Long-Term Safety Study of JNT-517 for Treating Phenylketonuria in Children and Adults

What this Trial Is About

Researchers are evaluating the long-term safety of JNT-517 in children and adults with Phenylketonuria PKU, a condition caused by a deficiency in the PAH enzyme. This Phase 3, open-label study includes participants who completed previous JNT-517 studies as well as those new to JNT-517 treatment. The goal is to understand how the drug performs over an extended period when used consistently in this population. All participants will receive JNT-517 orally twice daily with doses adjusted for age and weight. The study will follow a fixed dosing schedule regardless of prior exposure to JNT-517. Participants will be monitored for treatment-emergent adverse events and changes in blood and urine phenylalanine levels, dietary intake, and attention-related symptoms among children previously treated. Participants will attend regular visits for safety assessments, blood tests, dietary evaluations, and symptom rating scales. Plasma drug concentrations will be measured at specific times in younger children to understand drug levels. The study tracks adverse events from screening through two weeks after the last dose. Total participation duration may last up to approximately five years, allowing long-term safety and efficacy monitoring.

A Long-Term Study of JNT-517 in Participants With Phenylketonuria