Later, the trastuzumab monoclonal antibody (mAb) and gefitinib tyrosine kinase inhibitor (TKI), were as well approved for the treatment of epidermal growth factor receptor 2 (HER2)-positive breast cancers and certain types of epidermal growth factor receptor (EGFR) mutated-expressing non-small-cell lung cancers (NSCLC), respectively. This evidence concerns the gene ERBB2 and breast cancer.