Table 1 NTRK1-3 Testing Methodologies
Reverse transcriptase-polymerase chain reaction (RT-PCR) | â–ª Variable sensitivity â–ª High specificity | â–ª Fusion detection requires specific primers targeting suspected genes and exons â–ª Hindered by RNA degradation |
|---|---|---|
RNA based NGS alone | â–ª Ability to access for unknown fusion partners, including other oncogenic alterations as well as splice variants | â–ª Hindered by RNA degradation |
DNA-based NGS alone | â–ª Access for point mutations, fusions, and copy number changes â–ª Limited sensitivity to detect NTRK3 fusions | â–ª Reliant on decent tumor purity |
Dual DNA/RNA based NGS | â–ª Superior analysis while likely being the most expensive methodology | â–ª Reliant on decent tumor purity |
Fluorescent in situ hybridization (FISH) | ▪ Comparable turn-around time (approximately 1–3 days) compared to IHC ▪ Designed to detect specific breakpoints | ▪ Best utilized when there is high suspicion of ETV6-NTRK3 fusions |
Pan-TRK IHC | â–ª Ability to screen for NTRK1-3 fusions while remaining cost effective | â–ª Limited specificity â–ª Detects physiologic wild-type TRK expression |