Phenylketonuria (PKU)Phase 2NCT06637514
A Phase 2 Study of JNT-517 in Adolescent Participants With Phenylketonuria
A Phase 2 study testing JNT-517 Tablet in people with Phenylketonuria (PKU), run by Otsuka Pharmaceutical Development & Commercialization, Inc. at 7 sites in 2 countries.
Trial 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. Read more about this study
- Who is it for?
- Ages 12 to 17 years
- Conditions the study is for
- Phenylketonuria (PKU)
- What is being tested?
- JNT-517 Tablet
- Type of treatment
- Pill or oral medicine
- Could I receive a placebo?
- Yes, some participants may receive a placebo
- How many people
- 14 participants
- Where
- 7 sitesin 2 countries
- Study dates
- 16 Jul 2025to 8 May 2026
- Phase
- Phase 2
- Are there results?
- None posted in the registry
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages 12 to 17 years
- All sexes
- No healthy volunteers
- Child
Who may be able to join
- 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.
Who cannot join
- 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.
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- 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.
Trial locations and contacts
7 sites in 2 countries.
7 sites in 2 countries
United States6 sites
Children's Medical Center Dallas
Dallas, Texas, 75235
University of Florida (UF) Health Shands Hospital
Gainesville, Florida, 32608
University of Texas Health (UTHealth) Science Center at Houston
Houston, Texas, 77030
Oregon Health and Science University
Portland, Oregon, 97239
Utah Health - The University of Utah Hospital
Salt Lake City, Utah, 84112
University of South Florida
Tampa, Florida, 33606
Australia1 site
Murdoch Children's Research Institute
Parkville, Melbourne, Victoria, 3052
About this study
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)
- Being tested
- JNT-517 Tablet, Placebo
- Keywords
- PKU
- Medical subject headings
- Phenylketonurias
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
JNT-517 TabletDrug
JNT-517: 75 mg BID
PlaceboOther
Placebo Tablet: BID
JNT-517 TabletDrug
JNT-517: 150 mg BID
| Study group | Role | What they receive |
|---|---|---|
| JNT-517 - 75 mg BID | Experimental | Drug: JNT-517 Tablet Receives: Drug: JNT-517 Tablet |
| Placebo - BID | Placebo comparator | Drug: Placebo Tablet Receives: 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. Receives: Drug: JNT-517 Tablet |
What is being measured
The primary outcome is the main question the study is designed to answer.
Number of participants with treatment-emergent adverse events (TEAEs)
Reported based on results of 12-lead electrocardiograms (ECGs), vital signs and clinical laboratory tests.
Measured: Screening to Study Completion (Average of 9 weeks)
Secondary outcomes (5)
Plasma AUC (area under the concentration-time curve)
Measured: Screening to Study Completion (Average of 9 weeks)
Cmax (maximum observed concentration)
Measured: Screening to Study Completion (Average of 9 weeks)
Tmax (time to Cmax)
Measured: Screening to Study Completion (Average of 9 weeks)
Change over time in plasma phenylalanine (Phe) and other amino acids
Measured: Screening to Study Completion (Average of 9 weeks)
Change over time in urinary phenylalanine (Phe) and other amino acids
Measured: Screening to Study Completion (Average of 9 weeks)
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted15 Oct 2024
- Study start16 Jul 2025
- Primary completion8 May 2026
- Study completion8 May 2026
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for Phenylketonuria (PKU)Studies of the same condition, open and under way.
- More trials run by Otsuka Pharmaceutical Development & Commercialization, Inc.The sponsor's other registered studies.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Interventional
- Phase
- Phase 2
- Primary purpose
- Treatment
- Allocation
- Randomised
- Intervention model
- Parallel groups
- Masking
- Quadruple blind
- Who is masked
- Participant, Care provider, Investigator, Outcomes assessor
- Enrolment
- 14 participants (actual)
Sponsor and investigators
- Sponsor type
- Industry (pharma, biotech, devices)
- Responsible party
- Sponsor
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT06637514
- Sponsor's protocol ID
- JNT517-201
- Status last verified
- May 2026
- First submitted
- 7 Oct 2024
- Last updated
- 13 May 2026
- Results posted
- No
- Data monitoring committee
- No
- FDA-regulated drug
- Yes
- FDA-regulated device
- No
- Individual data sharing
- Yes: 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.
