profiling of changes in gut microbiome signatures. Compared to baseline, DIO mice assumed phylogenetically similar gut bacterial compositional changes following liraglutide and GUB09-145 treatment, characterized by discrete shifts in low-abundant species and related bacterial metabolic pathways. The microbiome alterations may potentially associate to the converging biological actions of GLP-1 and GLP-2 receptor signaling on caloric intake, glucose metabolism and lipid handling.

Gut peptide and neuroendocrine regulation of hepatic lipid and lipoprotein metabolism in health and disease.

Non-alcoholic fatty liver disease (NAFLD) is a continuum of disorders that can range from simple steatosis to non-alcoholic steatohepatitis (NASH). As a complex metabolic disorder, the pathophysiology of NAFLD is incompletely understood. Recently glucagon-like peptide (GLP)-1 and -2 signalling has been implicated in the pathogenesis of NAFLD. The role of these gut hormones in the hepatic abnormalities is complicated by lack of consensus on the presence of GLP-1 and GLP-2 receptors within the liver. Nevertheless, GLP-1 and GLP-2 receptor agonists have been associated with alterations in lipid metabolism and hepatic and systemic inflammation, pathological abnormalities characteristic of NAFLD. Treatment with GLP-1 analogues has been shown to reverse features of NAFLD including insulin resistance, and alterations in hepatic de novo lipogenesis and reactive oxygen species. In this review, we provide an overview of the role of GLP-1 and GLP-2 in lipid homeostasis and metabolic disease including NAFLD and NASH.

New Avenues in the Regulation of Gallbladder Motility-Implications for the Use of Glucagon-Like Peptide-Derived Drugs.

CONTEXT: Several cases of cholelithiasis and cholecystitis have been reported in patients treated with glucagon-like peptide 1 (GLP-1) receptor agonists (GLP-1RAs) and GLP-2 receptor agonists (GLP-2RAs), respectively. Thus, the effects of GLP-1 and GLP-2 on gallbladder motility have been investigated. We have provided an overview of the mechanisms regulating gallbladder motility and highlight novel findings on the effects of bile acids and glucagon-like peptides on gallbladder motility. EVIDENCE ACQUISITION: The articles included in the present review were identified using electronic literature searches. The search results were narrowed to data reporting the effects of bile acids and GLPs on gallbladder motility. EVIDENCE SYNTHESIS: Bile acids negate the effect of postprandial cholecystokinin-mediated gallbladder contraction. Two bile acid receptors seem to be involved in this feedback mechanism, the transmembrane Takeda G protein-coupled receptor 5 (TGR5) and the nuclear farnesoid X receptor. Furthermore, activation of TGR5 in enteroendocrine L cells leads to release of GLP-1 and, possibly, GLP-2. Recent findings have pointed to the existence of a bile acid-TGR5-L cell-GLP-2 axis that serves to terminate meal-induced gallbladder contraction and thereby initiate gallbladder refilling. GLP-2 might play a dominant role in this axis by directly relaxing the gallbladder. Moreover, recent findings have suggested GLP-1RA treatment prolongs the refilling phase of the gallbladder. CONCLUSIONS: GLP-2 receptor activation in rodents acutely increases the volume of the gallbladder, which might explain the risk of gallbladder diseases associated with GLP-2RA treatment observed in humans. GLP-1RA-induced prolongation of human gallbladder refilling may explain the gallbladder events observed in GLP-1RA clinical trials.

Central GLP-1 receptor activation modulates cocaine-evoked phasic dopamine signaling in the nucleus accumbens core.

Drugs of abuse increase the frequency and magnitude of brief (1-3s), high concentration (phasic) dopamine release events in terminal regions. These are thought to be a critical part of drug reinforcement and ultimately the development of addiction. Recently, metabolic regulatory peptides, including the satiety signal glucagon-like peptide-1 (GLP-1), have been shown to modulate cocaine reward-driven behavior and sustained dopamine levels after cocaine administration. Here, we use fast-scan cyclic voltammetry (FSCV) to explore GLP-1 receptor (GLP-1R) modulation of dynamic dopamine release in the nucleus accumbens (NAc) during cocaine administration. We analyzed dopamine release events in both the NAc shell and core, as these two subregions are differentially affected by cocaine and uniquely contribute to motivated behavior. We found that central delivery of the GLP-1R agonist Exendin-4 suppressed the induction of phasic dopamine release events by intravenous cocaine. This effect was selective for dopamine signaling in the NAc core. Suppression of phasic signaling in the core by Exendin-4 could not be attributed to interference with cocaine binding to one of its major substrates, the dopamine transporter, as cocaine-induced increases in reuptake were unaffected. The results suggest that GLP-1R activation, instead, exerts its suppressive effects by altering dopamine release - possibly by suppressing the excitability of dopamine neurons. Given the role of NAc core dopamine in the generation of conditioned responses based on associative learning, suppression of cocaine-induced dopamine signaling in this subregion by GLP-1R agonism may decrease the reinforcing properties of cocaine. Thus, GLP-1Rs remain viable targets for the treatment and prevention of cocaine seeking, taking and relapse.

Liraglutide for the treatment of type 2 diabetes mellitus: a meta-analysis of randomized placebo-controlled trials.

INTRODUCTION: Liraglutide has been widely used in the treatment of type 2 diabetes mellitus (T2DM), however, the results of a number of randomized placebo-controlled trials on the effects of liraglutide for the treatment of T2DM have varied. The purpose of this study was to assess the effects of liraglutide versus placebo for the treatment of T2DM. METHODS: We searched randomized controlled trials comparing liraglutide and placebo for the treatment of T2DM in the following databases: MEDLINE; EMBASE; Cochrane Library Central Register of Controlled Trials; and Clinical Trials Gov (through August 2014). The standard mean difference (SMD) was calculated for the continuous data and a χ (2) test was used to evaluate heterogeneity. RESULTS: Initially, 103 articles were retrieved through the literature search and 11 studies met the requirements for the meta-analysis. The effects of liraglutide on lowering glycosylated hemoglobin, fasting plasma glucose, reducing weight, lowering blood pressure, and the prevalence of adverse events were significantly different from placebo (P < 0.0001, SMD = -0.96, 95% CI = [-1.20, -0.73]; P < 0.0001, SMD = -0.72, 95% CI = [-0.99, -0.45]; P = 0.004, SMD = -0.24, 95% CI = [-0.40, -0.07]; P = 0.021, SMD = -0.15, 95% CI = [-0.27, -0.02], and P = 0.007, respectively). CONCLUSION: Liraglutide had greater hypoglycemic, weight-reducing and systolic blood pressure-lowering effects than placebo. However, there were more adverse events in the treatment with liraglutide. It is suggested that additional well-designed, large, studies be conducted to further support the use of liraglutide and provide objective guidance for clinical application of liraglutide.