Kevin J. Filipski

Discovery of (S)-6-(3-Cyclopentyl-2-(4-(trifluoromethyl)-1H-imidazol-1-yl)propanamido)nicotinic Acid as a Hepatoselective Glucokinase Activator Clinical Candidate for Treating Type 2 Diabetes Mellitus

Glucokinase is a key regulator of glucose homeostasis, and small molecule allosteric activators of this enzyme represent a promising opportunity for the treatment of type 2 diabetes. Systemically acting glucokinase activators (liver and pancreas) have been reported to be efficacious but in many cases present hypoglycaemia risk due to activation of the enzyme at low glucose levels in the pancreas, leading to inappropriately excessive insulin secretion. It was therefore postulated that a liver selective activator may offer effective glycemic control with reduced hypoglycemia risk. Herein, we report structure-activity studies on a carboxylic acid containing series of glucokinase activators with preferential activity in hepatocytes versus pancreatic β-cells. These activators were designed to have low passive permeability thereby minimizing distribution into extrahepatic tissues; concurrently, they were also optimized as substrates for active liver uptake via members of the organic anion transporting polypeptide (OATP) family. These studies lead to the identification of 19 as a potent glucokinase activator with a greater than 50-fold liver-to-pancreas ratio of tissue distribution in rodent and non-rodent species. In preclinical diabetic animals, 19 was found to robustly lower fasting and postprandial glucose with no hypoglycemia, leading to its selection as a clinical development candidate for treating type 2 diabetes.

Designing glucokinase activators with reduced hypoglycemia risk: discovery of N,N-dimethyl-5-(2-methyl-6-((5-methylpyrazin-2-yl)-carbamoyl)benzofuran-4-yloxy)pyrimidine-2-carboxamide as a clinical candidate for the treatment of type 2 diabetes mellitus

Glucokinase is a key regulator of glucose homeostasis and small molecule activators of this enzyme represent a promising opportunity for the treatment of Type 2 diabetes. Several glucokinase activators have advanced to clinical studies and demonstrated promising efficacy; however, many of these early candidates also revealed hypoglycemia as a key risk. In an effort to mitigate this hypoglycemia risk while maintaining the promising efficacy of this mechanism, we have investigated a series of substituted 2-methylbenzofurans as “partial activators” of the glucokinase enzyme leading to the identification of N,N-dimethyl-5-(2-methyl-6-((5-methylpyrazin-2-yl)-carbamoyl)benzofuran-4-yloxy)pyrimidine-2-carboxamide as an early development candidate.

Pyridones as glucokinase activators: Identification of a unique metabolic liability of the 4-sulfonyl-2-pyridone heterocycle

A promising area of novel anti-diabetic therapy involves identification of small molecule activators of the glucokinase enzyme to reduce blood glucose and normalize glucose stimulated insulin secretion. Herein, we report the identification and optimization of a series of 4-sulfonyl-2-pyridone activators. The activators were evaluated for in vitro biochemical activation and pharmacokinetic properties. As part of these efforts, a unique metabolic liability of the 4-sulfonyl-2-pyridone ring system was identified wherein this heterocycle readily undergoes conjugation with glutathione under non-enzymatic conditions.

The design and synthesis of a potent glucagon receptor antagonist with favorable physicochemical and pharmacokinetic properties as a candidate for the treatment of type 2 diabetes mellitus.

A novel and potent small molecule glucagon receptor antagonist for the treatment of diabetes mellitus is reported. This candidate, (S)-3-[4-(1-{3,5-dimethyl-4-[4-(trifluoromethyl)-1H-pyrazol-1-yl]phenoxy}butyl)benzamido]propanoic acid, has lower molecular weight and lipophilicity than historical glucagon receptor antagonists, resulting in excellent selectivity in broad-panel screening, lower cytotoxicity, and excellent overall in vivo safety in early pre-clinical testing. Additionally, it displays low in vivo clearance and excellent oral bioavailability in both rats and dogs. In a rat glucagon challenge model, it was shown to reduce the glucagon-elicited glucose excursion in a dose-dependent manner and at a concentration consistent with its rat in vitro potency. Its properties make it an excellent candidate for further investigation.

