The deal includes a drug approved in the U.S. and the EU for systemic mastocytosis, a rare immunology disease, as well as an early-stage immunology pipeline, the companies said.

Sanofi announced that it will buy pharma company Blueprint Medicines for $129 per share, making the deal worth more than $9 billion. Blueprint specializes in systemic mastocytosis and other diseases driven by KIT, a receptor on mast cells.

French drugmaker Sanofi said Monday it has agreed to acquire Blueprint Medicines for $9.5 billion, sending shares of the Cambridge, Mass.-based biopharma firm soaring in premarket trading.