What patient groups have been tested with sapropterin?

Which patients received sapropterin in clinical studies

Sapropterin has been tested mainly in children and adults with phenylketonuria (PKU) who show some response to the drug. Studies included newborns, toddlers, children, adolescents, and adults with confirmed BH4-responsive PKU.

What age ranges and phenotypes were covered

Age groups ranged from newborns under one week old to adults over 50. Tested phenotypes included classic PKU, mild PKU, and mild hyperphenylalaninemia.

How many patients and what trials supplied the data

Key trials enrolled several hundred patients across the PKU-001, PKU-003, and PKU-004 studies, plus extension phases. These covered short-term efficacy, long-term safety, and growth outcomes in young children.

How does sapropterin work in tested groups

Sapropterin acts as a synthetic form of tetrahydrobiopterin (BH4), helping the deficient phenylalanine hydroxylase enzyme in responsive patients to lower blood phenylalanine levels.

What happened if patients were non-responsive

Non-responsive patients showed no meaningful drop in blood phenylalanine after one month of treatment. Studies therefore focused only on those who responded after an initial test dose.

Can sapropterin be used in infants and newborns

Yes. Data from infants as early as a few days old showed that the drug was well tolerated and maintained growth parameters.

What side effects were patients in these groups reported asking about

Patients and families asked about gastrointestinal upset, headache, and nasal congestion. These occurred at rates similar to or higher than placebo in some studies.

Who makes sapropterin and when does patent expire

BioMarin manufactures sapropterin under the brand Kuvan. Patents expired in Europe in 2017 and the U.S. patent main compound protection ended around 2020, allowing biosimilar entry.