NHS cost regulators are planning to reject Alexion’s therapy for an ultra-rare bone disorder called paediatric-onset hypophosphatasia, which affects just seven people a year in England.

HPP is a progressive, genetic condition characterised by defective bone mineralisation that can lead to destruction and deformity of bones, profound muscle weakness, seizures, respiratory failure and premature death.

Juvenile and adult-onset forms of HPP have much lower mortality rates than those appearing in infancy, where 100% of those diagnosed in the first six months of their lives die before they reach one year. But later forms are often linked with debilitating and lead to bone deformities that may result in delayed walking, limb weaknesses, skeletal pain and non-traumatic fractures. 

The current mainstay of treatment is supportive care aiming to monitor and alleviate symptoms, and the enzyme replacement therapy Strensiq (asfotase alfa) is the first treatment to specifically target the underlying cause of the disease. 

NICE’s Committee concluded that the treatment improved the probability of survival in perinatal- and infantile-onset hypophosphatasia compared with best supportive care. It also agreed that Strensiq was likely to be clinically effective across a range of outcomes, including reducing the need for respiratory support and the severity of rickets in perinatal- and infantile-onset forms, and improving growth and mobility and reducing pain in juvenile-onset HPP.

But the Committee “was unable to estimate from the clinical evidence the precise size of these benefits that are relevant for patients in the longer term,” and “was not satisfied that the company had provided an adequate justification for the high cost per person of asfotase alfa, or for the overall cost to the NHS in terms of what could be expected to be reasonable in the context of a highly specialised service”.

The total cost per person per year of treatment is a whopping £366,912 (assuming an average weight of 19.3 kg and 100% adherence). Given its high cost and uncertain benefit, the Institute says does not represent value for money for the NHS.