Sanofi to acquire Blueprint Medicines for $9.1 billion in rare disease expansion

French pharmaceutical giant Sanofi announced Monday that it will acquire U.S.-based Blueprint Medicines for $9.1 billion to strengthen its portfolio in rare immunological diseases.

France-based pharmaceutical company Sanofi announced Monday that it will acquire U.S.-based Blueprint Medicines Corporation for $9.1 billion, in a strategic move to bolster its presence in rare immunological diseases.

Blueprint, a biopharmaceutical company specializing in systemic mastocytosis (SM) and other KIT-driven diseases, accepted Sanofi’s offer of $129 per share in cash. The offer represents a 27% premium over Blueprint’s last closing price of $101.35 on Friday.

The acquisition includes Ayvakit (avapritinib), a treatment for SM approved in both the U.S. and EU, along with a robust early- and late-stage immunology pipeline.

“Blueprint’s established relationships with allergists, dermatologists, and immunologists are expected to enhance Sanofi’s growing immunology portfolio,” the French company said in a statement.

The transaction is expected to close in the third quarter of 2025, pending regulatory approvals.

As part of the deal, Blueprint shareholders will also receive one non-tradeable contingent value right (CVR), entitling them to potential milestone payments of $2 and $4 per CVR based on future achievements.

Blueprint is currently the only company with an approved drug for systemic mastocytosis - a rare disorder caused by excess mast cells - and is also developing next-generation therapies for SM and other immune disorders.

The acquisition marks the largest healthcare M&A deal in Europe so far this year. It follows Sanofi’s recent purchase of Vigil Neuroscience for $470 million last month - the second time the French company has acquired Vigil in 2025, after an initial purchase in January.

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