Mayo Clinic -- ROCHESTER, Minn. — Two Mayo Clinic patients whose prostate cancer had been considered inoperable are now cancer free thanks in part to an experimental drug therapy that was used in combination with standardized hormone treatment and radiation therapy. The men were participating in a clinical trial of an immunotherapeutic agent called MDX-010 or ipilimumab. In these two cases, physicians say the approach initiated the death of a majority of cancer cells and caused the tumors to shrink dramatically, allowing surgery. In both cases, the aggressive tumors had grown well beyond the prostate into the abdominal areas.