A Study of ZW25 (Zanidatamab) With Palbociclib Plus Fulvestrant in Patients With HER2+/HR+ Advanced Breast Cancer

Official Title

Phase 2a Study of ZW25 in Combination With Palbociclib Plus Fulvestrant


This is a multicentre, Phase 2a, open-label, 2-part study to investigate the safety, tolerability, and anti-tumour activity of ZW25 (zanidatamab) in combination with palbociclib plus fulvestrant. Eligible patients include those with locally advanced (unresectable) and/or metastatic human epidermal growth factor receptor 2 (HER2)-positive, hormone receptor (HR)-positive breast cancer.

Trial Description

Primary Outcome:

  • Incidence of dose-limiting toxicities (DLTs; Part 1)
  • Incidence of AEs (Part 1)
  • Incidence of lab abnormalities (Part 1)
  • Progression-free survival 6 (PFS6; Part 2)
Secondary Outcome:
  • Maximum serum concentration of ZW25 (Parts 1 and 2)
  • Trough concentration of ZW25 (Parts 1 and 2)
  • Incidence of anti-drug antibodies (ADAs) (Parts 1 and 2)
  • Objective response rate (Part 2)
  • Duration of response (Part 2)
  • Disease control rate (Part 2)
  • Progression-free survival (PFS; Part 2)
  • Overall survival (Part 2)
  • Incidence of AEs (Part 2)
  • Incidence of lab abnormalities (Part 2)
Part 1 of the study will first evaluate the safety and tolerability of ZW25 in combination with palbociclib plus fulvestrant and will confirm the recommended doses (RDs) of ZW25 and palbociclib in this combination. Part 2 of the study will evaluate the anti-tumour activity of the combination of ZW25 with palbociclib plus fulvestrant at the RD level in patients with HER2-positive, HR-positive advanced breast cancer.

View this trial on ClinicalTrials.gov

Interested in this trial?

Print this page and take it to your doctor to discuss your eligibilty and treatment options. Only your doctor can refer you to a clinical trial.


Canadian Cancer Society

These resources are provided in partnership with the Canadian Cancer Society