Recently, adult and childhood cancers driven by novel chimeric TrkA-fusion oncogenes have been reported to exhibit profound and long-lived therapeutic responses to the Trk inhibitor Larotrectinib [18], highlighting a need to improve clinical detection of cancers driven by activated TrkA oncogenes in order to take full advantage of novel Trk-inhibitory therapies [13–18]. The gene discussed is NTRK1; the disease is cancer.