Abstract B43: SNP Q787Q of EGFR gene and efficacy of EGFR-TKI in patients with non-small cell lung cancer

Abstract

Abstract Background: Many activating mutations in epidermal growth factor receptor (EGFR) gene have been correlated with sensitivity to EGFR tyrosine kinase inhibitors (TKIs). Single nucleotide polymorphism (SNP) in exon 20 of EGFR gene (2361G>A transition) does not alter the amino acids of glutamine at codon 787 (Q787Q). We reviewed the relationship between this SNP and EGFR-TKI sensitivity. Patients and Methods: Twenty-five patients (male 19, female 6) with only SNP Q787Q in EGFR exon 20 were analyzed. Tissue or cytologic specimens were used for analysis of mutations in exon 18 to 21 of EGFR gene by direct sequencing. Treatments with EGFR-TKIs were performed in 16 patients and response evaluations were eligible in 15 cases. Results: In 15 response evaluable patients, there were 2 partial responses (PR) and 5 stable diseases (SD) [response rate: 13.3%, disease control rate: 46.7%]. Median time to progression (TTP) was 392 days (range: 105∼511). Five patients showed longer than 3 months of TTP (PR 2 and SD 3, adenocarcinoma 4 and squamous cell carcinoma 1, gefitinib 4 and erlotinib 1). Conclusion: Thirteen percent of NSCLC with 2361G>A transition without other activating mutations responded to EGFR-TKIs.