Kevin Richard Guertin

Small Molecule Glucokinase Activators as Glucose Lowering Agents: A New Paradigm for Diabetes Therapy

Glucokinase (GK) is a molecular sensor that regulates glucose induced insulin secretion in pancreatic beta-cells and glucose homeostasis in the liver via catalysis of glucose to glucose-6-phosphate. The recent discovery and development of small molecule glucokinase activators represents a potentially important development for the management of type 2 diabetes. Since the discovery of the first orally active small molecule GK activator RO0281675, a number of research groups have reported the identification of potent activators. In this review, the biological significance of GK in whole body glucose homeostasis is briefly described coupled with the recent progress regarding the identification of novel small molecule GK activators.

Discovery of Piragliatin—First Glucokinase Activator Studied in Type 2 Diabetic Patients

Glucokinase (GK) activation as a potential strategy to treat type 2 diabetes (T2D) is well recognized. Compound 1, a glucokinase activator (GKA) lead that we have previously disclosed, caused reversible hepatic lipidosis in repeat-dose toxicology studies. We hypothesized that the hepatic lipidosis was due to the structure-based toxicity and later established that it was due to the formation of a thiourea metabolite, 2. Subsequent SAR studies of 1 led to the identification of a pyrazine-based lead analogue 3, lacking the thiazole moiety. In vivo metabolite identification studies, followed by the independent synthesis and profiling of the cyclopentyl keto- and hydroxyl- metabolites of 3, led to the selection of piragliatin, 4, as the clinical lead. Piragliatin was found to lower pre- and postprandial glucose levels, improve the insulin secretory profile, increase β-cell sensitivity to glucose, and decrease hepatic glucose output in patients with T2D.

The discovery of the Factor Xa inhibitor otamixaban: from lead identification to clinical development.

Factor Xa (fXa) is a critical serine protease situated at the confluence of the intrinsic and extrinsic pathways of the blood coagulation cascade. FXa catalyses the conversion of prothrombin to thrombin via the prothrombinase complex. Its singular role in thrombin generation, coupled with its potentiating effects on clot formation render it an attractive target for therapeutic intervention. Otamixaban is a synthetically derived parenteral fXa inhibitor currently in late stage clinical development at Sanofi-Aventis for the management of acute coronary syndrome. Otamixaban is a potent (Ki = 0.5 nM), selective, rapid acting, competitive and reversible fXa inhibitor that effectively inhibits both free and prothrombinase-bound fXa. In vivo experiments have demonstrated that Otamixaban is highly efficacious in rodent, canine and porcine models of thrombosis. In addition, recent clinical findings indicate that Otamixaban is efficacious, safe and well tolerated in humans and therefore has considerable potential for the treatment of acute coronary syndrome. This review article chronicles the discovery and pre-clinical data surrounding the fXa inhibitor Otamixaban as well as the recent clinical findings in humans.

Discovery, structure-activity relationships, pharmacokinetics, and efficacy of glucokinase activator (2R)-3-cyclopentyl-2-(4-methanesulfonylphenyl)-N-thiazol-2-yl-propionamide (RO0281675).

Glucokinase (GK) is a glucose sensor that couples glucose metabolism to insulin release. The important role of GK in maintaining glucose homeostasis is illustrated in patients with GK mutations. In this publication, identification of the hit molecule 1 and its SAR development, which led to the discovery of potent allosteric GK activators 9a and 21a, is described. Compound 21a (RO0281675) was used to validate the clinical relevance of targeting GK to treat type 2 diabetes.

Identification of RO4597014, a Glucokinase Activator Studied in the Clinic for the Treatment of Type 2 Diabetes.

To resolve the metabolite redox cycling associated with our earlier clinical compound 2, we carried out lead optimization of lead molecule 1. Compound 4 showed improved lipophilic ligand efficiency and demonstrated robust glucose lowering in diet-induced obese mice without a liability in predictive preclinical drug safety studies. Thus, it was selected as a clinical candidate and further studied in type 2 diabetic patients. Clinical data suggests no evidence of metabolite cycling, which is consistent with the preclinical profiling of metabolism.