Abstract #1768

Ansiaux R, Baudelet C, O.Cron G, Martinive P, De Wever J, Grgoire V, Feron O, Gallez B

The transient normalization of the tumor vasculature at the early stage of an anti-angiogenic treatment has been described for several antiangiogenic agents. Our purpose was to assess the validity of this paradigm in the case of an inhibitor of Flk-1 tyrosine kinase, SU5416. EPR oximetry study indicates an early reoxygenation of the tumor. Surprisingly, however, this reoxygenation was not correlated to an increase in perfusion (as shown by DCE-MRI), but more likely due to an inhibition of oxygen consumption by the tumor cells. Consistently, we found that SU5416 potentiates the response to radiotherapy, but not to chemotherapy.