Cabozantinib (XL184) in Men With Castrate-Resistant Prostate Cancer

Cabozantinib (XL184) is a new drug that is being developed to treat cancer. Cabozantinib works by blocking the "angiogenesis," or the growth of new blood vessels, to the tumor. This is similar to how several other cancer drugs work but in addition Cabozantinib also blocks other pathways that may be responsible for allowing cancer cells to become resistant to these other "anti-angiogenic" treatments. So far cabozantinib has been investigated in treating brain cancer and a rare form of thyroid cancer. This study will explore lower doses of cabozantinib with the goal to find the most effective, safe, and tolerable dose without undesirable side effects.