Molecular Characteristics Predict Clinical Outcomes: Prospective Trial Correlating Response to the EGFR Tyrosine Kinase Inhibitor Gefitinib with the Presence of Sensitizing Mutations in the Tyrosine Binding Domain of the EGFR Gene

PURPOSE: To determine if tumor regression following treatment with gefitinib correlates with the presence of sensitizing mutations in epidermal growth factor receptor (EGFR). PATIENTS AND METHODS: Patients with resectable stage I and II non-small cell lung cancer (NSCLC) enriched for the likelihood of EGFR mutation (≤ 15 pack-year cigarette smoking history and/or a component of bronchioloalveolar carcinoma) received preoperative gefitinib for 21 days. Tumor specimens were analyzed for EGFR and KRAS mutations and EGFR protein expression and amplification. Patients with 25% or more reduction in tumor size measured bidimensionally at 3 weeks and/or patients with an EGFR mutation received adjuvant gefitinib for 2 years postoperatively. RESULTS: Fifty patients with stage I/II NSCLC were treated. After 21 days of preoperative gefitinib a response of 25% or more was observed in 21 of 50 (42%) patients. Seventeen of 21 patients with a response had an EGFR mutation and 4 of 21 patients with a response did not (P = 0.0001). Twenty-five of 50 patients were eligible to receive adjuvant gefitinib. With a median follow-up of 44.1 months, 2-year disease free survival for EGFR mutant patients and for those who received adjuvant gefitinib was not statistically different than those who were EGFR wild-type and those who did not receive adjuvant gefitinib. The median disease free and overall survivals have not been reached. CONCLUSIONS: The presence of sensitizing EGFR mutations correlates with radiographic response. A short course of preoperative treatment serves a platform for evaluating activity of new agents and assures sufficient tumor availability for correlative analyses.