Author of

• 11543

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  P2.06 - Poster Session 2 - Prognostic and Predictive Biomarkers (ID 165)

  • Event: WCLC 2013
  • Type: Poster Session
  • Track: Biology
  • Presentations: 1
  • Moderators:
  • Coordinates: 10/29/2013, 09:30 - 16:30, Exhibit Hall, Ground Level

  • 11552

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    P2.06-009 - Simultaneous Profiling of Multigene Mutations for the Effective And Efficient Diagnosis of Non-Small Cell Lung Carcinoma (ID 1078)

    09:30 - 09:30  |  Author(s): P.Y. Yip
    • Abstract

    Background
    Identification of actionable driver mutations in non-small cell lung carcinoma (NSCLC) has become increasingly important for the prioritisation of targeted therapies. Mutational analysis of formalin-fixed paraffin embedded (FFPE) tissues presents several challenges including generally limited and fragmented DNA, the need to identify a range of biologically significant mutations and a pressing need for a fast turn around time at a cost-effective way. Our aim was to determine optimal methods for quantification of DNA for mutational analysis in NSCLC and to develop a new custom assay that could perform multigene mutational analysis on the limited quantity of DNA available in the small NSCLC samples frequently submitted for testing.

    Methods
    DNA was extracted from FFPE tissues including cytology specimens. Spectrophotometry quantification was compared with Qubit 2 Fluorometer measurements and the Sequenom SampleID assay for accurate and meaningful assessment of extracted DNA for diagnostic mutational profiling. We have previously established a diagnostic protocol for somatic mutation profiling in NSCLC using a commercial DNA mass spectrometry kit (Oncocarta v1.0) and compared it with a new custom kit “OncoFocus” developed in collaboration with Sequenom. These assays utilise target amplicons of small sizes for efficient amplification in fragmented DNA and simultaneously profile a range of actionable mutations in EGFR, KRAS, BRAF and NRAS. Preliminary verification of the “OncoFocus” assay was performed in 27 NSCLC samples, 3 lung cancer cell lines and 2 control genomic DNA samples.

    Results
    We found spectrophotometry significantly overestimated DNA quantity particularly at low concentrations. We also studied the correlation of DNA quantities with estimated copies of DNA templates as determined by SampleID. The results suggested that a minimum of 300 ng DNA is needed to achieve the required 300 – 500 amplifiable genomic copies per reaction for the OncoCarta analysis, which remains difficult to achieve for many diagnostic NSCLC samples. We developed a more focused diagnostic panel “OncoFocus” which could be performed reliably with less DNA but which includes key actionable mutations in 159 hotspots in EGFR (n=109), KRAS (n=17), BRAF (n=15) and NRAS (n=18) requiring only 150 ng of DNA. Somatic mutations were identified in 23 samples and 3 cell lines including EGFR (n=22), KRAS (n=6) and BRAF (n=1). No false positive results were observed in 4 FFPE and 2 control samples. The whole process from the receipt of FFPE samples to issuing a report can be completed within 5 working days and the “OncoFocus” panel has increased our capacity per chip (iPLEX II) from 15 to 31 samples. The “OncoFocus” panel also results in decreased per sample testing costs.

    Conclusion
    The Qubit fluorometer is a more reliable and accurate method to quantify DNA derived from FFPE for mutational analysis than spectrophotometry. We also conclude that DNA mass spectrometric analysis using a new custom “OncoFocus” panel is an effective and efficient test that simultaneously detects 159 mutational hotspots, in the generally lower quantity of DNA obtained from routine FFPE NSCLC samples.