Sanofi has entered into an agreement to acquire Blueprint Medicines Corp., a U.S.-based biopharma company specializing in systemic mastocytosis (SM), a rare immunological disease, and other KIT-driven diseases, for a total transaction valued at approximately $9.5 billion.

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