Effective Dosing of Burosumab in XLH

Recruiting now

Conditions studied: X-linked Hypophosphatemia (XLH)

In brief

X-linked hypophosphataemia (XLH) is a rare, hereditary condition. The genetic defect leads to low blood phosphate levels and vitamin D suppression. Phosphate is required for strong bones and teeth and to store energy in cells. Low phosphate leads to soft bones (rickets). Patients experience bowed legs, short stature, bone pain and dental pain. Prior to Burosumab, conventional treatment of XLH previously consisted of two medications. On this regimen, patients take oral phosphate supplements 4-6 times a day and an active form of vitamin D daily. This treatment can leave patients with residual symptoms. They report significant disabilities and reduced quality of life. Burosumab (Crysvita, Kyowa Kirin) is now the standard paediatric treatment for XLH. It is given once a fortnight by injection under the skin. Early studies used a starting dose of 0.4mg/kg per dose. NICE recommends a starting dose of 0.4mg/kg, a normal maintenance dose of 0.8mg/kg and a maximum of 2mg/kg (up to 90mg). The British National Formulary for Children (BNFC) gives the same advice. However, the European Medicines Agency recommends a starting dose of 0.8mg/kg per dose which is, therefore, the standard starting dose now. Some patients achieve symptom and biochemical control on less than 0.8 mg/kg per dose. They may be exposed to higher doses than necessary. To date, approximately 200 patients have started on Burosumab in England. They are all managed by specialist centres. The rare status of XLH means there are relatively few patients in each centre. Treatment effects and trends can only be described by collating data from multiple centres. The investigators will undertake a review across multiple English centres of the doses of Burosumab. The review will only collect data already in the patients' health records. It will look at factors affecting the starting dose. The investigators will assess the association between dose, blood markers and growth.

Key facts

Study ID

NCT07183579

Run by

University of Nottingham

People needed

120

Starts

2025-11-03

Expected to finish

2026-07-01

Last updated by the study team

2026-05-11

Who can join

Age: 2 and older, up to 18. Sex: any. Healthy volunteers: not accepted.

You may qualify if…

• A diagnosis of x-linked hypophosphataemia (XLH) including genetic confirmation of a PHEX mutation.
• Has received at least 12 months of continuous Burosumab treatment under paediatric criteria (given Burosumab is not started till a child is 12 months old in England, the minimum age will, therefore, be 2 years old) prior to their 18th birthday.

You may not qualify if…

• Burosumab received under adult criteria (patients who have received both Burosumab under paediatric arrangements and, subsequently, adult arrangements, can have data obtained during paediatric dosing included).

Where it is running

• Nottingham University Hospitals NHS Trust — Nottingham, United Kingdom (enrolling)

Full record on ClinicalTrials.gov

Trial information comes from ClinicalTrials.gov and is refreshed daily. TrialsForMe does not provide medical care and does not run the studies it lists.