Pan-TRK immunohistochemistry as screening tool for NTRK fusions: A diagnostic workflow for the identification of positive patients in clinical practice

Article type: Research Article

Authors: Vingiani, Andrea^{a; b; 1} | Lorenzini, Daniele^{a; 1} | Conca, Elena^{a; 1} | Volpi, Chiara Costanza^a | Trupia, Desirè Viola^a | Gloghini, Annunziata^a | Perrone, Federica^a | Tamborini, Elena^a | Dagrada, Gian Paolo^a | Agnelli, Luca^a | Capone, Iolanda^a | Busico, Adele^{a; 2} | Pruneri, Giancarlo^{a; b; 2; *}

Affiliations: [a] Department of Diagnostic Innovation, Foundation IRCCS National Cancer Institute, Milan, Italy | [b] Department of Oncology and Hematoncology, University of Milan, Milan, Italy

Correspondence: [*] Corresponding author: Giancarlo Pruneri, Department of Diagnostic Innovation, Foundation IRCCS National Cancer Institute, 20133, Milan, Italy. Tel.: +39 223902260; E-mail: giancarlo.pruneri@istitutotumori.mi.it.

Note: [1] These authors contributed equally to this work.

Note: [2] Contributed equally to this work.

Abstract: BACKGROUND: Pan-TRK inhibitors Entrectinib and Larotrectinib have been recently approved as tumor-agnostic therapies in NTRK1-2-3 rearranged patients and there is therefore an urgent need to identify reliable and accessible biomarkers for capturing NTRK fusions in the real-world practice. OBJECTIVE: We aim to assess the analytical validity of the recently released pan-TRK assay (Ventana), running a head-to-head comparison between immunohistochemistry and Archer FusionPlex Lung Panel (ArcherDX) that is designed to detect key fusions in 13 genes, also including NTRK1-3. METHODS: Pan-TRK IHC and NGS analysis were conducted on a retrospective/prospective cohort of 124 cancer patients (carcinomas, 93 cases; soft tissue sarcomas, 19; primary central nervous system tumours, 10; and neuroblastomas, 2). FISH data were available in most of the IHC/NGS discordant cases. RESULTS: A comparison between IHC and NGS results was carried out in 117 cases: among 30 pan-TRK positive cases, NTRK rearrangement by NGS was found in 11 (37%), while one of the 87 (1.1%) pan-TRK negative cases (a case of NSCLC) showed a TPM3-NRTK1 rearrangement by NGS. Accordingly, sensitivity and specificity of IHC in predicting NTRK status were 91.7% and 81.9%, respectively, while negative (NPV) and positive predictive value (PPV) were 98.8% and 36.7%, respectively. CONCLUSIONS: These data lead to suggest that IHC with VENTANA pan-TRK antibody can be a reliable screening tool for the identification of patients potentially bearing NTRK rearranged tumours.

Keywords: NTRK, next-generation sequencing, immunohistochemistry, Fluorescent in Situ Ibridization, Biomarker

DOI: 10.3233/CBM-220357

Journal: Cancer Biomarkers, vol. 38, no. 3, pp. 301-309, 2023