The purpose of this study is to test the effectiveness of the experimental drug, 177Lu-J591, in combination with ketoconazole and hydrocortisone against prostate cancer.

The standard treatments for prostate cancer that has returned (PSA is elevated) after surgery and/or radiation and progressed on initial hormonal therapy are not curative. Existing treatments, such as the ketoconazole used as part of this study, may decrease PSA temporarily, but unfortunately the cancer continues to grow. The experimental drug used in this study is designed to seek out all of the prostate cancer cells and to deliver a lethal dose of radiation to the areas of cancer, but not to normal areas. Some of the normal organs (liver, kidney and bone marrow) do receive some radiation dose that is within the acceptable limits.

The experimental drug in this study includes an antibody called "J591." It is a protein molecule which can bind to a specific site on a prostate cancer cell. A very energetic radioactive (an unstable atom) metal called 177Lutetium (abbreviated: 177Lu) is attached to the J591 antibody. The fully assembled drug is called "177Lu-J591."

The study will assess the potential of the energy given off by the radioactive compound to kill cancer cells. This study may also involve the use of 111Indium (abbreviated 111In). This is also an energetic radioactive particle, but does not generally give off enough energy to kill cancer cells, but allows researchers to take pictures. This radioactive particle is also attached to the J591 antibody (called 111In-J591) and will serve as a placebo (treatment with no active medicine).