Author of

• 18975

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  P3.01 - Advanced NSCLC (ID 621)

  • Event: WCLC 2017
  • Type: Poster Session with Presenters Present
  • Track: Advanced NSCLC
  • Presentations: 1
  • Moderators:
  • Coordinates: 10/18/2017, 09:30 - 16:00, Exhibit Hall (Hall B + C)

  • 23914

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    P3.01-055 - The Usefulness of Liquid Biopsy for ctDNA in Patients with EGFR-Mutant NSCLC During and After Treatment with EGFR-TKIs (ID 9811)

    09:30 - 09:30  |  Presenting Author(s): Takuma Yokoyama
    • Abstract
    • Slides

    Background:
    Non-small-cell lung cancer (NSCLC) patients with activating mutation of epidermal growth factor receptor (EGFR) gene inevitably develop disease progression to EGFR-tyrosine kinase inhibitors (TKIs). T790M gatekeeper mutation accounts for approximately 60% of the acquired resistance, and osimertinib, third generation EGFR-TKI, is effective against such tumors. Demonstration of T790M requires second biopsy, which is inconvenient and sometimes hazardous. Liquid biopsy of circulating tumor DNA (ctDNA) in the plasma is a non-invasive alternative, but clinical relevance of this method is yet to be fully elucidated.
    
    Method:
    NSCLC patients with EGFR mutation undergoing 1st- or 2nd-generation EGFR-TKI treatment are monthly or bi-monthly monitored for plasma ctDNA EGFR mutations, including T790M, by Cobas EGFR mutation test® via 10 ml blood sampling. The treatment could be changed on the attending physicians’ discretion, including osimertinib in patients with documented T790M mutation, with continuation of the monitoring. The primary endpoints are T790M positivity rate of ctDNA among patients with tissue-confirmed T790M mutation, and T790M positivity rate of ctDNA at landmark points, such as radiological progression, clinical deterioration or second biopsy of the tumor. The secondary endpoints include EGFR mutation detection rate of plasma ctDNA at landmark points, the interval of tissue and plasma T790M detections, and response rate and progression-free survival in patients treated with osimertinib according to plasma/tissue T790M status.
    
    Result:
    From Oct 2016 to Mar 2017, 121 eligible patients were enrolled. The median age 73 years (range, 42-92), 42 male (34.7%), PS 0, 1 and 2 were 64 (52.9%), 54 (44.6%) and 3 (2.5%) respectively. EGFR mutation types were 61 patients (50.4%) del 19, 55 (45.5%) L858R and 5 (4.0%) others. 80 (66.1%) were never smokers. At the time of EGFR-TKI initiation, 82 (67.8%) had advanced and 39 (32.2%) had recurrent diseases. 65 (53.7%) had any prior therapy, including 21 (14.8%) with prior cytotoxic chemotherapy. Used EGFR-TKIs were gefitinib 50 (41.3%), erlotinib 40 (33.1%), and afatinib 31 (25.6%). Newly-diagnosed/on TKI therapy at enrollment was 18 (14.9%)/103 (85.1%). The median follow-up is 12[鈴木1] months. So far, plasma T790M was detected in 8 patients.
    
    Conclusion:
    This observational study will elucidate the clinical usefulness and limitations of monitoring of ctDNA for T790M mutation in the real-world setting.
    
    

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