ERBB2 and breast carcinoma: Novel ADCs, such as DS–8201 and SYD985, showed encouraging response rates in HER2‐low metastatic breast cancer patients in Phase 1 trials,52, 53 and the efficacy and safety of DS–8201 in unresectable and/or metastatic HER2‐low breast cancer patients have been proven in DESTINY‐Breast04.14