On November 18, 2004, erlotinib (Tarceva); OSI Pharmaceuticals, Inc., Melville, NY, http://www.osip.com, and Genentech, Inc., South San Francisco, CA, http://www.gene.com) received regular approval as monotherapy for the treatment of patients with locally advanced or metastatic non-small cell lung cancer (NSCLC) after failure of at least one prior chemotherapy regimen. Survival of erlotinib-treated patients was superior to that of placebo-treated patients. The median survival duration of erlotinib-treated patients was 6.67 months, compared with 4.70 months for placebo-treated patients. Exploratory univariate analyses showed a larger survival prolongation in two subsets of patients: those who never smoked and those with epidermal growth factor receptor (EGFR)-positive tumors. Patients who never smoked and were EGFR-positive had a large erlotinib survival benefit. Erlotinib was also superior to placebo for progression-free survival and a response rate of 8.9% versus 0.9%. Skin rash and diarrhea were the most common erlotinib adverse events. Severe rash occurred in 8%, and severe diarrhea occurred in 6% of erlotinib-treated patients. In the first-line treatment of NSCLC, two large, controlled, randomized trials showed no benefit from adding erlotinib to doublet, platinum-based chemotherapy. Therefore, erlotinib is not indicated for use in this setting.