Afatinib is an oral epidermal growth factor receptor tyrosine kinase inhibitor targeting the ERBB family (including EGFR, HER2, ERBB3, and ERBB4), and has been approved for the treatment of locally advanced or metastatic non-small-cell lung cancer (NSCLC) with an EGFR-sensitive mutation [22]. The gene discussed is ERBB3; the disease is non-small cell lung carcinoma.