P1.09-13 Detection of Actionable Mutations in Plasma cfDNA Samples From NSCLC Patients Using a Novel Amplicon-Based Firefly NGS Assay

Abstract

Detection of EGFR, KRAS and BRAF mutations can help guide cancer treatment for non-small cell lung cancer (NSCLC) patients. To identify an easy to use, accurate, multiplex molecular diagnostic assay, we evaluated the performance of a novel next-generation sequencing (NGS)-based cell-free DNA (cfDNA) assay, Firefly assay, which employs a concatemer-based noise suppression mechanism with an amplicon workflow. Performance of amplicon based Firefly assay, with a panel covering EGFR, BRAF, and KRAS mutations designed for targeted therapy selection of NSCLC was first evaluated using a cfDNA reference standard and blank control samples. This panel was then used to analyze plasma cfDNA samples from 134 NSCLC cancer patients and 50 non-cancerous controls, and results were compared with tumor tissue ARMS and cfDNA ddPCR results. Firefly assay demonstrated superior sensitivity and specificity with median detection of 100% at allele frequency of 0.1% for 20ng of cfDNA and zero false positive in all blank control samples. In cfDNA from plasma collected before treatment, EGFR mutation detection by Firefly assay was 94% concordant with tumor tissue ARMS. Firefly assay demonstrated strong per-variant detection-rate concordance (98%) and allele frequency concordance (R2 = 0.95) when compared with cfDNA ddPCR result. The amplicon-based Firefly assay offers multiplex capacity, de novo variant detection, high sensitivity and specificity. Thus, Firefly assay is a kitable NGS solution for cfDNA analysis, which can help guide targeted therapy selection, drug resistance detection, and disease monitoring in NSCLC and other cancer patients.