Progress in the discovery of Factor Xa inhibitors

Factor Xa is a serine protease that has a critical role in the blood coagulation cascade by ultimately regulating the production of thrombin. There is now ample evidence for the role of Factor Xa inhibitors as anticoagulants and they represent potential new therapeutic agents for the treatment and prevention of arterial and venous thrombosis. During the past five years, research in the field of Factor Xa inhibitors has been marked with enormous efforts to identify highly potent, selective and orally-active agents. This research has led to the discovery of a number of clinical candidates that are currently progressing at different stages of drug development. This review examines the patent and scientific literature during the period 2000 – 2005.

Novel and selective spiroindoline-based inhibitors of sky kinase

We report the discovery of a novel series of spiroindoline-based inhibitors of Sky kinase that bind in the ATP-binding site and exhibit high levels of kinome selectivity through filling the Ala571-subpocket. These inhibitors exhibit moderate oral bioavailability in the rat due to low absorption across the gut wall.

Intestinal Targeting of Drugs: Rational Design Approaches and Challenges

Targeting drugs to the gastrointestinal tract has been and continues to be an active area of research. Gut-targeting is an effective means of increasing the local concentration of active substance at the desired site of action while minimizing concentrations elsewhere in the body that could lead to unwanted side-effects. Several approaches to intestinal targeting exist. Physicochemical property manipulation can drive molecules to large, polar, low absorption space or alternatively to lipophilic, high clearance space in order to minimize systemic exposure. Design of compounds that are substrates for transporters within the gastrointestinal tract, either uptake or efflux, or at the hepato-biliary interface, may help to increase intestinal concentration. Prodrug strategies have been shown to be effective particularly for colon targeting, and several different technology formulation approaches are currently being researched. This review provides examples of various approaches to intestinal targeting, and discusses challenges and areas in need of future scientific advances.

A patent review of glucokinase activators and disruptors of the glucokinase – glucokinase regulatory protein interaction: 2011 – 2014

Introduction: Glucokinase (GK) is a key regulator of glucose homeostasis, and development of small molecule activators of this enzyme represents a promising new approach for the treatment of type 2 diabetes mellitus. Areas covered: This manuscript reviews small molecule patent disclosures between late 2011 and February 2014 for both GK activators (GKAs) and GK−glucokinase regulatory protein (GK−GKRP) disruptors. The review is organized by company and structural class. Expert opinion: The field of GKA research continues to progress, driven by research across many organizations. To date, > 20 candidates have entered clinical development with the most advanced in Phase II trials. Despite promising efficacy, a significant number of early candidates have been discontinued for various reasons including increased risk of hypoglycemia and lack of durability. Recent work in the field has focused on liver-selective activators, which have shown lower hypoglycemia risk, including the development of novel GK-GKRP disruptors that act to indirectly increase hepatic GK activity.

A novel series of glucagon receptor antagonists with reduced molecular weight and lipophilicity.

A novel series of glucagon receptor antagonists has been discovered. These pyrazole ethers and aminopyrazoles have lower molecular weight and increased polarity such that the molecules fall into better drug-like property space. This work has culminated in compounds 44 and 50 that were shown to have good pharmacokinetic attributes in dog, in contrast to rats, in which clearance was high; and compound 49, which demonstrated a dose-dependent reduction in glucose excursion in a rat glucagon challenge experiment.

Chemical Probe Identification Platform for Orphan GPCRs Using Focused Compound Screening: GPR39 as a Case Example.

Orphan G protein-coupled receptors (oGPCRs) are a class of integral membrane proteins for which endogenous ligands or transmitters have not yet been discovered. Transgenic animal technologies have uncovered potential roles for many of these oGPCRs, providing new targets for the treatment of various diseases. Understanding signaling pathways of oGPCRs and validating these receptors as potential drug targets requires the identification of chemical probe compounds to be used in place of endogenous ligands to interrogate these receptors. A novel chemical probe identification platform was created in which GPCR-focused libraries were screened against sets of oGPCR targets, with a goal of discovering fit-for-purpose chemical probes for the more druggable members of the set. Application of the platform to a set of oGPCRs resulted in the discovery of the first reported small molecule agonists for GPR39, a receptor implicated in the regulation of insulin secretion and preservation of beta cells in the pancreas. Compound 1 stimulated intracellular calcium mobilization in recombinant and native cells in a GPR39-specific manner but did not potentiate glucose-stimulated insulin secretion in human islet preparations.