A Long-Term Study of JNT-517 in Participants With Phenylketonuria
An Open-Label Study to Evaluate the Long-Term Safety of JNT-517 in Participants With Phenylketonuria
4 other identifiers
interventional
240
2 countries
12
Brief Summary
The goal of this Phase 3, open-label study is to evaluate the long-term safety of JNT-517 in pediatric and adult participants with Phenylketonuria (PKU) after completion of either Study JNT517-101 (NCT05781399) or JNT517-201 (NCT06637514) as well as participants who have not participated in a prior JNT-517 study. In this trial, all participants will receive JNT-517 using age- and weight-banded dosing as outlined in the protocol, regardless of any dose received in a previous study.
Trial Health
Trial Health Score
Automated assessment based on enrollment pace, timeline, and geographic reach
participants targeted
Target at P50-P75 for phase_3
Started Aug 2025
12 active sites
Health score is calculated from publicly available data and should be used for screening purposes only.
Trial Relationships
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Study Timeline
Key milestones and dates
First Submitted
Initial submission to the registry
October 2, 2024
CompletedFirst Posted
Study publicly available on registry
October 4, 2024
CompletedStudy Start
First participant enrolled
August 11, 2025
CompletedPrimary Completion
Last participant's last visit for primary outcome
November 1, 2027
ExpectedStudy Completion
Last participant's last visit for all outcomes
February 1, 2028
May 1, 2026
April 1, 2026
2.2 years
October 2, 2024
April 27, 2026
Conditions
Keywords
Outcome Measures
Primary Outcomes (1)
Number of Participants with Treatment-emergent Adverse Events (TEAEs)
Reported based on results of 12-lead electrocardiograms (ECGs), vital signs, clinical laboratory tests, and other medical assessments.
Screening to +2 weeks from last dose
Secondary Outcomes (11)
Absolute Change from Baseline in Plasma Phe
Baseline to +2 weeks from last dose
Percent Change from Baseline Over Time in Plasma Phe
Baseline to +2 weeks from last dose
Percentage of Participants with Plasma Phe <600 micromoles (µM) Over Time in Participants with Baseline Phe >600 µM
Baseline to +2 weeks from last dose
Percentage of Participants with Plasma Phe ≤360 µM Over Time in Participants with Baseline Phe >360 µM
Baseline to +2 weeks from last dose
Percentage of Participants with Plasma Phe ≥120 µM Over Time in Participants with Baseline Phe >120 µM
Baseline to +2 weeks from last dose
- +6 more secondary outcomes
Study Arms (1)
JNT-517
EXPERIMENTALInterventions
Eligibility Criteria
You may qualify if:
- Diagnosis of phenylketonuria (ie, PAH deficiency) by either molecular testing or biochemical criteria consistent with the applicable regional guidelines.
- Participants 4 years of age and older, inclusive, at time of Screening.
- Not on pegvaliase within 4 weeks of Screening.
- Not on sepiapterin within 2 weeks of Screening.
- If on sapropterin or large neutral amino acids at Screening, must be on a stable dose for 4 weeks prior to Screening.
- Willing and able to maintain a diet consistent in Phe content from the Screening period through the duration of the study, unless otherwise directed by a dietician as allowed in the protocol.
- Body weight ≥ 12.5 kg.
- If female of childbearing potential:
- Must have a negative serum pregnancy test at Screening and a negative urine pregnancy test by Day 1.
- Must practice sexual abstinence, or if involved in any sexual intercourse that could lead to pregnancy, must agree to use 2 different contraceptive methods, where at least 1 method must be highly effective, from Screening until at least 30 days after the last study drug administration.
- Must refrain from donating ova during the course of the study and for 30 days after the last dose of the study drug.
- Is a female not of childbearing potential or postmenopausal, defined as follows:
- Has had surgical sterilization (hysterectomy, bilateral oophorectomy, or bilateral salpingectomy).
- Has had amenorrhea for minimum of 1 year with confirmation by levels of follicle stimulating hormone testing.
- Has not achieved menarche (has not had first menstrual period). If a female achieves menarche during the study, she will need to follow the contraception requirement for females of childbearing potential.
- +4 more criteria
You may not qualify if:
- Participation in this study is not considered safe and/or feasible in the opinion of the Investigator.
- Participants have not completed a previous JNT-517 study and are eligible for another active JNT-517 trial at the site, unless approval is obtained from the medical monitor.
