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Reassessing NTRK Testing in Patients With Bone Tumors

By: Joseph Fanelli
Posted: Thursday, August 12, 2021

The chance of finding a neurotrophic tyrosine kinase receptor (NTRK) fusion in bone tumors in clinical practice is “extremely low,” according to the findings of a short report presented in the journal Histopathology. Thus, if more comprehensive, large-scale molecular studies confirm these results, Judith V.M.G. Bovée, PhD, of Leiden University Medical Center, The Netherlands, and colleagues believe routine, predictive NTRK testing in patients with bone tumors and advanced disease should be reconsidered.

In this study, the authors used immunohistochemical expression of pan-Trk to assess 354 primary bone tumors using tissue microarrays. In positive cases, the authors performed additional molecular analysis for NTRK fusion analysis in a large series of primary bone tumors.

The authors found positivity for NTRK fusion in 19 samples (5%), including Ewing sarcoma (6 cases), osteosarcoma (11 cases), and giant cell tumor of bone (2 cases). In all but one case, cytoplasmic staining was observed.

Although weak staining was most often found among the samples (13 cases), the authors found 5 cases of moderate staining and 1 case of focal strong staining. Molecular analysis was successful in six cases, with all reporting NTRK fusion negativity.

Disclosure: For full disclosure of the study authors, visit

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