It is spending about $14 billion (12.37 billion euros) with the main benefit being that it adds the successful prostate cancer treatment Xtandi to its portfolio.

The drug is projected to generate more than one billion euros a year in sales by 2020.

Pfizer, whose oncology offerings include breast cancer drug Ibrance and several other promising immuno-oncology products, will now also access to Talazoparib, another breast cancer treatment under development.

Medivation, which is based in San Francisco, put itself up for sale in April.

That attracted an offer from the French drugmaker Sanofi which was considerably bested by Pfizer.

It is possible but unlikely Sanofi could launch a counter bid, pharmaceutical industry analysts said.

“Given the already very high price being discussed, the difficult public relationship between Medivation and Sanofi … we see a higher bid as very unlikely, but not impossible,” RBC Capital Partners wrote in a client note ahead of the announcement.

Sanofi said while it recognised the potential strategic benefits of a combination with Medivation, it was a “disciplined acquirer and remained committed to acting in the best interests of Sanofi shareholders”.

Medivation’s shares jumped 20 percent on Monday while Pfizer’s slipped slightly. (Euronews)