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X. Chen



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    O01 - Prognostic and Predictive Biomarkers I (ID 94)

    • Event: WCLC 2013
    • Type: Oral Abstract Session
    • Track: Medical Oncology
    • Presentations: 1
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      O01.05 - EGFR wild-type NSCLC patients with high miR-200c expression can benefit from EGFR-TKI (ID 691)

      11:15 - 11:25  |  Author(s): X. Chen

      • Abstract
      • Presentation
      • Slides

      Background
      EGFR mutation is a strong positive predictive factor of EGFR-TKIs therapy. However, at least 10% of patients with wild-type EGFR are responsive to TKIs, suggesting that other determinants of outcome besides mutant EGFR might exist. miR-200c is an important regulator of epithelial-to-mesenchymal transition and might be associated with drug-resistance. Our objective was to characterize miR-200c expression in NSCLC and its role in TKI sensitivity in EGFR wild-type NSCLC.

      Methods
      miR-200c levels in 7 NSCLC cell lines were measured by real-time quantitative reverse transcription-PCR (qRT-PCR). Direct target of miR-200c was identified through the TargetScan database and was validated through qRT-PCR and Western blot analysis. The precursor of miR-200c was up-expressed in H1975 and A549 cells using a lentivirus construct, and miRNA inhibitor was used to down-regulate the expression of miR-200c in PC9 cell line. Effects of miR-200c on cell proliferation and sensitivity to EGFR-TKIs were evaluated by MTT assay in vitro. The expression of proteins correlating with signaling pathway was determined by western blot analysis. 141 FFPE samples of advanced NSCLC patients were enrolled in this study, and miR-200c expression and EGFR mutations were detected by qRT-PCR and amplification refractory mutation system (ARMS), respectively.

      Results
      We identified a tight association between the expression of miR-200c, epithelial phenotype, and sensitivity to TKIs in NSCLC cell lines. Up-expression of miR-200c in A549 and H1975 cells up-regulated E-cadherin levels, down-regulated expression of ZEB1, vimentin, pERK and pAKT. Up-regulated miR-200c increased sensitivity to gefitinib in the primary resistant cell line A549. Analysis of 141 NSCLC specimens indicated that median PFS of EGFR wild-type (n=57) and EGFR mutant NSCLC patients (n=73) treated with second/third line targeted therapy was 1.8m vs. 12.0m respectively (P<0.0001). Patients with high expression level of miR-200c had a positive association towards a longer PFS in NSCLC harboring EGFR wild-type when considering 2[-ΔCt]=0.01128 (median level) as cut-off value (3.95m vs. 1.60m, P=0.015). The objective response rate (ORR) was 7% in the EGFR wild-type cohort, and patients with high miR-200c expression level had better ORR than those with low level (12.5% and 3.0%, P=0.3). In Cox regression analysis, miR-200c expression also present the same trend for benefit from EGFR-TKIs in EGFR-negative NSCLC (HR= 0.375, 95%CI: 0.198-0.712, P= 0.003).

      Conclusion
      miR-200c appears to act as a critical role in EGFR-TKIs sensitivity in NSCLC patients with wild-type EGFR. Up-expression of miR-200c can trigger MET and suppress PI3K/AKT, MEK/ERK pathway, which can also partially overcome EGFR-TKIs resistance. miR-200c might be a predictive biomarker of clinical response to EGFR-TKIs and assist in selecting the subpopulation in patients with wild-type EGFR to benefit from targeted therapy.

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