비소세포폐암 환자에서 액체생검을 통한 EGFR 유전자변이 검출의 유용성 확인에 대한 연구

Abstract

Background: Liquid biopsy refers to assays capable of sampling, isolating and testing analytes from a biological fluid which is minimally invasive, reproducible, and cost-saving. Clinical application of liquid biopsy in patients with advanced non-small cell lung cancer (NSCLC) mainly focuses on detecting sensitizing epidermal growth factor receptor (EGFR) mutations. We aimed to evaluate the feasibility of liquid biopsy technique using circulating tumor cell (CTC) or circulating tumor DNA (ctDNA) from blood of patients with NSCLC in detection of EGFR sensitizing mutations, as well as the detectability of sensitizing EGFR mutation in plasma using next-generation sequencing (NGS) and promer-based technique. Methods: Two independent prospective cohort study was conducted. Firstly, patients who were diagnosed as advanced NSCLC by tissue biopsy and agreed to conduct blood sampling were prospectively enrolled. Medical records were reviewed and EGFR status from tissue sample, blood CTC, and ctDNA was analyzed to compare diagnostic performance of CTC and ctDNA. The other cohort study enrolled NSCLC patients benefited from previous EGFR-tyrosin kinase inhibitor treatment followed by treatment failure. Re-biopsy of tissue or plasma sampling was conducted. EGFR mutation was detected by extracting ctDNA from plasma, using both PANA mutyper and promer-based EGFR assay. Diagnostic performance of promer-based assay compared to PANA mutyper was evaluated, as well as further detectability of C797S mutation from plasma of patient who underwent at least 3 months of osimertinib treatment. Objective response rate (ORR) with osimertinib treatment was also evaluated. Results: In the first cohort study, 180 patients were enrolled between November 2019 and February 2022. Real-time polymerase chain reaction (RT-PCR) method using ctDNA detected EGFR mutation with superior accuracy (72.0% vs. 20.0%) and sensitivity (68.8% vs. 7.7%), compared to CTC (p-value < 0.01). NGS method using ctDNA detected EGFR mutation with 59.4% accuracy, 36% sensitivity, and 100% specificity. The other cohort study enrolled 123 NSCLC patients between January 2018 and December 2019. Median age was 63 years and 52 (42.3%) were male. 80 patients received osimertinib treatment and ORR was 66.3%. Promer-based EGFR assay showed superior sensitivity and specificity compared to PANA Mutyper in detection of L858R and T790M mutation. In addition, promer-based EGFR assay detected C797S mutation in plasma of two out of twenty-four patients who were treated over 3-months of osimertinib treatment. Conclusion: EGFR detection rate using plasma ctDNA was higher to blood CTC. RT-PCR method using promer showed superior detectability on EGFR mutation from ctDNA compared to PANA Mutyper, with possibility to detect further C797S mutation in patients treated with osimertinib, demonstrating clinical utility in predicting resistance to osimertinib.