Author of

• 30029

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  OA04 - Immuno Combinations and the Role of TMB (ID 126)

  • Event: WCLC 2019
  • Type: Oral Session
  • Track: Immuno-oncology
  • Presentations: 1
  • Now Available
  • Moderators:Solange Peters, Martin Reck
  • Coordinates: 9/08/2019, 15:15 - 16:45, Copenhagen (1980)

  • 30035

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    OA04.07 - Mutations Associated with Sensitivity or Resistance to Immunotherapy in mNSCLC: Analysis from the MYSTIC Trial (Now Available) (ID 901)

    15:15 - 16:45  |  Author(s): Song Wu
    • Abstract
    • Presentation
    • Slides

    Background
    

    In the Phase 3 MYSTIC study (NCT02453282), blood tumour mutational burden, at various thresholds from ≥12 to ≥20 mut/Mb (bTMB≥20), has been associated with improved OS and PFS with first-line durvalumab (D; anti-PD-L1) +/- tremelimumab (T; anti-CTLA-4) versus platinum-based chemotherapy (CT). Specific gene mutations have been associated with resistance (STK11 and KEAP1) or sensitisation (ARID1A) to anti-PD-(L)1 monotherapy. However, the relationship between gene alterations and response to anti-PD-(L)1 ± anti-CTLA-4 are not well characterised. Here we explore associations between mutations and survival outcomes in the MYSTIC patient population.

    Method
    

    Circulating tumour DNA from baseline blood specimens was profiled using the GuardantOMNI platform. Samples were available from 1003 patients (89.7% of ITT; 943 mutation-evaluable). Survival outcomes were analysed in patients with (m) or without (wt) non-synonymous somatic mutations in STK11, KEAP1, or ARID1A.

    Result
    

    In the mutation-evaluable population, STK11m, KEAP1m, and ARID1Am frequencies were 16%, 18% and 12%, respectively (19%, 20%, and 11% [nonsquamous]; 7%, 13%, and 15% [squamous]). Across treatment arms, patients with STK11m or KEAP1m had a shorter median OS (mOS) than patients with STK11wt (D, 10.3 vs 13.3 mo; D+T, 4.4 vs 11.3 mo; CT, 6.7 vs 13.1 mo) or KEAP1wt (D, 7.6 vs 14.6 mo; D+T, 9.2 vs 11.3 mo; CT, 6.3 vs 13.3 mo) mNSCLC. In the D+T arm, patients with ARID1Am had a longer mOS than patients with ARID1Awt mNSCLC (D, 8.6 vs 13.7 mo; D+T, 23.2 vs 9.8 mo; CT, 10.6 vs 12.4 mo). Additional mutational analyses will be presented.

    Conclusion
    

    In these analyses from the MYSTIC study, poorer outcomes were observed across treatment arms in patients with mNSCLC and mutations in STK11 or KEAP1 compared with those without the corresponding mutations. In patients receiving D+T, ARID1Am was associated with survival benefits compared with ARID1wt. These data are exploratory and require further validation.

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