Changes in Breast Tumor Kps and ADC After Treatment with the VEGFR-TK Inhibitor AG-013736 Correlate with Changes in Tumor Volume

Lisa J. Wilmes¹, Ka-Loh Li, Lisa M. Fleming, Maria G. Pallavicini², Savannah C. Partridge³, Sheye Aliu, Nola M. Hylton

Dynamic contrast enhanced (DCE) and diffusion weighted magnetic (DW) resonance imaging were utilized to investigate the treatment effects of the vascular endothelial growth factor receptor (VEGFR) tyrosine kinase inhibitor (TKI), AG-013736, in cohort of mice bearing human breast tumor xenografts. MRI data acquired after 7 days of treatment showed a large decrease in tumor endothelial transfer constant, Kps and an increase in tumor ADC in treated tumors. In contrast the mean tumor Kps and ADC values in the control group both decreased slightly over time. The changes in Kps and ADC in the treated group were seen in conjunction with tumor growth inhibition. Control tumors continued to grow. Multivariate analysis showed that both the decrease in tumor Kps and the increase in ADC are independently and significantly correlated with change in tumor volume.