France's Sanofi seeks to sack board of US takeover prey

French drugs giant Sanofi threatened Wednesday to sack the entire board of US rival Medivation, dramatically turning up the heat in an acrimonious, multibillion-dollar takeover battle.

Sanofi launched the attempt to replace all board members of Medivation after being repeatedly spurned in its attempts to purchase the group, which makes a high-priced, blockbuster prostate cancer medication called Xtandi.

As a shareholder in Medivation, the French company has the right to seek written support from fellow shareholders to overturn the board of its US rival.

The proposal by Sanofi, which offered a new slate of eight directors, needs the support of more than 50 percent of Medivation shareholders in a process that can last up to 60 days.

"We are seeking your support for the removal of the company board," said a copy of the request to shareholders, which was filed with the US market regulator, the New York-based Securities and Exchange Commission.

Sanofi accused Medivation directors of failing to act in the best interests of its shareholders.

"The company board has refused even to engage with us regarding our proposed offer," it said.

Sanofi said it was open to signing a confidentiality agreement so as obtain more information about Medivation, stressing that in such conditions it was in a position to increase its offer.

In a separate letter to the Medivation board, Sanofi chief executive Olivier Brandicourt urged the US firm to engage in talks.

Brandicourt said he believed Medivation shareholders "overwhelmingly support" the sale of the company, and his firm would drop its effort to replace the board if Medivation engages "in good faith" as part of a sales process.

The Sanofi boss said in a statement he had been left with no choice but to propose a new board of directors "who are more open to supporting the best interests of Medivation shareholders regarding a potential transaction".

Medivation said last month its board had unanimously rejected Sanofi's unsolicited, non-binding cash offer of $52.50 a share, declaring that it "substantially" undervalued the company and was not in the interests of shareholders.

The offer valued San Francisco-based Medivation at $9.3 billion (8.2 billion euros).

That would make it Paris-based Sanofi's biggest acquisition since it bought the US biotech group Genzyme in 2011 for more than $20 billion.