NewslettersMammary Cell News Mersana Therapeutics Announces FDA Fast Track Designation Granted to XMT-1660 for the Treatment of TNBC By Danielle Corrigan - September 15, 2022 0 Mersana Therapeutics, Inc. announced that the US FDA has granted fast track designation to XMT-1660 for the treatment of adult patients with advanced or metastatic TNBC. [Mersana Therapeutics, Inc.] Press Release