MAGNETIC-RESONANCE-IMAGING DETECTS SUPPRESSION OF TUMOR VASCULAR-PERMEABILITY AFTER ADMINISTRATION OF ANTIBODY TO VASCULAR ENDOTHELIAL GROWTH-FACTOR

Macromolecular contrast medium-enhanced magnetic resonance imaging (MR I) and tumor-volume measurements were applied to monitor the effects o f anti-vascular endothelial growth factor (anti-VEGF) antibody on micr ovascular characteristics and tumor growth of MDA-MB-435 human breast cancer cells implanted in nude rats. Administration of anti-VEGF antib ody (three 1 mg doses at 3-day intervals) induced significant reductio ns in tumor growth rates (p < 0.05) and in MRI-assayed microvascular p ermeabilities (p < 0.05). Results of the study were consistent with pr evious observations that new microvessels formed in response to angiog enesis are hyperpermeable, and with the hypothesis that hyperpermeabil ity is a mechanistic element in angiogenesis. Variations in tumor-vess el hyperpermeability can be measured by contrast-enhanced MRI, which m ay prove useful for assessing antiangiogenesis therapy.