Cancer drug group Medivation Inc (NASDAQ:MDVN) has officially rejected the latest acquisition bid from Sanofi SA (NYSE:SNY).
The French pharmaceutical group offered US$58 a share for Medivation, which specialises in hard-to-treat cancer therapy.
It comes a day after Medivation said it had agreed to provide confidential data to Sanofi as part of exploring a possible sale.
Sanofi was one of a number of companies which signed a confidentiality agreement in order to view non-public information on the group.
Shares jumped 4% after the news broke of a possible takeover.
Pharma giant Pfizer Inc (NYSE:PFE) has also reportedly shown interest in bidding for the group.
"Our board remains committed to objectively considering all avenues that may enhance our ability to deliver superior value," said a statement from Medivation earlier this week.
Shares rose 0.7% to US$62.