Clinical Trial

A Phase 3, Randomized, Open-Label, Multicenter, Controlled Study To
Evaluate The Efficacy And Safety Of Zanidatamab In Combination With
Physician’s Choice Chemotherapy Compared To Trastuzumab In
Combination With Physician’s Choice Chemotherapy For The Treatment
Of Participants With Metastatic HER2-Positive Breast Cancer Who Have
Progressed On, Or Are Intolerant To, Previous Trastuzumab Deruxtecan
Treatment (EmpowHER 303)

MOA: Zanidatamab is a bispecific antibody targeting two distinct HER2 epitopes, ECD2 and ECD4.

Key Eligibility Criteria:

• Histologically confirmed HER2+ MBC (central testing)
  • Archived tissue or fresh biopsy must be submitted for HER2 central testing
    confirmation up to 12 months prior to randomization
• Must have progressed on, or is intolerant to, previous T-DXd tx
• Must have received 2-4 lines of HER2-directed tx in MBC
  • Prior HER2-targeted (neo)adj tx with relapse within 6 months is a line of tx
  • Post-T-DXd therapy allowed (for ex: tucatinib-based regimen and/or T-DM1)
  • Prior participating in a zanidatamab clinical study is excluded
• Measurable disease per RECIST v1.1
• Treated or clinically inactive CNS metastases are eligible
• Washout periods for prior anticancer tx before randomization:
  • Monoclonal antibodies including ADCs: ≤ 3 weeks
  • Small molecule targeted tx: ≤ 2 weeks or 5 half-lives, whichever is shorter
  • No washout needed for ET or gonadotropin-releasing hormone agonists