e21615 Background: Epidermal growth factor receptor (EGFR) mutations on circulating tumour free DNA (ctDNA) by liquid biopsy is suitable option in those with difficulty in obtaining tissue samples. Correlation in tissue and plasma results of EFGRm has not been established in the Indian population. 1,2,3 This study was done to investigate the utility of ctDNA for EGFRm testing with Next-Generation Sequencing (NGS) in a real-world diagnostic setting. Methods: This is a multicentre, prospective, diagnostic observational study in 245 newly diagnosed treatment naïve, histologically confirmed, advanced lung adenocarcinoma patients. This was a single visit study. The primary objective of the study was to determine the level of concordance between EGFR mutation status obtained by tissue and ctDNA from blood (plasma) based testing in terms of overall concordance, sensitivity & specificity. Study was registered at Clinicaltrials.gov NCT03562819 & CTRI/2018/08/015290. Results: Seventy-five (30.6%) and eighty-four (34.3%) subjects showed positive mutation status by plasma & tissue testing respectively. The overall concordance of 82.9% was observed between tissue and ctDNA (Plasma) based testing. Sensitivity of EGFR mutation status between ctDNA and tissue was observed for EGFR mutation subtypes was observed to be 100% while specificity was observed to be 90.1%. Plasma and tissue sample testing detected 1.2% (n = 3) and 2.4% (n = 6) positive in exon 20 T790M EGFR mutation, respectively. In terms of secondary outcomes, plasma sample testing detected 16.7% (n = 41) positive for Exon 19 deletions type EGFR mutation followed Exon 21 L858R [11.4% (n = 28)]. Conclusions: CONCORDANCE, a real-world study in Indian patients suggest that ctDNA testing for EGFR mutation analysis is a diagnostic option in newly diagnosed lung adenocarcinoma patients. EGFR Mutation testing in ctDNA, being non-invasive and especially in patients without available/evaluable tumor sample may enable more patients to receive appropriate targeted therapies. [Table: see text]
A comparison of EGFR mutation status in tissue and plasma cell-free DNA detected by ADx-ARMS in advanced lung adenocarcinoma patients