In November 2018, larotrectinib was approved by the FDA for treatment of patients with solid tumors that have a neurotrophic receptor tyrosine kinase (NTRK) gene fusion. NTRK gene fusions are most commonly seen in salivary gland tumors, soft tissue sarcoma and thyroid cancer. Larotrectinib is an oral medicine that inhibits proteins encoded by the NTRK genes. The response rate of this medicine was 75%, often with a durable response. The most common side effects were fatigue, nausea, dizziness, diarrhea and anemia. This NTRK gene should now be evaluated in most patients’ tumors, although the likelihood of it being mutated is relatively low.