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Human Hexokinase IV, or glucokinase (GK), is a regulator of glucose concentrations in the body. It plays a key role in pancreatic insulin secretion as well as glucose biotransformation in the liver, making it a potentially viable target for treatment of Type 2 diabetes. Allosteric activators of GK have been shown to decrease blood glucose concentrations in both animals and humans. Here, the development of a mathematical model is presented that describes glucose modulation in an ob/ob mouse model via administration of a potent GK activator, with the goal of projecting a human efficacious dose and plasma exposure. The model accounts for the allosteric interaction between GK, the activator, and glucose using a modified Hill function. Based on model simulations using data from the ob/ob mouse and in vitro studies, human projections of glucose response to the GK activator are presented, along with dose and regimen predictions to maintain clinically significant decreases in blood glucose in a Type 2 diabetic patient. This effort serves as a basis to build a detailed mechanistic understanding of GK and its role as a therapeutic target for Type 2 diabetes, and it highlights the benefits of using such an approach in a drug discovery setting.

Specific retinoid X receptor (RXR) agonists, such as LG100268 (LG268), and the thiazolidinedione (TZD) PPARgamma agonists, such as rosiglitazone, produce insulin sensitization in rodent models of insulin resistance and type 2 diabetes. In sharp contrast to the TZDs that produce significant increases in body weight gain, RXR agonists reduce body weight gain and food consumption. Unfortunately, RXR agonists also suppress the thyroid hormone axis and generally produce hypertriglyceridemia. Heterodimer-selective RXR modulators have been identified that, in rodents, retain the metabolic benefits of RXR agonists with reduced side effects. These modulators bind specifically to RXR with high affinity and are RXR homodimer partial agonists. Although RXR agonists activate many heterodimer partners, these modulators selectively activate RXR:PPARalpha and RXR:PPARgamma, but not RXR:RARalpha, RXR:LXRalpha, RXR:LXRbeta, or RXR:FXRalpha. We report the in vivo characterization of one RXR modulator, LG101506 (LG1506). In Zucker fatty (fa/fa) rats, LG1506 is a potent insulin sensitizer that also enhances the insulin-sensitizing activities of rosiglitazone. Administration of LG1506 reduces both body weight gain and food consumption and blocks the TZD-induced weight gain when coadministered with rosiglitazone. LG1506 does not significantly suppress the thyroid hormone axis in rats, nor does it elevate triglycerides in Sprague Dawley rats. However, LG1506 produces a unique pattern of triglycerides elevation in Zucker rats. LG1506 elevates high-density lipoprotein cholesterol in humanized apolipoprotein A-1-transgenic mice. Therefore, selective RXR modulators are a promising approach for developing improved therapies for type 2 diabetes, although additional studies are needed to understand the strain-specific effects on triglycerides.