Abstract 5023: Analytical validation of the Oncomine™ Dx Express Test using liquid biopsy samples as an IUO assay in a CAP/CLIA lab
Authors: Espinoza Juan C. , Ramsamooj Rajendra , Yuki Akemi , Williamson John , Hassell Diarra , Jasti Madhu , Salazar Suzanne , Ginzinger David 
Published: March 2024

Introduction: The Oncomine™ Dx Express Test (ODxET) is a next-generation sequencing (NGS) test. It can be used as an investigational use only (IUO**) test to detect somatic DNA and RNA alterations in human cell-free total nucleic acid (cfTNA) isolated from plasma samples. This study outlines the analytical validation of the ODxET for relevant single nucleotide variants (SNV) and insertion/deletions (INDEL) in liquid biopsy specimens. The Ion Torrent Genexus™ platform has a short turnaround time with minimal operator input. This study was performed in a College of American Pathologists (CAP™) accredited and Clinical Laboratory Improvement Act (CLIA) licensed laboratory.

Methods: Forty-seven unique samples (39 clinical, 3 derived, 2 reference and 3 commercially available DNA controls) were analyzed. All experiments began with sample extraction, except the lower input limit of detection (LLOD). We evaluated limit of detection, variant calling accuracy, and precision. Two control NIST™ samples were sequenced with 3 technical replicates each for INDEL and SNVs analytical accuracy. The LOD was evaluated at both the target input of 2ng/µl (40ng), and the minimum input,0.33ng/µl (6.6ng) with allele frequency (AF) levels at 1%, 0.5%, and 0.25%. The 39 clinical plasma samples were used for variant calling accuracy. Inter-assay reproducibility was assessed by sequencing DNA controls across four runs by different operators over multiple days/systems. Intra-assay repeatability was assessed by sequencing 4 samples in replicate on the same run by one operator on the same day/system.

Results: The analytical accuracy and NPV was 100% for SNV/INDEL variants. The 40ng input LOD sensitivity was 96% for SNVs at 0.5% AF and 100% for INDELs at 0.25% Minimum AF. The lower input LOD sensitivity was 89% for SNVs and 100% for INDEL at 1% AF. Variant calling accuracy on samples with pre-characterized data was 100% for the 13 positive samples. Specificity was &gt;99% for all samples including both healthy donor and positive samples. Repeatability was 100% for INDELs and &gt;96% for SNVs, reproducibility was 100% for both variant classes.

Conclusion: This validation study to estimate analytical accuracy, limit of detection, variant calling accuracy and precision has demonstrated that the ODxET assay is highly robust in detecting SNV and INDEL mutations in plasma samples and is suitable for use in a CAP/CLIA laboratory as an IUO assay.**=In Vitro Diagnostic use only. Not available in all regions including North America.

Citation Format: Juan C. Espinoza, Rajendra Ramsamooj, Akemi Yuki, John Williamson, Diarra Hassell, Madhu Jasti, Suzanne Salazar, David Ginzinger. Analytical validation of the Oncomine™ Dx Express Test using liquid biopsy samples as an IUO assay in a CAP/CLIA lab [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 5023.