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MO21 - Prognostic and Predictive Biomarkers V - EGFR (ID 98)
- Event: WCLC 2013
- Type: Mini Oral Abstract Session
- Track: Medical Oncology
- Presentations: 1
MO21.05 - Integrated genomic analysis by whole exome and transcriptome sequencing of tumor samples from EGFR-mutant non-small-cell lung cancer (NSCLC) patients with acquired resistance to erlotinib. (ID 1426)
10:30 - 12:00 | Author(s): R. Stahel
NSCLC patients with EGFR mutations initially respond to EGFR tyrosine kinase inhibitors (TKIs) but ultimately relapse. Sub-genomic molecular studies indicate that the EGFR T790M mutation and the activation of MET, PI3K, AXL, HER2 and MAPK can lead to acquired resistance to EGFR TKIs. To date, no integrated comprehensive genomic investigation of EGFR TKI resistance has been reported.
FFPE biopsies of erlotinib-sensitive and erlotinib-resistant tumors were obtained from 13 EGFR mutant NSCLC patients. The samples were analyzed by whole exome sequencing and whole transcriptome sequencing utilizing the Illumina HiSeq2500 platform. In addition, targeted gene sequencing was performed with the Illumina TruSeq Amplicon-Cancer Panel and run on the MiSeq system.
Erlotinib resistant NSCLC specimens harbored known resistance drivers, including EGFR T790M mutations (9/13; 69%), MET amplification (3/13; 23%), HER2 amplification (3/13; 23%), and AXL upregulation (3/13; 23%). Differential expression analysis between resistant and pre-treatment states revealed enrichment in the pre-treatment tumors of immune signaling pathways, and in the resistant tumors upregulation of ERBB2, mTOR, PI3 kinase and ribosomal signaling pathways. PI3K/AKT pathway upregulation also occurred through somatic mutations in AKT and LKB1 in the resistant tumors. Copy number analysis demonstrated both large scale and focal amplifications and deletions in the resistant tumors, including the focal loss of EGFR and gain of c-Myc and NKX2-1. There was strong correlation between the copy number changes observed and the expression mRNA levels of the involved cancer-associated genes. Of note, each resistant tumor exhibited greater copy number similarity to the corresponding matched pre-treatment sample compared to other tumors within the resistance cohort.
We conducted the first ever comprehensive integrated genomic analysis of EGFR TKI resistant NSCLC patients, and identified both known and potentially novel drivers of EGFR TKI resistance. This study demonstrated the feasibility and utility of comprehensive genomic analysis in the clinical management of NSCLC receiving targeted therapy. Together, our data provide unprecedented insight into the molecular pathogenesis of escape from EGFR oncogene inhibition in NSCLC. We are now conducting a prospective observational study in additional NSCLC patients on targeted therapy.
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