What is JNT-517 studying for phenylketonuria (PKU)?

JNT-517 is being studied to evaluate its safety, effectiveness, and how well it is tolerated in adults with PKU. The trial compares JNT-517 with a placebo to see its effects on blood phenylalanine levels and related health outcomes. The study is sponsored by Otsuka Pharmaceutical Development & Commercialization, Inc.

Who may be eligible for this phenylketonuria clinical trial?

Adults aged 18 years or older with a clinical diagnosis of PKU may be eligible. Participants should have stable dietary intake of phenylalanine and protein, and not have used pegvaliase recently. The trial is open to all genders. Please review eligibility criteria for more details.

Is there any cost to participate in this phenylketonuria clinical trial?

Study-related care, including the study drug and all trial visits, is provided at no cost. However, personal travel expenses may vary and are not guaranteed to be covered.

Actively Recruiting

Phase 3

Age: 18Years +

All Genders

ID06971731

Phase 3 Study of Oral JNT-517 to Treat Adults With Phenylketonuria PKU Evaluating Safety and Effectiveness

Led by Otsuka Pharmaceutical Development & Commercialization, Inc. · Updated on 2026-07-08

120

Participants Needed

Research Sites

4 weeks

Total Duration

AI-Summary

What this Trial Is About

Researchers are conducting a Phase 3 randomized study to evaluate the safety, effectiveness, tolerability, and how the body processes pharmacokinetics the oral drug JNT-517 in adults aged 18 years or older who have phenylketonuria PKU. The study aims to compare JNT-517 with a placebo to understand its impact on plasma phenylalanine levels and other health outcomes related to PKU. Participants will be randomly assigned to receive either JNT-517 or a placebo for the first six weeks, with about a 67% chance of receiving JNT-517. After this initial period, all participants continuing in the study will receive one of two doses of JNT-517 75 mg or 150 mg twice daily for an additional 46 weeks. The study includes a screening period of up to 35 days to ensure dietary stability and proper amino acid levels before treatment begins. During the study, participants will take the study medication twice daily for up to 365 days. They will attend clinic visits or receive visits from a mobile health nurse for checkups and tests. Participants will also collect urine samples at home on specific days and keep a food diary for three days before each visit. Researchers will measure changes in plasma phenylalanine levels, ADHD symptoms, dietary intake, and monitor for any treatment-emergent adverse events throughout the study.

CONDITIONS

Brief Title

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

Who Can Participate

Age: 18Years +

All Genders

Eligibility Criteria

You may qualify if you...

Males and females 18 years of age or older on Day 1
Clinical diagnosis of phenylketonuria (PKU)
Average of at least 3 plasma phenylalanine (Phe) levels of 360 bcmol/L or higher during screening after a 4-hour fast
Not treated with pegvaliase within 4 weeks prior to screening
Stable dose of sapropterin or large neutral amino acids if used, for 4 weeks prior to screening and throughout the study
Willing and able to maintain a stable diet in phenylalanine and total protein as per guidelines
Body weight greater than 40 kilograms
Females of childbearing potential must have negative pregnancy tests, use effective contraception, and avoid donating ova during and 30 days after the study
Females not of childbearing potential defined by surgical sterilization, amenorrhea for at least 1 year with hormone confirmation, or pre-menarche status
Biological males must use effective contraception or practice sexual abstinence and avoid donating sperm during and for 30 days after the study, unless vasectomized more than 4 months prior
Participants with psychiatric illness must be well-controlled for 6 months and on stable medications for 3 months prior to screening
Capable of giving informed consent and complying with study procedures

You will not qualify if you...

Any acute or uncontrolled chronic medical condition that prevents compliance or poses risk
Positive for hepatitis B, hepatitis C, or HIV
History of malignancy (other than certain skin or cervical cancers) within 5 years
History of significant liver disease
History of cataracts more than minimal as defined by screening exam
Surgical or medical conditions affecting drug absorption, distribution, metabolism, or excretion
Estimated glomerular filtration rate (eGFR) less than 60 mL/min/1.73 m2
Participation in another investigational drug trial within 30 days or known drug half-life period
Alcohol use within 5 days of randomization or unwillingness to limit alcohol during first 6 months
History of drug or alcohol abuse in the last year
Use of medications affecting certain liver enzymes or transporters within 4 weeks prior to randomization
Current, recent, or suspected active viral or bacterial infection within 2 weeks prior to and during screening
Unable to tolerate oral medication or conditions interfering with JNT-517 absorption
Allergy to JNT-517 or components of the study drug
Abnormal laboratory values at screening including liver enzymes, bilirubin, hemoglobin, white blood cell count, or platelets as specified

Research Team

Otsuka Call Center

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Phase 3 Study of Oral JNT-517 to Treat Adults With Phenylketonuria PKU Evaluating Safety and Effectiveness

On this page

AI-Summary

What this Trial Is About

Brief Title

Who Can Participate

Eligibility Criteria

Research Team

Not the Right Trial for You?

On this page

Who Can Participate

Eligibility Criteria