This study is a prospective, open-label, multicenter, randomized, parallel Phase II clinical trial. This study aims to investigate the efficacy and safety of trastuzumab rezetecan or trastuzumab deruxtecan in HER2 positive advanced/metastastic breast cancer
Female patients aged ≥18 and ≤75 years.
Histologically or cytologically confirmed HER2-positive (IHC 3+ and/or ISH positive) unresectable or metastatic breast cancer.
Prior treatment with trastuzumab and a taxane in the recurrent or metastatic setting. Or recurrence during or within 12 months (disease-free interval, DFI) after completing neoadjuvant/adjuvant chemotherapy and/or anti-HER2 targeted therapy.
Documented radiological disease progression (during or after the most recent prior therapy).
Patients with known untreated spinal cord compression or active central nervous system (CNS) metastases, except for those who have been treated and have remained stable for at least 1 month and have discontinued corticosteroids for >2 weeks.
History of other malignancies within the past 5 years, excluding cured basal cell carcinoma of the skin and carcinoma in situ of the cervix.
Uncontrolled third-space fluid accumulation (e.g., massive ascites, pleural effusion, pericardial effusion) that cannot be managed by drainage or other methods.
Having undergone major cancer-related surgery, radiotherapy, chemotherapy, immunotherapy, molecular targeted therapy, biotherapy, or other clinical investigational therapy within 4 weeks prior to the first dose.