A phase II study of gefitinib as a first-line therapy for advanced non-small cell lung cancers with epidermal growth factor receptor (EGFR) gene mutations

13014 Background: Activating mutations in exon 18–21 of the epidermal growth factor receptor (EGFR) gene have been reported to be a predictor of response to gefitinib. We conducted a phase II study to evaluate the efficacy and safety of gefitinib as a first-line therapy for advanced non-small cell lung cancers (NSCLCs) with EGFR gene mutations. Methods: The primary endpoint was response rate (RR). Eligiblity criteria were stage IIIB or IV chemotherapy naive NSCLC, ECOG PS of 0–2, adequate organ functions, measurable lesions, and written informed consent. First, we examined EGFR gene mutations in exon 18–21 by direct sequencing of PCR products of DNA extracted from paraffin-embedded tissues. Those who had EGFR gene mutations received gefitinib 250 mg daily. This study, with a sample size of 14, had 90% power to support the hypothesis that true RR was ≥70%, and 5% significance to deny the hypothesis that true RR was ≤30%. Assuming an inevaluality rate ≤15%, we projected an accrual of 16 patients. Results: From Nov. 2004 to Jan. 2006, EGFR gene mutations were analyzed in tumor specimens from 82 patients. Twenty patients (24%) had EGFR gene mutations (16 with deletions in or near E746-A750, 4 with L858R). While there were no significant differences between mutation status and age, sex, histology, or the procedures to obtain tumor specimens, EGFR gene mutations were more frequently observed in never-smokers than in smokers (39% vs. 11%, p<0.01). Sixteen patients (median age, 68; male/female, 3/13; adenocarcinoma/SCC, 15/1; current/former/never smoker, 2/1/13) were enrolled and treated with gefitinib. To date, best response is 2 CR, 7 PR, 1 SD and 1 PD (RR, 82%). Two patients had grade 3 toxicities, including 1 skin eruption and 1 liver dysfunction. One patient had grade 1 interstitial lung disease, leading to the termination of gefitinib treatment. Conclusions: Gefitinib is very active and well tolerated as a first-line therapy for advanced NSCLCs with EGFR gene mutations. No significant financial relationships to disclose.