Five TKIs (erlotinib, gefitinib, afatinib, dacomitinib, and osimertinib) have been approved by the FDA for the treatment of EGFR-mutated NSCLC with exon 19 deletions or an L858R mutation5, with first generation TKIs such as erlotinib previously recommended as optimal first-line treatment6. The gene discussed is EGFR; the disease is non-small cell lung carcinoma.