Global pharmaceutical giant AstraZeneca announced that IRESSA received approval from the U.S. FDA for the first-line treatment of patients with metastatic non-small cell lung cancer (NSCLC) whose tumors harbor epidermal growth factor receptor (EGFR) exon 19 deletions or exon 21 (L858R) mutations, as detected by an FDA-approved test, therascreen EGFR RGQ PCR kit manufactured by Qiagen. Lung cancer is the leading cause of cancer-related death among both men and women. IRESSA is an oral, EGFR tyrosine kinase inhibitor (TKI). In 2014, the FDA granted IRESSA Orphan Drug Designation for the treatment of EGFR mutation-positive NSCLC. This approval was based on efficacy and safety data from a multi-center clinical trial in patients with previously untreated EGFR mutation-positive metastatic NSCLC and a retrospective analysis of another clinical trial, which identified a subgroup of patients with EGFR mutation-positive metastatic NSCLC. IRESSA was first approved by the FDA in 2003 for the treatment of patients with locally advanced or metastatic NSCLC after failure of both platinum-based and docetaxel chemotherapies. This current approval is for a different patient population (EGFR mutation-positive, previously untreated) than the 2003 approval and is another anti-cancer drug whose indication is guided by a companion diagnostic test.