Magnetic Resonance Imaging in Measuring the Effect of Cabozantinib in Patients With Castrate Resistant Prostate Cancer

Inclusion Criteria: * Histologically or cytologically confirmed prostate cancer with progressive disease * Evidence of castration resistance defined as disease progression despite a testosterone level \< 50ng/dL (or surgical castration) * Evidence of metastatic disease to the bones within the lumbar spine, sacrum, or pelvic bones that is identifiable on screening pelvic MRI * If patient has had prior pelvis radiation therapy (RT), then bone metastases must be out of radiated port (e.g. lumbar or sacral spine) * Any prior therapy for castrate disease acceptable other than prior XL184 with a minimum washout of 28 days for any other anticancer therapy * Patients with castrate resistant disease post antiandrogen therapy/withdrawal must meet at least one of the following criteria: * Have not received docetaxel chemotherapy * Have received docetaxel chemotherapy but received less then 225mg/m2 cumulative dose * Have documented liver metastases * Have no pain or pain that does not require a long acting (SR) narcotic * Have received mitoxantrone chemotherapy in the past for CRPC Exclusion Criteria: * Patients who have had chemotherapy or radiotherapy within 4 weeks prior to entering the study * Patients who are receiving any other investigational agents * Prior treatment with other vascular endothelial growth factor (VEGF) or c-MET targeted therapies * History of hematemesis or hemoptysis * The subject has uncontrolled or significant intercurrent illness * The patient r…