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X. Xu



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    MA 20 - Recent Advances in Pulmonology/Endoscopy (ID 685)

    • Event: WCLC 2017
    • Type: Mini Oral
    • Track: Pulmonology/Endoscopy
    • Presentations: 1
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      MA 20.13 - etDNA: Tumor-Derived DNA from Pleural Effusion Supernatant as a Promising Source for NGS-Based Mutation Profiling in Lung Cancer  (ID 10091)

      15:50 - 15:55  |  Author(s): X. Xu

      • Abstract
      • Presentation
      • Slides

      Background:
      Mutation profiling of circulating tumor DNA (ctDNA) and pleural effusion sediment containing tumor cells (ETCs) were commonly applied in clinical practice. Several studies suggested that tumor-derived DNA from pleural effusion supernatant (etDNA) might be a better candidate for detecting gene alterations in lung cancer. However, little is known regarding the abundance and diversity of tumor DNA acquired among different types of liquid biopsy.

      Method:
      We performed targeted next generation sequencing (NGS)-based genetic profiling on tumor tissue, pleural effusion (etDNA & ETCs) and contemporaneous ctDNA from 63 lung cancer patients (58 adenocarcinoma, 2 adenosquamous carcinoma, 2 SCLC, 1 neuroendocrine carcinoma), among which 28 patients had paired tumor tissue samples. Genomic DNA from whole blood of each patient was used for germline control. Driver mutation and rearrangement profiling was validated using ARMS-PCR, FISH, or Ventana IHC assay in tumor tissue as golden standard.

      Result:
      We identified tumor-specific mutations in 98%, 89%, 86%, and 100% of patients in their etDNAs, ETCs, ctDNAs and tumor tissues, respectively (p<0.01). etDNAs showed a significantly higher tumor-specific mutation number per patient (Median: 5) compared to ETCs and plasma ctDNAs (Median of 3 for both), while the median number in tumor tissues is 4 per patient. The detection sensitivity for EGFR mutations in etDNAs is 95%, higher than that in ETCs and ctDNAs (89% and 63%, respectively). Two patients detected ALK fusion in tumor tissue were also positive in etDNA, only one patient was positive in ETCs and ctDNA, respectively. A total of 298 genetic alterations, including point mutations, indels, copy number variations (CNVs) and gene fusions, were identified in etDNAs from all the patients. However, only 74% and 57% of these alterations were detected in contemporaneous ETCs and ctDNA samples, with CNVs having the lowest detection sensitivity as 49% and 11%, especially in lung cancer patients without extrathoracic metastasis, as none of the CNVs detected in etDNAs were captured in plasma ctDNAs of these patients. Furthermore, driver mutations and rearrangements in etDNA showed a strong correlation to targeted therapy efficacy.

      Conclusion:
      This study demonstrated that etDNA had significantly higher tumor-specific mutation detection rate and sensitivity compared to ETCs and ctDNA. etDNA from supernatant of pleural effusion is a promising source for genetic testing to guide treatment-decision making in lung cancer. This study is funded by Shanghai Science and Technology Program (15ZR1406400).

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