Gefitinib (GEF) is recognized for its crucial role in the therapy of non-small-cell lung cancer (NSCLC), and in 2015, it was accepted by the Food and Drug Administration (FDA) as the first-line therapy against tumors bearing the EGFR mutation and NSCLC [7, 20]. The gene discussed is EGFR; the disease is non-small cell lung carcinoma.