Erlotinib: an EGF receptor tyrosine kinase inhibitor in non-small-cell lung cancer treatment

Approximately 213,380 new cases of non-small-cell lung cancer (NSCLC) were estimated to occur in the USA in 2007, which caused 160,390 NSCLC-related deaths. The majority of patients will be diagnosed with nonoperable, advanced-stage disease. Although combination chemotherapy remains the standard treatment, median survival with these regimens is only 8-10 months. Recent advances in our understanding of lung cancer on a molecular level have led to the introduction of targeted therapies. The EGF receptor (EGFR) was the first receptor to be proposed for cancer therapy and two EGFR-targeted pharmacologic approaches have been successfully developed: monoclonal antibodies (mAbs) and small-molecule inhibitors of the EGFR tyrosine kinase enzymatic activity. Erlotinib is a quinazoline derivative that selectively and reversibly inhibits the tyrosine kinase activity of the EGFR. Here, we review the mechanism(s) of action of erlotinib, as well as the results of Phase I, II and III trials with this drug in NSCLC, which have led to the worldwide approval of erlotinib treatment as monotherapy for therapy-refractory, advanced NSCLC patients.