HER2 Expression of CTC to Predict Response in HER2-positive Advanced Breast Cancer Patients Treated With ADC

Inclusion Criteria

• •Has pathologically documented breast cancer that:
• •1. Is unresectable or metastatic
• •2. has confirmed HER2-positive expression defined as IHC 2+/ISH+ or IHC 3+
• •3. was previously treated with trastuzumab and taxane in the advanced setting or progressed within 6 months after neoadjuvant or adjuvant treatment involving a regimen including trastuzumab and taxane
• •Has adequate cardiac, bone marrow, renal, hepatic and blood clotting functions
• •Receives anti-HER2 ADC treatment
• •Life expectancy \> 3 months
• •Evidence of measurable or evaluable disease (RECIST 1.1 criteria)in the 28 days before selection
• •ECOG ≤2