EGFR and lung cancer: In a landmark placebo-controlled study, Iressa Survival Evaluation in Lung Cancer (ISEL), of advanced non-small cell lung cancer (NSCLC) refractory to previous chemotherapy, the EGFR-tyrosine kinase inhibitor (TKI) showed an efficacy in a subset of the study population, suggesting the need for biomarkers to predict therapeutic responses [4].