The mutation status of the epidermal growth factor receptor (EGFR) as a selection criterion for therapy with EGFR tyrosine kinase inhibitors (TKI's) in non-small cell lung cancer (NSCLC)

10073 Background: Somatic mutations in the EGFR gene have been shown to be closely associated with a favorable response to small-molecule TKI’s, while K-ras mutations seem to be associated with primary resistance. We present an exploratory study confirming the importance of mutation status for response on anti EGFR therapy. Methods: Mutations in the EGFR TK domain were looked for in tumor material extracted from two series of patients with advanced NSCLC. In the first series, mutations were determined in patients with an objective response or clearly progressive under gefitinib therapy. In the second series, EGFR mutations were determined prospectively in an enriched population (two of three characteristics: female gender, non-smoking status, bronchoalveolar -or adenocarcinoma pathology). The presence of a mutation was the criterion for treatment with TKI’s. Response assessment was done according to RECIST. K-Ras mutations were determined retrospectively. Results: In the retrospective series, 15 biopsies ...