French drugmaker Servier has agreed to acquire US-based Day One Biopharmaceuticals in an all-cash deal valued at approximately USD 2.5 billion, as the company seeks to strengthen its presence in rare oncology and brain tumour therapies.

Under the agreement, Servier will offer USD 21.50 per share in cash for Day One, representing a premium of about 68 Percent to the biotech company’s closing share price prior to the announcement. The transaction is expected to close in the second quarter of 2026, subject to shareholder tender and regulatory approvals.

The acquisition will give Servier access to Day One’s flagship therapy Ojemda (tovorafenib), a targeted treatment approved in 2024 for relapsed or refractory pediatric low-grade glioma, the most common form of brain tumour in children.

Servier already markets the brain tumour drug Voranigo, and the addition of Ojemda is expected to strengthen its oncology portfolio and expand its pipeline in rare cancers. The deal also brings Day One’s broader research pipeline, including additional programmes targeting solid tumours, into Servier’s portfolio.

The acquisition aligns with Servier’s long-term strategy to expand its oncology franchise and accelerate development of targeted therapies for patients with rare cancers.