Author of

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  P2.13 - Targeted Therapy (Not CME Accredited Session) (ID 962)

  • Event: WCLC 2018
  • Type: Poster Viewing in the Exhibit Hall
  • Track:
  • Presentations: 1
  • Moderators:
  • Coordinates: 9/25/2018, 16:45 - 18:00, Exhibit Hall

  • 27199

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    P2.13-24 - Prospective Efficacy of Osimertinib in Circulating Tumour DNA (ctDNA) T790M-Mutant NSCLC Patients (ID 14031)

    16:45 - 18:00  |  Author(s): Maud Ngocamus1
    • Abstract
    • Slides

    Background
    

    Liquid biopsy circulating tumor DNA (ctDNA) analysis in advanced EGFR-mutant NSCLC patients is an approved tool for molecular profiling and disease surveillance when tissue is not available. Long-term efficacy of osimertinib in patients with the T790M resistance mutation positive detected only by ctDNA (without tissue information) has not been fully validated.

    a9ded1e5ce5d75814730bb4caaf49419 Method
    

    In a prospective study, EGFR-mutant advanced NSCLC patients with acquired resistance to EGFR TKI, in whom a repeat tissue biopsy was not feasible, were assessed for ctDNA T790M mutational status using InVisionSeqTM. T790M-positive NSCLC patients received osimertinib (80 mg daily; extended access program or approval) at RECIST progression. The objectives were to assess: proportion of patients with acquired ctDNA-T790M positive; overall survival (OS) of the overall EGFR-mutant population as well as OS comparison for T790M +ve/-ve. Also, for those T790M-positive NSCLC patients who received osimertinib in a real world data we assessed: response rate (RR) according to RECIST 1.1 by investigator and progression free survival (PFS), calculated from the date of osimertinib initiation until the date of progression or death (whichever came first), or the date of last follow-up are also reported.

    4c3880bb027f159e801041b1021e88e8 Result
    

    We recruited 82 patients (71% female, median age 64 years, 72% Del19 EGFR mutation, 71% never-smokers). The ctDNA T790M mutation was detected in 55% (N=45) of NSCLC patients. Median OS of EGFR-mutant population was 38.2 months (mo.). According to T790M status, median OS was 41.2 months and 30.4 mo. for T790M-positive and T790M-negative NSCLC patients, respectively. Both cohorts had already received a median of 3 previous treatment lines. In 40 T790M-positive NSCLC patients who receive osimertinib, RR was 55% (PR: 55%, SD 27.5% and PD: 12.5%) and median PFS of 8.5 mo. Median OS on osimertinib among 10 patients with brain and/or leptomeningeal metastases at baseline was of 13.4 months.

    8eea62084ca7e541d918e823422bd82e Conclusion
    

    In patients with acquired resistance to first- or second-generation EGFR TKIs, ctDNA T790M detection by InVisionSeq™ is equivalent to what has been reported in tissue biopsy. Osimertinib has clinical benefit in patients for which the T790M resistance mutation is detected only through a liquid biopsy procedure.

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