The goal of Parts A and B of this Phase 1/2, first-in-human, randomized study is to assess the safety, tolerability, and pharmacokinetics (PK) of single (SAD) and multiple (MAD) ascending doses of oral JNT-517 in healthy participants. In Part C, the goal is to evaluate the differences in bioavailability between a tablet and suspension formulation of JNT-517 and the food effect in healthy volunteers. All participants in Part C will receive JNT-517. The goal of Part D is to assess the safety, tolerability, PK, and effect on urinary Phe and other amino acids of JNT-517 in participants with phenylketonuria (PKU). Participants in Part D will receive either JNT-517 or placebo and will be blinded to their treatment assignment. The study consists of 6 parts: * Part A: SAD in healthy participants -randomized, double-blind, placebo-controlled * Part B: MAD in healthy participants (14 days)-randomized, double-blind, placebo-controlled * Part C: Relative bioavailability of 2 formulations and food effect in healthy participants-randomized, open-label * Part D: Phase 2 in participants with PKU (4 weeks)-randomized, double-blind, placebo-controlled * Part E: Phase 2 in participants with PKU (4 weeks) open label * Part F: SAD Phase 1 in healthy participants, randomized, double-blind, placebo-controlled In each part, participants will complete a Screening Period, a Treatment Period, and a Follow-up Period for safety.
Age range
18 Years – 65 Years
Sex
ALL
See this in plain English?
AI-rewrites the medical criteria so a patient or caregiver can understand them. Always confirm with the trial site.
Bring these to your next appointment. They're a starting point for a shared conversation — not a sign you qualify or a recommendation to enrol.
Generated to help you prepare — always confirm anything about your own eligibility and care with the study team and your doctor.
The trial coordinator is the person who runs the study day to day. These cover the practical side — logistics, costs, and what taking part would actually mean for your life. The study team confirms whether you meet the criteria; these are questions to ask, not a sign you qualify.
A starting point for the conversation — always confirm anything about your own eligibility, costs, and care with the study team and your doctor.
Number of participants with treatment-emergent adverse events
Timeframe: Parts A/C/F: Screening to Day 8; Part B: Screening to Day 21; Part D/E: Screening to Day 35