Author of

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  P2.01 - Advanced NSCLC (Not CME Accredited Session) (ID 950)

  • Event: WCLC 2018
  • Type: Poster Viewing in the Exhibit Hall
  • Track:
  • Presentations: 1
  • Moderators:
  • Coordinates: 9/25/2018, 16:45 - 18:00, Exhibit Hall

  • 26920

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    P2.01-115 - Evaluation of EGFR T790M of Cell Free Circulating DNA in Plasma by Droplet Digital PCR for Progressive Non-Small Cell Lung Cancer (ID 13588)

    16:45 - 18:00  |  Presenting Author(s): Zhihong Zhang
    • Abstract
    • Slides

    Background
    

    In Non-Small Cell Lung Cancer (NSCLC) harboring EGFR mutations, a second-site point mutation at position 790 (T790M) is associated with acquired resistance to the EGFR kinase inhibitors, gefitinib and erlotinib. Osimertinib is selective for T790M resistance mutation in patients with NSCLC. However, the mutation rate of EGFR T790M is unclear in Chinese patients.The purpose of this study is to understand the status of EGFR T790M in the real world.

    a9ded1e5ce5d75814730bb4caaf49419 Method
    

    422 Patients with recurrent NSCLC who had been receiving TKI treatment at The First Affiliated Hospital of Nanjing Medical University were enrolled consecutively. Patient blood samples were drawn after the first generation TKI failure. Patients who met the following criteria : patients harboring EGFR activating mutation who developed PD during TKI treatment. Patients had received TKI alone therapy or TKI plus chemotherapy . The droplet digital PCR assay was conducted by droplets generation using QX200 generator (Bio- Rad Laboratories, Inc., Hercules, CA, USA).

    4c3880bb027f159e801041b1021e88e8 Result
    

    374 (88.6%) of them were successfully analyzed for EGFR T790M genotyping analysis by droplet digital PCR. 48(11.4%) of them failed to follow-up analysis owing to insufficient cfDNA amount,177(47%) plasma samples had found EGFR T790M mutation (Fig1a). Analyzing the allele frequency of EGFR T790M, we found 19% (33/177) positive patients of EGFR T790M was Less than 0.1% (Fig1b). The allele frequency of EGFR T790M between 0.1% and 0.5% was account for 38%（68/177）. The 32% (56/177) of patents were more than 1%. This result indicated that the detection of EGFR T790M required higher sensitive method, otherwise it might cause missed detection.

    8eea62084ca7e541d918e823422bd82e Conclusion
    

    Droplet digital PCR is a highly sensitive, absolute quantitative detection technique. The EGFR T790M is detected in up to 47% of these patients in the real world. Almost 68% of the allele frequency of EGFR T790M is less than 1%. It means that the detection of EGFR T790M requires a higher sensitive detection method.

    6f8b794f3246b0c1e1780bb4d4d5dc53

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