Characterization of renal biomarkers for use in clinical trials: biomarker evaluation in healthy volunteers.

BACKGROUND: Several preclinical urinary biomarkers have been qualified and accepted by the health authorities (US Food and Drug Administration, European Medicines Agency, and Pharmaceuticals and Medical Devices Agency) for detecting drug-induced kidney injury during preclinical toxicologic testing. Validated human assays for many of these biomarkers have become commercially available, and this study was designed to characterize some of the novel clinical renal biomarkers. The objective of this study was to evaluate clinical renal biomarkers in a typical Phase I healthy volunteer population to determine confidence intervals (pilot reference intervals), intersubject and intrasubject variability, effects of food intake, effect of sex, and vendor assay comparisons. METHODS: Spot urine samples from 20 male and 19 female healthy volunteers collected on multiple days were analyzed using single analyte and multiplex assays. The following analytes were measured: α-1-microglobulin, ß-2-microglobulin, calbindin, clusterin, connective tissue growth factor, creatinine, cystatin C, glutathione S-transferase-α, kidney injury marker-1, microalbumin, N-acetyl-ß-(D) glucosaminidase, neutrophil gelatinase-associated lipocalin, osteopontin, Tamm-Horsfall urinary glycoprotein, tissue inhibitor of metalloproteinase 1, trefoil factor 3, and vascular endothelial growth factor. RESULTS: Confidence intervals were determined from the single analyte and multiplex assays. Intersubject and intrasubject variability ranged from 38% to 299% and from 29% to 82% for biomarker concentration, and from 24% to 331% and from 10% to 67% for biomarker concentration normalized to creatinine, respectively. There was no major effect of food intake or sex. Single analyte and multiplex assays correlated with r (2)≥0.700 for five of six biomarkers when evaluating biomarker concentration, but for only two biomarkers when evaluating concentration normalized to creatinine. CONCLUSION: Confidence intervals as well as intersubject and intrasubject variability were determined for novel clinical renal biomarkers/assays, which should be considered for evaluation in the next steps of the qualification process.

Vandetanib inhibits both VEGFR-2 and EGFR signalling at clinically relevant drug levels in preclinical models of human cancer.

Vandetanib is a multi-targeted receptor tyrosine kinase inhibitor that is in clinical development for the treatment of solid tumours. This preclinical study examined the inhibition of two key signalling pathways (VEGFR-2, EGFR) at drug concentrations similar to those achieved in the clinic, and their contribution to direct and indirect antitumour effects of vandetanib. For in vitro studies, receptor phosphorylation was assessed by Western blotting and ELISA, cell proliferation was assessed using a cell viability endpoint, and effects on cell cycle determined using flow cytometry. For in vivo studies, Western blotting, ELISA and immunohistochemistry (IHC) were used to assess receptor phosphorylation. Cell culture experiments demonstrated that anti-proliferative effects of vandetanib resulted from inhibition of either EGFR or VEGFR-2 signalling in endothelial cells, but were associated with inhibition of EGFR signalling in tumour cells. Vandetanib inhibited both EGFR and VEGFR-2 signalling in normal lung tissue and in tumour xenografts. In a lung cancer model expressing an activating EGFR mutation, the activity of vandetanib was similar to that of a highly selective EGFR inhibitor (gefitinib), and markedly greater than that of a highly selective VEGFR inhibitor (vatalanib). These data suggest that at the plasma exposures achieved in the clinic, vandetanib will significantly inhibit both VEGFR-2 and EGFR signalling, and that both inhibition of angiogenesis and direct inhibition of tumour cell growth can contribute to treatment response.

Effect of pretreatment with atenolol and nifedipine on ZD6126-induced cardiac toxicity in rats.

Antivascular agents that act by destabilizing microtubules, such as ZD6126 (N-acetylcolchinol-O-phosphate), are associated with adverse cardiovascular effects, including transient hypertension, cardiac ischemia, myocardial infarction, and increases in circulating levels of markers of cardiac damage (e.g., troponins). We investigated mechanisms underlying these effects of ZD6126 in rats by continuously monitoring their heart rate and blood pressure and by assessing heart histopathology and plasma troponin T levels. ZD6126 induced acute transient hemodynamic changes (hypertension and delayed tachycardia), which were associated with statistically significant increases in circulating troponin T levels (median level 3 hours after treatment with vehicle or 12.5 mg/kg ZD6126: <9 pg/mL and 563 pg/mL, respectively; P <.001 [two-sided Wilcoxon rank sum test]) and in the incidence of left ventricular myocardial fiber necrosis (incidence 24 hours after treatment with vehicle or 12.5 mg/kg ZD6126: 0/10 rats and 9/10 rats, respectively; P <.001 [two-sided Wilcoxon rank sum test]). Pretreatment of rats with atenolol and nifedipine ameliorated the acute hemodynamic changes and prevented ZD6126-induced increases in both troponin T and myocardial necrosis but did not prevent ZD6126-induced tumor necrosis in an Hras5 tumor xenograft model in nude rats. Our findings suggest that ZD6126-induced acute hemodynamic changes are a prerequisite for cardiac damage in rats.