HQ Team
July 29, 2025: The US Food and Drug Administration cleared PTC Therapeutics’ sepiapterin for treating children and adults with a rare genetic condition where the body cannot break down a part of protein called phenylalanine, which comes from foods like meat, eggs, and milk.
The FDA approval is based on evidence of significant efficacy and safety from an end-stage trial, as well as the durability of the treatment effect in a long-term extension study, according to a company statement.
Branded as Sephience, the regulator’s nod for the medicine includes broad labelling for the treatment of hyperphenylalaninemia in adult and pediatric patients one month of age and older living with sepiapterin-responsive phenylketonuria (PKU).
“The broad labelling reflects the potential of Sephience to meet the significant unmet need of PKU patients,” said Matthew B. Klein, MD, Chief Executive Officer of PTC Therapeutics.
“The clinical data, along with our expertise in launching rare disease therapies, position Sephience to become the future standard of care.”
Japan, Brazil
The European Commission recently granted Sephience marketing authorisation. Review of approval applications is ongoing in several other countries, including Japan and Brazil.
“The approval marks an exciting milestone for the PKU community,” said Catherine Warren, Executive Director of the National PKU Alliance.
“This progress brings renewed hope, and we are eager to see the positive impact this new treatment option will have on advancing care and potentially improving quality of life for individuals of all ages and PKU subtypes that respond to this therapy.”
Phenylketonuria is a rare inherited genetic disorder characterised by the body’s inability to properly break down the amino acid phenylalanine due to a deficiency or malfunction of the enzyme phenylalanine hydroxylase.
This enzyme normally converts phenylalanine into other compounds needed by the body. When this enzyme is lacking or defective, phenylalanine accumulates in the blood and brain to toxic levels, which can lead to intellectual disability, seizures, behavioural problems, and other mental disorders if untreated.
58,000 people globally
PKU, a metabolic disease, is caused by mutations in one of the genes, inherited in an autosomal recessive pattern, meaning a person needs two mutated copies of the gene to develop the condition.
It is usually diagnosed shortly after birth through newborn screening programs. Treatment involves a lifelong diet low in phenylalanine, which helps prevent brain damage and allows affected individuals to live healthy lives.
Babies are tested soon after birth, and if they have PKU, they must follow a special diet low in phenylalanine to stay healthy and avoid learning problems or brain damage.
There are an estimated 58,000 people with phenylketonuria globally, according to PTC Therapeutics. Males and females are equally likely to inherit the defective gene and develop phenylketonuria.
