Gefitinib: Gefitinib (Iressa) is another oral EGFR TKI that was "re-approved" by the FDA for first-line treatment of NSCLC with EGFR mutations in exon 19 deletions or exon 21 L858R substitution gene mutations (FDA, 2015b). This evidence concerns the gene EGFR and non-small cell lung carcinoma.