Author of

• 34852

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  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

  • 34866

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    FP07.12 - Underdiagnosis of EGFR Exon 20 Insertion Mutation Variants: Estimates from NGS-based Real-World Datasets (ID 3399)

    00:00 - 00:00  |  Author(s): Nicholas Le Croy
    • Abstract
    • Presentation

    Introduction
    

    Exon 20 insertion mutations (Exon20ins) account for up to 10% of all mutations in epidermal growth factor receptor (EGFR) mutant non-small cell lung cancers (NSCLCs). Exon20ins specific drugs are in development. Because Exon20ins are molecularly heterogenous, the ability to identify the range of variants is dependent on the test methods used. Real-time polymerase chain reaction (PCR) and next-generation sequencing (NGS) are two molecular tests widely used to identify mutations in the EGFR. We analyzed real-world genomic data to determine the frequency of Exon20ins variants and to assess the ability of PCR and NGS to comprehensively identify them.

    Methods
    

    Two US-based genomic databases were utilized for this analysis. NGS data from US institutions were extracted from the American Association for Cancer Research (AACR) Project Genomics Evidence Neoplasia Information Exchange (GENIE) database, version 8.5 (The AACR Project GENIE Consortium. Cancer Discov. 2017;7(8):818-831). The FoundationInsights™ database (Foundation Medicine, Cambridge, MA) was used to obtain EGFR Exon20ins variants in real-world NSCLC samples. Coverage of Exon20ins from commercially available PCR tests (therascreen^® and cobas^®) was obtained from their instructions for use.

    Results
    

    The GENIE database included 12,497 patients with NSCLC. A total of 2,316 patients with EGFR mutant lung adenocarcinoma were identified and of these patients, 175 (7.6%) harbored Exon20ins. A total of 40 unique Exon20ins variants were identified. Of the 9 most common Exon20ins variants (≥5 patients), only 4 would have been identified at the protein level using commercially available PCR tests. PCR tests would have identified only 89 (50.9%) of the 175 patients with Exon20ins identified by NGS (Figure). The FoundationInsights™ database included 627 patients with lung adenocarcinomas who harbored Exon20ins and identified 102 unique Exon20ins variants. Of the 17 most common variants (≥5 patients), only 4 would have been identified at the protein level with commercially available PCR tests. PCR tests would have identified just 305 (48.6%) of the 627 patients with Exon20ins identified by NGS (Figure).

    Conclusion
    

    PCR methods are projected to miss 50% or more of Exon20ins. Reliance on commercially available PCR kit methods may provide insufficient information to support appropriate decision-making for emergent Exon20ins-directed therapies. The large number of insertion variants suggests that NGS platforms, academic or commercially available, would also improve their detection rate by capturing the full breadth of variants that have been identified.

    

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