Abstract 1196: BALF liquid biopsy provides a novel platform for speedy and accurate EGFR mutation testing in advanced NSCLC patients

Abstract

Abstract Background EGFR mutation testing is an essential step for the therapeutic decision in newly diagnosed advanced NSCLC patients and usually performed by using DNA extracted from biopsied tumor tissue with a turnaround time(TAT) of 2-3 weeks. Plasma liquid biopsy using ctDNA is minimally invasive and less time-consuming, but shows limited usefulness due to low sensitivity. We conducted a prospective study to demonstrate clinical usefulness of bronchoalveolar lavage fluid (BALF) liquid biopsy using extracellular vesicle(EV)-derived DNA in advanced NSCLC patients by comparing the sensitivity and TAT with conventional tissue biopsy and plasma liquid biopsy Methods The analysis set for liquid EGFR genotyping is 224 BALF samples and 110 plasma samples obtained from newly diagnosed 224 advanced non-squamous NSCLC patients. EGFR genotyping was done through peptide nucleic acid(PNA)-mediated real-time PCR after extracting BALF EV DNA and plasma cfDNA separately. The sensitivity, specificity, and concordance rate of BALF liquid biopsy were calculated in comparison to matched tissue genotyping and plasma liquid biopsy. In addition, TAT was compared between BALF liquid biopsy and tissue genotyping. Results Tissue genotyping revealed 93 EGFR mutant cases (41.5%) and 131 wild-type cases (58.5%). The sensitivity, specificity, positive predictive value, negative predictive value, and concordance rate of BALF liquid biopsy to tissue genotyping were 97.8%, 96.9%, 96.8%, 98.4%, and 97.7%, respectively. BALF liquid biopsy showed almost identical performance with standard tissue genotyping, while only 5 cases were mismatched each other. On the other hand, plasma liquid biopsy using cfDNA (n=110) revealed 48.5% sensitivity, 86.3% specificity, and 63.6% concordance rate in comparison to tissue genotyping. The mean turnaround times of BALF liquid biopsy was significantly shortened to 2.6±2.0 days in contrast to 13.9±12.4 days of tissue genotyping. (p<0.001). Conclusion BALF liquid biopsy can be developed as a novel platform for EGFR mutation testing in advanced NSCLC with almost identical performance with conventional tissue genotyping and significantly shorten TAT to 1-2 days. Citation Format: In Ae Kim, Jae Young Hur, Hee Joung Kim, Wan Seop Kim, Kye Young Lee. BALF liquid biopsy provides a novel platform for speedy and accurate EGFR mutation testing in advanced NSCLC patients [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 1196.