Mark A. Bush

Pharmacodynamics, Pharmacokinetics, Safety, and Tolerability of Albiglutide, a Long-Acting Glucagon-Like Peptide-1 Mimetic, in Patients with Type 2 Diabetes

CONTEXT Native glucagon-like peptide-1 increases insulin secretion, decreases glucagon secretion, and reduces appetite but is rapidly inactivated by dipeptidyl peptidase-4. Albiglutide is a novel dipeptidyl peptidase-4-resistant glucagon-like peptide-1 dimer fused to human albumin designed to have sustained efficacy in vivo. OBJECTIVES The objectives were to investigate pharmacodynamics, pharmacokinetics, safety, and tolerability of albiglutide in type 2 diabetes subjects. METHODS In a single-blind dose-escalation study, 54 subjects were randomized to receive placebo or 9-, 16-, or 32-mg albiglutide on d 1 and 8. In a complementary study, 46 subjects were randomized to a single dose (16 or 64 mg) of albiglutide to the arm, leg, or abdomen. RESULTS Significant dose-dependent reductions in 24-h mean weighted glucose [area under the curve((0-24 h))] were observed, with placebo-adjusted least squares means difference values in the 32-mg cohort of -34.8 and -56.4 mg/dl [95% confidence interval (-54.1, -15.5) and (-82.2, -30.5)] for d 2 and 9, respectively. Placebo-adjusted fasting plasma glucose decreased by -26.7 and -50.7 mg/dl [95% confidence interval (-46.3, -7.06) and (-75.4, -26.0)] on d 2 and 9, respectively. Postprandial glucose was also reduced. No hypoglycemic episodes were detected in the albiglutide cohorts. The frequency and severity of the most common adverse events, headache and nausea, were comparable with placebo controls. Albiglutide half-life ranged between 6 and 7 d. The pharmacokinetics or pharmacodynamic of albiglutide was unaffected by injection site. CONCLUSIONS Albiglutide improved fasting plasma glucose and postprandial glucose with a favorable safety profile in subjects with type 2 diabetes. Albiglutides long half-life may allow for once-weekly or less frequent dosing.

Safety, tolerability, pharmacodynamics and pharmacokinetics of albiglutide, a long-acting glucagon-like peptide-1 mimetic, in healthy subjects.

Aims:  Albiglutide is a glucagon‐like peptide‐1 (GLP‐1) mimetic generated by genetic fusion of a dipeptidyl peptidase‐IV‐resistant GLP‐1 dimer to human albumin. Albiglutide was designed to retain the therapeutic effects of native GLP‐1 while extending its duration of action. This study was conducted to determine the pharmacokinetics and initial safety/tolerability profile of albiglutide in non‐diabetic volunteers.

Effects of the mu-opioid receptor antagonist GSK1521498 on hedonic and consummatory eating behaviour: a proof of mechanism study in binge-eating obese subjects

The opioid system is implicated in the hedonic and motivational processing of food, and in binge eating, a behaviour strongly linked to obesity. The aim of this study was to evaluate the effects of 4 weeks of treatment with the mu-opioid receptor antagonist GSK1521498 on eating behaviour in binge-eating obese subjects. Adults with body mass index ⩾30 kg m−2 and binge eating scale scores ⩾19 received 1-week single-blind placebo run-in, and were then randomized to 28 days with either 2 mg day−1 GSK1521498, 5 mg day−1 GSK1521498 or placebo (N=21 per arm) in a double-blind parallel group design. The outcome measures were body weight, fat mass, hedonic and consummatory eating behaviour during inpatient food challenges, safety and pharmacokinetics. The primary analysis was the comparison of change scores in the higher-dose treatment group versus placebo using analysis of covariance at each relevant time point. GSK1521498 (2 mg and 5 mg) was not different from placebo in its effects on weight, fat mass and binge eating scores. However, compared with placebo, GSK1521498 5 mg day−1 caused a significant reduction in hedonic responses to sweetened dairy products and reduced calorific intake, particularly of high-fat foods during ad libitum buffet meals, with some of these effects correlating with systemic exposure of GSK1521498. There were no significant effects of GSK1521498 2 mg day−1 on eating behaviour, indicating dose dependency of pharmacodynamics. GSK1521498 was generally well tolerated and no previously unidentified safety signals were detected. The potential for these findings to translate into clinically significant effects in the context of binge eating and weight regain prevention requires further investigation.

