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Poster Display session 3

5664 - Analysis of circulating tumor DNA in paired plasma and sputum samples of EGFR-mutated NSCLC patients


30 Sep 2019


Poster Display session 3


Translational Research

Tumour Site

Non-Small Cell Lung Cancer


Christina Grech


Annals of Oncology (2019) 30 (suppl_5): v574-v584. 10.1093/annonc/mdz257


C. Grech1, K. Hackner2, M. Strieder2, A. Buder1, M.J. Hochmair3, M. Filipits1, P. Errhalt2

Author affiliations

  • 1 Institute Of Cancer Research, Department Of Medicine I, Comprehensive Cancer Center, Medical University of Vienna, 1090 - Vienna/AT
  • 2 Department Of Pneumology, University Hospital Krems, Karl Landsteiner University of Health Sciences, 3500 - Krems/AT
  • 3 Department Of Respiratory And Critical Care Medicine, And Ludwig Boltzmann Institute Of Copd And Respiratory Epidemiology, Otto Wagner Hospital, 1140 - Vienna/AT


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Abstract 5664


Liquid biopsy is a minimally invasive strategy to detect genetic alterations in non-small cell lung cancer (NSCLC) patients. In particular, it is clinically useful for the detection of the EGFR T790M resistance mutation in advanced EGFR-mutated NSCLC patients who had progressed under treatment with an EGFR-TKI. While plasma analysis is commonly performed, sputum could be another potential source for circulating tumor DNA (ctDNA) in NSCLC, which has not yet been entirely evaluated.


Paired plasma and sputum samples from 23 patients with EGFR-mutated lung adenocarcinoma were analyzed for EGFR exon 19 deletions (del19), L858R, and T790M mutations by droplet digital PCR (ddPCR). All patients had histologically confirmed lung adenocarcinoma with EGFR mutations in their initial tissue biopsy at diagnosis.


Tissue genotyping at diagnosis revealed 18 patients with EGFR del19 and 5 patients with L858R mutations. Among the 18 EGFR del19-positive patients, 8 showed concordant test results in plasma and sputum (2 positive, 6 negative), 6 had del19-positive plasma samples but del19-negative sputum samples, 4 were del19 negative in plasma and del19 positive in sputum. Among 5 L8585R-positive patients, 4 had concordant test results in plasma and sputum (3 positive, 1 negative), one patient was L858R positive in the plasma sample but L858R negative in sputum. In 10 out of 23 patients the T790M mutation was assessed in paired samples, 9 showed concordant test results in plasma and sputum (3 positive, 6 negative), one patient was T790M positive only in the sputum sample.


Our results show a high concordance between plasma and sputum for EGFR L858R and T790M mutation testing. A lower concordance was observed for EGFR del19. Thus liquid biopsy from sputum is a promising strategy that should be further evaluated.

Clinical trial identification

GS1-EK4/479-2017, 20.07.2017 EK-18-172-0918, 08.11.2018.

Editorial acknowledgement

Legal entity responsible for the study

The authors.


Has not received any funding.


All authors have declared no conflicts of interest.

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