This study is designed to compare efficacy and safety of GQ1005 versus T-DM1 in HER2-positive, unresectable and/or metastatic breast cancer patients previously treated with trastuzumab and taxane.
Male or female adults ≥ 18 years at the time of voluntary signing of informed consent.
Pathologically confirmed unresectable or metastatic HER2 positive breast cancer previously treated with trastuzumab and taxane
Eastern Cooperative Oncology Group (ECOG) performance status score is 0 or 1.
Presence of at least one measurable lesion according to RECIST v1.1
Prior anti-HER2 ADC therapy.
Previous history of interstitial lung disease/noninfectious pneumonitis/radiation pneumonitis requiring steroid therapy.
Known serious hypersensitivity to the active ingredients of the study drug, inactive ingredients in the formulation, or other antibody drugs.
Multiple primary malignancies within 3 years, except for adequately resected non-melanoma skin cancer, curatively treated in situ tumor, or contralateral breast cancer