title: Double mutation and gene copy number of EGFR in gefitinib refractory non-small-cell lung cancer.
abstract: Mutations of the epidermal growth factor receptor (EGFR) gene have been reported in non-small-cell lung cancer (NSCLC), especially in patients with adenocarcinoma and never smokers. Some common somatic mutations in EGFR, including deletion mutations in exon 19 and leucine-to-arginine substitution at amino acid position 858 (L858R) in exon 21, have been examined for their ability to predict sensitivity to gefitinib or erlotinib, which are selective EGFR tyrosine kinase inhibitors (EGFR-TKIs). On the other hand, reports have shown that the threonine-to-methionine substitution at amino acid position 790 (T790M) in exon 20 is related to gefitinib resistance. Some studies have indicated that high copy numbers of the EGFR gene may be a more effective molecular predictor to responsiveness and prolonged survival in patients treated with EGFR-TKIs. Here, we describe two NSCLC patients with the L858R mutation who did not respond to gefitinib. Case 1 harbored both the T790M and L858R mutations, and fluorescence in situ hybridization showed EGFR gene amplification. Case 2 harbored both the L858R and aspartic acid-to-tyrosine substitution at amino acid position 761 in exon 19 of EGFR mutations and had a high polysomy status for EGFR. In these two cases, tumors showed resistance to gefitinib treatment despite the presence of EGFR L858R mutation and increased copy number. Our findings encourage further molecular analysis to elucidate the relationship between the EGFR status, including mutations and amplifications, and the responsiveness of NSCLC to gefitinib.
authors.affiliation: Department of Cancer and Thoracic Surgery, Graduate School of Medicine and Dentistry, Okayama University, 2-5-1 Shikata-cho, Okayama 700-8558, Japan.
authors.forename: Masaki
authors.initials: M
authors.lastname: Tokumo
authors.forename: Shinichi
authors.initials: S
authors.lastname: Toyooka
authors.forename: Shuji
authors.initials: S
authors.lastname: Ichihara
authors.forename: Kadoaki
authors.initials: K
authors.lastname: Ohashi
authors.forename: Kazunori
authors.initials: K
authors.lastname: Tsukuda
authors.forename: Kouichi
authors.initials: K
authors.lastname: Ichimura
authors.forename: Masahiro
authors.initials: M
authors.lastname: Tabata
authors.forename: Katsuyuki
authors.initials: K
authors.lastname: Kiura
authors.forename: Motoi
authors.initials: M
authors.lastname: Aoe
authors.forename: Yoshifumi
authors.initials: Y
authors.lastname: Sano
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Date
authors.forename: Nobuyoshi
authors.initials: N
authors.lastname: Shimizu
mesh_terms: D000368:Aged; D000970:Antineoplastic Agents / Q000627:therapeutic use*; D002289:Carcinoma, Non-Small-Cell Lung / Q000188:drug therapy* / Q000235:genetics; D004252:DNA Mutational Analysis / Q000379:methods; D066246:ErbB Receptors / Q000037:antagonists & inhibitors / Q000235:genetics*; D005091:Exons; D005260:Female; D000077156:Gefitinib; D018628:Gene Dosage; D005838:Genotype; D006801:Humans; D017404:In Situ Hybridization, Fluorescence; D008175:Lung Neoplasms / Q000188:drug therapy* / Q000235:genetics; D009154:Mutation / Q000235:genetics*; D011799:Quinazolines / Q000627:therapeutic use*
chemical_list: D000970:Antineoplastic Agents; D011799:Quinazolines; D066246:ErbB Receptors; D000077156:Gefitinib