U.S. law firms Weil, Gotshal & Manges and Goodwin are taking lead advisory roles on the $1.45 billion acquisition of Cambridge-based biotech firm Kymab by French pharma giant Sanofi. 

Under the deal terms, Sanofi will pay $1.1 billion upfront and up to $350 million upon achievement of certain milestones, according to an announcement by the firms on Monday.