A Phase 2 Study of JNT-517 in Adolescent Participants With Phenylketonuria

NCT06637514 | Recruiting Phase 2 FDA Drug

• 1 other identifier: JNT517-201
• Study Type: interventional
• Target: 10
• Locations: 2 countries
• Sites: 7

Brief Summary

The goal of this Phase 2, randomized study is to assess the safety, tolerability, and pharmacokinetics (PK) of oral JNT-517 in adolescents (12 to less than 18 years of age) with PKU. Participants will receive either JNT-517 or placebo and will be blinded to their treatment assignment. Participants will have a 4 in 5 (or 80%) chance of receiving JNT-517. The study will last for up to 63 days including a Screening period, Treatment period and Follow-up period for safety. Participants will:

• Take 75 mg JNT-517 or a placebo BID (2x per day) for 28 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

Conditions

Phenylketonuria (PKU)

Keywords

PKU

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 and clinical laboratory tests.

  Screening to Study Completion (Average of 9 weeks)

Secondary Outcomes (5)

• Plasma AUC (area under the concentration-time curve)

  Screening to Study Completion (Average of 9 weeks)

• Cmax (maximum observed concentration)

  Screening to Study Completion (Average of 9 weeks)

• Tmax (time to Cmax)

  Screening to Study Completion (Average of 9 weeks)

• Change over time in plasma phenylalanine (Phe) and other amino acids

  Screening to Study Completion (Average of 9 weeks)

• Change over time in urinary phenylalanine (Phe) and other amino acids

  Screening to Study Completion (Average of 9 weeks)

Other Outcomes (1)

• Plasma metabolites of JNT-517

  Screening to Study Completion (Average of 9 weeks)

Study Arms (3)

JNT-517 - 75 mg BID

EXPERIMENTAL

Drug: JNT-517 Tablet

Drug: JNT-517 Tablet

Placebo - BID

PLACEBO COMPARATOR

Drug: Placebo Tablet

Other: Placebo

JNT-517 - 150 mg BID

EXPERIMENTAL

Drug: JNT-517 Tablet - 150 mg BID is a potential dose that may be used in the study. After safety, efficacy and pharmacokinetic data (PK) data have been reviewed for the first 5 participants assigned in the study, a decision will be made to increase dosage for additional participants.

Drug: JNT-517 Tablet

Interventions

JNT-517 Tablet DRUG

JNT-517: 75 mg BID

JNT-517 - 75 mg BID

Placebo OTHER

Placebo Tablet: BID

Placebo - BID

Eligibility Criteria

• Age: 12 Years - 17 Years
• Sex: all
• Healthy Volunteers: No
• Age Groups: Child (0-17)

You may qualify if:

• Males and females 12 to less than 18 years of age, inclusive on Day 1.
• Clinical diagnosis of PKU.
• Ability to swallow tablets.
• Average of 2 plasma Phe levels during the Screening period greater than 360 μM and no plasma Phe level less than 300 μM.
• Body weight equal or greater than 45 kg and body mass index less than 40 kg/m2.
• Females of childbearing potential must practice sexual abstinence or agree to use 2 highly effective contraceptive methods.
• Capable of giving signed informed consent (emancipated minors) or parent/legal guardian to provide informed consent and the participant to give assent and confirm ability to comply with study procedures.

You may not qualify if:

• 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 malignancy in the last 5 years, excluding nonmelanoma skin cancer.
• Any history of 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.
• Creatinine clearance less than 90 mL/min by Cockcroft-Gault formula.
• History of drug or alcohol abuse in the last year
• Current, recent, or suspected infection within 14 days of Screening of SARS CoV 2/COVID 19.
• Participation in another investigational drug trial within 30 days or, if known 5 half-lives of investigational drug (whichever is longer).
• Unable to tolerate oral medication.
• Allergy to JNT-517 or any component of the investigational product.
• Received greater than 50 mL of blood or plasma within 30 days of Screening or greater than 500 mL of blood or plasma within 60 days of Screening.

Sponsors & Collaborators

• Otsuka Pharmaceutical Development & Commercialization, Inc.: lead

Study Sites (7)

University of Florida (UF) Health Shands Hospital

Gainesville, Florida, 32608, United States

RECRUITING

University of South Florida

Tampa, Florida, 33606, United States

RECRUITING

Oregon Health and Science University

Portland, Oregon, 97239, United States

RECRUITING

Children's Medical Center Dallas

Dallas, Texas, 75235, United States

RECRUITING

University of Texas Health (UTHealth) Science Center at Houston

Houston, Texas, 77030, United States

RECRUITING

Utah Health - The University of Utah Hospital

Salt Lake City, Utah, 84112, United States

RECRUITING

Murdoch Children's Research Institute

Parkville, Melbourne, Victoria, 3052, Australia

RECRUITING

Related Links

• Otsuka Clinical Trial Website:
• Otsuka Clinical Trial Transparency:

MeSH Terms

Conditions

Phenylketonurias

Condition Hierarchy (Ancestors)

Brain Diseases, Metabolic, Inborn; Brain Diseases, Metabolic; Brain Diseases; Central Nervous System Diseases; Nervous System Diseases; Amino Acid Metabolism, Inborn Errors; Metabolism, Inborn Errors; Genetic Diseases, Inborn; Congenital, Hereditary, and Neonatal Diseases and Abnormalities; Metabolic Diseases; Nutritional and Metabolic Diseases

Central Study Contacts

Otsuka Call Center

CONTACT

844-687-8522; otsuka-professionalservices@otsuka-us.com

Study Design

• Study Type: interventional
• Phase: phase 2
• Allocation: RANDOMIZED
• Masking: QUADRUPLE
• Who Masked: PARTICIPANT, CARE PROVIDER, INVESTIGATOR, OUTCOMES ASSESSOR
• Purpose: TREATMENT
• Intervention Model: PARALLEL
• Sponsor Type: INDUSTRY
• Responsible Party: SPONSOR

Study Record Dates

• First Submitted: October 7, 2024
• First Posted: October 15, 2024
• Study Start: July 16, 2025
• Primary Completion (Estimated): May 9, 2026
• Study Completion (Estimated): May 9, 2026
• Last Updated: April 24, 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/

Locations

US (6); AU (1)