| Abstract: |
In human lung adenocarcinomas harboring EGFR mutations, a second-site point mutation that substitutes methionine for threonine at position 790 (T790M) is associated with approximately half of cases of acquired resistance to the EGFR kinase inhibitors, gefitinib and erlotinib. To identify other potential mechanisms that contribute to disease progression, we used array-based comparative genomic hybridization (aCGH) to compare genomic profiles of EGFR mutant tumors from untreated patients with those from patients with acquired resistance. Among three loci demonstrating recurrent copy number alterations (CNAs) specific to the acquired resistance set, one contained the MET proto-oncogene. Collectively, analysis of tumor samples from multiple independent patient cohorts revealed that MET was amplified in tumors from 9 of 43 (21%) patients with acquired resistance but in only two tumors from 62 untreated patients (3%) (P = 0.007, Fisher's Exact test). Among 10 resistant tumors from the nine patients with MET amplification, 4 also harbored the EGFRT790M mutation. We also found that an existing EGFR mutant lung adenocarcinoma cell line, NCI-H820, harbors MET amplification in addition to a drug-sensitive EGFR mutation and the T790M change. Growth inhibition studies demonstrate that these cells are resistant to both erlotinib and an irreversible EGFR inhibitor (CL-387,785) but sensitive to a multikinase inhibitor (XL880) with potent activity against MET. Taken together, these data suggest that MET amplification occurs independently of EGFRT790M mutations and that MET may be a clinically relevant therapeutic target for some patients with acquired resistance to gefitinib or erlotinib. © 2007 by The National Academy of Sciences of the USA. |
| Keywords: |
controlled study; human tissue; unclassified drug; gene mutation; human cell; mutation; erlotinib; antineoplastic agents; adenocarcinoma; in situ hybridization, fluorescence; proto oncogene; cohort studies; gene amplification; amino acid substitution; lung neoplasms; epidermal growth factor receptor; gene locus; receptor, epidermal growth factor; drug resistance, neoplasm; cancer resistance; protein kinase inhibitors; gene expression regulation, neoplastic; lung adenocarcinoma; gefitinib; dna mutational analysis; point mutation; quinazolines; comparative genomic hybridization; phosphotransferase inhibitor; epidermal growth factor receptor kinase inhibitor; growth inhibition; proto-oncogene proteins c-met; xl880; cl 387785; xl 880; chromosomes, human, pair 7
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