Neurotrophic tyrosine kinase (NTRK) is a family of receptor tyrosine kinase.The NTRK gene family contains three members, NTRK1, NTRK2 and NTRK3, which produce TRKA, TRKB and TRKC proteins, respectively.TRK kinases leads to cell differentiation and may play important roles in normal neural functions.Rearrangements in the NTRK genes can result in two genes fusing together and producing altered TRK proteins, which can lead to uncontrolled growth of cancer cells. Neurotrophic tyrosine receptor kinase (NTRK) gene fusions are an actionable biomarker for cancer therapy and can be found in over 25 different types of cancer.