As the newly launched drug in 2020, Trastuzumab deruxtecan (DS-8201a) is currently the most effective ADC drug that targeting HER2, which has obtained accelerated approval from FDA and conditional authorization from EMA for advanced or metastatic HER2+ BC patients who have received anti-HER2 drugs before, containing T-DM1 (Doi et al., 2017; Modi et al. The gene discussed is ERBB2; the disease is breast cancer.