The study drug is designed to reduce the activity of a protein known as "heat shock protein 90", or "Hsp90". Hsp90 is found in every cell in the human body and normally helps those cells (and the body) cope with stressful situations. In certain cancers, however, Hsp90 helps the cancer cells survive and grow. By reducing the activity of Hsp90, the study drug may slow the growth, and reduce the survival, of those cancer cells.