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Author Spotlight: Unlocking Insights into the Immune Cell Landscape of Tumors
Published on: August 18, 2023
A systematic comparison of pan-Trk immunohistochemistry assays among multiple cancer types
Martina Haberecker1, Antonia Töpfer1, Francesca Melega1
1Department of Pathology and Molecular Pathology, University Hospital Zurich, Zurich, Switzerland.
Aims:
NTRK rearranged tumours are rare but can be successfully treated using anti-TRK-targeted therapies, making NTRK testing important for treatment choices in patients with advanced cancers. Pan-Trk immunohistochemistry (IHC) has become a valuable and affordable screening tool in many laboratories. Unfortunately, the choice of antibodies and IHC protocols to investigate biomarkers is not standardised. In this study, we compared the performance of four pan-Trk IHC methods, using three different clones, primarily in NTRK fusion-positive tumours.
Methods And Results:
We studied the performance of four pan-Trk IHC methods using three different clones: EPR17341 (Abcam and Ventana), EP1058Y (Abcam) and A7H6R (Cell Signaling) in 22 molecularly confirmed NTRK rearranged tumours. Additionally, selected NTRK fusion-negative tumours were further included: NTRK mutated (n = 8) and amplified (n = 15) tumours as well as NTRK fusion-negative tumours driven by other gene fusions, such as ALK, ROS1 and BCOR (n = 20), as well as salivary gland tumours (n = 16). Inter-rater agreement of three pathologists was additionally calculated, including H-score. With clone EPR17341 (Abcam in-house and ready-to-use Ventana protocol), all molecularly confirmed NTRK1-3 rearranged tumours were positively detected by immunohistochemistry, while the other clones missed NTRK2-3 rearranged tumours. For the fusion-negative cohort we found the best performance (least false-positive cases) using the clone A7H6R (Cell Signalling).
Conclusion:
Given the therapeutic importance, testing for NTRK rearrangements in daily practice has become necessary and, despite IHC being a fast and affordable tool, using it in routine diagnostics is complicated and requires a high level of expertise.
Insights
Testing for NTRK rearrangements is crucial for advanced cancer treatment. The EPR17341 pan-Trk immunohistochemistry (IHC) clone accurately detected all NTRK fusions, while A7H6R showed the best specificity in fusion-negative cases.
Area of Science:
- Oncology
- Molecular Pathology
- Cancer Diagnostics
Background:
- NTRK rearrangements are rare but targetable in advanced cancers.
- Pan-Trk immunohistochemistry (IHC) is a valuable screening tool for NTRK fusions.
- Standardization of IHC methods and antibody selection is lacking.
Purpose of the Study:
- To compare the diagnostic performance of four pan-Trk IHC methods using three different antibody clones.
- To evaluate IHC accuracy in detecting NTRK rearrangements in fusion-positive and fusion-negative tumors.
Main Methods:
- Evaluated four pan-Trk IHC methods with clones EPR17341, EP1058Y, and A7H6R.
- Tested on 22 molecularly confirmed NTRK rearranged tumors.
- Included fusion-negative tumors (mutated, amplified, other fusions) and salivary gland tumors.
Main Results:
- Clone EPR17341 (Abcam/Ventana) detected all NTRK1-3 rearranged tumors.
- Other clones (EP1058Y, A7H6R) missed some NTRK2-3 rearranged tumors.
- Clone A7H6R (Cell Signaling) demonstrated the best specificity with the fewest false positives in fusion-negative cases.
Conclusions:
- Pan-Trk IHC is essential for identifying NTRK fusions in advanced cancers.
- Clone EPR17341 offers high sensitivity for NTRK rearrangements.
- Clone A7H6R provides good specificity for ruling out fusions in negative cases.
- Routine IHC diagnostics for NTRK rearrangements require expertise due to protocol variations.
