Additional Dietary Large Neutral Amino Acids (LNAA) for Improved Symptoms in Adult Classical Phenylktonuria (PKU)

November 30, 2023 updated by: Shoji Yano, University of Southern California

Can Care of Adult PKU Be Improved With Additional Dietary Large Neutral Amino Acids: An N-of-1 Study

This research investigates the effects of combining a phenylalanine restricted diet (usual care) with LNAA supplementation (adjuvant LNAA) in well-controlled adults with classical PKU. The hypothesis is that symptoms are improved in well-controlled patients who receive adjuvant LNAA therapy compared with diet monotherapy. Six symptomatic classical PKU adults will be enrolled to test the hypothesis in a small series of N-of-1 randomized controlled trials over 18-weeks. All assessments will be collected in patient's homes. A 3-month follow-up period will assess the longer-term effects of adjuvant LNAA in patients who show clinical benefit at the end of the intervention period.

Study Overview

Status

Status

Indicates the current recruitment status or the expanded access status.
Active, not recruiting

Conditions

Conditions

The disease, disorder, syndrome, illness, or injury that is being studied. On ClinicalTrials.gov, conditions may also include other health-related issues, such as lifespan, quality of life, and health risks.

Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.

Detailed Description

Clinical care of PKU confronts an increasing proportion of early-treated well-controlled adults, with a treatment goal that quality of life be as normal as possible. Even adults who have successfully managed their blood phenylalanine levels from birth can have symptoms which impact daily function. New therapies that target symptoms are needed, especially for symptomatic well-controlled classical adults with few treatment options. In Denmark and the LAC+USC U.S. clinic, adults are offered large neutral amino acid (LNAA) supplements when diet monotherapy becomes less effective for symptom management, or the patient wants a less restrictive diet. Many patients report improved symptoms. LNAA supplementation doesn't significantly reduce blood phenylalanine, suggesting a different mechanism for patient perceived benefits. Both LNAA supplementation and a phenylalanine restricted diet aim to improve brain neurotransmitter biochemistry to optimize outcomes through dietary intervention. The overall objective of this research is to evaluate additional dietary LNAAs on symptom management in adults with classical PKU at an individual level. N-of-1 randomized controlled trials will provide the highest level of evidence. The scientific premise is that manipulation of dietary LNAAs affects blood LNAA concentrations. LNAAs compete with phenylalanine for a shared transporter from blood to brain, dependent on blood concentrations and transporter affinities. Higher blood phenylalanine levels in adult PKU, with high transport affinity, produces excessive phenylalanine brain entry at the expense of other LNAAs. Insufficient LNAAs impairs synthesis of chemicals in the brain (neurotransmitters), a suggested mechanism of action for adult PKU symptoms. Additional dietary LNAAs may help to overcome this limitation of adult usual care. The study uses established PKU treatment products (medical foods) and biomarkers, (1) to determine effect of the adjuvant LNAA diet in symptom management; and (2) to evaluate correlations between changes in biomarkers and changes in symptoms during the intervention. Should findings show additive clinical value of LNAAs to the PKU diet, the strategy may become a useful adjunct. For participants, results will bring them closer to evidence-based individualized care. This work could advance the field closer toward personalized management.

Study Type

Study Type

Describes the nature of a clinical study. Study types include interventional studies (also called clinical trials), observational studies (including patient registries), and expanded access.
Interventional

Enrollment (Estimated)

Enrollment

The number of participants in a clinical study. The "anticipated" enrollment is the target number of participants that the researchers need for the study.
10

Phase

Phase

The stage of a clinical trial studying a drug or biological product, based on definitions developed by the U.S. Food and Drug Administration (FDA). The phase is based on the study's objective, the number of participants, and other characteristics. There are five phases: Early Phase 1 (formerly listed as Phase 0), Phase 1, Phase 2, Phase 3, and Phase 4. Not Applicable is used to describe trials without FDA-defined phases, including trials of devices or behavioral interventions.
  • Not Applicable

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Contact

Study Contact

The name and contact information for the person who can answer enrollment questions for a clinical study. Each location where the study is being conducted may also have a specific contact, who may be better able to answer those questions.
  • Name: Kathryn Moseley, RD, MS
  • Phone Number: 714-642-8790
  • Email: kmoseley@usc.edu

Study Contact Backup

  • Name: Annie Prince, RD. PhD
  • Phone Number: 9713733482
  • Email: ap_867@usc.edu

Study Locations

  • United States
    • California
      • Los Angeles, California, United States, 90033
        • University of Southern California

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Eligibility Criteria

The key requirements that people who want to participate in a clinical study must meet or the characteristics they must have. Eligibility criteria consist of both inclusion criteria (which are required for a person to participate in the study) and exclusion criteria (which prevent a person from participating). Types of eligibility criteria include whether a study accepts healthy volunteers, has age or age group requirements, or is limited by sex.

