ABSTRACT
A potent, selective glucagon receptor antagonist 9m, N-[(4-{(1S)-1-[3-(3,5-dichlorophenyl)-5-(6-methoxynaphthalen-2-yl)-1H-pyrazol-1-yl]ethyl}phenyl)carbonyl]-ß-alanine, was discovered by optimization of a previously identified lead. Compound 9m is a reversible and competitive antagonist with high binding affinity (IC(50) of 6.6 nM) and functional cAMP activity (IC(50) of 15.7 nM). It is selective for glucagon receptor relative to other family B GPCRs, showing IC(50) values of 1020 nM for GIPR, 9200 nM for PAC1, and >10000 nM for GLP-1R, VPAC1, and VPAC2. Compound 9m blunted glucagon-induced glucose elevation in hGCGR mice and rhesus monkeys. It also lowered ambient glucose levels in both acute and chronic mouse models: in hGCGR ob/ob mice it reduced glucose (AUC 0-6 h) by 32% and 39% at 3 and 10 mpk single doses, respectively. In hGCGR mice on a high fat diet, compound 9m at 3, and 10 mpk po in feed lowered blood glucose levels by 89% and 94% at day 10, respectively, relative to the difference between the vehicle control and lean hGCGR mice. On the basis of its favorable biological and DMPK properties, compound 9m (MK-0893) was selected for further preclinical and clinical evaluations.
Subject(s)
Blood Glucose/metabolism , Diabetes Mellitus, Type 2/drug therapy , Glucagon/metabolism , Pyrazoles/pharmacology , Receptors, Glucagon/antagonists & inhibitors , beta-Alanine/analogs & derivatives , Animals , Area Under Curve , CHO Cells , Cricetinae , Cricetulus , Diet, High-Fat/adverse effects , Disease Models, Animal , Dogs , Glucagon-Like Peptide-1 Receptor , Humans , Inhibitory Concentration 50 , Macaca mulatta , Mice , Mice, Obese , Microsomes, Liver/metabolism , Pyrazoles/chemistry , Pyrazoles/therapeutic use , Rats , Receptors, Gastrointestinal Hormone/antagonists & inhibitors , Receptors, Pituitary Adenylate Cyclase-Activating Polypeptide/antagonists & inhibitors , Receptors, Vasoactive Intestinal Peptide, Type II/antagonists & inhibitors , Receptors, Vasoactive Intestinal Polypeptide, Type I/antagonists & inhibitors , beta-Alanine/chemistry , beta-Alanine/pharmacology , beta-Alanine/therapeutic useABSTRACT
A novel class of 1,3,5-pyrazoles has been discovered as potent human glucagon receptor antagonists. Notably, compound 26 is orally bioavailable in several preclinical species and shows selectivity towards cardiac ion channels, other family B receptors such hGIP and hGLP1, and a large panel of enzymes and additional receptors. When dosed orally, compound 26 is efficacious in suppressing glucagon induced plasma glucose excursion in rhesus monkey and transgenic murine pharmacodynamic models at 1 and 10 mpk, respectively.
Subject(s)
Pyrazoles/chemistry , Receptors, Glucagon/antagonists & inhibitors , Administration, Oral , Animals , Blood Glucose/metabolism , Dogs , Drug Evaluation, Preclinical , Humans , Macaca mulatta , Mice , Mice, Transgenic , Pyrazoles/chemical synthesis , Pyrazoles/pharmacokinetics , Rats , Receptors, Glucagon/metabolism , Structure-Activity RelationshipABSTRACT
The discovery and optimization of potent and selective aminobenzimidazole glucagon receptor antagonists are described. One compound possessing moderate pharmacokinetic properties in multiple preclinical species was orally efficacious at inhibiting glucagon-mediated glucose excursion in transgenic mice expressing the human glucagon receptor, and in rhesus monkeys. The compound also significantly lowered glucose levels in a murine model of diabetes.
Subject(s)
Benzimidazoles/chemistry , Receptors, Glucagon/antagonists & inhibitors , Receptors, Glucagon/chemistry , Administration, Oral , Animals , Benzimidazoles/pharmacokinetics , CHO Cells , Chemistry, Pharmaceutical/methods , Cricetinae , Cricetulus , Diabetes Mellitus, Experimental/metabolism , Glucagon/chemistry , Humans , Inhibitory Concentration 50 , Macaca mulatta , Mice , Mice, TransgenicABSTRACT
Glucose homeostasis is maintained by the combined actions of insulin and glucagon. Hyperglucagonemia and/or elevation of glucagon/insulin ratio have been reported in diabetic patients and in animal models of diabetes. Therefore, antagonizing glucagon receptor function has long been considered a useful approach to lower hyperglycemia. Dogs serve as an excellent model for studying glycemic control and various aspects of glucagon biology in vivo; however, the amino acid sequence of the dog glucagon receptor has not been reported. To better understand the pharmacology of the dog glucagon receptor and to characterize glucagon receptor antagonists, we cloned a cDNA corresponding to the glucagon receptor from dog liver RNA. The dog glucagon receptor shares a significant (>75%) homology at both nucleotide and amino acid levels with the glucagon receptor from human, monkey, mouse, and rat. The protein is highly conserved among all species in areas corresponding to the 7 trans-membrane domains. However, it shows significant divergence at the carboxy terminus such that the receptor from dog has the longest cytoplasmic tail among all species examined. When expressed in chinese hamster ovary cells, the dog glucagon receptor bound [125I]Glucagon with a K(d) of 477+/-106 pM. Glucagon stimulated the rise of intracellular cAMP levels in these cells with an EC(50) of 9.6+/-1.7 nM and such effects could be blocked by known peptidyl and non-peptidyl small molecule antagonists. In addition we show that a small molecule glucagon receptor antagonist with significant activity in cell based assays also blocked the ability of glucagon to induce elevation in blood glucose in beagle dogs. These data demonstrate that the cloned cDNA encodes a functional dog glucagon receptor. The availability of the dog cDNA will facilitate the understanding of glucagon pharmacology and aid in the characterization of novel glucagon antagonists that may serve as anti-hyperglycemic treatment for type 2 diabetes mellitus.