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Z. Chen



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    JCHS - Joint IASLC - Chinese Society for Clinical Oncology - Chinese Alliance Against Lung Cancer Session (ID 239)

    • Event: WCLC 2015
    • Type: Joint Chinese/ English Session
    • Track: Other
    • Presentations: 1
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      JCHS.08 - Role of T790M Mutation in EGFR-TKI Rechallenge for Patients with EGFR-Mutant Advanced Non-Small Cell Lung Cancer (ID 3525)

      Z. Chen

      • Abstract
      • Presentation
      • Slides

      Background:
      Epidermal growth factor receptor (EGFR) exon 20 T790M mutation may have a predictive role before EGFR-tyrosine kinase inhibitors (TKIs) treatment and it also might have a prognostic role after acquired resistance to EGFR-TKIs. However, its role in EGFR-TKI rechallenge after failure of initial EGFR-TKIs in EGFR-mutant advanced non-small cell lung cancer (NSCLC) remains unknown.

      Methods:
      We retrospectively evaluated the clinical course of 515 EGFR-mutant advanced NSCLC patients who received first generation EGFR-TKIs (gefitinib or erlotinib) from December 2009 to November 2014 at Guangdong General Hospital. Of these 515 patients, 65 patients recieved same EGFR-TKI rechallenge, including 51 patients who underwent rebiopsy and secondary EGFR mutation detection after failure of initial EGFR-TKIs. EGFR detection was performed by Sanger sequencing or Amplification Refractory Mutation System (ARMS) methods. Progression-free survival (PFS) and overall survival (OS) were both calculated from commencement of EGFR-TKI rechallenge. Survival data were analyzed using the Kaplan-Meier method and log-rank test.

      Results:
      EGFR activating mutations still existed in all the 51 patients who received rebiopsy and 18 patients were with T790M mutation while 33 patients were without T790M. The median PFS for the T790M+ and T790M- groups were 1.8 months (95%CI 1.180~2.420) and 2.0 months (95%CI 1.100~2.900), respectively (P=0.261). The median OS for the two groups were 7.7 months (95%CI 6.548~8.852) and 6.8 months (95%CI 4.730~8.870), respectively (P=0.565). No statistical difference was found in PFS or OS between two groups(Figure 1). Fig 1. Kaplan-Meier curves of patients in two groups. (A)Progression-free survival. (B) Overall survival.

      Conclusion:
      EGFR T790M mutation is neither a predictive nor a prognostic factor for first generation EGFR-TKI rechallenge in EGFR-mutant advanced NSCLC patients, indicating that whether T790M occurs or not, same EGFR-TKI rechallenge could not be recommended as a good strategy to overcome the resistance to first generation EGFR-TKIs.

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    P3.04 - Poster Session/ Biology, Pathology, and Molecular Testing (ID 235)

    • Event: WCLC 2015
    • Type: Poster
    • Track: Biology, Pathology, and Molecular Testing
    • Presentations: 1
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      P3.04-036 - Rare Discrepancies in a Driving Gene Alteration within Histologically Heterogeneous Primary Lung Cancers (ID 2229)

      Z. Chen

      • Abstract
      • Slides

      Background:
      Most lung adenocarcinomas consist of a mixture of histological subtypes among which driving gene mutations occurred with different frequencies. However, little is known about intratumoral heterogeneity within histologically heterogeneous primary lung cancers. Investigating key driver genes in respective morphological pattern is crucial to clinical practice and personalized treatment.

      Methods:
      Morphologically different tumor areas within the same surgically resected primary tumors were extracted from tissue sections and the gene status in each growth pattern was analyzed. Driving genes, epidermal growth factor receptor (EGFR), KRAS, and rearrangements in echinoderm microtubule-associated protein-like 4-anaplastic lymphoma kinase (EML4-ALK), were assessed by assays of different sensitivity.

      Results:
      Seventy-nine consecutive, surgically resected, adenocarcinomas or adeno-squamouse cell carcinomas harboring a driving gene mutation or rearrangement (EGFR, n = 65; KARS, n = 10; EML4-ALK, n = 4) were selected. For EGFR mutations in adenocarcinomas, ITH occurred in 13.3% (8/60) as determined by direct sequencing, but in only 1.7% (1/60) by ARMS(P= 0.016). A consistent intratumoral EGFR mutation status was found within 5 histologically heterogeneous adeno-squamous cell carcinomas, as shown with ARMS. ITH among KRAS mutations were detected in 20% (2/10) of regions examined by direct sequencing ,whereas a consistent status (10/10) was obtained with HRM. There were no discrepancies in EML4-ALK rearrangements according to FISH for four tumors.

      Conclusion:
      Rare ITHs deriving from EGFR/KRAS/EML4-ALK alterations within histologically heterogeneous primary lung adenocarcinomas were found with methods of high sensitivity. Discrepancies might be due to the abundance of cells harboring driving gene and detection assays.

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