Effects of the Src kinase inhibitor saracatinib (AZD0530) on bone turnover in healthy men: a randomized, double-blind, placebo-controlled, multiple-ascending-dose phase I trial.

Src is a nonreceptor tyrosine kinase thought to be essential for osteoclast function and bone resorption. We investigated the effect of the orally available Src inhibitor saracatinib (AZD0530) on bone turnover in healthy men. The study was part of a randomized, double-blind, placebo-controlled multiple-ascending-dose phase I trial of saracatinib. Fifty-nine healthy men (mean age 34.6 years) were divided into five cohorts; four with 12 subjects and one with 11 subjects, and randomized within each cohort in the ratio 3:1 to receive a single dose of saracatinib or placebo, respectively, followed 7 to 10 days later with daily doses for a further 10 to 14 days. Dosing levels of saracatinib ascended by cohort (60 to 250 mg). Markers of bone turnover were measured predose and 24 and 48 hours after the initial single dose and immediately before and 24 and 48 hours and 10 to 14 days after the final dose. Data from 44 subjects were included in the analysis. There was a dose-dependent decrease in bone resorption markers [serum cross-linked C-telopeptide of type I collagen (sCTX) and urinary cross-linked N-telopeptide of type I collagen normalized to creatinine (uNTX/Cr)]. At a dose of 250 mg (maximum tolerated dose), sCTX decreased by 88% [95% confidence interval (CI) 84-91%] and uNTX/Cr decreased by 67% (95% CI 53-77%) from baseline 24 hours after the final dose. There was no significant effect on bone formation markers. There were no significant adverse events. We conclude that inhibition of Src reduces osteoclastic bone resorption in humans. Saracatinib is a potentially useful treatment for diseases characterized by increased bone resorption, such as metastatic bone disease and osteoporosis.

Acute hyperinsulinemia raises plasma interleukin-6 in both nondiabetic and type 2 diabetes mellitus subjects, and this effect is inversely associated with body mass index.

Hyperinsulinemia is a characteristic of type 2 diabetes mellitus (T2DM) and is believed to play a role in the low-grade inflammation seen in T2DM. The main aim was to study the effect of hyperinsulinemia on adipokines in individuals with different levels of insulin resistance, glycemia, and obesity. Three groups of sex-matched subjects were studied: young healthy subjects (YS; n = 10; mean age, 26 years; body mass index [BMI], 22 kg/m(2)), patients with T2DM (DS; n = 10; 61 years; BMI, 27 kg/m(2)), and age- and BMI-matched controls to DS (CS; n = 10; 60 years; BMI, 27 kg/m(2)). Plasma concentrations of adipokines were measured during a hyperinsulinemic euglycemic clamp lasting 4 hours. Moreover, insulin-stimulated glucose uptake in isolated adipocytes was analyzed to address adipose tissue insulin sensitivity. Plasma interleukin (IL)-6 increased significantly (P < or = .01) in all 3 groups during hyperinsulinemia. However, the increase was smaller in both DS (P = .06) and CS (P < .05) compared with YS (approximately 2.5-fold vs approximately 4-fold). A significant increase of plasma tumor necrosis factor (TNF) alpha was observed only in YS. There were only minor or inconsistent effects on adiponectin, leptin, and high-sensitivity C-reactive protein levels during hyperinsulinemia. Insulin-induced rise in IL-6 correlated negatively to BMI (P = .001), waist to hip ratio (P = .05), and baseline (fasting) insulin (P = .03) and IL-6 (P = .02) levels and positively to insulin-stimulated glucose uptake in isolated adipocytes (P = .07). There was no association with age or insulin sensitivity. In a multivariate analysis, also including T2DM/no T2DM, an independent correlation (inverse) was found only between BMI and fold change of IL-6 (r(2) = 0.41 for model, P < .005). Hyperinsulinemia per se can produce an increase in plasma IL-6 and TNFalpha, and this can potentially contribute to the low-grade inflammation seen in obesity and T2DM. However, obesity seems to attenuate the ability of an acute increase in insulin to further raise circulating levels of IL-6 and possibly TNFalpha.

Single dose glucagon (0.5 mg IV bolus) administration in healthy human volunteers is a robust model for assessment of glycogenolysis: characterisation of the glucose excursion after glucagon challenge.

INTRODUCTION: In the assessment of potential new treatments for Type 2 diabetes, robust pharmacological methods are helpful in assessing efficacy, defining dose response, duration of effect and ultimately in deciding whether to progress compounds to the next phase of drug development. Hepatic glucose handling is abnormal in Type 2 diabetes. We evaluated glucagon challenge as a way of assessing effects on the glycogenolytic pathway. METHODS: In each of 2 studies healthy subjects received glucagon as an IV bolus of 0.5 mg studied after an overnight fast and plasma glucose was monitored before and for 180 min after glucagon challenge. Study 1 was a double-blind placebo controlled study comparing glucagon administered twice with saline placebo. In study 2, subjects were studied on a single occasion and the glucagon challenge was carried out in the morning and then repeated 7 h later. In study 2, insulin concentrations were also monitored before and after the glucagon challenge. RESULTS: In study 1, glucose rose in a reproducible manner with a peak glucose 20 min after challenge falling to baseline values by 120 min and then fell below values for saline challenge between 120 and 180 min. Analysis of the data showed that the corrected AUC(0-20) min was the most robust variable and could be expected to detect clinically relevant changes in small numbers (<10) of subjects. In study 2, we demonstrated that when glucagon challenge was repeated 7 h after the first challenge, the glucose excursion was highly variable. The plasma insulin response was robust following the initial challenge but variable following the second challenge. DISCUSSION: We have demonstrated that an IV bolus glucagon challenge (0.5 mg) results in a reproducible rise in glucose in healthy volunteers and can be repeated within a week but when repeated on the same day gave a poorly reproducible rise in glucose. Glucagon challenge may be useful in studying novel drugs that affect glycogen handling in the liver.