A Study to Evaluate the Safety and Efficacy of JNT-517 in Participants With Phenylketonuria (PKU)
Trial Parameters
Brief Summary
The goal of this Phase 3, randomized study is to assess the safety, efficacy, tolerability, and pharmacokinetics (PK) of oral JNT-517 in adults (18 years of age or older) with PKU. Participants will receive either JNT-517 or placebo and will be blinded to their treatment assignment. Participants will have a 2 in 3 (or approximately 67%) chance of receiving JNT-517 during the first part of the study which will last approximately six weeks. During the second part of the study every participant who continues in the study will receive one of two doses of JNT-517 for an additional 46 weeks. The study requires a screening period of up to 35 days to ensure dietary stabilization and amino acid levels required to meet study eligibility. In total, participation in the study could last for up to 400 days. Participants will: Take 75 mg JNT-517 or 150 mg JNT-517, or a placebo BID (2x per day) for approximately 365 days; Visit the clinic or have a mobile health nurse visit your home for checkups and tests; Collect urine sample at home and bring to clinic on specified days; Keep a food diary 3 days before each study visit
Eligibility Criteria
Inclusion Criteria: 1. Males and females ≥18 years of age on Day 1 2. Clinical diagnosis of PKU 3. Average of at least 3 plasma Phe levels (after \>4-hour fast) during Screening period of ≥360 μmol/L 4. Not on pegvaliase within 4 weeks prior to Screening 5. If on sapropterin or large neutral amino acids, such as PheBloc®, NeoPhe®, and PreKunil® at Screening, must be on a stable dose 4 weeks prior to Screening and for the entire study duration. 6. Willing and able to maintain a stable diet in Phe and total protein (intact protein and medical food protein) and able to adjust diet through the duration of the study according to the Dietary Management Guidelines 7. Body weight \>45 kg 8. If biologically female of childbearing potential: 1. Must have a negative serum pregnancy test at Screening and a negative urine pregnancy test by Day 1 2. Must practice sexual abstinence, or if involved in any sexual intercourse that could lead to pregnancy, must agree to use 2 highly effective contracepti