Pharma BD Deal Intelligence

Day One Biopharmaceuticals Inc. / Mersana Therapeutics, Inc.

2025 · Acquisition/Merger · $285M · Complete

Day One Biopharmaceuticals agreed to acquire Mersana Therapeutics, gaining Mersana's antibody-drug conjugate platform and its lead B7-H4-directed ADC emiltatug ledadotin. Mersana shareholders receive USD 25.00 per share in cash at closing, approximately USD 129 million, plus non-tradeable contingent value rights worth up to USD 30.25 per share, for aggregate consideration of up to approximately USD 285 million. The transaction was expected to close by the end of January 2026.

This deal is too recent to grade. Critic Score and Outcome Score are assigned after the announcement-week coverage settles and, for Outcome, after the 5-year post-close assessment window opens — expected 2030 at the earliest for this deal, once/if it closes.

Key facts

Related deals

See the full interactive analysis, sources & comparables →

← Browse all deals  ·  How we score deals

More: 2025 deals