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Gregory J. Riely, MD, PhD


Comparing the Performance of Pan-TRK Antibody Clones and Immunohistochemistry Assays

By: Julia Fiederlein Cipriano
Posted: Thursday, April 6, 2023

Although NTRK testing is frequently used to inform clinical decision-making in patients with advanced cancers, the choices of antibodies and pan-TRK immunohistochemistry protocols are not standardized. Chantal Pauli, MD, of the University Hospital Zurich, and colleagues conducted a study to compare the performance of different pan-TRK antibody clones and assays. Their findings, which were published in the journal Histopathology, highlight the potential challenges of employing this laboratory procedure in routine diagnostics.

“Despite immunohistochemistry being a fast and affordable tool, using it in routine diagnostics is complicated and requires a high level of expertise,” the investigators commented. “The potential cost increase due to low specificity, particularly in the presented subgroups, and the chance to miss cases, primarily with NTRK3 rearrangements, have to be discussed to generate awareness.”

Using EPR17341, EP1058Y, and A7H6R clones, the investigators studied the performance of 4 pan-TRK immunohistochemistry methods in 22 molecularly confirmed NTRK-rearranged tumors. Comparisons with selected NTRK gene fusion–negative tumors were performed: NTRK-mutated tumors (n = 8); NTRK-amplified tumors (n = 15); tumors driven by other gene fusions, such as ALK, ROS1, and BCOR (n = 20); and salivary gland tumors (n = 16). All of the NTRK1/2/3-rearranged tumors were positively detected by immunohistochemistry with the EPR17341 clone; this did not seem to hold true for NTRK2/3-rearranged tumors with the other clones. In NTRK gene fusion–negative tumors, false-positive staining was seen the least frequently using the A7H6R clone.

Disclosure: For full disclosures of the study authors, visit

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