Abstract 3819: Validation of TruSight Oncology Comprehensive for detecting and reporting clinically relevant mutations

Abstract Comprehensive genomic profiling (CGP) is transforming cancer diagnostics by enabling the detection of a wide range of actionable biomarkers and immunotherapy response signatures in a single test. TruSight Oncology Comprehensive (TSO Comp) is a qualitative in vitro diagnostic test that evaluates both DNA and RNA from formalin-fixed, paraffin-embedded (FFPE) tissue and analyzes 517 cancer-associated genes with known clinical relevance in one integrated workflow. This study presents the verification and validation of TSO Comp with added laboratory developed test (LDT) claims by conducting accuracy, analytical specificity, and precision (inter and intra run repeatability) studies. Assay performance was assessed using 19 cell lines, contrived and Seraseq® reference materials, and 41 clinical samples to detect the following variant classes: small variants (SNVs, MNVs and indels), fusions/splice variants, Tumor Mutational Burden (TMB), Copy Number Variants (CNVs), and Microsatellite Instability (MSI). The latter two, along with 31 additional fusions and two additional splice variants, were validated as part of the LDT. Overall, the study resulted in 99.4% positive percent agreement (PPA) rates and 99.9% negative percent agreement (NPA) rates for small variants. 100% PPA was estimated across 17 CNVs, 41 fusions/splice variants, and two MSI positives. Furthermore, 100% NPA was estimated for all evaluated samples considered for CNV, fusions/splice variants, and MSI status. TMB scores between reference results and TSO Comp were highly correlated, with R2 = 0.97. The LoD for CNVs resulted in 100% detection rates for ≥ 2.6 fold change (i.e., 5 copies) in gene amplification when measured across five replicates of four clinical samples. Three contrived cell lines with replicates were used to establish the LoD of 20% tumor content for MSI. In addition, 23 healthy donor samples resulted in 100% analytical specificity for CNV and MSI. All variants and MSI status resulted in ≥ 98.8% inter and intra runs concordance across nine clinical and one Seraseq reference material with replicates.This study demonstrates how TSO Comp can be extended to include additional variant claims with high sensitivity and specificity as an LDT while maintaining clinical interpretation and reporting of cancer mutations central to the CGP of FFPE. Indeed, TSO Comp significantly reduces the burden of validating certain variant classes (e.g. study size was reduced by a minimum factor of two) and allows laboratories to validate and report on additional claims as cancer diagnostics knowledge evolves. Citation Format: Mauro Chavez, Silvia Chan, Stewart Comer, Gajalakshmi Dakshinamoorthy, Dan Schmidt, Giang Howard, Lisa Tulathimutte, Martin Martchovsky, Carey Davis, Eileen de Feo, Denise Perry. Validation of TruSight Oncology Comprehensive for detecting and reporting clinically relevant mutations abstract. In: Proceedings of the American Association for Cancer Research Annual Meeting 2026; Part 1 (Regular Abstracts); 2026 Apr 17-22; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2026;86(7 Suppl):Abstract nr 3819.