Gefitinib, marketed as Iressa, received FDA approval as a first-line treatment for metastatic non–small cell lung cancer with specific epidermal growth factor receptor (EGFR) gene mutations, as detected by an approved companion diagnostic test.
Iressa is a kinase inhibitor that blocks proteins that promote the development of cancerous cells with certain EGFR mutations. It is intended to treat patients with tumors that express exon 19 deletions or exon 21 L858R substitution mutations in the EGFR oncogene. The Therascreen EGFR RGQ PCR Kit helps physicians determine which patients may benefit from Iressa treatment by detecting EGRF gene mutations, which are present in about 10% of non–small cell lung cancers.
Voelker R. Lung Cancer Drug and Companion Diagnostic Test Are Approved. JAMA. 2015;314(7):662. doi:10.1001/jama.2015.9768