Additional Study Information: This study is being done to learn if the study drug called Lutetium-177 PSMA I&T is safe and effective in patients with castration-resistant metastatic prostate cancer. The study drug contains radioactive Lutetium-177, which is targeted to treat certain prostate cancers cells that have a protein called the prostate-specific membrane antigen (PSMA) on the surface of the prostate cancer cells. Not all cancer cells have PSMA on their surface. This targeted approach has the potential of treating the cancerous cells with radiation while limiting the radiation exposure to the healthy parts of your body. This study is the first study the sponsor has conducted in humans, although the study drug has been used in over a thousand patients outside of the United States on a compassionate use basis in patients with metastatic prostate cancer the study drug is not FDA approved.