Pharmacological differentiation of opioid receptor antagonists by molecular and functional imaging of target occupancy and food reward-related brain activation in humans

Opioid neurotransmission has a key role in mediating reward-related behaviours. Opioid receptor (OR) antagonists, such as naltrexone (NTX), can attenuate the behaviour-reinforcing effects of primary (food) and secondary rewards. GSK1521498 is a novel OR ligand, which behaves as an inverse agonist at the μ-OR sub-type. In a sample of healthy volunteers, we used [11C]-carfentanil positron emission tomography to measure the OR occupancy and functional magnetic resonance imaging (fMRI) to measure activation of brain reward centres by palatable food stimuli before and after single oral doses of GSK1521498 (range, 0.4–100 mg) or NTX (range, 2–50 mg). GSK1521498 had high affinity for human brain ORs (GSK1521498 effective concentration 50=7.10 ng ml−1) and there was a direct relationship between receptor occupancy (RO) and plasma concentrations of GSK1521498. However, for both NTX and its principal active metabolite in humans, 6-β-NTX, this relationship was indirect. GSK1521498, but not NTX, significantly attenuated the fMRI activation of the amygdala by a palatable food stimulus. We thus have shown how the pharmacological properties of OR antagonists can be characterised directly in humans by a novel integration of molecular and functional neuroimaging techniques. GSK1521498 was differentiated from NTX in terms of its pharmacokinetics, target affinity, plasma concentration–RO relationships and pharmacodynamic effects on food reward processing in the brain. Pharmacological differentiation of these molecules suggests that they may have different therapeutic profiles for treatment of overeating and other disorders of compulsive consumption.

Safety, tolerability, pharmacokinetics and pharmacodynamics of albiglutide, a long-acting GLP-1-receptor agonist, in Japanese subjects with type 2 diabetes mellitus

Abstract Objective: To investigate safety, pharmacokinetics and pharmacodynamics of albiglutide in Japanese subjects with type 2 diabetes mellitus. Research design and methods: This randomized, single-blind, placebo-controlled study examined four doses/dose schedules of subcutaneously (sc) administered albiglutide: 15 mg weekly, 30 mg weekly, 50 mg biweekly, and 100 mg monthly (cohorts A–D, respectively) in 40 subjects (mean age 54.5 years, mean range of glycosylated hemoglobin [HbA1c] 7.1–8.3%), over a 4-week treatment period. Main outcome measures: Safety parameters, including adverse events, clinical laboratory tests, vital signs, and 12-lead electrocardiogram; plasma concentrations of albiglutide; and pharmacodynamic parameters, including change from baseline and weighted mean AUC0–4 in plasma glucose, glucagon, insulin, and C-peptide levels. Clinical trial registration: NCT00530309. Results: At day 29, mean changes from baseline (vs. placebo) in fasting plasma glucose (FPG) were: cohort A, −1.92 mmol/L; B, −1.98 mmol/L; C, −1.74 mmol/L; D, −0.73 mmol/L; changes in weighted mean glucose AUC0–4 were: cohort A, −2.86 mmol/L; B, −3.58 mmol/L; C, −2.51 mmol/L; D, −1.44 mmol/L (for FPG and AUC0–4, all p ≤ 0.002 except 100 mg sc monthly, p = NS); changes from baseline HbA1c were: cohort A, −0.58%; B, −0.57%; C, −0.63%; and D, −0.51% (all p < 0.03). Albiglutide sc had a median half-life of 5.3 days, plasma apparent systemic clearance of 68.7 mL/h, and apparent volume of distribution of 12.6 L. Incidence of adverse events was low and comparable to sc placebo in all albiglutide treatment arms except 100 mg sc monthly, where gastrointestinal (GI) adverse events were most common. Limitations of this study include the small sample size, short treatment duration, and enrollment of predominantly male subjects. Conclusions: Weekly and biweekly albiglutide improved glycemic control and were well-tolerated in Japanese subjects with type 2 diabetes mellitus.

