Burosumab (Crysvita®; Kyowa Hakko Kirin Co., Ltd. and Ultragenyx Pharmaceutical 
Inc.) is a fully human monoclonal antibody directed at fibroblast growth factor 
23 (FGF23). Excessive FGF23 production has been implicated in various 
hypophosphataemic diseases. Inhibition of FGF23 by burosumab results in 
increased renal phosphate reabsorption and increased serum levels of phosphorus 
and active vitamin D. In February 2018, the EMA granted subcutaneous burosumab 
conditional marketing authorization for the treatment of X-linked 
hypophosphataemia (XLH) with radiographic evidence of bone disease in children 
one year of age and older and adolescents with growing skeletons. In April 2018, 
the US FDA approved burosumab for the treatment of XLH in adults and children 
one year of age and older. Multinational phase III trials of burosumab are 
currently underway in adult and paediatric patients with XLH. Burosumab is also 
being evaluated in the phase II setting in adults with tumour-induced 
osteomalacia and epidermal nevus syndrome in the USA, as well as in Japan and 
Korea. This article summarizes the milestones in the development of burosumab 
leading to its first global approval in the EU for XLH in paediatric patients.