Clinical Validation of the TruSight Oncology 500 Assay for the Detection and Reporting of Pan-Cancer Biomarkers

The TruSight Oncology 500 (TSO500) High-Throughput Assay is a genomic profiling assay, supported by a bioinformatic analysis pipeline to evaluate somatic single-nucleotide variations/deletions/insertions, gene amplification, microsatellite instability, tumor mutational burden (TMB), gene fusion, and splice variants in solid tumors. This study outlines the approach used by the Genomics Laboratory at the Mayo Clinic to evaluate the technical performance of TSO500. The assessment involved 104 DNA and 223 RNA samples extracted from >20 tumor types. The assay demonstrated robust performance using 40 ng of input DNA and RNA, with slightly improved results observed at 60 ng of input DNA. Tumor percentage significantly influenced assay performance, with all variants being detected at 93% and 85% and above at tumor percentage >50% and >20%, respectively. Precision exceeded 93% across all variant types, including single-nucleotide variations and deletions/insertions with a variant allele frequency of ≥5%. Accuracy was ≥97% for all variant types except for TMB, which was 83.3% when compared with the reference method. Most discordant TMB cases had scores in the range of 8 to 12 mutations per megabase. Overall, the TSO500 assay demonstrated strong performance and reliable accuracy in detecting the evaluated markers.