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.
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.
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.
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