IHC is widely available, inexpensive, and efficient in terms of the amount of tissue required and has a fast turnaround time (typically within 24 hours).
Several recent studies suggest that pan-TRK IHC is a sensitive technique for detecting NTRK gene fusions [1-3]. Sensitivity was 93%–97% for infantile fibrosarcoma , paediatric mesenchymal tumours , and solid tumours . Another study reported a lower overall sensitivity of 75% across common solid tumours . However, concordance between IHC and RNA-based NGS (Archer fusion assay) was 88%–89% for NTRK1 and NTRK2 gene fusions, compared with 55% for NTRK3 gene fusions .
The advantages of IHC are summarised in the following table.
Table 19: Advantages of IHC for Testing of NTRK Gene Fusions
- Hechtman JF, Benayed R, Hyman DM et al. Pan-Trk Immunohistochemistry Is an Efficient and Reliable Screen for the Detection of NTRK Fusions. Am J Surg Pathol 2017; 41: 1547-1551.
- Hung YP, Fletcher CDM, Hornick JL. Evaluation of pan-TRK immunohistochemistry in infantile fibrosarcoma, lipofibromatosis-like neural tumour and histological mimics. Histopathology 2018; 73: 634-644.
- Rudzinski ER, Lockwood CM, Stohr BA et al. Pan-Trk Immunohistochemistry Identifies NTRK Rearrangements in Pediatric Mesenchymal Tumors. Am J Surg Pathol 2018; 42: 927-935.
- Gatalica Z, Xiu J, Swensen J, Vranic S. Molecular characterization of cancers with NTRK gene fusions. Mod Pathol 2019; 32.