NTRK1 and cancer: Neurotrophic tyrosine receptor kinase (NTRK) genes encode tropomyosin receptor kinase (Trk) proteins that help regulate pain, proprioception, appetite, and memory.1,2 Chromosomal rearrangements of NTRK genes are found across diverse tumor types that occur in children and adults leading to Trk fusion proteins in less than 1% of all solid tumors.2,3 Larotrectinib and Entrectinib are both highly selective Trk inhibitors that are FDA approved for the treatment of NTRK gene fusion positive cancers across all solid tumor types.