Day One Biopharmaceuticals (NASDAQ:DAWN) on Thursday agreed to acquire Mersana Therapeutics Inc. (NASDAQ:MRSN) , a clinical-stage biopharmaceutical company focused on the development of antibody-drug conjugates (ADCs) targeting cancers.DAWN is among today’s weakest performers. Get the scoop hereThe deal value comprises an upfront consideration of $25.00 per share in cash plus up to an aggregate of $30.25 per share in cash potentially payable under contingent value rights, representing a total equity value o ...