Study at a glance
From the registry record, last updated by the sponsor on 13 May 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- A Phase 2 Study of JNT-517 in Adolescent Participants With Phenylketonuria
- ClinicalTrials.gov ID
- NCT06637514
- Acronym / sponsor ID
- JNT517-201
- Conditions
- Phenylketonuria (PKU)
- Keywords
- PKU
- Phase
- Phase 2
- Study type
- Interventional
- Recruitment status
- Completed
- Enrolment
- 14 participants (actual)
- Lead sponsor
- Otsuka Pharmaceutical Development & Commercialization, Inc.Industry (pharma, biotech, devices)
- Study start
- 16 Jul 2025 (actual)
- Primary completion
- 8 May 2026 (actual)
- Study completion
- 8 May 2026 (actual)
- First posted
- 15 Oct 2024 (actual)
- Results
- Not posted in the source record
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
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
Study design
- Primary purpose
- Treatment
- Allocation
- Randomised
- Intervention model
- Parallel groups
- Masking
- Quadruple blind (participant, care provider, investigator, outcomes assessor)
- Number of arms
- 3
| Arm | Type | Receives |
|---|---|---|
| JNT-517 - 75 mg BID | Experimental | Drug: JNT-517 TabletDrug: JNT-517 Tablet |
| Placebo - BID | Placebo comparator | Other: PlaceboDrug: Placebo Tablet |
| JNT-517 - 150 mg BID | Experimental | Drug: JNT-517 TabletDrug: 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. |
Who may qualify
- Ages
- 12 to 17 years
- Sex
- All
- Healthy volunteers
- Not accepted
- Age groups
- Child
Key inclusion criteria (7 listed)
- 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.
Key exclusion criteria (13 listed)
- 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.
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Interventions
| Intervention | Type | Arms |
|---|---|---|
| JNT-517 TabletJNT-517: 75 mg BID | Drug | JNT-517 - 75 mg BID |
| PlaceboPlacebo Tablet: BID | Other | Placebo - BID |
| JNT-517 TabletJNT-517: 150 mg BID | Drug | JNT-517 - 150 mg BID |
Primary outcome
Number of participants with treatment-emergent adverse events (TEAEs)
Time frame: Screening to Study Completion (Average of 9 weeks)
Reported based on results of 12-lead electrocardiograms (ECGs), vital signs and clinical laboratory tests.
5 secondary outcomes
Plasma AUC (area under the concentration-time curve)
Time frame: Screening to Study Completion (Average of 9 weeks)
Cmax (maximum observed concentration)
Time frame: Screening to Study Completion (Average of 9 weeks)
Tmax (time to Cmax)
Time frame: Screening to Study Completion (Average of 9 weeks)
Change over time in plasma phenylalanine (Phe) and other amino acids
Time frame: Screening to Study Completion (Average of 9 weeks)
Change over time in urinary phenylalanine (Phe) and other amino acids
Time frame: Screening to Study Completion (Average of 9 weeks)
Results and safety
The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 13 May 2026.
- Otsuka Clinical Trial Website:Link provided by the sponsor.
- Otsuka Clinical Trial Transparency:Link provided by the sponsor.
- Individual participant dataSharing planned: Yes. 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.
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Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part. This study is not recruiting at the moment.
The record lists no contact. Use the official record to reach the sponsor.
7 sites in 2 countries: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A Phase 2 study testing JNT-517 Tablet in people with Phenylketonuria (PKU), run by Otsuka Pharmaceutical Development & Commercialization, Inc. at 7 sites in 2 countries.
The full registered description is in the About this study section and the official record.
Who may be eligible to take part?
The sponsor lists 7 inclusion and 13 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.
Is this clinical trial currently recruiting?
The record says: finished, as of the sponsor's last update on 13 May 2026. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 7 sites in United States, Australia. Whether a site is taking part right now should be confirmed with that site. See every site.
What are the possible benefits and risks?
They depend on the study and the treatment, and no study can promise a benefit. Some participants in this study may receive a placebo. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
What does this phase mean?
Phase 2 studies give the treatment to a larger group to see whether it has the intended effect and to keep checking safety.
Not every study follows the same path, and some studies (observational studies, device studies) have no phase.
Are results available for this study?
The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.
How can a doctor refer a patient or contact the research team?
The record lists no contact. The official record names the sponsor, who can be asked directly. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Number of participants with treatment-emergent adverse events (TEAEs) (time frame: Screening to Study Completion (Average of 9 weeks)). It is what the study was designed to measure, not a finding.
Where can I read the original study information?
Does a listing mean the treatment is approved or proven to work?
No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.
How often is this information updated?
AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 13 May 2026.