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G.W. Wellde Jr.



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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
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      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)

      10:50 - 10:55  |  Author(s): G.W. Wellde Jr.

      • Abstract
      • Presentation
      • Slides

      Background
      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.

      Methods
      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.

      Results
      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.

      Conclusion
      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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    P3.06 - Poster Session 3 - Prognostic and Predictive Biomarkers (ID 178)

    • Event: WCLC 2013
    • Type: Poster Session
    • Track: Biology
    • Presentations: 1
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      P3.06-006 - Integrated genomic analysis of EGFR-mutant non-small cell lung cancer immediately following erlotinib initiation in patients (ID 1003)

      09:30 - 09:30  |  Author(s): G.W. Wellde Jr.

      • Abstract

      Background
      Major obstacles limiting the clinical success of EGFR TKI therapy in EGFR mutant non-small cell lung cancer (NSCLC) patients are heterogeneity and variability in the initial anti-tumor response to treatment. The underlying molecular basis for this heterogeneity has not been explored in patients immediately after initiation of therapy.

      Methods
      We conducted CT-guided core needle biopsies immediately prior to erlotinib treatment initiation and at 6 days and 60 days post erlotinib initiation in a patient with histologically confirmed NSCLC harboring an established activating mutation in EGFR. DNA and RNA from each of the frozen biopsies were analyzed by whole exome sequencing and whole transcriptome sequencing, respectively. High-resolution CT images were also obtained at the time of each biopsy to assess the degree of molecular and radiographic responses observed.

      Results
      Two established activating somatic mutations were identified in EGFR (p.G719A and p. R776H). Gene expression analysis revealed that several proapoptotic genes including BID, CASP3 and several growth inhibitory genes including GADD45B, GADD45G were upregulated at 6 days post erlotinib treatment, while at 60 days their expression levels decreased to below pretreatment levels. Other proapoptotic genes such as BAD and BAX and were noted to be upregulated most significantly 60 days, as was growth inhibitory gene CDKN1A. In contrast, the growth-promoting genes CCNB1 and CCND3 exhibited a progressive decrease in expression across time points. Whole exome sequencing demonstrated the progressive evolution of global copy number abnormalities. High-resolution CT scans revealed no interval radiographic change in tumor size after 6 days of erlotinib treatment, and a decrease in tumor size 60 days into therapy. No clinical complications were encountered.

      Conclusion
      This study is the first reported longitudinal integrated genomic analysis of EGFR-mutant NSCLC in a patient treated with an EGFR TKI. We documented the feasibility, safety and utility of this strategy to establish initial drug efficacy at the molecular level prior to any radiographic evidence of response (6 days), as well as evidence that acquired resistance can emerge early in the course of TKI therapy. Serial integrated genomic analysis is ongoing in other TKI treated patients to enhance the management of NSCLC patients on targeted therapy.