Shares of Blueprint Medicines Corp. (NASDAQ:BPMC) soared 26.5% after Sanofi (NASDAQ:SNY) revealed plans to acquire the biopharmaceutical company in a deal valued at approximately $9.5 billion. The acquisition strengthens Sanofi’s rare disease and immunology portfolio, while adding a promising pipeline of early-stage immunology assets.
Under the terms of the agreement, Sanofi will pay $129.00 per share in cash – representing a 27% premium over Blueprint’s closing price on May 30, 2025. In addition, Blueprint shareholders will receive a non-tradeable contingent value right (CVR) tied to potential future development milestones for BLU-808, Blueprint’s investigational KIT inhibitor.
The deal brings Ayvakit (also marketed as Ayvakyt in Europe) – the only approved treatment for both advanced and indolent systemic mastocytosis (ASM & ISM) – into Sanofi’s growing immunology lineup. Ayvakit generated nearly $150 million in net revenue during Q1 2025, marking a year-over-year growth of more than 60%.
In addition to Ayvakit, Sanofi will gain access to elenestinib, a next-generation therapy for systemic mastocytosis currently in Phase 2/3 development, and BLU-808, a novel oral wild-type KIT inhibitor with broad potential.
Blueprint CEO Kate Haviland called the deal a testament to the company’s innovation and collaborative success in improving outcomes for patients with rare diseases. She noted the acquisition will help Blueprint scale its mission globally with Sanofi’s support.
Sanofi plans to fund the transaction through available cash and new debt issuance. The company expects the acquisition to be accretive to both gross margin and earnings per share after 2026. The transaction is slated to close in Q3 2025, subject to regulatory approval and the successful tender of a majority of Blueprint’s shares.
The sharp rise in Blueprint’s stock reflects investor optimism around the deal’s strategic benefits, positioning Sanofi for continued growth in rare and immunological diseases.