Pharmacodynamic Study With FLT-PET/CT in Patients With Prostate/Other Solid Malignancies Treated With High Dose Axitinib

The main purpose of this study is to learn more about the safety of an investigational drug, axitinib. An investigational drug is a drug that has not been approved by the Food and Drug Administration (FDA) and is available for research use only. Researchers will also see what changes happen to the tumors while taking the axitinib and after it is stopped (during the scheduled breaks), and what changes in the tumor may be responsible for this growth. This will be done by using a special kind of scan called an 18F-FLT PET/CT. This scan is considered an investigational type of scan and is not used for clinical care. These scans are not approved by the FDA, their use in this study is just for research purposes. In addition, the investigators want to find out how the drug is processed and distributed in the human body. The investigators will also look at how different types of cancer are affected by axitinib.