Author of

• 36336

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  P76 - Targeted Therapy - Clinically Focused - EGFR (ID 253)

  • Event: WCLC 2020
  • Type: Posters
  • Track: Targeted Therapy - Clinically Focused
  • Presentations: 1
  • Moderators:
  • Coordinates: 1/28/2021, 00:00 - 00:00, ePoster Hall

  • 36450

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    P76.94 - Survival Analyses and Molecular Predictors of Outcomes in Patients Treated with Osimertinib for Metastatic NSCLC Harboring EGFR Mutation (ID 3809)

    00:00 - 00:00  |  Presenting Author(s): Danilo Giffoni M. M. Mata
    • Abstract
    • Slides

    Introduction
    

    Tyrosine kinase inhibitors (TKI) are the cornerstone targeted therapy for metastatic non-small cell lung cancer (NSCLC). This retrospective study was undertaken to investigate the impact of the third generation epidermal growth factor receptor (EGFR)-TKI, Osimertinib, on the two most frequent EGFR mutations, exon 21-L158R and exon 19-deletion, encountered in NSCLC. The primary objective was to evaluate potential differences in overall survival (OS) and disease-free survival (DFS) between patients harboring exon 21-L858R mutation and exon 19 deletion when treated with Osimertinib.

    Methods
    

    From January 2010 to December 2018, consecutive patients with metastatic NSCLC-EGFR mutations, treated with Osimertinib 80 mg once daily, were analyzed. Retrospective data was extracted through the electronic medical records located at Sunnybrook Health Sciences Centre. All patients had EGFR mutation positivity by cytology, plasma or tissue sampling.

    Results
    

    A total of 56 patients were included. The median age at initial diagnosis was 65 years old (range 27 – 85 years). A similar percentage of 46.42% (n=26) of the patients had an EGFR mutation on exon 21-L858R and on the exon 19-deletion. A total of 7.1% (n=4) had either an uncommon type of EGFR mutation or the location of gene modification was unknown. The majority, 76.7% (n=43), were T790m mutation positive, 8.9% (n=5) were negative, and 14.2% (n=8) had unknown T790m mutation status. For those who had T790m mutation, 46.4% (n=24) were positive by plasma and 28.5% by biopsy. Only 16% (n=9) received Osimertinib in the first-line setting and the majority, 84% (n=47), were treated with Osimertinib as second-line or beyond. 50% (n = 28) of this study cohort had brain metastases.

    Among the 56 patients treated with Osimertinib, the median DFS for those who had an EGFR mutation on exon 21-L858R was 15.2 months (95% confidence interval [CI] 11.3 - 19.0 months) and 14.2 months for the exon 19-deletion (95% [CI], 6.0 - 22.4 months); p= 0.25.

    The median OS was 52.6 months in the exon 21-L858R group (95% [CI] 35.4 - 69.7 months) and 49.6 months for the exon 19-deletion group (95% [CI], 25.6 - 73.6 months); p= 0.58.

    Conclusion
    

    Although lung cancer is a heterogeneous disease with variable responses to EGFR-targeted drugs, our study did not show a difference in OS and DFS between the two most common EGFR mutations treated with Osimertinib. A larger population for further investigation is needed.

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