Dominique Patton and Geert de Clercq

PARIS (Reuters) - Francis’ Sanofi has agreed to buy U.S. Blueprint Medicines for up to $9.5 billion to improve its position in rare immune diseases, the largest deal for European healthcare companies to date this year.

Blueprint is an expert in the treatment of systemic hypertrophy, a rare blood disorder.

Sanofi initially paid $129.00 per share of cash, or about $9.1 billion, the two companies said Monday. Blueprint stock rose 27% to $128.74. Sanofi shares fell about 1%.

Sanofi has increased R&D spending in recent years, prompting the company to abandon its long-term profit margin target two years ago as it attempts to build on blockbuster drugs for eczema and other diseases.

However, last week it suffered a setback after an experimental drug for patients with lung disease commonly referred to as the "smoker's lung."

Paul Hudson, CEO of Sanofi, said: “The Blueprint’s acquisition represents a strategic step in our rare and immunology portfolio. It strengthens our pipeline and accelerates our transition into the world’s leading immunology companies.

The deal will increase Sanofi's portfolio, the rare immunologic disease drug Ayvakit, also known as Ayvakyt, approved in the United States and the European Union, as well as a promising advanced and early immunology pipeline.

Ayvakit is the only approved drug for advanced and lazy systemic hypertrophy, a rare blood disorder that occurs when the body produces abnormal mast cells (a type of white blood cells). It triggers a continuous allergic reaction.

The acquisition will also bring Elenestinib, a next-generation drug for systemic hypertrophy, and Blu-808, a highly selective and effective oral wild-type kit inhibitor that has the potential to treat a wide range of diseases in immunology.

JP Morgan analysts said the deal had "strategic and financial implications", noting that Blueprint expects Ayvakit to have annual sales of about $2 billion by fiscal year 2030.

They added: "We think this deal is very suitable for Sanofi's wise valuation and investors should see it as a positive time."

This is the latest in a series of Sanofi deals. Last month, it announced the purchase of $470 million in Vigil Neuroscience and reached a $2.2 billion deal for U.S. biotech company Inhibrx in January 2024.

Hudson said the deal complements Sanofi's recent acquisition of other early drugs, adding that it still retains considerable trading capabilities.