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Mahmoud Shahin

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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
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      28P - Applicability of ctDNA at diagnosis and during the monitoring of EGFR-mutated patients (ID 557)

      12:30 - 13:00  |  Author(s): Mahmoud Shahin

      • Abstract


      Identification of activating mutations in the EGFR enabled to change the therapeutic approach for NSCLC patients as therapeutic targets. Liquid biopsy is a new option for analysis of biomarkers with valuable prognostic and predictive information, allowing the detection of EGFR mutations with a reproducible and minimally invasive approach. The aim of this study was to correlate EGFR mutational status in ctDNA at diagnosis and follow-up of NSCLC patients as a complementary/alternative to tissue-based molecular profiling.

      a9ded1e5ce5d75814730bb4caaf49419 Methods

      Study included 20 patients with EGFR-mutated advanced NSCLC. Blood samples were collected at diagnosis, during follow-up and at progression. CtDNA was obtained from plasma and EGFR mutations were assessed by BEAMing dPCR (Sysmex®). Concordance between tissue and plasma EGFR mutation status was calculated as the number of positive plasma samples out of the total number of tissue samples. Cases at which T790M were first detected in blood were compared to date of progression as determined by radiological imaging in standard practice.

      20c51b5f4e9aeb5334c90ff072e6f928 Results

      A total of 262 plasma samples from 20 patients were analyzed, 75% percent of patients were females; 60% had never smoked; with a median of 18 months of follow- up (range: 5.13-61.77). The Positive Percent Agreement (PPA) at baseline for EGFR del19 and L858R mutation status between plasma and tissue was 75%; in 12 cases the clearance of the primary mutation happens during the first four to eight weeks after initiation of EGFR TKI. Furthermore, eight patients with radiological progression presented the resistance mutation T790M (66%), remarking that the majority of these tumors presented again the sensitizing mutation. In 6 of these patients plasma T790M-positivity was detected an average of 16 weeks (range: 4-24) prior to radiological progression. These results suggest that periodic monitoring of EGFR status in ctDNA could provide information regarding diagnoses, response or resistance to TKI-treatment.

      fd69c5cf902969e6fb71d043085ddee6 Conclusions

      Analyses of EGFR mutations in cfDNA have important clinical applicability and can be a useful alternate biomarker of diagnoses and early detection of TKIs resistance mechanisms.

      b651e8a99c4375feb982b7c2cad376e9 Legal entity responsible for the study

      Fundación de Investigación del Hospital General Universitario de Valencia.

      213f68309caaa4ccc14d5f99789640ad Funding

      Work supported in part by AstraZeneca (ISSIRES 0110); CIBERONC (CB16/12/00350); López-Trigo Grant.

      682889d0a1d3b50267a69346a750433d Disclosure

      All authors have declared no conflicts of interest.