Abstract 5452: Complimentary use of DNA- and RNA-based NGS assays optimizes detection of clinically relevant translocations for comprehensive genomic profiling
Authors: Ren Rongqin , Jackson Jennifer , Kames Jacob , Riles David , Coldren Christopher , Wheeler Scott , Chandra Pranil , Shiller Michelle 
Published: June 2023

Introduction: Detection of gene translocations is a key component of clinical diagnostics to enable precision medicine in oncology. Several methods such as fluorescence in situ hybridization or RT-PCR have historically been employed, however, next-generation sequencing (NGS)-based comprehensive genomic profiling (CGP) including DNA and RNA sequencing approaches have been validated for this purpose. Here we explore the complimentary nature of these methods to enable detection of clinically relevant translocations to guide patient care.

Methods: We utilized Endeavor, a 505 gene DNA-based CGP assay developed by Personal Genome Diagnostics, to assess single nucleotide variants, insertion/deletions, amplifications, translocations, microsatellite instability, and tumor mutation burden as well as a 53 gene RNA-based Invitae NGS FusionPlex Solid Tumor v1 assay. 151 patients with advanced or metastatic solid tumors, including lung, colorectal, esophageal, breast, brain, bladder, and prostate cancers, were consecutively enrolled and only overlapping target regions were evaluated to compare performance.

Results: Of the 151 cases selected for the study, failure rates were 2.0% and 9.9% for Endeavor and FusionPlex, respectively. Translocations were detected in 21/151 (13.9%) cases by Endeavor and 17/105 (11.3%) cases by FusionPlex. For the 133 cases where data was available from both assays, 12 (9.0%) concordant translocation positive cases were detected involving ALK, RET, NTRK1, NTRK3, MET exon 14 skipping, EGFRvIII, and EWSR1 with 109 (82.0%) cases translocation negative by both assays achieving a concordance rate of 91%. For 7 (5.3%) cases, Endeavor detected translocations events in FGFR1, FGFR2, ETV4, ETV6, MYC, and NTRK3 that were not detected by FusionPlex. Conversely, FusionPlex identified 5 (3.8%) cases with translocations in ROS1, NTRK2, and EGFRvIII that were not detected by Endeavor (Table 1). Discrepancies in translocation detection were attributed to variability in assay failure rates, panel design, and underlying biological differences in detectability associated with DNA- and RNA-based methods.

Conclusions: In this study, comparison of translocation detection using DNA and RNA-based NGS approaches revealed a high concordance between the two assays and were equally valuable for identifying actionable targets. These findings provide confirmatory support for the complimentary use of DNA- and RNA-based NGS approaches to most accurately identify clinically relevant translocations thereby providing more comprehensive results to help guide cancer treatment strategies.

Citation Format: Rongqin Ren, Jennifer Jackson, Jacob Kames, David Riles, Christopher Coldren, Scott Wheeler, Pranil Chandra, Michelle Shiller. Complimentary use of DNA- and RNA-based NGS assays optimizes detection of clinically relevant translocations for comprehensive genomic profiling. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 5452.