🏛️ Verified NIH Record • Updated 2026-07-06

A Study of JNT-517 in Participants With Phenylketonuria (PKU) (NCT06971731)

A Phase 3, Double-Blind, Randomized, Two-Period, Multicenter, Placebo-Controlled, Efficacy and Safety Study of JNT-517 for the Treatment of Participants With Phenylketonuria

🟢 Recruiting Phase3 💊 Investigational Drug / Biologic Sponsor: Otsuka Pharmaceutical Development & Commercialization, Inc.

🩺 Plain-English Summary (8th-Grade Level)

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

Who can join: To join this study, participants generally need to meet the listed inclusion criteria (19 items) and avoid the listed exclusions (18 items).

Location: University of California Los Angeles (UCLA) School of Medicine — Los Angeles, California

Age range: 18 Years

🧪 Interventions in This Study

📋 "Do I Qualify?" — 1-Minute Self Screener

Instant Checklist

Check every box below. If you can check all of them, you may meet the study's basic screening requirements (final eligibility is confirmed by the site team).

Usually NOT eligible if any of the following apply:

  • Exclusion Criteria:
  • Exclusion Criteria Participants will be excluded from the study if any of the following criteria are met:
  • Any acute or uncontrolled chronic medical condition that would prevent the participant from complying with the procedures or place the participant at risk if they participate in the study
  • Positive for hepatitis B or C or human immunodeficiency virus
  • Any history of malignancy of any organ system (other than non-melanoma skin cancer or in situ cervical cancer), treated or untreated, within the past 5 years, regardless of whether there is evidence of local recurrence or metastases
  • Any history of significant liver disease
  • Any history of cataracts or more than minimal cataracts observed during the Screening ophthalmologic examination. Minimal cataracts are defined as changes similar to lens opacities classification system III (LOCS III), lens grade C1, N1 or P1
  • Any surgical or medical conditions that may affect study drug absorption, distribution, metabolism, or excretion
  • Estimated glomerular filtration rate (eGFR) \<60 mL/min/1.73 m2 by 2021 Chronic Kidney Disease Epidemiology Collaboration formula
  • Participation in another investigational drug trial within 30 days or, if known, 5 half-lives of the investigational drug (whichever is longer). For gene therapy or editing trials, participants must have received the intervention \>6 months prior to Screening visit and with stable plasma Phe in the past 2 months prior to Screening visit.
  • Alcohol consumption within 5 days of randomization and/or unwilling to limit to 1 alcoholic drink per day until after the 6-month study visit
  • History of drug/alcohol abuse in the last year

🔍 Extracted verbatim from the official NIH eligibility criteria. Always confirm with the study coordinator.

📍 All Participating Trial Locations (26 Sites)

Showing the first 25 of 26 sites.

  • University of California Los Angeles (UCLA) School of Medicine — Los Angeles, California
  • University of Florida (UF) Health Shands Hospital — Gainesville, Florida
  • University of South Florida — Tampa, Florida
  • Ann & Robert H. Lurie Children's Hospital of Chicago — Chicago, Illinois
  • Oregon Health and Science University — Portland, Oregon
  • University of Pittsburgh Medical Center (UPMC) - Children's Hospital of Pittsburgh — Pittsburgh, Pennsylvania
  • Vanderbilt University Medical Center — Nashville, Tennessee
  • University of Texas Southwestern — Dallas, Texas
  • University of Texas Health (UTHealth) Science Center at Houston — Houston, Texas
  • Utah Health - The University of Utah Hospital — Salt Lake City, Utah
  • Royal Adelaide Hospital — Adelaide,
  • Royal Melbourne Hospital — Parkville,
  • Mater Health - Mater Hospital Brisbane — South Brisbane,
  • M.A.G.I.C Clinic — Calgary, Alberta
  • Fakultní nemocnice Královské Vinohrady — Prague,
  • Centre Hospitalier Régional Universitaire (CHRU) de Tours - Hôpital Bretonneau — Tours,
  • Universitaetsmedizin der Johannes Gutenberg-Universitaet Mainz — Mainz,
  • Universitätsklinikum Münster — Münster,
  • Nihon University Hospital — Chiyoda-ku,
  • Fujita Health University — Kutsukake-cho,
  • Osaka Metropolitan University Hospital — Osaka,
  • Universitair Medisch Centra (AMC)- Amsterdam — Amsterdam,
  • Beatrix Children's Hospital — Groningen,
  • Pomorski Uniwersytet Medyczny w Szczecinie — Szczecin,
  • Hospital Universitario Ramón y Cajal — Madrid,

📞 Contact the Study Coordinator

Phone: (844) 687-8522

Email: otsuka-professionalservices@otsuka-us.com

Coordinator details come directly from the registered NIH protocol. Confirm the study is still recruiting before traveling.

💰 Cost, Insurance & Patient Rights

  • 100% Free Items: The investigational treatment and protocol-required procedures are supplied at zero cost by the sponsor.
  • Routine Patient Care: Under federal law (ACA § 2709) and many state statutes, routine care costs are covered during participation.
  • Voluntary Participation: You may withdraw at any time without affecting your standard medical care.
  • 💵 Compensation indicated: Participants will receive either JNT-517 or placebo and will be blinded to their treatment assignment.

More studies in Phenylketonuria

Explore by condition: All Phenylketonuria clinical trials

💡 How to Participate

  1. Check the checklist above to see if you may qualify.
  2. Contact the study coordinator using the phone/email above.
  3. Ask about the visit schedule, what is covered at no cost, and any travel support.
  4. Confirm with your own doctor before making a decision.
🏛️ View Official NIH Record ↗