ERBB2 and breast cancer: Strikingly, approximate two-thirds of breast cancer patients were tolerant and developed resistance during the treatment.18–20 The unresponsiveness is attributed, at least in part, to the divergent forms of ERBB2 including mutations21 and abnormal dimerization.22,23 To date, antibody-drug conjugates (ADCs) targeting ERBB2 have made great progression and demonstrated promising therapeutic potential in various cancers.24–26 This has once again solidified ERBB2 as a highly attractive target for cancer therapy.