Abstract LB004: Ultra-sensitive targeted DNA panel for very low-frequency mutation detection in circulating cell-free DNA

Abstract

Abstract Due to its noninvasive nature and being readily available in peripheral blood and other bodily fluids, analysis of cell-free DNA (cfDNA) has become a promising application in cancer diagnosis, prognosis and treatment monitoring. However, disease-relevant cfDNA is present in a very limited amount in the huge background of normal cfDNA. This remains a challenge for any detection technology. Many currently available target enrichment and library preparation methods use regular DNA polymerase and amplification processes that introduce substantial bias and artifacts. This results in artifactual errors that greatly limit the detection of true low-frequency variants below 0.5% in heterogeneous samples, such as cfDNA. Here, we present a new targeted cfDNA workflow that overcomes challenges such as biases and artifacts. The workflow uses a highly optimized, high-fidelity reaction chemistry and incorporates UMIs into a single gene-specific, primer-based targeted enrichment process. Compared to regular DNA polymerase, this high-fidelity chemistry resulted in a five- to ten-fold decrease in base substitution error. An individual cancer panel was designed to specifically cover cancer-relevant hotspots and copy number genes with a dense primer design to accommodate the short length of cfDNA. Due to its high-fidelity chemistry and optimal panel design, our streamlined workflow can be completed in a single day. We also report consistent panel performance across different samples. Detection sensitivity and specificity were evaluated on a reference cfDNA sample and a simulated cfDNA sample by mixing enzyme-digested Genome in a Bottle samples, NA12878 and NA24385. We achieved close to 90% detection sensitivity and above 99.9% specificity for 0.1% variant. In addition, copy number variation could be successfully detected with a 1.5-fold difference over normal control samples. These results demonstrate an efficient targeted cfDNA panel workflow that enables cancer-relevant mutation detection with high sensitivity and accuracy. The applications presented here are for research use only. Not for use in diagnostic procedures. Citation Format: Michelle Baird, Mariam Ashraf, Emil Chistensen, Christa Haldrup, Zhong Wu, Eric Lader. Ultra-sensitive targeted DNA panel for very low-frequency mutation detection in circulating cell-free DNA [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 2 (Clinical Trials and Late-Breaking Research); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(8_Suppl):Abstract nr LB004.