Sanofi Makes $9.5 Billion Bet on Rare Disease Drugmaker

France’s Sanofi has agreed to acquire U.S.-based Blueprint Medicines Corporation in a deal valued at up to $9.5 billion, marking what would be the largest healthcare acquisition in Europe this year, based on LSEG data. The transaction is intended to enhance Sanofi’s position in rare immunological diseases.
Blueprint is a specialist in therapies for systemic mastocytosis, a rare immunological disorder involving the accumulation and activation of abnormal mast cells in various organs. Its lead product, Ayvakit (marketed as Ayvakyt in the EU), is the only approved treatment for both advanced and indolent forms of the disease. Sanofi will add this drug to its portfolio, along with a pipeline of advanced and early-stage immunology candidates.

Sanofi CEO Paul Hudson stated the acquisition “represents a strategic step forward in our rare and immunology portfolios” and “accelerates our transformation into the world’s leading immunology company.” The deal will also provide Sanofi with Blueprint’s established relationships across key medical specialties, including allergists, dermatologists, and immunologists.
The agreement includes a cash payment of $129.00 per share, a 27% premium over Blueprint’s closing price on May 30 and 34% above its average share price over the previous 30 days. In addition, shareholders will receive one non-tradeable contingent value right (CVR) per share, entitling them to potential milestone payments of $2 and $4 based on the progress of BLU-808, an early-stage wild-type KIT inhibitor.
With this acquisition, Sanofi obtains additional investigational treatments, including elenestinib, a KIT D816V inhibitor in phase 2/3 studies, and BLU-808. Sanofi noted that KIT plays a central role in mast cell activation, which is implicated in a broad range of inflammatory diseases. Blueprint previously projected Ayvakit’s peak sales potential at $2 billion, following sales of $479 million last year.

The acquisition follows several other transactions by Sanofi. In May, the company announced the $470 million purchase of Vigil Neuroscience, and in January, it agreed to acquire Inhibrx for $2.2 billion. Sanofi has also completed earlier deals, including Dren Bio’s DR-0201 for $600 million upfront, and prior acquisitions such as Translate Bio and Provention Bio for $3.2 billion and $2.9 billion, respectively.
Sanofi stated that the Blueprint acquisition complements its recent purchases of early-stage medicines. Hudson added that the company still retains significant capacity for future deals. In April, Sanofi revealed plans to sell a controlling stake in its consumer health unit, Opella, for €10 billion ($11.4 billion), with the intention to pursue external growth opportunities.
Sanofi expects to complete the Blueprint transaction in the third quarter. The company reported that the acquisition will not impact its 2025 financial guidance. While Blueprint’s shares rose by 26% following the announcement, Sanofi’s shares opened with little change.