Larotrectinib (VITRAKVI®) is an orally administered, small molecule, highly-selective, tropomyosin receptor kinase (TRK) inhibitor that was developed by Loxo Oncology in collaboration with Bayer AG as a treatment for adult and paediatric patients whose cancers harbour neurotrophic receptor tyrosine kinase (NTRK) gene fusions. In November 2018 larotrectinib received its first global approval in the USA for the treatment of adult and paediatric patients with solid tumours that have a NTRK gene fusion without a known acquired resistance mutation, are metastatic or where surgical resection is likely to result in severe morbidity, and have no satisfactory alternative treatments or that have progressed following treatment. A registration application for the use of larotrectinib in paediatric and adult patients with locally advanced or metastatic solid tumours with NTRK gene fusion proteins has been submitted in the EU. This article summarizes the milestones in the development of larotrectinib leading to its first approval for the treatment of adult and paediatric patients with solid tumours that have NTRK gene fusion.