Virtual Library

Start Your Search

Normand Blais



Author of

  • +

    FP07 - Pathology (ID 109)

    • Event: WCLC 2020
    • Type: Posters (Featured)
    • Track: Pathology, Molecular Pathology and Diagnostic Biomarkers
    • Presentations: 1
    • Moderators:
    • Coordinates: 1/28/2021, 00:00 - 00:00, ePoster Hall
    • +

      FP07.08 - A Pan-Canadian Validation Study for the Detection of EGFR-T790M Mutations Using Circulating Tumour DNA (ctDNA) from Blood (ID 1294)

      00:00 - 00:00  |  Author(s): Normand Blais

      • Abstract
      • Presentation
      • Slides

      Introduction

      In advanced non-small cell lung cancer (NSCLC) patients with resistance to EGFR inhibitors, tumor genotyping to identify T790M resistance mutations is mandated. However, because of challenges such as tumour inaccessibility, tumour heterogeneity and patient morbidity, the measurement of circulating tumour DNA (ctDNA) in peripheral blood has emerged as a promising non-invasive clinical tool to detect this mutation. To facilitate standardization and clinical adoption of ctDNA testing across Canada, we developed a 2-phase multicentre RING study to standardize EGFR-T790M mutation detection using plasma ctDNA testing.

      Methods

      In Phase 1, commercially available cell-free DNA reference standards including a variety of clinically relevant variants were distributed to nine participating clinical molecular laboratories. Each site employed their existing platforms for mutation detection, including next generation sequencing (ThermoFisher Oncomine Lung cfDNA assay; Illumina TruSight Tumor 15 - TST15 panel), Bio-Rad digital droplet PCR, EntroGen ARMS-based ctEGFR mutation detection kit, Roche cobas EGFR mutation kit and the MassARRAY UltraSEEK Lung Panel). Baseline performance characteristics were established to ensure that the methods at each site were compatible with clinical application. Performance characteristics, including limit of detection, were further tested through distribution of blinded engineered plasma samples spiked with predetermined concentrations of T790M and L858R variants. Six of the labs proceeded to Phase II, where a series of blood samples, collected from local patients with known EGFR activating mutations progressing on treatment, were assayed for the presence of the primary mutation and the T790M variant. A blood sample was also sent out to the reference center using a clinically validated test (ddPCR, Bio-Rad). Blinded results were reported to a central repository to assess the concordance between the results.

      Results

      All labs in Phase I detected variants (T790M, L858R, Ex19 deletion alone or T790M/L858R) at allele frequencies of 0.5% and 5.0%. Four labs also reported detection of some variants at 0.05%. For the blinded samples, all labs identified the T790M and T790M/L858R variants at 0.5% and 5.0% (100% concordance). No false positives were reported for the EGFR wild type control.

      Six labs proceeded to Phase II using local patient-derived samples with the Cobas (Lab1), EntroGen (Labs 2, 4), NGS (Labs 3, 5) and ddPCR (Lab 6) platforms. The concordance between the reference and local labs for detection of both the sensitizing mutation and the resistance mutation was high, with NGS and ddPCR showing the best overall (~100%) concordance. The overall detection rate of T790M in this project was 22%. One lab using the EntroGen assay had lower concordance overall, but the other lab using the same kit had higher concordance, suggesting this could be a lab specific issue. These data suggest that the ability to detect EGFR resistance mutations at clinically relevant limits of detection is generally not only platform specific, but also impacted by lab specific practices.

      Conclusion

      These results indicate that the NGS and ddPCR platforms yielded the most concordant results for EGFR T790M detection in ctDNA when compared to a clinically validated reference lab. Discrepancies between sending labs using the same assay suggest that lab-specific factors may impact performance.

      Only Members that have purchased this event or have registered via an access code will be able to view this content. To view this presentation, please login, select "Add to Cart" and proceed to checkout. If you would like to become a member of IASLC, please click here.

      Only Active Members that have purchased this event or have registered via an access code will be able to view this content. To view this presentation, please login or select "Add to Cart" and proceed to checkout.