Effects of liraglutide on gallbladder emptying: A randomized, placebo-controlled trial in adults with overweight or obesity.

AIMS: Treatment with liraglutide 3.0 mg has been associated with gallbladder-related adverse events. To conduct a single-centre, double-blind, 12-week trial comparing the effect of 0.6 mg liraglutide and steady-state liraglutide 3.0 mg with placebo on gallbladder emptying in adults with body mass index (BMI) ≥27 kg/m2 and without diabetes. METHODS: Participants were randomized 1:1 to once-daily subcutaneous liraglutide (n = 26) or placebo (n = 26), starting at 0.6 mg with 0.6-mg weekly increments to 3.0 mg, with nutritional and physical activity counselling. A 600-kcal (23.7 g fat) liquid meal test was performed at baseline, after the first dose and after 12 weeks. The primary endpoint was the 12-week maximum postprandial gallbladder ejection fraction (GBEFmax ), measured over 240 minutes after starting the meal. RESULTS: Baseline characteristics were similar between groups (mean ± SD overall age 47.6 ± 10.0 years, BMI 32.6 ±3.4 kg/m2 , 50% women). Mean 12-week GBEFmax (treatment difference -3.7%, 95% confidence interval [CI] -13.1, 5.7) and area under the GBEF curve in the first 60 minutes (-390% × min, 95% CI -919, 140) did not differ for liraglutide 3.0 mg (n = 23) vs placebo (n = 24). The median (range) time to GBEFmax was 151 (11-240) minutes with liraglutide 3.0 mg and 77 (22-212) minutes with placebo. Similar findings were noted after the first 0.6-mg liraglutide dose. Gastrointestinal disorders, notably nausea and constipation, were the most frequently reported adverse events. CONCLUSIONS: Treatment with liraglutide did not affect the GBEFmax but appeared to prolong the time to GBEFmax .

The uncovering and characterization of a CCKoma syndrome in enteropancreatic neuroendocrine tumor patients.

OBJECTIVE: Neuroendocrine tumors in the pancreas and the gastrointestinal tract may secrete hormones which cause specific syndromes. Well-known examples are gastrinomas, glucagonomas, and insulinomas. Cholecystokinin-producing tumors (CCKomas) have been induced experimentally in rats, but a CCKoma syndrome in man has remained unknown until now. MATERIAL AND METHODS: Using a panel of immunoassays for CCK peptides and proCCK as well as for chromogranin A, we have examined plasma samples from 284 fasting patients with gastroenteropancreatic neuroendocrine tumors. In hyperCCKemic samples, plasma CCK was further characterized by chromatography. RESULTS: One of the patients displayed gross hyperCCKemia. She was a 58-year old woman with a pancreatic endocrine tumor, liver metastases, 500-1000-fold elevated basal CCK concentration in plasma, diarrhea, severe weight loss, recurrent peptic ulcer and bilestone attacks from a contracted gallbladder. The CCK concentrations in plasma were not affected by resection of the pancreatic tumor, but decreased to normal after hemihepatectomy with removal of the metastases. CONCLUSION: A CCKoma syndrome with severe hypersecretion of CCK exists in man. The duodenal ulcer disease and diarrhea with permanently low gastrin in plasma suggest that CCKomas may mimic gastrinoma-like symptoms, because CCK peptides are full agonists of the gastrin/CCK-B receptor.

Measurement of nonsulfated cholecystokinins.

Most proteins undergo posttranslational modifications that govern the function of the protein. In synchrony, correspondingly unmodified proteins that are functionally silent or act differently may also be synthesized. The gut hormone precursor, procholecystokinin (proCCK) is an example of a protein that is heavily modified. An essential modification is O-sulfation of Y77, which is necessary for the gallbladder emptying effect of CCK peptides via the CCKA-receptor. In order to examine possible in vivo synthesis also of nonsulfated CCK, we have established a two-step analysis that requires tryptic cleavage at a defined processing site in proCCK (R75-D76) followed by monospecific RIA-measurement of the then exposed nonsulfated N-terminal sequence of CCK-8 (DYMGW…). The analysis shows that endocrine cells in the gut synthesize nonsulfated CCK peptides (-58, -33, -22, and -8) in the order of 20-35% of the corresponding sulfated CCKs. Since nonsulfated CCK peptides are full agonists of the CCKB-receptor, the assay has revealed a hitherto unrecognized gut hormonal peptide system. The assay may prove useful in the diagnosis and control of diseases with hyperCCKemia. This includes CCK-producing neuroendocrine tumors such as the recently described CCKomas and medullary thyroid C-cell carcinomas.

