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V. Talwar



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    Poster Display session (Friday) (ID 65)

    • Event: ELCC 2018
    • Type: Poster Display session
    • Track:
    • Presentations: 1
    • Moderators:
    • Coordinates: 4/13/2018, 12:30 - 13:00, Hall 1
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      56P - Plasma circulating ctDNA: Potential biomarker in non-small cell lung carcinoma and clinical significance (ID 355)

      12:30 - 13:00  |  Author(s): V. Talwar

      • Abstract

      Background:
      Circulating cell free tumour DNA (ctDNA) from liquid biopsy is a potential source of tumour genetic material especially in case of non-availability of tissue biopsy for EGFR testing. Detectable levels of oncogenic driver mutations in peripheral blood have been shown to be associated with poorer prognosis and good predictor of EGFR TKI efficacy.

      Methods:
      Liquid biopsy was performed on 95 NSCLC patients with matched tumour tissue for genomic analysis. An EGFR mutation of one major molecular subtype in NSCLC was performed on massive parallel sequencing. Single gene EGFR mutation analysis was performed on the ctDNA by using ultra deep sequencing on the HiSeq platform. Then custom designed bioinformatics algorithms were used to detect somatic mutations at allele frequencies as low as 0.01%.

      Results:
      Overall concordance of mutation status between 95 pairs of tissue and plasma ctDNA samples for EGFR mutation status was about 93%. 30.5% (29/95) of the study subset was EGFR mutated on tissue typing and 27.36% (26/95) in ctDNA. Positive predictive value was 100% and negative predictive value was 95.6% – with diagnostic accuracy of 97%. A false negative rate of 4% was observed in this study. 12 out of 95 (12.63%) samples which had rare Exon19 deletions and complex indels could be confidently detected by NGS methods only. An objective efficacy response rate for Gefitinib was estimated at 70%, with a disease control rate of 94%. Median period of follow-up was 13.9 months. Median PFS was 16.8 months (95% CI 11.168–26.198).

      Conclusions:
      12% of newly diagnosed NSCLC patients could get the additional benefit of targeted therapy, by using the NGS which detected oncogenic driver mutations. Liquid Biopsy offer significant diagnostic, prognostic, and predictive information.

      Clinical trial identification:


      Legal entity responsible for the study:
      Rajiv Gandhi Cancer Hospital and Research Center

      Funding:
      Has not received any funding

      Disclosure:
      All authors have declared no conflicts of interest.