Differential Effects of Vascular Endothelial Growth Factor Receptor-2 Inhibitor ZD6474 on Circulating Endothelial Progenitors and Mature Circulating Endothelial Cells: Implications for Use as a Surrogate Marker of Antiangiogenic Activity

Abstract

VEGF inhibitors can have differential effects on mature CECs and CEPs, and agents inhibiting tumor angiogenesis may cause a concomitant increase in mature CECs. This increase occurs in tumor-bearing but not in nontumor-bearing mice, suggesting that tumor endothelium is a potential source of mature CECs. Therefore, assessing both mature CECs and CEPs may provide insights into the mechanism of antiangiogenic agents and serve as an early surrogate marker of biological activity.