gene amplification in patients with metastatic cancer

Purpose Neurotropic tropomyosin receptor kinase (NTRK) fusions have been identified in a variety of cancers, and tyrosine kinase inhibitors targeting the tropomyosin receptor kinase (TRK) receptor are currently in clinical trials. However, no reports are available on the effects of NTRK gene amplification. Methods Samples from patients enrolled in the sequencing program were analyzed using a next-generation sequencing (NGS) cancer panel. For cases in which NTRK amplification (defined as ≥ 4.0 copies) was identified, panTRK immunohistochemical (IHC) staining of tissue microarrays was performed. Results A total of 1,250 tumor specimens collected between February 2014 and January 2016 were analyzed using the NGS cancer panel. NTRK amplification was detected in 28 cases of various types of cancer. Among 27 cases, only four were positive for pan-TRK IHC. These four cases were melanoma, sarcoma, lung cancer, and gastric cancer. We found that 2.2% of cancer patients showed NTRK amplification using NGS cancer panel and NTRK amplification resulted in protein overexpression in 14.8% of these patients. Conclusion Patients with NTRK amplification and increased TRK protein expression may be considered for inclusion in clinical trials for NTRK inhibitors.