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A Study to Evaluate the Long-Term Safety and Efficacy of JNT-517 in Participants With Phenylketonuria | Clinical Trials | Clareo Health

NOT_YET_RECRUITINGPHASE3

A Study to Evaluate the Long-Term Safety and Efficacy of JNT-517 in Participants With Phenylketonuria

An Open-Label Extension Study to Evaluate the Long-Term Safety and Efficacy of JNT-517 in Participants With Phenylketonuria

NCT06628128•Otsuka Pharmaceutical Development & Commercialization, Inc.

View on ClinicalTrials.gov

Summary

The goal of this Phase 3, open-label extension study is to evaluate the long-term safety and efficacy of JNT-517 in participants with Phenylketonuria (PKU) after completion of either Study JNT517-101 or JNT517-201. In this long-term extension (LTE) study, all adults (aged ≥18 years) who complete Study JNT517-101 will be randomized 1:1 to receive JNT-517 at 75 mg twice daily (BID) or 150 mg BID, regardless of their previous dose. Adolescent participants who complete Study JNT517-201 will receive the same JNT-517 dose of the cohort they were initially assigned to, either 75 mg BID or 150 mg BID.

Eligibility

Age

12 - No limit years

Sex

ALL

Healthy Volunteers

Inclusion Criteria

•1. Clinical diagnosis of PKU and has completed Study JNT517-101 or Study JNT517-201.
•2. Not on pegvaliase within 4 weeks of Screening.
•3. If on sapropterin or large neutral amino acids at Screening, must be on a stable dose for 4 weeks prior to Screening and expected to be on stable dose for the study duration.
•4. Willing and able to maintain a diet consistent in protein content from natural intact and medical food protein sources from the Screening period through the duration of the study under the direction of a dietician.
•5. If 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 contraceptive methods (see Section 7.3.1 for details of contraception) from Screening until at least 30 days after the last study drug administration.
•3. If taking estrogen- or progesterone-based oral contraceptives, must agree to use 2 other highly effective methods of contraception or must agree to sexual abstinence during the study.
•6. Is a female not of childbearing potential or postmenopausal, defined as follows:
•1. Has had surgical sterilization (hysterectomy, bilateral oophorectomy, or bilateral salpingectomy).
+6 more criteria

Exclusion Criteria

•1. Continuation into the LTE is not considered safe and/or feasible in the opinion of the Investigator.
•2. 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.
•3. Positive for hepatitis B or C or human immunodeficiency virus.
•4. Any history of liver disease.
•5. Any history of cataracts or more than minimal cataracts observed during the Screening ophthalmologic examination. Minimal cataracts are defined as changes similar to LOCS II (lens opacities classification system II) lens grade C1, N1, or P1, or an equivalent grading system.
•6. Any surgical or medical conditions that may affect study drug absorption, distribution, metabolism, or excretion.
•7. Creatinine clearance ˂90 mL/min by 2021 Chronic Kidney Disease Epidemiology Collaboration formula for adults and by the Schwartz formula for adolescents (˂18 years of age)
•8. History of drug or alcohol abuse in the last year.
•9. 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 randomization and unwilling and/or unable to avoid these medications throughout the treatment duration.
•10. Use of any medication that is a substrate of CYP3A4, or a substrate of the transporters P gp, breast cancer resistance protein (BCRP), organic anion transporter 3 (OAT3), multidrug and toxin extrusion (MATE)1, or MATE2-K within 4 weeks prior to randomization and unwilling and/or unable to avoid these medications throughout the treatment duration.
+10 more criteria

Key Dates

Start Date

June 1, 2025

Primary Completion Date

November 1, 2027

Completion Date

February 1, 2028

Last Updated

June 3, 2025

Enrollment

ESTIMATED participants

Conditions

Phenylketonuria (PKU)

Interventions

JNT-517 Tablet

DRUG

Contacts

Otsuka Call Center

CONTACT

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

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Data Source & Attribution

This clinical trial information is sourced from ClinicalTrials.gov, a service of the U.S. National Institutes of Health.

ClinicalTrials.gov last update: June 3, 2025Data synced to Clareo: March 29, 2026

Modifications: This data has been reformatted for display purposes. Eligibility criteria have been parsed into inclusion/exclusion sections. Location data has been geocoded to enable distance-based search. For the authoritative and most current information, please visit ClinicalTrials.gov.

Neither the United States Government nor Clareo Health make any warranties regarding the data. Check ClinicalTrials.gov frequently for updates.

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A Study to Evaluate the Long-Term Safety and Efficacy of JNT-517 in Participants With Phenylketonuria

Inclusion Criteria

Exclusion Criteria

Study to Evaluate the Safety and Efficacy of Pegvaliase in Adolescents (Ages 12-17) With Phenylketonuria

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