FDA Grants Fast Track Designation to Mersana Therapeutics' XMT-1660 for Triple-Negative Breast Cancer Treatment

Mersana Therapeutics, Inc., a clinical-stage biopharmaceutical company, has received Fast Track designation from the U.S. Food and Drug Administration (FDA) for XMT-1660, a B7-H4-directed Dolasynthen antibody drug conjugate, targeting the treatment of adult patients with advanced or metastatic triple-negative breast cancer (TNBC). TNBC is known for its poor outcomes and limited treatment options, making this development particularly significant.

XMT-1660 features a precise, target-optimized drug-to-antibody ratio (DAR 6) and utilizes Mersana’s clinically validated DolaLock microtubule inhibitor payload with a controlled bystander effect. The drug has demonstrated promising anti-tumor effects in preclinical studies, leading to the initiation of a Phase 1 trial to investigate its safety and clinical activity.

The ongoing multicenter Phase 1 trial is designed to assess the safety, tolerability, and anti-tumor activity of XMT-1660 in patients with solid tumors, including breast, endometrial, and ovarian cancers. The trial includes an initial dose escalation portion to evaluate safety and tolerability, followed by a dose expansion portion to assess safety, tolerability, and efficacy.

The FDA’s Fast Track program facilitates the development and expedites the review of drug candidates aimed at treating serious conditions and filling an unmet medical need. Benefits of this designation include more frequent meetings and communications with the FDA, and potentially, Accelerated Approval, Priority Review, or Rolling Review of a Biologics License Application (BLA).

Mersana Therapeutics is dedicated to discovering and developing a pipeline of antibody-drug conjugates (ADCs) targeting cancers with high unmet medical needs. The company’s lead product candidate, upifitamab rilsodotin (UpRi), is currently being studied in several trials for ovarian cancer, alongside other promising candidates like XMT-1660 and XMT-2056.

This press release contains forward-looking statements regarding the therapeutic potential of Mersana’s product candidates, including XMT-1660, and the expected progression of its Phase 1 clinical trial. However, actual results may differ due to various factors, including uncertainties inherent in research and development, clinical trial outcomes, and regulatory processes.