About Prostate Cancer

Prostate cancer kills more than 27,000 men each year in the U.S., making it the second leading cause of cancer death in men. Patients with hormone-refractory prostate cancer have few treatment options and a poor prognosis.

MDV3100 Clinical Development Program

We are conducting an open-label, Phase 1-2 clinical trial of MDV3100 in patients with hormone-refractory prostate cancer. The trial is being conducted at several clinical sites in the United States, including Memorial Sloan-Kettering Cancer Center in New York. The study endpoints include safety, tolerability, pharmacokinetics, effects on serum prostate-specific antigen (PSA) levels and disease progression.

In November 2007, we announced early PSA data from the two lowest dose groups in this clinical trial. MDV3100 reduced serum PSA levels in all six patients enrolled in both dose groups in a dose-dependent manner. In the lowest dose group, after two months of treatment, PSA levels declined 45 percent to 66 percent. PSA levels in the second lowest dose group declined 75 percent to 89 percent after the first month of treatment. MDV3100 has been well-tolerated to date in both dose groups. No dose-limiting toxicities have been identified and dose-escalation continues in the study. These PSA reductions are early data from a small number of patients, and we do not yet know whether they will be confirmed at the end of the study or if PSA reductions will correlate with an improvement in overall survival, which generally is required for approval. Nonetheless, we believe these early data provide encouragement regarding MDV3100’s potential as a treatment for hormone-refractory prostate cancer.

The original design of this trial provided for expansion of a single dose group to 20 patients once a maximum tolerated dose was established. However, based on the early tolerability and PSA data, we have obtained approval to expand additional dose groups. Enrollment in these expansion groups, which include both patients who are chemotherapy naïve and patients who have failed chemotherapy, is underway. Given these expansions, we expect to enroll approximately 100 patients in this trial. We expect to complete the study in 2008. If the results are positive, we plan to seek FDA agreement in 2008 to enter pivotal Phase 3 registration studies.