Sanofi to acquire Blueprint Medicines for up to USD 9.5 billion

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 an 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.

Under the terms of the acquisition, Sanofi will pay $129.00 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.

Paul Hudson, CEO, Sanofi said, "The proposed acquisition of Blueprint Medicines represents a strategic step forward in our rare and immunology portfolios. It enhances our pipeline and accelerates our 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. We are excited to welcome Blueprint’s talented people and we look forward to chasing the miracles of science together. This makes sense for science, for both companies, for healthcare professionals, and – most of all – for patients.”

Kate Haviland, CEO, Blueprint Medicines said, “Since our founding, Blueprint Medicines has worked at the intersection of scientific innovation and operational excellence. I’m incredibly proud of the medical innovations our people have created and delivered to patients. We have translated our 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.”

Mast cells play an important role in immune responses and are typically found in tissues that encounter the external environment, such as the skin, lungs, and gastrointestinal tract. Upon activation, mast cells release pro-inflammatory molecules such as histamines and proteases. 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.

Ayvakit achieved net revenues of $479 million in 2024 and nearly $150 million in Q1 2025, representing year-on-year growth of more than 60 percent over Q1 2024. The oral medicine is a potent and selective inhibitor of activated KIT and PDGFRA mutant kinases. In certain diseases, mutations in KIT and PDGFRA force protein kinases into an increasingly active state and Ayvakit/Ayvakyt is designed to bind and inhibit these proteins.

Elenestinib is a next-generation, potent and highly selective KIT D816V inhibitor with limited central nervous system penetration. The oral investigational ISM medication is the subject of HARBOR, a phase 2/3 study (clinical study identifier: NCT04910685). The ongoing, randomized, double-blind, placebo-controlled study is designed to evaluate the efficacy and safety of elenestinib plus symptom-directed therapy in patients with ISM and smoldering SM.

BLU-808 is an investigational oral, highly potent and selective wild-type KIT inhibitor that was developed leveraging Blueprint’s expertise in mast cell biology. Wild-type KIT plays a central role in mast cell activation, which is implicated in a broad range of inflammatory diseases.

• $2 per share, conditioned upon the achievement of a clinical development milestone for BLU-808, and
• $4 per share, conditioned upon the achievement of a regulatory milestone for BLU-808.

The upfront offer price represents a premium of approximately 27% over the closing price of Blueprint on May 30, 2025 and a premium of approximately 34% over the 30 trading days volume weighted average price (VWAP) of Blueprint as of May 30, 2025. Together with the CVR, the premium is approximately 33% over the closing price on May 30, 2025 and approximately 40% over the 30 trading days VWAP.

The consummation of the tender offer is subject to customary closing conditions, including the tender of a number of shares of Blueprint common stock representing at least a majority of the outstanding shares of Blueprint common stock, the receipt of required regulatory approvals, and other customary conditions.

If the tender offer is successfully completed, a wholly owned subsidiary of Sanofi will merge with and into Blueprint and all of the outstanding Blueprint shares that are not tendered in the tender offer will be converted into the right to receive the same $129.00 per share in cash and one CVR per share offered to Blueprint shareholders in the tender offer. Sanofi plans to finance the transaction with a combination of cash on hand and proceeds from new debt. The tender offer is not subject to any financing condition. Subject to the satisfaction or waiver of customary closing conditions, Sanofi currently expects to complete the acquisition in the third quarter of 2025. The acquisition will not have a significant impact on Sanofi’s financial guidance for 2025. It is immediately accretive to gross margin and accretive to business operating income and EPS after 2026.