Robert Ross1, Jose L. Figueiredo2,
Peter Waterman2, Ralph Weissleder3, Alexander R.
Guimaraes4,5
1Lank Center for Genitourinary Oncology,
Dana Farber Cancer Institute, Boston, MA, United States; 2Center
for Systems Biology, Massachusetts General Hospital, Boston, mA, United
States; 3Center for Systems Biology, Massachusetts General
Hospital, Boston, MA, United States; 4Radiology, Massachusetts
General Hospital/Martinos Center for Biomedical Imaging, Charlestown, MA,
United States; 5Center for Systems Biology, Massachusetts General
Hospital/Martinos Center for Biomedical Imaging, Boston, mA, United States
Inhibitors
of the mammalian target of rapamycin (mTOR) are approved in patients with
metastatic renal cell cancer (RCC).
Our aim was to evaluate in vivo, mTOR inhibition on the vascularity of
a RCC mouse model using magnetic nanoparticle enhanced MRI and to compare
these effects to the established VEGF inhibitor, sorafenib. There was excellent correlation (R^2 0.95)
of MRI measures of vascular volume fraction to histologic microvessel density
. VVF in all treatment arms differed from control (p<0.05) at end of
therapy. This study demonstrates that MRI can monitor noninvasively, the in
vivo antiangiogenic effects of chemotherapeutic agents.