Here is a little history of the Pfixer/Astellas partnership in owning XTANDI. I hope this isn't considered off-topic but this Board is quiet anyway and might be of interest to some, it was to me.

Medivation, Inc. in-licensed the IP for enzalutamide in 2005. They started their first clinical trial in 2007. They entered a collaboration with Astellas in 2009 receiving positive Phase 3 results for treatment of mCRPC in 2011. FDA approval for treatment of mCRPC was received in Aug. 2012 and promotion of XTANDI along with Astellas began in Sept. 2012.

In Jan. 2012, a collaboration with Pfizer and Medivation for an Alzheimer's drug (different drug) ended due to poor Phase 3 results.

Medivation and Astellas had a 50/50 partnership in costs and profits except for some minor exceptions for the development and commercialization of XTANDI. By Dec. 31, 2012, Medivation had accumulated $291.5 million of losses. 

In Sept. 2016, Pfizer bought Medivation for $81.50/share for a little over 167 million shares which comes out to about $13.6 billion. All numbers are USD. This resulted in a 50/50 partnership between Astellas and Pfizer for XTANDI. 

I found a lot of parallels to RVX and Zenith (except achieving commercialization) in this story so thought it worth posting.