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T. Kubo



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    P3.01 - Advanced NSCLC (ID 621)

    • Event: WCLC 2017
    • Type: Poster Session with Presenters Present
    • Track: Advanced NSCLC
    • Presentations: 1
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      P3.01-088k - Significance of Second Rebiopsy for Detecting T790M Mutation (ID 8642)

      09:30 - 09:30  |  Author(s): T. Kubo

      • Abstract

      Background:
      Osimertinib is an essential drug for the treatment of non-small cell lung cancer (NSCLC) with epidermal growth factor receptor (EGFR) T790M mutation and rebiopsy is recommended for detecting T790M. However, significance of repeating rebiopsy in NSCLCs that were T790M negative with first rebiopsy remains unclear. Here, we sought to clarify this issue using a retrospective cohort.

      Method:
      We reviewed the medical records of patients with consecutive advanced NSCLC harboring activating EGFR mutations who underwent EGFR tyrosine kinase inhibitor (TKI) at Okayama University Hospital between Jan 2015 and Jan 2017.

      Result:
      In total, 104 patients were included in this study, and 47 patients underwent rebiopsy after acquiring resistance to prior EGFR TKIs. Preexisting activating EGFR mutations were found in all the 47 rebiopsied samples. Nineteen of them were T790M positive (40%). In the remaining 28 patients (T790M negative with first rebiopsy), 18 patients underwent additional rebiopsies following to interval therapies. Eleven (61%) of them were T790M positive with 2nd/3rd rebiopsy (10 with 2nd rebiopsy and 1 with 3rd rebiopsy). In majority of the 11 patients, rebiopsied samples were obtained from different lesions between first and 2nd/3rd rebiopsy (8/11, 73%). We also evaluated the efficacy of osimertinib in the 11 patients who needed 2nd/3rd rebiopsy for detecting T790M. Osimertinib showed good activity with the objective response rate 56% and the median progression free survival 5.5 months (95% confidence interval 4.1-6.9), though it is worse compared to with historical control osimertinib therapy.

      Conclusion:
      T790M could be found even in T790M negative NSCLCs with first rebiospy. Data will be updated at the meeting.