Based on data establishing that EGFR TKIs confer the most benefit when used in molecularly selected patients, erlotinib was granted an additional indication by the FDA in May 2013 for first-line treatment of patients with metastatic NSCLC whose tumors have EGFR exon 19 deletions or exon 21 (L858R) mutations as detected by an FDA-approved test 4. Here, EGFR is linked to non-small cell lung carcinoma.