Tumor microvascular changes in antiangiogenic treatment: assessment by magnetic resonance contrast media of different molecular weights.
OBJECTIVE
To test magnetic resonance (MR) contrast media of different molecular weights (MWs) for their potential to characterize noninvasively microvascular changes in an experimental tumor treatment model.


METHODS
MD-MBA-435, a poorly differentiated human breast cancer cell line, was implanted into 31 female homozygous athymic rats. Animals were assigned randomly to a control (saline) or drug treatment (monoclonal antibody vascular endothelial growth factor (Mab-VEGF) antibody) group. In both groups, dynamic MR imaging (MRI) was performed in each animal using up to three different contrast media on sequential days at baseline and follow-up examination. The MWs of the contrast media used ranged from 557 Da to 92 kDa. Using a bidirectional kinetic model, tumor microvessel characteristics, including the fractional plasma volume (fPV) and transendothelial permeability (K(PS)), were estimated for each contrast medium. These microvascular characteristics were compared between drug and control groups and between contrast media of different MWs.


RESULTS
Tumors grew significantly slower (P < 0.0005) in the drug treatment group than in the control group. Mean K(PS) and fPV values decreased significantly (P < 0.05) in the Mab-VEGF antibody-treated group compared to baseline values using intermediate or macromolecular contrast media (MMCM), but did not change significantly using small molecular contrast media (SMCM). In the control groups, mean K(PS) and mean fPV values did not reach statistical significance for any of the contrast media used.


CONCLUSIONS
Therapeutic effects of a Mab-VEGF antibody on tumor microvessel characteristics can be monitored by dynamic MRI. Intermediate-size agents, such as Gadomer-17, offer a substantial dynamic range and are less limited by imaging precision and therefore should be considered a practical alternative to monitor antiangiogenesis treatment effects in a clinical setting.
Turetschek
Karl
K
Center for Pharmaceutical and Molecular Imaging, Department of Radiology, University of California, San Francisco, California, USA.
Preda
Anda
A
Novikov
Viktor
V
Brasch
Robert C
RC
Weinmann
Hanns J
HJ
Wunderbaldinger
Patrick
P
Roberts
Timothy P L
TP
D020533:Angiogenesis Inhibitors / Q000627:therapeutic use*; D000818:Animals; D000911:Antibodies, Monoclonal / Q000627:therapeutic use*; D001943:Breast Neoplasms / Q000098:blood supply* / Q000175:diagnosis / Q000378:metabolism / Q000628:therapy; D045744:Cell Line, Tumor; D003287:Contrast Media; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008970:Molecular Weight; D009368:Neoplasm Transplantation; D009389:Neovascularization, Pathologic / Q000175:diagnosis* / Q000517:prevention & control; D051381:Rats; D011923:Rats, Nude; D042461:Vascular Endothelial Growth Factor A / Q000276:immunology* / Q000378:metabolism
D020533:Angiogenesis Inhibitors; D000911:Antibodies, Monoclonal; D003287:Contrast Media; D042461:Vascular Endothelial Growth Factor A