The US Food and Drug Administration (FDA) granted Breakthrough Therapy designation to DS-8201 for the treatment of patients with locally advanced or metastatic, HER2-positive breast cancer who have been treated with trastuzumab, pertuzumab, and have progressed after ado-trastuzumab emtansine (T-DM1).1

DS-8201 is an investigational HER2-targeting antibody drug conjugate (ADC), a targeted therapy for cancer that delivers cytotoxic chemotherapy by means of a linker on the monoclonal antibody that attaches to a specific target on cancer cells.

Breakthrough therapy designation was granted based on evidence from an ongoing 2-part stage 1 dosing trial ( Identifier: NCT02564900) evaluating the safety and efficacy of DS-8201. A maximum tolerated dose was not reached and no dose-limiting toxicities were reported in the phase 1 study.

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Preliminary results demonstrated that patients achieved a 46.7% overall response rate (ORR) (14 of 30 patients) and a 100% disease control rate. Patients who were previously treated with T-DM1 achieved an ORR of 45.7% (16 of 35 patients) and a 100% disease control rate.2


  1. FDA Grants Breakthrough Therapy Designation to Daiichi Sankyo’s DS-8201 for HER2-Positive Metastatic Breast Cancer [news release]. Tokyo, Japan, Basking Ridge, NJ, and Munich, Germany: PRNewswire; August 29, 2017. Accessed August 29, 2017.
  2. New Precision Medicine Data on DS-8201 in HER2-Expressing Breast Cancer Revealed at 2017 American Society of Clinical Oncology (ASCO) Annual Meeting [news release]. Tokyo, Japan, Parsippany, NJ, and Munich, Germany: Daiichi-Sankyo. June 6, 2017. Accessed August 29, 2017