Acquisition of Mersana Therapeutics N O V E M B E R 2 0 2 5 Day One's Mission Inspired by the urgent needs of children, Day One creatively and intentionally develops new medicines for people of all ages with life- threatening diseases Q&A Session All Participants 2 Confidential Information. For internal use only. Forward Looking Statements This communication contains forward-looking statements. Forward-looking statements are generally identified by the words "expects", "anticipates", "believes", "intends", ...