This is a prospective, multicenter, open-label, randomized, controlled Study. The purpose of this study is to evaluate the efficacy and safety of SHR-A1811 versus pyrotinib plus capecitabine in the treatment of trastuzumab primary-resistant HER2-positive advanced breast cancer.
Age ≥18 years.
Histologically or cytologically confirmed HER2-positive advanced breast cancer (IHC 3+, or IHC 2+ with ISH amplification).
ECOG performance status 0-2.
Estimated life expectancy >12 weeks.
Prior or current exposure to antibody-drug conjugates (ADCs) containing a topoisomerase I inhibitor, including but not limited to fam-trastuzumab deruxtecan (DS-8201a).
Active brain metastases or leptomeningeal metastases (patients with asymptomatic/inactive brain metastases are allowed to be enrolled);
Other malignancy diagnosed within 5 years prior to enrollment, excluding cured non-melanoma skin cancer, cervical carcinoma in situ, ductal carcinoma in situ, or stage I grade 1 endometrial cancer;
Radiotherapy, any anti-HER2 targeted therapy, or chemotherapy within 4 weeks prior to enrollment; endocrine therapy within 2 weeks prior to enrollment;