Sanofi to Acquire Blueprint Medicines for $9.5 Billion

French drug maker Sanofi has agreed to acquire Blueprint Medicines Corporation (Blueprint), a US-based, publicly traded biopharmaceutical company specialising in systemic mastocytosis (SM), a rare immunological disease, and other KIT-driven diseases, for $9.5 billion.

Under the terms of the acquisition, Sanofi will pay $129 per share in cash at closing, representing an equity value of approximately $9.1 billion. Blueprint shareholders also will receive one non-tradeable contingent value right (CVR) which will entitle the holder to receive two potential milestone payments of $2 and $4 per CVR for the achievement, respectively, of future development and regulatory milestones for BLU-808.

The total equity value of the transaction, including potential CVR payments, represents approximately $9.5 billion on a fully diluted basis.

Subject to the satisfaction or waiver of customary closing conditions, Sanofi currently expects to complete the acquisition in the third quarter of 2025. The company plans to finance the transaction with a combination of cash on hand and proceeds from new debt and the tender offer is not subject to any financing condition.

The acquisition includes a rare immunology disease medicine, Ayvakit/Ayvakyt (avapritinib), approved in the US and the EU, and a promising advanced and early-stage immunology pipeline. Furthermore, Blueprint’s established presence among allergists, dermatologists, and immunologists is expected to enhance Sanofi’s growing immunology pipeline.

Ayvakit/Ayvakyt is the only approved medicine for advanced and indolent systemic mastocytosis (ASM & ISM), a rare immunology disease, which is characterized by the accumulation and activation of aberrant mast cells in bone marrow, skin, the gastrointestinal tract, and other organs. The acquisition will also bring elenestinib, a next-generation medicine for SM, as well as BLU-808, a highly selective and potent oral wild-type KIT inhibitor that has the potential to treat a broad range of diseases in immunology.

Sanofi CEO Paul Hudson said that the proposed acquisition represents a strategic step forward in Sanofi’s rare and immunology portfolios. It enhances the company’s pipeline and accelerates their transformation into the world’s leading immunology company.

“This acquisition is fully aligned with our strategic intent to strengthen our existing therapeutic areas, to bring relevant and differentiated medicines to patients and to secure attractive returns to our shareholders. It complements recent acquisitions of early-stage medicines that remain our main field of interest. Sanofi still retains a sizeable capacity for further acquisitions,” he said.

Beginning of Next Chapter

Blueprint Medicines CEO Kate Haviland said that they have worked at the intersection of scientific innovation and operational excellence and translated their unique scientific understanding of mast cell biology into a portfolio of important therapies including Ayvakit – the first and only medicine approved to treat the root cause of systemic mastocytosis – and worked collaboratively with communities to improve standards of care and patient outcomes.

“With this agreement, we begin our next chapter with Sanofi, whose exceptional leadership in rare disease and immunology and proven ability to solve medical challenges at scale stand to accelerate our joint mission to bring life-changing medicines to many more patients around the world,” Kate said.

Systemic mastocytosis is a rare immunologic disorder that can lead to a range of debilitating symptoms across multiple organ systems and a significant impact on patients’ quality of life. The symptoms that patients with SM experience can include anaphylaxis, bone disease, gastrointestinal distress and skin lesions. ISM represents the majority of SM cases.