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  Lunch & Poster Display session (ID 58)

  • Event: ELCC 2019
  • Type: Poster Display session
  • Track:
  • Presentations: 1
  • Moderators:
  • Coordinates: 4/11/2019, 12:30 - 13:00, Hall 1

  • 29071

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    137P - Detection and clinicopathologic features of ctDNA in T790M-positive advanced lung adenocarcinomas patients after failure of treatment with first- and second-generation EGFR-TKIs (ID 359)

    12:30 - 13:00  |  Author(s): hua wen Zhao
    • Abstract
    • Slides

    Background
    

    We aimed to detect ctDNA in patients with advanced lung adenocarcinomas after failure of treatment with first- and second-generation EGFR-TKIs and to analyze it’s clinicopathologic features in a subset of patients harbouring the T790M mutation.

    a9ded1e5ce5d75814730bb4caaf49419 Methods
    

    We retrospectively collected data from November 2016 to October 2018 in patients with lung adenocarcinomas who had been analysed by Next-Generation Sequencing or ddPCR after progression on EGFR-TKIs at GuangXi Medical University Affiliated Tumor Hospital. Statistical analyses were performed to examine the associations between clinicopathologic features and acquired T790M mutation in patients.

    20c51b5f4e9aeb5334c90ff072e6f928 Results
    

    A total of 72 plasma samples were collected, of which 17 had matched tissue biopsies. Of these patients, 48 were analysed by NGS and the rest by ddPCR. The T790M mutation was detected in 43 cases (59.7%). We found this mutation was higher than that of mPFS>11.5 months (79% vs. 44%; odds ratio, 4.516; 95%CI, 1.53 to 13.30; p=0.006), and in which longer median PFS (13.0 months vs. 9.0 months; p = 0.042). Those who received chemotherapy before EGFR-TKIs were more likely to have the T790M mutation (80% vs. 53%, p=0.03) compared to those who received EGFR-TKIs in the first-line. In this study, the occurrence of T790M mutation in patients with L858R mutation was higher than seen in patients with 19-del (65% vs.57%; p=0.809). Among 17 patients who were sequenced by NGS in both samples, 7 had T790M positive blood samples and 8 were T790M positive in tissue biopsies. The coincidence rate was 94%.10 cases after the progression of the third generation TKI treatment. Three cases of T790M with C797S cis-mutation were detected and 3 cases with PIK3CA, BRAF V600E and MAP2K1 mutations, respectively. Secondary resistance mutations were not detected by NGS in 4 cases.

    fd69c5cf902969e6fb71d043085ddee6 Conclusions
    

    Patients with advanced lung adenocarcinomas harbouring the T790M mutation who failed with first- or second-generation EGFR-TKIs were more likely to have longer mPFS. In this study, NGS testing using ctDNA was a feasible means for monitoring acquired resistance mutations during or after progression on targeted therapy.

    b651e8a99c4375feb982b7c2cad376e9 Legal entity responsible for the study
    

    Cancer Hospital of Guangxi Medical University.

    213f68309caaa4ccc14d5f99789640ad Funding
    

    Has not received any funding.

    682889d0a1d3b50267a69346a750433d Disclosure
    

    All authors have declared no conflicts of interest.

    cffcb1a185b2d7d5c44e9dc785b6bb25

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