Rare Cancer Targeted Therapy Developer Receives 3 Trillion Won Premium Acquisition Offer

Servier has agreed to acquire Day One Biopharmaceuticals, Inc. (NASDAQ: DAWN) in an all-cash transaction valued at $2.5 billion—equivalent to $21.50 per share, or approximately KRW 3.3 trillion. The offer price represents a premium of about 68% over Day One’s closing share price on March 5 and roughly 86% above its one-month volume-weighted average price. Servier plans a two‐step acquisition: first, a tender offer funded with available cash and investments, followed by a merger to purchase any remaining shares at the same price. Subject to customary conditions, including U.S. antitrust approval and tendering of a majority of Day One’s common stock, the transaction is expected to close in the second quarter of 2026.

In January 2026, Day One completed its acquisition of antibody-drug conjugate specialist Mersana Therapeutics in a deal valued at approximately $285 million (about KRW 370 billion) on a contingent-value basis, bolstering its rare cancer and adult oncology pipeline. Since the launch of OJEMDA, its treatment for pediatric low-grade glioma, the company has leveraged early product revenues and licensing income to expand both its pipeline and strategic partnerships.

Day One is a Nasdaq-listed biotech focused on developing targeted therapies for rare and difficult-to-treat cancers in both pediatric and adult populations. Upon closing, it will become part of Servier’s rare oncology and targeted therapy portfolio. The deal underscores a broader trend in the global biopharma sector, where large pharmaceutical firms are accelerating pipeline growth by acquiring small to mid-sized biotechs with rare-disease and antibody-drug conjugate expertise at significant premiums.