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Validation of liquid biopsy: plasma cell-free DNA testing in clinical management of advanced non-small cell lung cancer

Authors Veldore VH, Choughule A, Routhu T, Mandloi N, Noronha V, Joshi A, Dutt A, Gupta R, Vedam R, Prabhash K

Received 31 July 2017

Accepted for publication 24 September 2017

Published 3 January 2018 Volume 2018:9 Pages 1—11

DOI https://doi.org/10.2147/LCTT.S147841

Checked for plagiarism Yes

Review by Single-blind

Peer reviewers approved by Dr Amy Norman

Peer reviewer comments 3

Editor who approved publication: Dr Sai-Hong Ignatius Ou


Vidya H Veldore,1,* Anuradha Choughule,2,* Tejaswi Routhu,1 Nitin Mandloi,1 Vanita Noronha,2 Amit Joshi,2 Amit Dutt,3 Ravi Gupta,1 Ramprasad Vedam,1 Kumar Prabhash2

1MedGenome Labs Private Ltd,, Bangalore, India; 2Tata Memorial Centre, Parel, Mumbai, India; 3The Advanced Centre for Treatment, Research and Education in Cancer, Tata Memorial Center, Kharghar, Navi Mumbai, Maharashtra, India

*These authors contributed equally to this work

Abstract: Plasma cell-free tumor DNA, or circulating tumor DNA (ctDNA), from liquid biopsy is a potential source of tumor genetic material, in the absence of tissue biopsy, for EGFR testing. Our validation study reiterates the clinical utility of ctDNA next generation sequencing (NGS) for EGFR mutation testing in non-small cell lung cancer (NSCLC). A total of 163 NSCLC cases were included in the validation, of which 132 patients had paired tissue biopsy and ctDNA. We chose to validate ctDNA using deep sequencing with custom designed bioinformatics methods that could detect somatic mutations at allele frequencies as low as 0.01%. Benchmarking allele specific real time PCR as one of the standard methods for tissue-based EGFR mutation testing, the ctDNA NGS test was validated on all the plasma derived cell-free DNA samples. We observed a high concordance (96.96%) between tissue biopsy and ctDNA for oncogenic driver mutations in Exon 19 and Exon 21 of the EGFR gene. The sensitivity, specificity, positive predictive value, negative predictive value, and diagnostic accuracy of the assay were 91.1%, 100% 100%, 95.6%, and 97%, respectively. A false negative rate of 3% was observed. A subset of mutations was also verified on droplet digital PCR. Sixteen percent EGFR mutation positivity was observed in patients where only liquid biopsy was available, thus creating options for targeted therapy. This is the first and largest study from India, demonstrating successful validation of circulating cell-free DNA as a clinically useful material for molecular testing in NSCLC.

Keywords: liquid biopsy, NSCLC, EGFR, ctDNA, NGS

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