Sanofi to Buy U.S. Vaccine Maker for Up to $750 Million

Sanofi agreed to buy closely held Protein Sciences Corp. for as much as $750 million in a deal that will bolster the flu vaccines portfolio at France’s biggest drugmaker.

The company will pay $650 million upfront, with another $100 million to be given if Protein Sciences reaches certain undisclosed development milestones, Paris-based Sanofi said in a statement July 11. The deal is poised to close in the third quarter.

The transaction gives Sanofi a vaccine called Flublok, which unlike traditional shots can be produced within weeks to adjust to mutations in the flu virus because it’s not grown in eggs—giving ...