Macromolecular Versus Small Molecular MRI Contrast Media for Monitoring Anti-Angiogenic Drug Effect of Bevacizumab on Experimental Human Breast Cancer Xenografts

Clemens C. Cyran^1,2, Yanjun Fu², Victor Rogut², Bundit Chaopathomkul², David M. Shames², Michael F. Wendland², Robert C. Brasch²

The macromolecular contrast media (MMCM) albumin-(Gd-DTPA) ₂₇ was compared to the small molecular contrast media (SMCM) Gd-DTPA for their suitability to monitor early anti-angiogenic effect of bevacizumab on human breast cancer xenografts in dynamic MRI assays of endothelial permeability in a tandem experiment. Rats were imaged at baseline and 24h after intraperitoneal bevacizumab application. MRI assays of tumor endothelial permeability revealed a significant decrease of endothelial permeability using albumin-(Gd-DTPA) ₂₇ whereas no significant effect was detected using Gd-DTPA. The MMCM albumin-(Gd-DTPA) ₂₇ proved to be superior to the SMCM Gd-DTPA for the detection of early anti-angiogenic effect of bevacizumab.