Opioid receptor modulation of hedonic taste preference and food intake: a single-dose safety, pharmacokinetic, and pharmacodynamic investigation with GSK1521498, a novel μ-opioid receptor inverse agonist.

Endogenous opioids and μ‐opioid receptors have been linked to hedonic and rewarding aspects of palatable food intake. The authors examined the safety, pharmacokinetic, and pharmacodynamic profile of GSK1521498, a μ‐opioid receptor inverse agonist that is being investigated primarily for the treatment of overeating behavior in obesity. In healthy participants, GSK1521498 oral solution and capsule formulations were well tolerated up to a dose of 100 mg. After single doses (10–150 mg), the maximum concentration (Cmax) and area under the curve (AUC) in plasma increased in a dose‐proportional manner. GSK1521498 selectively reduced sensory hedonic ratings of high‐sugar and high‐fat dairy products and caloric intake of high‐fat/high‐sucrose snack foods. These findings provide encouraging data in support of the development of GSK1521498 for the treatment of disorders of maladaptive ingestive behavior or compulsive consumption.

Pharmacokinetics and Pharmacodynamics of Recombinant FGF‐2 in a Phase I Trial in Coronary Artery Disease

Fibroblast growth factor‐2 (FGF‐2) is a heparin‐binding protein capable of inducing angiogenesis in multiple animal models of chronic ischemia. The pharmacokinetics and pharmacodynamics of a single dose of recombinant FGF‐2 (rFGF‐2) administered by intracoronary or intravenous infusion were evaluated in a Phase I trial in 66 patients with severe coronary artery disease. rFGF‐2 displayed biphasic elimination with a mean studywide distribution t1/2 of 21 minutes and a mean apparent terminal elimination t1/2 of 7.6 hours. Systemic exposure to rFGF‐2 was comparable following intracoronary or intravenous administration. Peak plasma concentration and area under the concentration‐time curve increased proportionally with dose, indicating linear pharmacokinetics over the dose range examined (0.33 to 48.0 μg/kg). Greater systemic exposure was observed when heparin was administered closer to rFGF‐2 infusion, consistent with slower clearance of heparin/rFGF‐2 complexes. Infusion of rFGF‐2 was associated with changes in acute hemodynamics. While a clear PK/PD dose‐response relationship was not established, a trend toward hypotension and tachycardia with higher rFGF‐2 doses was observed.

Gut Hormone Pharmacology of a Novel GPR119 Agonist (GSK1292263), Metformin, and Sitagliptin in Type 2 Diabetes Mellitus: Results from Two Randomized Studies

GPR119 receptor agonists improve glucose metabolism and alter gut hormone profiles in animal models and healthy subjects. We therefore investigated the pharmacology of GSK1292263 (GSK263), a selective GPR119 agonist, in two randomized, placebo-controlled studies that enrolled subjects with type 2 diabetes. Study 1 had drug-naive subjects or subjects who had stopped their diabetic medications, and Study 2 had subjects taking metformin. GSK263 was administered as single (25–800 mg; n = 45) or multiple doses (100–600 mg/day for 14 days; n = 96). Placebo and sitagliptin 100 mg/day were administered as comparators. In Study 1, sitagliptin was co-administered with GSK263 or placebo on Day 14 of dosing. Oral glucose and meal challenges were used to assess the effects on plasma glucose, insulin, C-peptide, glucagon, peptide tyrosine-tyrosine (PYY), glucagon-like peptide-1 (GLP-1) and glucose-dependent insulinotropic peptide (GIP). After 13 days of dosing, GSK263 significantly increased plasma total PYY levels by ∼five-fold compared with placebo, reaching peak concentrations of ∼50 pM after each of the three standardized meals with the 300 mg BID dose. Co-dosing of GSK263 and metformin augmented peak concentrations to ∼100 pM at lunchtime. GSK263 had no effect on active or total GLP-1 or GIP, but co-dosing with metformin increased post-prandial total GLP-1, with little effect on active GLP-1. Sitagliptin increased active GLP-1, but caused a profound suppression of total PYY, GLP-1, and GIP when dosed alone or with GSK263. This suppression of peptides was reduced when sitagliptin was co-dosed with metformin. GSK263 had no significant effect on circulating glucose, insulin, C-peptide or glucagon levels. We conclude that GSK263 did not improve glucose control in type 2 diabetics, but it had profound effects on circulating PYY. The gut hormone effects of this GPR119 agonist were modulated when co-dosed with metformin and sitagliptin. Metformin may modulate negative feedback loops controlling the secretion of enteroendocrine peptides. Trial Registration: Clinicaltrials.gov NCT01119846 Clinicaltrials.gov NCT01128621

