A Clinical Study to Evaluate the Efficacy and Safety of DP303c versus trastuzumab emtansine in patients with HER2-positive Advanced Breast Cancer
1．Voluntarily agree to participate in the study and sign the informed consent;
2．Age≥18 years old;
3．Patients with unresectable locally advanced or metastatic breast cancer confirmed by histology;
4．Confirmed to be HER2 positive (HER2-positive is defined as IHC 3+ or IHC 2+ with ISH positive);
1. Patients who have previously received tubulin inhibitor-loaded HER2 ADC therapy
2. History of any other malignant tumors within three years
3. With uncontrollable serous effusion within 14 days before randomization, which required frequent drainage or medical intervention.
4. Known contraindication to the study drugs;