Pharmacokinetics, Safety, and Tolerability of Glepaglutide, a Long-Acting GLP-2 Analog, in Subjects with Renal Impairment.

BACKGROUND: Glepaglutide is a novel, ready-to-use, long-acting, glucagon-like peptide-2 (GLP-2) analog intended for the treatment of patients with short bowel syndrome (SBS). This study investigated the impact of renal function on the pharmacokinetics and safety of glepaglutide. METHODS: In this 3-site, non-randomized, open-label study, 16 subjects were enrolled: 4 with severe renal impairment (eGFR 15 to < 30 mL/min/1.73 m2), 4 with end stage renal disease (ESRD) not on dialysis (eGFR < 15 mL/min/1.73 m2), and 8 matching controls with normal renal function (eGFR ≥ 90 mL/min/1.73 m2). Blood samples were collected over a 14-day period following a single subcutaneous (SC) dose of glepaglutide 10 mg. Safety and tolerability were assessed throughout the study. The primary pharmacokinetic parameters were area under the curve between dosing and 168 h (AUC0-168 h) and the maximum plasma concentration (Cmax). RESULTS: There was no clinically relevant difference between subjects with severe renal impairment/ESRD and normal renal function with respect to total exposure (AUC0-168 h) and peak plasma concentrations (Cmax) of glepaglutide following a single SC dose. A single SC dose of glepaglutide 10 mg appeared safe and well tolerated in subjects with normal renal function and subjects with severe renal impairment or ESRD. No serious adverse events were reported, and no safety issues were identified. CONCLUSIONS: No difference in glepaglutide pharmacokinetics was seen between renal impaired and normal subjects. Based on this trial, dose adjustment appears not to be warranted in SBS patients with renal impairment. TRIAL REGISTRATION: The trial is registered at http://www. CLINICALTRIALS: gov (NCT04178447) and has the EudraCT number: 2019-001466-15.

Pharmacokinetics of Glepaglutide, A Long-Acting Glucagon-Like Peptide-2 Analogue: A Study in Healthy Subjects.

BACKGROUND AND OBJECTIVE: Glepaglutide is a novel, long-acting, glucagon-like peptide-2 analogue in a stable aqueous formulation for subcutaneous dosing to treat patients with short bowel syndrome. This study was conducted primarily to characterise the pharmacokinetics of glepaglutide in healthy subjects. METHODS: In this open-label, partially randomised, parallel-group study, healthy subjects were evenly randomised to glepaglutide 5 or 10 mg dosed subcutaneously once weekly for 6 weeks or to a single intravenous infusion of glepaglutide 1 mg. Each group comprised 15 subjects. Blood samples were drawn to determine plasma concentrations of the parent drug and its two main metabolites. Concentrations of glepaglutide were calculated as the sum of these three analytes. Citrulline was included as a pharmacodynamic biomarker. Safety was assessed throughout the study. RESULTS: From a comparison of pharmacokinetic parameters following subcutaneous versus intravenous dosing, it is concluded that the pharmacokinetics of glepaglutide following subcutaneous dosing are primarily determined by slow release of the two main glepaglutide metabolites from a subcutaneous depot. For subcutaneous dosing once weekly, the two main metabolites accounted for >98% of the overall glepaglutide exposure at steady state, with the parent drug contributing to less than 1% of exposure. The estimated mean (95% confidence interval) effective half-life for glepaglutide 5 and 10 mg was 124 (73-185) h and 88 (31-146) h, respectively. There was an increase in the citrulline concentration for both glepaglutide subcutaneous dose levels. No safety issues were identified. CONCLUSIONS: Slow release of active metabolites following subcutaneous dosing leads to a significantly protracted pharmacokinetic profile for glepaglutide. These results support that once- or twice-weekly subcutaneous dosing of glepaglutide could be an efficacious therapy for intestinal rehabilitation. GOV IDENTIFIER: NCT03279302.

Nonsulfated cholecystokinins in cerebral neurons.

