French healthcare company Sanofi S.A. (Euronext Paris:SAN) (Nasdaq:SNY) announced on Monday that it has entered into an agreement to acquire Blueprint Medicines Corporation (NASDAQ:BPMC) for an equity value of approximately USD9.1bn, plus up to USD400m in additional contingent payments.

Blueprint Medicines is a US-based biopharmaceutical company focused on systemic mastocytosis (SM), a rare immunological disease, and other KIT-driven diseases.

This acquisition adds Ayvakit/Ayvakyt (avapritinib), the only approved therapy for both advanced and indolent systemic mastocytosis in the United States and European Union, to Sanofi's immunology portfolio. The drug generated USD479m in revenue in 2024 and nearly USD150m in Q1 2025, reflecting over 60% year-over-year growth.

Sanofi also gains Blueprint's immunology pipeline, including elenestinib, a next-generation KIT D816V inhibitor currently in phase 2/3 trials, and BLU-808, a highly selective oral wild-type KIT inhibitor with broad potential in inflammatory diseases.

Blueprint shareholders will receive USD129.00 per share in cash and one non-tradeable contingent value right, which could yield an additional USD6 per share based on future BLU-808 milestones.

The upfront offer represents a 27% premium over Blueprint's closing price on 30 May 2025 and a 34% premium over its 30-day volume weighted average price.

Subject to regulatory approvals and a majority tender of Blueprint shares, the acquisition is expected to close in the third quarter of 2025.

Sanofi anticipates that the addition of Blueprint Medicines will be immediately accretive to gross margin and accretive to operating income and EPS after 2026, with no material impact on 2025 guidance.