- Any acute or 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 significant liver disease.
- Any history of cataracts or more than minimal cataracts observed during the Screening ophthalmologic examination.
- Any surgical or medical conditions that may affect study drug absorption, distribution, metabolism, or excretion.
- Estimated glomerular filtration rate \< 60 milliliters per minute per 1.73 square meters (mL/min/1.73 m\^2) by 2021 Chronic Kidney Disease Epidemiology Collaboration formula (participants aged 17 years or greater) or by Schwartz formula (participants aged 4 to 16 years of age).
- History of drug or alcohol abuse in the last year.
- Use of any medication that are inhibitors or inducers of cytochrome P450 (CYP)3A4 or inhibitors of the transporter P glycoprotein (P-gp) within 4 weeks prior to the first dose of study drug and unwilling and/or unable to avoid these medications throughout the treatment duration.
- Use of any medications that are a substrate of breast cancer resistance protein (BCRP), multidrug and toxin extrusion (MATE)1, MATE2-K, organic anion transporter 3 (OAT3), or CYP3A4 within 4 weeks prior to the first dose of study drug and unwilling and/or unable to avoid these medications throughout the treatment duration (Appendix A). CYP3A4 substrates may be allowed if reduction in exposure is not expected to impact safety of the participant after consultation with the Medical Monitor.
- NOTE: Participants of childbearing potential will be permitted to continue with estrogen- or progesterone based oral contraceptives, but must agree to use 2 other methods of contraception, where at least 1 must be highly effective, or must agree to sexual abstinence during the study.
- Current, recent, or suspected infection within 2 weeks of Screening of Severe Acute Respiratory Syndrome Coronavirus 2/Coronavirus Disease 2019 (SARS-CoV-2/COVID-19).
- Unable to tolerate oral medication or inability to swallow tablets.
- Allergy to JNT-517 or any component of the investigational product.
- +6 more criteria
Contact the study team to confirm eligibility.
Sponsors & Collaborators
Study Sites (12)
University of Florida (UF) Health Shands Hospital
Gainesville, Florida, 32608, United States
University of South Florida
Tampa, Florida, 33606, United States
Oregon Health and Science University
Portland, Oregon, 97239, United States
University of Pittsburgh Medical Center (UPMC) - Children's Hospital of Pittsburgh
Pittsburgh, Pennsylvania, 15224, United States
Children's Medical Center Dallas
Dallas, Texas, 75235, United States
University of Texas Southwestern Medical Center
Dallas, Texas, 75390, United States
University of Texas Health (UTHealth) Science Center at Houston
Houston, Texas, 77030, United States
Utah Health - The University of Utah Hospital
Salt Lake City, Utah, 84112, United States
Children's Health Queensland - Queensland Children's Hospital
South Brisbane, Queensland, 4101, Australia
Mater Health - Mater Hospital Brisbane
South Brisbane, Queensland, 4101, Australia
Royal Adelaide Hospital
Adelaide, South Australia, 5000, Australia
Murdoch Children's Research Institute
Parkville, Victoria, 3052, Australia
Related Links
MeSH Terms
Conditions
Condition Hierarchy (Ancestors)
Central Study Contacts
Study Design
- Study Type
- interventional
- Phase
- phase 3
- Allocation
- NA
- Masking
- NONE
- Purpose
- TREATMENT
- Intervention Model
- SINGLE GROUP
- Sponsor Type
- INDUSTRY
- Responsible Party
- SPONSOR
Study Record Dates
First Submitted
October 2, 2024
First Posted
October 4, 2024
Study Start
August 11, 2025
Primary Completion (Estimated)
November 1, 2027
Study Completion (Estimated)
February 1, 2028
Last Updated
May 1, 2026
Record last verified: 2026-04
Data Sharing
- IPD Sharing
- Will share
- Shared Documents
- STUDY PROTOCOL, SAP, ICF
- Time Frame
- Data will be available after marketing approval in global markets, or beginning 1-3 years following article publication. There is no end date to the availability of the data.
- Access Criteria
- Otsuka will share data on the Vivli data sharing platform which can be found here: https://vivli.org/ourmember/Otsuka/
Anonymized Individual participant data (IPD) that underlie the results of this study will be shared with researchers to achieve aims pre-specified in a methodologically sound research proposal. Small studies with less than 25 participants are excluded from data sharing.