Day One Biopharma Expands Oncology Pipeline With $285 Million Mersana Buyout

1. Day One Biopharmaceuticals acquires Mersana Therapeutics for approximately $285 million. 2. DAWN shares dropped 5.78% amid acquisition news; MRSN shares surged 206.82%. 3. Day One's Ojemda revenue guidance raised to $145-$150 million for 2025. 4. Transaction expected to close by the end of January 2026. 5. Emi-Le development targets high unmet need in adenoid cystic carcinoma.