The European Commission has approved an expanded indication for Crysvita (burosumab), allowing the therapy to be used in infants aged one month to one year with X-linked hypophosphataemia (XLH) across the European Union and European Economic Area.
The approval, announced by Kyowa Kirin EMEA, broadens access to the treatment for one of the youngest patient populations affected by the rare genetic disorder and marks an important milestone in the management of XLH, where early intervention is considered critical to improving long-term outcomes.
Until now, treatment options for infants diagnosed with XLH have been limited. The expanded indication enables healthcare professionals to begin treatment earlier, potentially helping to reduce disease progression during a crucial stage of skeletal development.
XLH is a rare, lifelong inherited disease caused by excessive phosphate loss through the kidneys. Low phosphate levels impair normal bone mineralisation, resulting in weak bones, skeletal deformities, poor growth, bone pain, muscle weakness, and other serious complications. Because symptoms can begin during infancy, delays in treatment may allow irreversible skeletal abnormalities to develop as children grow.
The European Commission’s decision follows a positive opinion issued in April 2026 by the European Medicines Agency’s Committee for Medicinal Products for Human Use (CHMP), which recommended extending the indication after reviewing clinical evidence supporting the therapy’s use in infants.
The approval is based on results from the Phase 1/2 BUR-CL207 study, an open-label, multicentre clinical trial evaluating the safety, tolerability, pharmacokinetics, and efficacy of burosumab in children from birth to one year of age diagnosed with XLH.
According to Kyowa Kirin, the study showed that the treatment’s safety profile in infants was consistent with the well-established safety profile already observed in older children and adults receiving Crysvita. These findings provided regulators with confidence that the therapy could be safely introduced earlier in life.
Myriam Hakim, Regional Franchise Head at Kyowa Kirin EMEA, said the approval represents an important advance for patients and their families.
“For families affected by XLH, the impact of the disease can begin in the earliest months of a child’s life,” Hakim said. “Healthcare professionals can now consider treatment with burosumab from as young as one month of age, creating an opportunity to address the disease earlier than ever before. This is an important step forward for infants living with XLH and the families who care for them.”
Medical experts also welcomed the expanded indication, highlighting the importance of treating the disease before significant skeletal damage occurs.
Professor Agnès Linglart of AP-HP and Paris Saclay University said XLH is a progressive disorder in which disease manifestations often begin during infancy, affecting bone development from the earliest stages of life.
“The approval of a treatment option for infants is an important milestone because it enables evidence-based therapy to begin earlier in the course of the disease,” Linglart said. “The goal is to limit disease progression and improve long-term patient outcomes.”
Beyond expanding treatment access, the European Commission’s decision also provides additional regulatory benefits for the therapy. The approval qualifies Crysvita for a two-year extension of orphan market exclusivity in the European Union for XLH, extending its regulatory protection from February 2028 to February 2030.
Crysvita is already approved in multiple countries for the treatment of XLH in eligible pediatric and adult patients. By extending its use to infants as young as one month old, European regulators have further strengthened treatment options for a disease where early diagnosis and timely intervention can have a lasting impact on growth, bone health, and overall quality of life.
The latest approval reinforces the growing emphasis on early management of rare genetic disorders and is expected to help clinicians intervene before permanent skeletal complications develop, offering new hope to infants diagnosed with XLH and their families.