A Study to Evaluate the Long-Term Safety and Efficacy of JNT-517 in Participants With Phenylketonuria

The goal of this Phase 3, open-label extension study is to evaluate the long-term safety and efficacy of JNT-517 in participants with Phenylketonuria (PKU) after completion of either Study JNT517-101 or JNT517-201. In this long-term extension (LTE) study, all adults (aged ≥18 years) who complete Study JNT517-101 will be randomized 1:1 to receive JNT-517 at 75 mg twice daily (BID) or 150 mg BID, regardless of their previous dose. Adolescent participants who complete Study JNT517-201 will receive the same JNT-517 dose of the cohort they were initially assigned to, either 75 mg BID or 150 mg BID.