In July 2015, 10 years after the initial pivotal trial results were published, gefitinib was approved by the FDA for front line treatment of NSCLC positive for EGFR exon 19 deletion or L858R mutation in exon 21 [28], contemporaneous with the companion diagnostic assay kit that was used in its pivotal registration (Table 1, Food and Drug Administration PMA #P120022). Here, EGFR is linked to non-small cell lung carcinoma.