The National Institute for Health and Care Excellence (NICE) has changed its position on NHS funding for Kyowa Kirin International’s Crysvita, now endorsing the drug’s use to treat X-linked hypophosphataemia (XLH) in children and young people with growing bones in England and Wales.

The firm says the positive recommendation “marks a step change in the management of XLH for children and young people, and the first significant clinical advancement for the condition in the last 35 years”.

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 (burosumab) 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 initially rejected funding for the drug, on the basis that data is “limited and uncertain”, particularly relating to young people aged between 13 and 17 years. It also said that while Crysvita can prevent irreversible bone damage, the long-term consequences of disease progression - which the drug may not affect - were uncertain.

The new positive recommendation follows a commercial arrangement for the drug offered by the company, NICE said, also noting that Crysvita meets the criteria for applying a QALY weight because of the number of additional QALYs gained compared with current treatments (estimated at around 15).

Crysvita “is therefore considered to provide value for money,” it concluded.

“This is important news for children and young adults with XLH who will now be able to benefit from Crysvita routinely on the NHS,” said Oliver Gardiner, board member at XLH UK.

“Access to a treatment that tackles the underlying mechanism and has the potential to avoid or mitigate substantial physical and emotional challenges, will truly make a difference to the lives of patients and their families.”

Kyowa has been providing access to Crysvita for eligible patients at no cost, via the UK’s Early Access to Medicines programme. This will now be extended, the group confirmed, to allow time for NHS England to implement the NICE final guidance, enabling a smooth transition to NHS supply in England and Wales.

The annual cost of treatment, based on Crysvita’s list price, is estimated to range from £77,792 for someone aged one to five, and up to £388,960 for a 16/17 year old (up to 60kg).