US-based global biopharmaceutical company PTC Therapeutics, Inc. (NASDAQ: PTCT) announced on Monday that the US FDA has set a target action date of 29 July 2025, for the review of its New Drug Application (NDA) for sepiapterin.

The application seeks approval for the treatment of paediatric and adult patients with phenylketonuria (PKU) across all age groups and disease subtypes. The NDA includes data from the Phase 3 APHENITY trial, recently published in The Lancet, as well as ongoing data from the APHENITY open-label extension study.

Sepiapterin, an oral synthetic compound, has a dual mechanism that enhances the activity of the phenylalanine hydroxylase (PAH) enzyme. This mechanism helps reduce blood phenylalanine levels, offering potential treatment for a broad range of PKU patients. Results from the Phe tolerance assessment show that around 60% of subjects can increase protein intake while maintaining safe phenylalanine levels. PKU is a rare genetic metabolic disorder affecting brain function, with approximately 58,000 individuals affected worldwide.