Mersana Therapeutics Announces Additional FDA Fast Track Designation Granted to Emiltatug Ledadotin (XMT-1660)

Company Updates - Mersana Therapeutics announced that the FDA granted an additional Fast Track designation to XMT-1660 for the treatment of advanced or metastatic breast cancer in patients with HER2 low or HER2-negative disease, including triple-negative breast cancer (TNBC), who have received a prior topoisomerase-1 inhibitor ADC [1][2] - The World Health Organization approved emiltatug ledadotin (Emi-Le) as the international nonproprietary name (INN) for XMT-1660 [1] - The company will host a conference call to discuss initial Phase 1 clinical data for Emi-Le, with a live webcast available on the Mersana website [4] Product Development - Emi-Le (XMT-1660) is a Dolasynthen ADC targeting B7-H4, part of Mersana's proprietary ADC platforms, which also include Immunosynthen ADCs like XMT-2056 targeting a novel HER2 epitope [5] - The FDA previously granted Fast Track designation to Emi-Le for the treatment of adult patients with advanced or metastatic recurrent TNBC [2] - Fast Track designation may provide benefits such as more frequent FDA communications, Accelerated Approval, Priority Review, or Rolling Review of a Biologics License Application (BLA) [3] Industry Insights - Topoisomerase-1 inhibitor ADCs are becoming the standard of care for metastatic TNBC and hormone-receptor positive breast cancer, with research indicating these patients are difficult to treat after initial therapy [3] - Mersana's focus on developing novel ADCs addresses the unmet medical need for new cancer treatment options, particularly for advanced or metastatic breast cancer [5]