ERBB2 and breast carcinoma: Clinical studies with other ERBB2-targeting drugs, either antibodies (e.g. pertuzumab, T-DM1) or tyrosine kinase inhibitors (e.g. lapatinib, neratinib...), later demonstrated that metastatic ERBB2-amplified breast cancer cells display an “oncogenic addiction” and that anti-ERBB2 therapy should be pursued despite disease progression.