The National Institute for Health and Care Excellence (NICE) has issued final draft guidance recommending BioMarin’s Kuvan (sapropterin) as an option for treating phenylketonuria (PKU) in pregnant women until they give birth, as well as for treating the condition in people until they turn 22.

PKU, a chronic and life-long metabolic condition caused by the deficiency of an enzyme which breaks down phenylalanine, is currently treated by a lifetime adherence to a severely protein-restricted diet.

Following public consultation on NICE’s previous draft guidance, which recommended Kuvan for children up to 18 years old, the committee agreed that PKU is a particular concern if poorly controlled during pregnancy because it can cause severe congenital defects in unborn children.

The new recommendation could allow women to have Kuvan earlier in their pregnancy with potentially better outcomes for their unborn children. The committee acknowledged that Kuvan could prevent long-term irreversible brain damage in children, because childhood is the most critical period for brain development.

Kuvan is now also recommended for people aged from 18 until they turn 22 to cover brain development and transition into adulthood.

Weight-based dosing of Kuvan means the costs are higher for adults. This, plus uncertainties about the extent to which it reduces reliance on a protein-restricted diet, means the cost-effectiveness estimates are substantially higher for adults aged 22 and above that which NICE considers an acceptable use of NHS resources.