NTRK1 and neoplasm: TRK inhibitors have been recently approved for tumors with NTRK (neurotrophic tyrosine receptor kinase 3 gene) fusions, which are rare but are detected in multiple tumor types including salivary gland, thyroid, colon, lung, gastrointestinal stroma, appendix, breast, pancreas, sarcoma, melanoma and cholangiocarcinoma with NTRK gene fusions, showing highly positive results with larotrectinib treatment [3].