A Study to Evaluate Vascular Normalization in Patients With Recurrent Glioblastoma Treated With Bevacizumab Using [11C]Temozolomide PET and Vascular MRI

Detailed Summary

This research study is exploring how the blood vessels in the participant's tumor change from treatment with bevacizumab, and how these changes affect the way their tumor absorbs temozolomide (TMZ). The pilot part of this study is to evaluate the use of \[11C\] temozolomide PET (TMZ-PET) scans and MRI scans to tell investigators more about how standard treatment with bevacizumab affects the blood vessels in the participant's tumor, and how these changes affect the way the participant's tumor absorbs temozolomide. "Investigational" means that the role of TMZ-PET scans is still being studied and that research doctors are trying to find out more about it. Bevacizumab is approved by the U.S. Food and Drug Administration for use in people with the participant's type of cancer. It works by blocking signals on a specific protein called vascular endothelial growth hormone (VEGF), which plays a role in promoting the growth of spread of tumor blood vessels. Bevacizumab is an "anti-VEGF' agent because it is designed to slow the growth of the participant's cancer. Since anti-VEGF agents also affect normal blood vessels in the brain, they can inhibit the way other drugs used in combination with bevacizumab are delivered to the tumor. Researchers are looking for how bevacizumab affects delivery of chemotherapy, in this case temozolomide. In PET scans, a radioactive substance is injected into the body. The scanning machine finds the radioactive substance, which tends to go to cancer cells. For the PET scans in this research study, the investigators are using a radioactive substance called \[11C\] temozolomide, which is chemically identical to the prescription drug TMZ. TMZ is FDA approved as a chemotherapeutic agent in cancer but \[11C\] temozolomide is an investigational agent. In this research study, participants will receive standard treatment with bevacizumab and oral temozolomide as well as standard MRI scans. In addition, participants will undergo TMZ-PET scans before and after treatment with bevacizumab. The first TMZ-PET scan will occur 7-13 days after starting treatment with oral temozolomide but before beginning treatment with bevacizumab, day 1 after starting treatment with bevacizumab and 1 month after starting bevacizumab. TMZ-PET scans will be given at the same time as a vascular MRI, which will evaluate the changes in tumor blood flow, blood volume, and how receptive blood vessels are while also measuring how much TMZ is in the brain.

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