Cholecystokinin (CCK) is a widely expressed neuropeptide system originally discovered in the gut. Both cerebral and peripheral neurons as well as endocrine I-cells in the small intestine process proCCK to tyrosyl-O-sulfated and α-carboxyamidated peptides. Recently, we reported that gut endocrine I-cells also synthetize nonsulfated CCK in significant amounts. Accordingly, we have now examined whether porcine and rat cerebral tissues (four cortical regions, hypothalamus and cerebellum) also synthesize nonsulfated CCK. A new, specific radioimmunoassay showed that all brain samples from pigs (n=15) and rats (n=6) contained nonsulfated CCK. The highest concentrations were measured in the neocortex; 4.7±0.25pmol/g (7.4%) in the rat and 4.3±1.88pmol/g (2.3%) in the pig. Chromatography of porcine cortical extracts revealed that 96.4% of the CCK was O-sulfated CCK-8. A higher fraction of the larger peptides (CCK-58 and CCK-33) was nonsulfated in comparison with the shorter forms (CCK-22 and CCK-8), i.e., 8.1% and 4.3% versus 0.9% and 1.5%. Immunohistochemical analysis of the rat brain showed an overall similar distribution pattern in selected regions when comparing the antibody specific for nonsulfated CCK-8 with an antibody recognizing both sulfated and nonsulfated CCK. However, nonsulfated CCK immunoreactivity was stronger than that of sulfated CCK in cell bodies and weaker in nerve terminals. We conclude that only a small fraction of neuronal CCK is nonsulfated. The intracellular distribution of nonsulfated CCK in neurons suggests that they contribute only modestly to the CCK transmitter activity.

Nonsulfated cholecystokinins in the small intestine of pigs and rats.

Cholecystokinin (CCK) is a gut hormone that acts via two receptors. The CCKA-receptor requires the tyrosyl residue in the C-terminal bioactive site of CCK to be O-sulfated, whereas, the CCKB-receptor binds irrespective of sulfation. Consequently, unsulfated CCK peptides - if present - may constitute a hormone system that acts only through the CCKB-receptor. Therefore, we have now examined whether, CCK peptides occur in nonsulfated form in the small intestine of pigs and rats. The concentrations of sulfated and nonsulfated CCK were measured by RIAs, one specific for sulfated CCKs and a new two-step assay specific for nonsulfated CCK. For further characterization, the intestinal extracts were subjected to size- and ion exchange-chromatography. The intestinal concentrations of sulfated and nonsulfated CCK were highest in the duodenum and the proximal part of jejunum both in the pig and the rat. The porcine duodenal mucosa contained 193±84pmol/g sulfated CCK and 31±10pmol/g nonsulfated CCK, and the upper rat intestine 70±19pmol/g and 8±2pmol/g, respectively. The degree of sulfation correlated with the endoproteolytic proCCK processing. Thus, 38% of porcine CCK-58 was unsulfated, whereas, only 12% of CCK-8 was unsulfated. The results show that a substantial part of intestinal CCK peptides in rats and pigs are not sulfated, and that the longer peptides (CCK-58 and CCK-33) are less sulfated than the shorter (CCK-22 and CCK-8). Hence, the results demonstrate that proCCK in the gut is processed both to sulfated and unsulfated α-amidated peptides of which the latter are assumed to act via the CCKB-receptor.

Unsulfated cholecystokinin: An overlooked hormone?

Tyrosyl O-sulfation is a common posttranslational derivatization of proteins that may also modify regulatory peptides. Among these are members of the cholecystokinin (CCK)/gastrin family. While sulfation of gastrin peptides is without effect on the bioactivity, O-sulfation is crucial for the cholecystokinetic activity (i.e. gallbladder emptying) of CCK peptides. Accordingly, the purification of CCK as a sulfated peptide was originally monitored by its gallbladder emptying effect. Since then, the dogma has prevailed that CCK peptides are always sulfated. The dogma is correct in a semantic context since the gallbladder expresses only the CCK-A receptor that requires sulfation of the ligand. CCK peptides, however, are also ligands for the CCK-B receptors that do not require ligand sulfation. Consequently, unsulfated CCK peptides may act via CCK-B receptors. Since in vivo occurrence of unsulfated products of proCCK with an intact α-amidated C-terminal tetrapeptide sequence (-Trp-Met-Asp-PheNH(2)) has been reported, it is likely that unsulfated CCK peptides constitute a separate hormone system that acts via CCK-B receptors. This review discusses the occurrence, molecular forms, and possible physiological as well as pathophysiological significance of unsulfated CCK peptides.