P2-14-5 - Comparison of the Efficacy of Gefitinib in Patients with Nsclc According to the Type of Egfr Mutation

Abstract

Background: Exon 19 deletion of the epidermal growth factor receptor (EGFR) and point mutation of exon 21 (L858R point mutation) are the most commonly encountered EGFR mutations in non-small cell lung cancer (NSCLC), and predict higher response rates and longer progression-free survival (PFS) following treatment with EGFR tyrosine kinase inhibitors (EGFR-TKIs). The objective of this study was to evaluate the differential clinical outcomes of gefitinib in patients with NSCLC according to the type of active EGFR mutation: exon 19 deletion or L858R point mutation.Methods: We identified patients with advanced NSCLC harboring exon 19 deletion or L858R point mutation of EGFR and were receiving gefitinib therapy. The clinical outcomes of gefitinib therapy, including the response rate, PFS and OS were evaluated in the patients with the two EGFR genotypes. Evaluation of the EGFR genotypes was performed in histologic or cytologic specimens by means of the PNA-LNA PCR clamp method.Results: Of the 124 patients with NSCLC harboring active EGFR mutations, the overall response rate, PFS and OS were 60.5%, 11.3 and 27.3 months, respectively. The response rate, PFS and OS did not differ significantly among the patients with exon 19 deletion (55%, 11.3 and 27.7 months, respectively) and those with L858R point mutation (45%, 9.0 and 32.2 months, respectively).Conclusion: It may be considered that there is no difference in the clinical efficacy of gefitinib between patients with NSCLC harboring the two types of mutations, namely, exon 19 deletion and L858R point mutation.