Sanofi Acquires Blueprint Medicines for $9.1 Billion to Strengthen Rare Disease and Immunology Portfolio

French pharmaceutical giant SanofiView company profile announced Monday its agreement to acquire Blueprint Medicines CorporationView company profile, a US-based biopharmaceutical company specializing in systemic mastocytosisSearch disease treatments, for $9.1 billion in cash. The strategic acquisition significantly expands Sanofi's rare disease and immunology portfolio while adding a fast-growing approved therapy and promising pipeline assets.

Transaction Details and Financial Terms

Under the merger agreement, SanofiView company profile will pay $129.00 per share in cash at closing, representing an equity value of approximately $9.1 billion. The offer price reflects a premium of approximately 27% over Blueprint's closing price on May 30, 2025, and approximately 34% over the 30-day volume weighted average price.

Blueprint shareholders will also receive one non-tradeable contingent value right (CVR) per share, entitling holders to two potential milestone payments: $2 per CVR for achieving a clinical development milestone for BLU-808Search drug, and $4 per CVR for achieving a regulatory milestone for the same compound. Including potential CVR payments, the total transaction value reaches approximately $9.5 billion on a fully diluted basis.

"The proposed acquisition of Blueprint Medicines represents a strategic step forward in our rare and immunology portfolios," said Paul Hudson, CEO of SanofiView company profile. "It enhances our pipeline and accelerates our transformation into the world's leading immunology company."

Key Asset: Ayvakit/Ayvakyt

The centerpiece of the acquisition is Ayvakit/Ayvakyt (avapritinibSearch drug), the first and only approved medicine for treating the root cause of systemic mastocytosisSearch disease. The oral therapy achieved net revenues of $479 million in 2024 and nearly $150 million in Q1 2025, representing year-on-year growth of more than 60% over Q1 2024.

Ayvakit/Ayvakyt is approved by the FDA for treating advanced systemic mastocytosisSearch disease (June 2021) and indolent systemic mastocytosisSearch disease (May 2023). The drug is indicated for adults with indolent systemic mastocytosis, advanced systemic mastocytosis including aggressive systemic mastocytosisSearch disease, systemic mastocytosisSearch disease with an associated hematological neoplasm, mast cell leukemiaSearch disease, and certain gastrointestinal stromal tumors. The medicine is approved for one or more indications in 16 countries globally.

Understanding Systemic Mastocytosis

Systemic mastocytosisSearch disease is a rare immunologic disorder characterized by the accumulation and activation of aberrant mast cells in bone marrow, skin, the gastrointestinal tract, and other organs. The condition can lead to debilitating symptoms across multiple organ systems, significantly impacting patients' quality of life. Symptoms include anaphylaxis, bone disease, gastrointestinal distress, and skin lesions, with indolent systemic mastocytosisSearch disease representing the majority of cases.

Mast cells normally 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, these cells release pro-inflammatory molecules such as histamines and proteases.

Pipeline Assets and Future Potential

The acquisition brings two promising investigational compounds to SanofiView company profile's portfolio. ElenestinibSearch drug is a next-generation, potent and highly selective KIT D816VSearch term inhibitor with limited central nervous system penetration. The oral investigational medication is currently being evaluated in HARBOR, a phase 2/3 randomized, double-blind, placebo-controlled study (NCT04910685View clinical trial) designed to assess efficacy and safety in patients with indolent systemic mastocytosisSearch disease and smoldering systemic mastocytosisSearch disease.

BLU-808Search drug represents a potentially transformative asset as an investigational oral, highly potent and selective wild-type KITSearch term inhibitor. Developed leveraging Blueprint's expertise in mast cell biology, BLU-808 targets wild-type KIT, which plays a central role in mast cell activation implicated in a broad range of inflammatory diseases.

Strategic Rationale and Market Position

Kate Haviland, CEO of Blueprint Medicines, emphasized the strategic fit: "With this agreement, we begin our next chapter with SanofiView company profile, 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."

Blueprint's established presence among allergists, dermatologists, and immunologists is expected to enhance SanofiView company profile's growing immunology pipeline. The acquisition complements Sanofi's recent focus on early-stage medicine acquisitions while maintaining capacity for additional strategic transactions.

Financial Impact and Timeline

SanofiView company profile plans to finance the transaction through a combination of cash on hand and proceeds from new debt, with no financing condition attached to the tender offer. The acquisition is expected to close in the third quarter of 2025, subject to customary closing conditions including regulatory approvals and the tender of at least a majority of Blueprint's outstanding shares.

The transaction will not significantly impact SanofiView company profile's financial guidance for 2025 but is expected to be immediately accretive to gross margin and accretive to business operating income and earnings per share after 2026. Hudson noted that Sanofi retains sizeable capacity for further acquisitions, indicating continued strategic expansion plans in the immunology space.