For the first time in more than 30 years children and young adults in England and Wales with the rare bone disorder XLH will have access to a new treatment option via the NHS.

The National Institute for Health and Care Excellence has published final guidance recommending use of Kyowa Kirin’s Crysvita (burosumab) within its marketing authorisation, that is for treating X-linked hypophosphataemia (XLH) in children and young people with growing bones.

There are around 250 children and young people in England with XLH, an inherited genetic disorder that causes low levels of phosphate in the blood. This leads to soft, weak bones, and children with the condition usually have bowed or bent legs, short stature, bone pain and delayed walking, and may also have dental problems and hearing loss.

Current treatment mainly consists of vitamin D supplementation and oral phosphate, and is aimed at improving growth, lessening the severity of symptoms and preventing skeletal abnormalities.

Crysvita is an anti-FGF23 fully human monoclonal antibody, and the first treatment to target the underlying pathophysiology of XLH.

An injection given every two weeks from the age of one until the skeleton stops growing, aims to increase reabsorption of phosphate from the kidney and, through vitamin D production, improve intestinal absorption of calcium and phosphate.

NICE’s stamp of approval for the drug “is important news for children and young adults with XLH” as it allows routine access to a treatment “that tackles the underlying mechanism and has the potential to avoid or mitigate substantial physical and emotional challenges,” said Oliver Gardiner, board member at XLH UK.

“This treatment represents a significant improvement for a condition in which there have been no advances in management for 35 years and will be much easier to adhere to compared to current therapy options. It will result in better healing of rickets, linear growth and muscle function among affected individuals,” added Dr Poonam Dharmaraj, chairperson of the British Paediatric and Adolescent Bone Group.

The company has been providing access to Crysvita for eligible patients via the UK’s early access programme, which will now be extended to allow time for NHS England to implement NICE’s guidance, it said.