JSKN003 Versus Trastuzumab Emtansine (T-DM1) for HER2-Positive, Advanced Breast Cancer

This is a randomized, controlled, open-label, multicenter, phase 3 clinical study to compare the efficacy and safety of JSKN003 versus T-DM1 in unresectable locally advanced and/or metastatic HER2-positive breast cancer participants previously treated with trastuzumab and taxane. Participants will be treated with JSKN003 at 6.3 mg/kg or trastuzumab emtansine at 3.6 mg/kg every 3 weeks (Q3W). Participants will continue to receive treatment until disease progression, intolerable toxicity, withdrawal of informed consent, death, or any other reasons for treatment discontinuation, whichever occurs first.