Medivation, Inc. (MDVN) shares received a huge boost as the company and its partner, Astellas Pharma Inc., announced detailed results on their prostate cancer candidate, MDV3100, from the phase III AFFIRM study.

Results showed a 4.8-month advantage in median overall survival compared to placebo (18.4 months versus 13.6 months). MDV3100 met its secondary endpoints as well, compared to placebo. These included radiographic progression-free survival (8.3 versus 2.9 months), soft tissue response rate (28.9% versus 3.8%) and time to prostate-specific antigen (PSA) progression (8.3 versus 3.0 months).

Medivation and Astellas said that PSA declines of 50% or greater were more common in the MDV3100 group compared to placebo (54.0% versus 1.5%). PSA declines of 90% or greater were also more in the MDV3100 group (24.8% versus 0.9%).

MDV3100’s safety profile was also favorable with the candidate being well tolerated. While common side effects included fatigue, diarrhea and hot flush, serious adverse events, adverse events resulting in the cessation of treatment, and adverse events leading to death were lower in the MDV3100 group compared to placebo.

The phase III randomized, double-blind, placebo-controlled study, AFFIRM, was conducted in men with advanced prostate cancer previously treated with chemotherapy.

Medivation and Astellas had presented positive results from a planned interim analysis of the study in November 2011. At that time, the companies had said that they intend to conduct a pre-NDA meeting with the FDA in early 2012. We believe Medivation and Astellas will file for regulatory approval soon thereafter and expect MDV3100 to hit the market in 2013.

In addition to the AFFIRM study, MDV3100 is currently in another phase III study, PREVAIL, which is being conducted in men with advanced prostate cancer who have not received chemotherapy. A phase II study is also being conducted in hormone-na?ve men.

Our Take

Based on the data that we have seen so far, we believe MDV3100 has blockbuster potential and could be a game-changer for Medivation. The positive data and the convenient once-daily oral dosing regimen should help MDV3100 gain share once launched. We currently have a Neutral recommendation on Medivation, which carries a Zacks #3 Rank (short-term Hold rating).

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