Evaluation of drug interactions of GSK1292263 (a GPR119 agonist) with statins: from in vitro data to clinical study design

1. This work investigated the drug interaction potential of GSK1292263, a novel GPR119 agonist, with the HMG-coA reductase inhibitors simvastatin and rosuvastatin. 2. In vitro experiments assessed the inhibition of transporters and CYP enzymes by GSK1292263, and a clinical drug interaction study investigated the effect of GSK1292263 (300 mg BID) on the pharmacokinetic profile of simvastatin (40 mg single dose) and rosuvastatin (10 mg single dose). 3. In vitro, GSK1292263 demonstrated little/weak inhibition (IC50 values >30 μM) towards CYPs (CYP1A2, 2C9, 2C19, 2D6, 3A4), Pgp, OATP1B3, or OCT2. However, GSK1292263 inhibited BCRP and OATP1B1, which are transporters involved in statin disposition. 4. In the clinical study, small increases in the AUC(0-inf) of simvastatin [mean ratio (90% CI) of 1.34 (1.22, 1.48)] and rosuvastatin [mean ratio (90% CI) of 1.39 (1.30, 1.49)] were observed when co-administered with GSK1292263, which is consistent with an inhibitory effect on intestinal BCRP and CYP3A4. In contrast, GSK1292263 did not inhibit OATP1B1 based on the lack of changes in simvastatin acid exposure [mean AUC(0-inf) ratio (90% CI) of 1.05 (0.91, 1.21)]. 5. GSK1292263 has a weak drug interaction with simvastatin and rosuvastain. This study provides a mechanistic understanding of the in vivo inhibition of transporters and enzymes by GSK1292263.

A randomized dose-finding study demonstrating the efficacy and tolerability of albiglutide in Japanese patients with type 2 diabetes mellitus

Abstract Objective: To investigate the optimal dosage/regimen and to evaluate the efficacy and safety of albiglutide in Japanese patients with type 2 diabetes mellitus. Research design and methods: This was a randomized, double-blind, placebo-controlled, multicenter, parallel-group, dose-ranging, superiority study in Japanese patients with type 2 diabetes mellitus. Patients (n = 215) who were treatment naive or washed out of one oral antidiabetic drug were randomized to placebo or albiglutide 15 mg weekly, 30 mg weekly, or 30 mg every other week (biweekly). Clinical trial registration: NCT01098461. Main outcome measures: The primary end point was the change from baseline in HbA1c at week 16, measured using the Japan Diabetes Society standardization scheme and presented here using the National Glycohemoglobin Standardization Program equivalents. Other measures of efficacy as well as safety and population pharmacokinetics and pharmacokinetics/pharmacodynamics of albiglutide were assessed. Results: Baseline HbA1c was 8.53%. There was a statistically significant difference between each albiglutide treatment group and placebo for change from baseline in HbA1c at week 16, with treatment effects of −0.89% for 15 mg weekly, −1.55% for 30 mg weekly, and −1.10% for 30 mg biweekly (P < 0.0001 for all groups vs placebo). By week 16, 63.0% and 33.3% of patients in the 30 mg weekly albiglutide group compared with 6.0% and 0% of patients in the placebo group achieved HbA1c <7.4% and <6.9%, respectively. No serious adverse events were related to study therapy; no deaths occurred. Nasopharyngitis was the most frequently reported adverse event in all treatment groups (n = 43 [20.3%]). Conclusions: Albiglutide exhibited therapeutic hypoglycemic effects with good tolerability among Japanese patients with type 2 diabetes mellitus; the 30 mg weekly dose was the most efficacious in this study. The 16 week duration of the study prevents generalizing these conclusions to longer treatment periods.