title: Characterization of EGFR T790M, L792F, and C797S Mutations as Mechanisms of Acquired Resistance to Afatinib in Lung Cancer.
abstract: Lung cancers harboring common EGFR mutations respond to EGFR tyrosine kinase inhibitors (TKI). We previously reported that tumors with exon 18 mutations are particularly sensitive to irreversible second-generation (2G) afatinib compared with first-generation TKIs (1G-TKI). However, data on the mechanisms of acquired resistance to afatinib are limited. We established afatinib-resistant cells by transfecting Ba/F3 cells with common or exon 18 (G719A and Del18) mutations and subjecting them to chronic exposure to increasing concentrations of afatinib. Afatinib-resistant clones were separately established through N-ethyl-N-nitrosourea (ENU) mutagenesis and exposure to fixed concentrations of afatinib. Rebiopsy samples from patients whose tumors acquired resistance to afatinib were analyzed. Afatinib-resistant cells with Del19, L858R, or G719A developed T790M, whereas those with Del18 acquired novel L792F mutation. ENU mutagenesis screening established 84 afatinib-resistant clones. All Del19 clones and most of the other clones acquired only T790M. However, C797S occurred in subsets of L858R, G719A, and Del18 clones. In addition, subsets of Del18 clones acquired L792F. C797S-acquired cells were sensitive to 1G erlotinib. L792F demonstrated intermediate resistance between T790M and C797S to both 1G- and 3G-TKIs, whereas L792F was the least resistant to 2G-TKIs, particularly dacomitinib. Chronic exposure of Del18 + L792F cells to dacomitinib induced additional T790M. T790M was detected in one of four clinical samples. In conclusion, L792F and C797S, in addition to the major T790M, can develop in afatinib-resistant cells particularly using a low dose of afatinib, and these minor mutations appear to exhibit sensitivity to dacomitinib and erlotinib, respectively. These secondary mutations should be tested in clinical practice. Mol Cancer Ther; 16(2); 357-64. ©2016 AACRSee related article by Talbert et al., p. 344.
authors.affiliation: Department of Thoracic Surgery, Kindai University Faculty of Medicine, Osaka-Sayama, Japan.
authors.forename: Yoshihisa
authors.initials: Y
authors.lastname: Kobayashi
authors.affiliation: Division of Respirology, Neurology, and Rheumatology, Department of Internal Medicine, Kurume University School of Medicine, Kurume, Fukuoka, Japan.
authors.forename: Koichi
authors.initials: K
authors.lastname: Azuma
authors.affiliation: Department of Respiratory Medicine, Graduate School of Medicine, Kyoto University, Kyoto, Japan.
authors.forename: Hiroki
authors.initials: H
authors.lastname: Nagai
authors.affiliation: Department of Respiratory Medicine, Graduate School of Medicine, Kyoto University, Kyoto, Japan.
authors.forename: Young Hak
authors.initials: YH
authors.lastname: Kim
authors.affiliation: Division of Cancer Immunology, EPOC, National Cancer Center, Kashiwa, Japan.|Department of Genome Biology, Kindai University Faculty of Medicine, Osaka-Sayama, Japan.
authors.forename: Yosuke
authors.initials: Y
authors.lastname: Togashi
authors.affiliation: Department of Thoracic Surgery, Kindai University Faculty of Medicine, Osaka-Sayama, Japan.
authors.forename: Yuichi
authors.initials: Y
authors.lastname: Sesumi
authors.affiliation: Department of Thoracic Surgery, Kindai University Faculty of Medicine, Osaka-Sayama, Japan.
authors.forename: Masato
authors.initials: M
authors.lastname: Chiba
authors.affiliation: Department of Thoracic Surgery, Kindai University Faculty of Medicine, Osaka-Sayama, Japan.
authors.forename: Masaki
authors.initials: M
authors.lastname: Shimoji
authors.affiliation: Department of Thoracic Surgery, Kindai University Faculty of Medicine, Osaka-Sayama, Japan.
authors.forename: Katsuaki
authors.initials: K
authors.lastname: Sato
authors.affiliation: Department of Thoracic Surgery, Kindai University Faculty of Medicine, Osaka-Sayama, Japan.
authors.forename: Kenji
authors.initials: K
authors.lastname: Tomizawa
authors.affiliation: Department of Thoracic Surgery, Kindai University Faculty of Medicine, Osaka-Sayama, Japan.
authors.forename: Toshiki
authors.initials: T
authors.lastname: Takemoto
authors.affiliation: Department of Genome Biology, Kindai University Faculty of Medicine, Osaka-Sayama, Japan.
authors.forename: Kazuto
authors.initials: K
authors.lastname: Nishio
authors.affiliation: Department of Thoracic Surgery, Kindai University Faculty of Medicine, Osaka-Sayama, Japan. mitsudom@surg.med.kindai.ac.jp.
authors.forename: Tetsuya
authors.initials: T
authors.lastname: Mitsudomi
mesh_terms: D000077716:Afatinib; D000483:Alleles; D019943:Amino Acid Substitution; D000818:Animals; D000970:Antineoplastic Agents / Q000737:chemistry / Q000494:pharmacology*; D001665:Binding Sites; D045744:Cell Line, Tumor; D003062:Codon; D019008:Drug Resistance, Neoplasm / Q000235:genetics*; D066246:ErbB Receptors / Q000737:chemistry / Q000235:genetics*; D006801:Humans; D008175:Lung Neoplasms / Q000188:drug therapy / Q000235:genetics*; D051379:Mice; D008958:Models, Molecular; D008968:Molecular Conformation; D016296:Mutagenesis; D009154:Mutation; D011485:Protein Binding; D047428:Protein Kinase Inhibitors / Q000737:chemistry / Q000494:pharmacology; D011799:Quinazolines / Q000737:chemistry / Q000494:pharmacology*; D052999:Quinazolinones / Q000494:pharmacology; D013329:Structure-Activity Relationship
chemical_list: D000970:Antineoplastic Agents; D003062:Codon; D047428:Protein Kinase Inhibitors; D011799:Quinazolines; D052999:Quinazolinones; D000077716:Afatinib; C525726:dacomitinib; D066246:ErbB Receptors