Abstract #1035

Assessment of Rapamycin Effects on Tumor Oxygenation and Angiogenesis by Using EPRI and MRI

Keita Saito¹, Shingo Matsumoto¹, Nallathamby Devasahayam¹, Sankaran Subramanian¹, Jeeva P. Munasinghe², Vyomesh Patel³, Silvio Gutkind³, James B. Mitchell¹, Murali C. Krishna¹

¹National Cancer Institute, Bethesda, MD, United States; ²National Institute of Neurological Disorder and Stroke; ³National Institute of Dental and Craniofacial Research

Effects of anti-tumor drug rapamycin on tumor oxygenation and angiogenesis in tumor bearing mice were investigated by using pulsed electron spin resonance imaging and magnetic resonance imaging. Blood volume in tumor region was significantly decreased after 2 days from beginning of the rapamycin treatment. Tumor oxygenation did not drastically change by rapamycin treatments, but pO₂ level slightly increased and the ratio of hypoxic area to tumor region slightly decreased after 2 days rapamycin treatments. These results suggest that rapamycin can normalize blood volume and suppress depletion of oxygen in the tumor region.