Neurotrophic tropomyosin receptor kinase (NTRK) and nerve growth factor (NGF) are not expressed in Caucasian patients with biliary tract cancers: pooled data from three independent cohorts

Background: Neuronal signaling has been implicated in the pathophysiology of multiple malignancies. In biliary tract cancers (BTCs), tumor cell expression of nerve growth factor (NGF) and its receptor neurotrophic tropomyosin receptor kinase (NTRK) has been reported in Asian patients and linked to inferior clinical outcome. Furthermore, NTRK fusions have emerged as a promising target in various cancers. Expression patterns of these markers in Caucasian patients remain unknown. Methods: In this study, 106 patients with BTCs were included. Immunohistochemistry for pan-NTRK and NGF-beta was performed on > 90 samples of this cohort. Additionally, samples from two independent cohorts, incorporating 254 cases, were used to confirm the findings of the original cohort. Results: While expression of pan-NTRK and NGF-beta was readily detectable in peri-tumoral nerves, these markers were not detectable in malignant epithelial cells in our cohort. Conclusions: In a large cohort of Caucasian patients with BTC, NTRK and NGF-beta were not detectable, underscoring potential differences between Caucasian and Asian patient populations.