A prospective phase II study of gefitinib in non-small cell cancer patients with epidermal growth factor receptor gene (EGFR) mutations

Abstract

18081 Background: Somatically acquired mutations in the EGFR gene in non-small cell lung cancer are associated with a significant clinical response to gefitinib, a tyrosine kinase inhibitor that targets EGFR, especially in patients with adenocarcinoma, females, and/or never/light smokers. In our retrospective study, cases with EGFR mutations (exon19del or L858R) showed a high sensitivity to gefitinib, and the patients with sensitive EGFR mutations also tended to have a more favorable prognosis than those with wild-type after gefitinib treatment (Uramoto, et al. Lung Cancer 2006;51:71). In the present study, we prospectively assessed the efficacy of gefitinib and the survival benefit for patients with EGFR mutations. Methods: Patients with either recurrent disease after undergoing surgery or advanced disease (IIIB or IV) of NSCLC which demonstrated EGFR mutations were eligible for this study. EGFR mutations in exons 19–21 were examined by our previously described screening method (Sugio, et al. Br J Cancer 2006;94:896) and confirmed by direct sequencing after informed consent was obtained from all patients. The patients with EGFR mutations were enrolled in this study after obtaining informed consent a second time, and they were thereafter treated with gefitinib. Results: Between 2005 and 2006, 16 patients (10 males/6 females, all adenocarcinoma) who had EGFR mutations were enrolled onto this study. Six pts had a deletion in exon 19, 8 pts had a missense mutation in exon 21 (L858R), 1 pt had both an exon 19 del and L858R, and 1 pts had an exon19 del and missense mutation in exon 20 (G796A). The overall response rate was 50%, and the disease control rate was 88%. In patients with exon19 del and L858R, the response rates were 83% and 25%, respectively. A case with a deletion in exon19 and a missense mutation in exon20 (G796A) showed resistance to gefitinib. The median progression-free survival time was 8.8 months, and the median survival time was 15.4 months. No life-threatening toxicity was observed. Conclusions: EGFR mutations in exons 19 or 21 are therefore considered to a good predictor of the efficacy of gefitinib, and the treatment with gefitinib was also found to achieve a prolonged survival. No significant financial relationships to disclose.