Correlation Study of Serum HER 2 Against HER 2-ADC Drug Efficacy in HER 2 Low-expressing Breast Cancer

Breast cancer subjects receiving anti-HER2-ADC drugs were treated with a 3-week treatment cycle lasting 6 cycles. Serum of patients before and after treatment was collected, and the changes of serum HER2 level before chemotherapy and after 2, 4 and 6 cycles of chemotherapy were dynamically monitored, and the relationship between HER2 level and the therapeutic effect of different targeted drugs was analyzed.