Genzyme said that Sanofi-Aventis's chief executive had privately opened the door in September to paying as much as $80 per share for the U.S. company before going hostile with a lower bid.
Sanofi CEO Chris Viehbacher proposed to Henri Termeer, his counterpart at Genzyme, that the two sides discuss a deal price range of $69 to $80 per share, according to a Genzyme filing with the U.S. Securities and Exchange Commission on Thursday.

Viehbacher said the price range was "manageable," but doubted he could reach the higher end based on his current understanding of the company's business, according to the filing.
The proposal was made at a Sept. 20 meeting between Viehbacher and Termeer, according to the filing. Two weeks later, France's Sanofi took a $69 per share, or $18.5 billion, offer directly to Genzyme shareholders.

Sanofi officials were not available for comment.

Termeer refused to discuss the sale of the company at that price range, or suggest an alternative, according to the filing. At the end of the meeting, Viehbacher indicated that walking away from a deal was "an unacceptable option" given its potential value to Sanofi and the time invested in it.

The disclosure came as Genzyme said it would evaluate alternatives for its assets, including reaching out to other companies, as it tries to prove it is worth more to investors than what Sanofi has offered.

Genzyme also stressed that it was not putting the company up for sale.

"These probes do not constitute authorization of a process to sell the company or any of its assets," Genzyme said in the filing.

The company said it plans to hold an investor meeting in New York to outline its financial prospects, but it has not specified a date. In the interim, Genzyme urged shareholders not to respond to Sanofi's tender offer that expires on Dec. 10.

No other potential bidder for Genzyme has emerged since Sanofi's interest in the U.S. biotech was first reported in July.