Medivation, Inc. ( MDVN - Analyst Report ) and Astellas Pharma Inc. recently announced that the US Food and Drug Administration (FDA) will deliver a decision regarding their oncology candidate, enzalutamide, by November 22, 2012.

Medivation and Astellas are looking to get enzalutamide approved for the treatment of men with castration-resistant prostate cancer previously treated with docetaxel-based chemotherapy. The companies are seeking EU approval as well for the candidate.

Enzalutamide is the lead pipeline candidate at Medivation. Earlier this year, Medivation and Astellas had presented positive results on enzalutamide from the phase III AFFIRM study that was conducted in prostate cancer patients previously treated with chemotherapy. The companies said that besides meeting the primary and secondary endpoints, enzalutamide’s safety profile was favorable.

Meanwhile, enzalutamide is in a phase III study (PREVAIL) which is being conducted in chemotherapy naïve prostate cancer patients. Enzalutamide is also in a phase II study (TERRAIN), which will compare enzalutamide with bicalutamide, in advanced prostate cancer patients who have progressed following medical castration with LHRH analog therapy or surgical castration.

Another open-label phase II study is being conducted to evaluate enzalutamide in advanced prostate cancer patients who have not had any previous hormonal therapies. Enzalutamide is also being studied for breast cancer (phase I).

With the FDA action date being announced, we expect investor focus to remain on the regulatory status of the candidate. Enzalutamide could very well be a game-changer for Medivation.

The prostate cancer market represents huge commercial potential. According to the American Cancer Society, prostate cancer is the most commonly diagnosed cancer among men in the US, other than skin cancer. It is estimated by the American Cancer Society that about 241,740 new cases of prostate cancer will be diagnosed in the US in 2012 with 28,170 men expected to die from the disease.

Currently approved prostate cancer treatments include Sanofi’s ( SNY - Analyst Report ) Jevtana and Johnson and Johnson’s ( JNJ - Analyst Report ) Zytiga among others.