A Pilot Study to Evaluate PBR PET in Brain Tumor Patients Treated With Chemoradiation or Immunotherapy

This research study is studying the changes in primary and metastatic brain tumor inflammation using positron emission tomography (PET) imaging using a radioactive substance called \[11C\] PBR28a, which is also known as peripheral benzodiazepine receptors (PBR), or PBR-PET.

This research study is a Pilot Study, which is the first time investigators are examining this study intervention. The purpose of a pilot study is to obtain the preliminary data needed to justify performing a larger clinical trial on the effectiveness of an investigational intervention. Standard treatment for the subjects' disease includes chemoradiation and immunotherapy. 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 and areas of inflammation. For the PET scans in this study, the investigators are using a radioactive substance called \[11C\]PBR28. The investigators would like to see if this tracer can be used to detect changes in inflammation during tumor treatment. PBR-PET scans will be performed at screening before therapy and then several weeks/months after the start of therapy, depending on the type of therapy used. No diagnostic decisions or clinical treatment decisions will be made based on any results obtained from these PET scans, and there will be no change in care. The information from these studies may help the investigators design methods that could be used in larger studies to more completely understand the role of inflammation in the treatment of cancer.