Medivation just rejected Sanofi's $9.3 billion takeover bid

One of the bids for a San Francisco biotech has already fallen flat.

On Friday, cancer drugmaker Medivation rejected pharma giant Sanofi's $9.3 billion takeover offer.

The Sanofi bid was one of three major healthcare acquisitions that were announced on Thursday, with AbbVie buying up cancer drug startup Stemcentrx for up to $10 billion, and Abbott's $25 billion acquisition of St. Jude Medical.

But Medivation isn't going to go easily, calling the bid "inadequate."

Medivation wrote in a statement:

"Sanofi's opportunistically-timed proposal, which comes during a period of significant market dislocation, and prior to several important near-term events for the company, is designed to seize for Sanofi value that rightly belongs to our stockholders. We believe the continued successful execution of our well-defined strategic plan will deliver greater value to Medivation's stockholders than Sanofi's substantially inadequate proposal."

Medivation's stock took a hit in March after congressional leaders called out the price of the company's prostate-cancer drug Xtandi.

In response to the rejection, Sanofi said in a statement:

"Sanofi is a disciplined acquirer and has a strong acquisition track-record. While to date Medivation has chosen not to enter into discussions regarding this value-creating transaction, Sanofi remains committed to the combination and looks forward to engaging directly with Medivation shareholders with regard to our proposal."

Let the the back-and-forth begin.