Comparison of NTRK fusion detection methods in microsatellite-instability-high metastatic colorectal cancer

AbstractTropomyosin receptor kinase (TRK) inhibitors have been approved for metastatic solid tumors harboringNTRK fusions, but the detection ofNTRK fusions is challenging. International guidelines recommend pan-TRK immunohistochemistry (IHC) screening followed by next generation sequencing (NGS) in tumor types with low prevalence ofNTRK fusions, including metastatic colorectal cancer (mCRC). RNA-based NGS is preferred, but is expensive, time-consuming, and extracting good-quality RNA from FFPE tissue is challenging. Alternatives in daily clinical practice are warranted. We assessed the diagnostic performance of RNA-NGS, FFPE-targeted locus capture (FFPE-TLC), fluorescence in situ hybridization (FISH), and the 5 ′/3′ imbalance quantitative RT-PCR (qRT-PCR) after IHC screening in 268 patients with microsatellite-instability-high mCRC, the subgroup in whichNTRK fusions are most prevalent (1 –5%). A consensus result was determined after review of all assay results. In 16 IHC positive tumors, 10NTRK fusions were detected. In 33 IHC negative samples, no additional transcribedNTRK fusions were found, underscoring the high sensitivity of IHC. Sensitivity of RNA-NGS, FFPE-TLC, FISH, and qRT-PCR was 90%, 90%, 78%, and 100%, respectively. Specificity was 100% for all assays. Robustness, defined as the percentage of samples that provided an interpretable result in the first run, was 100% for FFPE-TLC, yet more limited for RNA-NGS (85%), FISH (70%), and qRT-PCR (70%). Overall, we do...
Source: Virchows Archiv - Category: Pathology Source Type: research