Liquid biopsy such as plasma, has emerged as one of the most valuable sample types for profiling circulating tumor DNA (ctDNA) for screening, response to treatment, and monitoring relapse in oncology patients. Due to the diffuse nature of ctDNA however, both extraction and library preparation must be optimized for the efficient downstream next-generation sequencing (NGS) application. We initially addressed the optimization of quality and quantity of cfDNA recovery from healthy and various oncology patients by evaluating QIAsymphony DSP Circulating DNA Kit and Apostle MiniMax cfDNA isolation kits. Overall, the cfDNA yields from Apostle MiniMax kit were approximately 12X higher. We then optimized high-volume automated cfDNA extraction from 1ml, 3ml and 6ml plasma samples using the Biomek i7 for Apostle MiniMax kit. Colorectal, Gastric and Ovarian cancer gave the highest yield of cfDNA whereas, Esophageal, Lung and Kidney cancers were the lowest cfDNA yielding samples. We then analyzed ctDNA from plasma from healthy donors, colorectal, kidney, Breast, and endometrial cancer patients along with Oncospan and Seraseq ctDNA mutation mix (5-0.5% AF) to evaluate the mutation detection efficacy, repeatability, and reproducibility by targeted NGS using TSO 500ctDNA assay ay 10ng, 20ng, and 30ng inputs. For library preparation batches of 48 samples were prepared using a fully automated processes for the library prep, Hybridization capture and post capture enrichment on the Beckman i5 robot. Libraries were sequenced on NovaSeq 6000 at 600M Paired-end depth. This method demonstrates an overall concordance of inter-run and intra-run accuracy of variant detection to be 90% demonstrating that this method run as described produces highly repeatable and reproducible variant detection to sub-1% allele frequencies. The inter-run, lot-to-lot, and operator-to-operator variability was ≥99%. Down-sample analysis demonstrated high levels of assay performance with sample inputs of 30 ng with ≥96% sample passing Illumina cut-off metrics at 150M PE read depth as compared to Illumina recommended 420M PE reads. Taken together, we provide a high-volume automated solution for cfDNA extraction from plasma samples, additionally these data demonstrate a robust, reproducible, and highly accurate targeted DNA sequencing method that can be used for low allele frequency variant detection in cfDNA.

Citation Format: Nripesh Prasad, Rachel Rock, Rebecca Beatty, Melanie Robinson, Dineen Wildman, Michael Sykes, Boris Umylny, Thomas Halsey. Optimization of high-volume cell free DNA extraction and end-to-end automation for TSO 500 ctDNA library prep [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 2298.