Author of

• 20167

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  P2.03 - Chemotherapy/Targeted Therapy (ID 704)

  • Event: WCLC 2017
  • Type: Poster Session with Presenters Present
  • Track: Chemotherapy/Targeted Therapy
  • Presentations: 1
  • Moderators:
  • Coordinates: 10/17/2017, 09:30 - 16:00, Exhibit Hall (Hall B + C)

  • 23287

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    P2.03-016 - Clinical Utility of Liquid Biopsy for Detecting EGFR T790M Mutation Is Very Limited (ID 8370)

    09:30 - 09:30  |  Author(s): E. Simizu
    • Abstract

    Background:
    Osimertinib, a third-generation EGFR tyrosine kinase inhibitor targeting EGFR T790M acquired resistance mutation, has demonstrated strong clinical activity. Therefore, we have to do a second biopsy to detect T790M when the tumor has progressed. On the other hand, liquid based assays are expected as minimally invasive methods for detecting resistance mutations. Recently, liquid-biopsy for detecting EGFR T790M mutation has been approved by the Japanese ministry of health, labor and welfare. The aim of this study is to assess the clinical utility of liquid biopsy for detecting EGFR T790M mutation.
    
    Method:
    Seventeen consecutive patients who underwent cobas® EGFR Mutation Test ver.2 for liquid biopsy from January to April 2017 were enrolled. Patient information and examination results were collected from electronic medical records and analyzed retrospectively. Concordance between liquid biopsy and tissue or cytological specimen was assessed in patients who underwent re-biopsy at the same time as liquid biopsy.
    
    Result:
    Median age: 70 (51-82); Women: 10 (58.8%); Never smoker: 12 (70.6%); Adenocarcinoma: 17 (100%); Stage IV: 16 (94.1%); Primary EGFR mutation: exon19 deletion = 11 (64.7%), exon21 L858R = 5 (29.4%), exon18+20 mutations = 1 (5.9%). Two patients (11.8%) were positive for T790M mutation in plasma. Tissue biopsy or cytology was done in 8 cases at the same time as liquid biopsy. Only one patient of four patients who were positive for T790M in tissue or pleural effusion was positive for T790M in plasma (sensitivity: 25%). One patient of two patients who were positive for T790M in plasma was negative for T790M in spinal fluid.
    
    Conclusion:
    There is no doubt that liquid biopsy is a minimally invasive and very convenient method. However, at least currently, liquid biopsy cannot replace tissue biopsy in clinical setting because of its sensitivity. In order to deliver the appropriate medication to the patient, it is necessary to selectively use well the tissue biopsy and liquid biopsy.