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K. Azuma



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    MA08 - Treatment Monitoring in Advanced NSCLC (ID 386)

    • Event: WCLC 2016
    • Type: Mini Oral Session
    • Track: Advanced NSCLC
    • Presentations: 1
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      MA08.10 - Detection of the T790M Mutation of EGFR in Plasma of Advanced NSCLC Patients with Acquired Resistance to EGFR-TKI (WJOG8014LTR) (ID 5377)

      12:06 - 12:12  |  Author(s): K. Azuma

      • Abstract
      • Presentation
      • Slides

      Background:
      NSCLC patients with activating mutations of the EGFR initially respond well to TKIs, but about half such patients develop TKI resistance through acquisition of a secondary T790M mutation. Whereas next-generation EGFR-TKIs have been developed to overcome T790M-mediated resistance, performance of a second tumor biopsy to assess T790M mutation status can be problematic.

      Methods:
      We developed and evaluated liquid biopsy assays for detection of TKI-sensitizing and T790M mutations of EGFR by droplet digital PCR (ddPCR) in EGFR mutation–positive patients with acquired EGFR-TKI resistance.

      Results:
      A total of 260 patients was enrolled between November 2014 and March 2015 at 29 centers for this West Japan Oncology Group (WJOG 8014LTR) study. Plasma specimens from all subjects as well as tumor tissue or malignant pleural effusion or ascites from 41 patients were collected after the development of EGFR-TKI resistance. All plasma samples were genotyped successfully and the results were reported to physicians within 14 days. TKI-sensitizing and T790M mutations were detected in plasma of 120 (46.2%) and 75 (28.8%) patients, respectively. T790M was detected in 56.7% of patients with plasma positive for TKI-sensitizing mutations. For the 41 patients with paired samples obtained after acquisition of EGFR-TKI resistance, the concordance for mutation detection by ddPCR in plasma compared with tumor tissue or malignant fluid specimens was 78.0% for TKI-sensitizing mutations and 65.9% for T790M.

      Conclusion:
      Noninvasive genotyping by ddPCR with cell-free DNA extracted from plasma is a promising approach to the detection of gene mutations during targeted treatment.

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    P3.02b - Poster Session with Presenters Present (ID 494)

    • Event: WCLC 2016
    • Type: Poster Presenters Present
    • Track: Advanced NSCLC
    • Presentations: 1
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      P3.02b-073 - A Phase II, Liquid Biopsy Study Using Digital PCR in EGFR Mutated, Lung Cancer Patients Treated with Afatinib (WJOG 8114LTR) (ID 4754)

      14:30 - 14:30  |  Author(s): K. Azuma

      • Abstract

      Background:
      Liquid biopsy is an ideal strategy to monitor mutation status of cancer repeatedly and less invasively. In chronic myeloid leukemia, early remission of mutated cells was reported as a surrogate of longer efficacy. In epidermal growth factor (EGFR) mutated non-small cell lung cancer (NSCLC), to detect resistant mutation (exon20 T790M) during treatment is clinically important because newer tyrosine kinase inhibitors (TKIs) have been developed. Although some reports have mentioned the utility of liquid biopsy in EGFR mutated NSCLC, most were single-institutional, retrospective studies.

      Methods:
      West Japan Oncology Group (WJOG) 8114LTR is a multi-institutional, prospective liquid biopsy study in advanced NSCLC. Chemotherapy naïve, advanced NSCLC patients with EGFR-sensitizing mutation will receive afatinib monotherapy (40 mg/body) until progressive disease (PD) or unacceptable toxicity. Plasma DNA will be obtained from patients at baseline, 2, 4, 8, 12, 24, 48 weeks, and at PD. Three types of common EGFR mutations (exon 19 deletion, exon 20 T790M and exon 21 L858R) will be analyzed using plasma DNA with multiplexed, pico-droplet digital PCR assay (RainDrop® system, RainDance Technologies, Billerica, MA). Primary endpoint of this study is the concordance of EGFR mutation status between tissue and plasma at baseline. Secondary endpoints are overall response rate, progression-free survival and safety. This is the first report on the primary endpoint and early remission rate based on mutated cf-DNA. This study was registered at UMIN (ID: 000015847).

      Results:
      Fifty-seven patients were registered and samples from 55 patients were analyzed. Clinical characteristics were as follows; median age: 69 years, male / female: 25/30, PS 0/1: 23/32, c-stage III / IV / post-operative relapse: 2/37/16, exon 19 deletion / exon 21 L858R: 28/27. Sensitivity of plasma sample was 63.6% among overall, while that was 84.6% in patients with distant metastasis. Eighty-two percent of plasma positive patients at baseline showed molecular response in plasma after two weeks of afatinib treatment. De novo T790M mutation was detected in one patient (2%) from plasma samples.

      Conclusion:
      Liquid biopsy seemed to be suitable especially in patients with distant metastasis. Early molecular remission (within two weeks) was observed in 70% of patients.