Research on gefitinib-sensitive non-small cell lung cancers has shown that a mutation in the EGFR tyrosine kinase domain is responsible for activating anti-apoptotic pathways.

[3] It was approved as monotherapy for the treatment of people with locally advanced or metastatic NSCLC after failure of both platinum-based and docetaxel chemotherapies.

This label was granted after gefitinib demonstrated as a first-line treatment to significantly improve progression-free survival vs. a platinum doublet regime in patients harbouring such mutations.

However, applications to expand its label as a first-line treatment in patients harbouring EGFR mutations is currently in process based on the latest scientific evidence.

[14][15] As at August 2012 New Zealand has approved gefitinib as first-line treatment for patients with EGFR mutation for naive locally advanced or metastatic, unresectable NSCLC.

[17] In August 2013, the BBC reported that researchers in Edinburgh and Melbourne found, in a small-scale trial of 12 patients, that the effectiveness of Methotrexate for treating ectopic pregnancy was improved when Gefitinib was also administered.

A pre-planned sub-group analyses showed that progression-free survival (PFS) was significantly longer for gefitinib than chemotherapy in patients with EGFR mutation positive tumours (HR 0.48, 95 per cent CI 0.36 to 0.64, p less than 0.0001), and significantly longer for chemotherapy than gefitinib in patients with EGFR mutation negative tumours (HR 2.85, 95 per cent CI 2.05 to 3.98, p less than 0.0001).

Roche Diagnostics, Genzyme, QIAGEN, Argenomics S.A. & other companies make tests to detect EGFR mutations, designed to help predict which lung cancer patients may respond best to some therapies, including gefitinib and erlotinib.

Other common adverse effects (≥1% of patients) include: diarrhoea, nausea, vomiting, anorexia, stomatitis, dehydration, skin reactions, paronychia, asymptomatic elevations of liver enzymes, asthenia, conjunctivitis, blepharitis.

[20] Infrequent adverse effects (0.1–1% of patients) include: interstitial lung disease, corneal erosion, aberrant eyelash and hair growth.

[24] Even if the mutated versions of EGFR have a higher affinity for ATP, they will eventually use the irreversible inhibitors as ligands, which effectively shuts down their activity.