This study is designed to compare the anti-tumor activity as well as the safety and efficacy of DS-8201a versus T-DM1 in HER2-positive, unresectable and/or metastatic breast cancer subjects previously treated with trastuzumab and taxane.



Eligible Ages
Over 18 Years
Eligible Genders
Accepts Healthy Volunteers

Inclusion Criteria

  • Is the age of majority in their country
  • Has pathologically documented breast cancer that:
  • is unresectable or metastatic
  • has confirmed HER2-positive expression as determined according to American Society of Clinical Oncology - College of American Pathologists guidelines evaluated at a central laboratory
  • was previously treated with trastuzumab and taxane in the advanced/metastatic setting or progressed within 6 months after neoadjuvant or adjuvant treatment involving a regimen including trastuzumab and taxane
  • Has documented radiologic progression (during or after most recent treatment or within 6 months after completing adjuvant therapy)
  • Is HER2 positive as confirmed by central laboratory assessment of most recent tumor tissue sample available. If archived tissue is not available, agrees to provide a fresh biopsy.
  • If of reproductive/childbearing potential, agrees to use a highly effective form of contraception or avoid intercourse during and upon completion of the study for at least 4.5 months after the last dose of DS-8201a or 7 months after the last dose of T-DM1
  • Has adequate renal and hepatic function

Exclusion Criteria

  • Has previously been treated with an anti-HER2 antibody drug conjugate (ADC)
  • Has uncontrolled or significant cardiovascular disease
  • Has a history of (noninfectious) interstitial lung disease (ILD)/pneumonitis that required steroids, has current ILD/pneumonitis, or where suspected ILD/pneumonitis cannot be ruled out by imaging at screening
  • Has spinal cord compression or clinically active central nervous system (CNS) metastases, defined as untreated and symptomatic, or requiring therapy with corticosteroids or anticonvulsants to control associated symptoms.
  • Participants with clinically inactive brain metastases may be included in the study.
  • Participants with treated brain metastases that are no longer symptomatic and who require no treatment with corticosteroids or anticonvulsants may be included in the study if they have recovered from the acute toxic effect of radiotherapy. A minimum of 2 weeks must have elapsed between the end of whole brain radiotherapy and study enrollment.

Study Design

Phase 3
Study Type
Intervention Model
Parallel Assignment
Primary Purpose
None (Open Label)

Arm Groups

ArmDescriptionAssigned Intervention
Trastuzumab deruxtecan (DS-8201a)
HER2-positive, unresectable and/or metastatic breast cancer participants previously treated with trastuzumab and taxane randomized to treatment with DS-8201a
  • Drug: Trastuzumab deruxtecan (DS-8201a)
    DS-8201a is sterile lyophilized powder reconstituted into a sterile aqueous solution (100 mg/5 mL) to be administered intravenously
    Other names:
    • DS-8201a
Active Comparator
Ado-trastuzumab emtansine (T-DM1)
HER2-positive, unresectable and/or metastatic breast cancer participants previously treated with trastuzumab and taxane randomized to treatment with T-DM1
  • Drug: Ado-trastuzumab emtansine (T-DM1)
    The treatment will be in accordance with the approved label
    Other names:
    • T-DM1

Recruiting Locations

More Details

Daiichi Sankyo, Inc.

Study Contact

(For Sites in Asia Only) Daiichi Sankyo Contact for Clinical Trial Information
+81-3-6225-1111(M-F 9-5 JST)


Study information shown on this site is derived from ClinicalTrials.gov (a public registry operated by the National Institutes of Health). The listing of studies provided is not certain to be all studies for which you might be eligible. Furthermore, study eligibility requirements can be difficult to understand and may change over time, so it is wise to speak with your medical care provider and individual research study teams when making decisions related to participation.