Ages Eligible for Study

18 years and older (Adult, Older Adult)

Accepts Healthy Volunteers

No

Description

Inclusion Criteria:

  • age ≥ 18 years
  • diagnosis of classical PKU (blood phenylalanine ≥1200 µmol pre-treatment or off-treatment
  • ≥ 2 PKU-related symptoms with clinically meaningful negative impact on daily life
  • is in regular clinical monitoring and is treated with a PKU diet with a natural protein restriction and medical foods
  • average blood phenylalanine levels between 360 and 900 µmol in past one year
  • able and willing to provide consent
  • demonstrates capacity to complete all requirements of the protocol
  • if on medications approved by the Principal Investigator agrees not to alter dose for duration of study
  • has stable daily access to phone, internet, and physical address

Exclusion Criteria:

  • women who are breastfeeding, pregnant or planning to become pregnant in the next year
  • use of adjuvant PKU treatments (LNAAs, Kuvan®, Palinziq®) within past 3 months
  • use of psychotropic medications, melatonin, or any serotonin-reuptake inhibitors within past 3 months
  • demonstrates insufficient motivation or time required to complete full trial

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Primary Purpose: Treatment
  • Allocation: Randomized
  • Interventional Model: Crossover Assignment
  • Masking: Triple

Arms and Interventions

Participant Group / Arm

Participant Group / Arm

A group or subgroup of participants in a clinical trial that receives a specific intervention/treatment, or no intervention, according to the trial's protocol.
Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.
Active Comparator: Active LNAA
Active LNAA tablets are given to each participant in 3 multiple crossovers for a total exposure to the Active Comparator 3 times. The allocation is randomized within each cycle of two treatments (active/inactive). There are 3 total cycles for each participant. The intervention is PreKUnil® tablets.
Other: PreKUnil® LNAA Medical Food for PKU
PreKUnil® LNAA Medical Food for PKU is a commercially available active LNAA treatment product for PKU. PreKUnil® inactive LNAA is a customized placebo for this research.
Placebo Comparator: Inactive LNAA
Inactive LNAA tablets (placebos) are given to each participant in 3 multiple crossovers for a total exposure to the Inactive Comparator 3 times. The allocation is randomized within each cycle of two treatments (inactive/active). There are 3 total cycles for each participant. The placebo intervention is PreKUnil® placebo tablets.
Other: PreKUnil® LNAA Medical Food for PKU
PreKUnil® LNAA Medical Food for PKU is a commercially available active LNAA treatment product for PKU. PreKUnil® inactive LNAA is a customized placebo for this research.

What is the study measuring?

Primary Outcome Measures

Primary Outcome Measures

In a clinical study's protocol, the planned outcome measure that is the most important for evaluating the effect of an intervention/treatment. Most clinical studies have one primary outcome measure, but some have more than one.
Outcome Measure
Measure Description
Time Frame
Personalized Symptom Index
Time Frame: 3 weeks
Assesses the subjective effect of the interventions on the personally relevant two most bothersome symptoms for the individual patient as identified in a Symptom Elicitation Interview
3 weeks

Secondary Outcome Measures

Secondary Outcome Measures

In a clinical study's protocol, a planned outcome measure that is not as important as the primary outcome measure for evaluating the effect of an intervention but is still of interest. Most clinical studies have more than one secondary outcome measure.
Outcome Measure
Measure Description
Time Frame
Absolute plasma phenylalanine concentration, dried blood spots (finger-prick method)
Time Frame: 3 weeks
Primary FDA-qualified biomarker for PKU
3 weeks
Fasting plasma LNAAs, dried blood spots (finger-prick method)
Time Frame: 3 weeks
Secondary biomarkers such as the plasma Phe/Tyr ratio, Tyr/LNAA, Trp/LNAA ratio
3 weeks
Urine peripheral biomarkers of neurotransmitters, dried urine spots
Time Frame: 3 weeks
6-sufatoxymelatonin and dopamine
3 weeks
Computerized neuropsychological testing (responses over study iPad from home)
Time Frame: 3 weeks
Cambridge Neuropsychological Test Automated Assessment Battery (CANTAB) customized for study
3 weeks
PKU-QOL Questionnaire Adult version (responses over study iPad from home)
Time Frame: 3 weeks
65-item (20 min) Patient-Reported Outcome Measure of the impact of PKU and the PKU diet on quality of life
3 weeks
Psychological General Well-Being Index (responses over study iPad from home)
Time Frame: 3 weeks
22-item (15 min) Patient-Reported Outcome Measure of well-being
3 weeks
Adult ADHD Self-Report Scale (ASRS v1.1)
Time Frame: 3 weeks
9-item inattention subscale (10 min) Patient-Reported Outcome Measure of attention
3 weeks
3-Day Diet Record
Time Frame: 3 weeks
Complete recording of 24-hr intake for 3 days (45 min)
3 weeks

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Sponsor

The organization or person who initiates the study and who has authority and control over the study.
University of Southern California

Collaborators

Collaborators

An organization other than the sponsor that provides support for a clinical study. This support may include activities related to funding, design, implementation, data analysis, or reporting.
National PKU Alliance

Investigators

Investigators

A researcher involved in a clinical study. Related terms include site principal investigator, site sub-investigator, study chair, study director, and study principal investigator.
  • Principal Investigator: Shoji Yano, MD, PhD, Keck School of Medicine at USC

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Actual)

Study Start

The actual date on which the first participant was enrolled in a clinical study. The "anticipated" study start date is the date that the researchers think will be the study start date.
September 1, 2023

Primary Completion (Estimated)

Primary Completion

The date on which the last participant in a clinical study was examined or received an intervention to collect final data for the primary outcome measure. Whether the clinical study ended according to the protocol or was terminated does not affect this date. For clinical studies with more than one primary outcome measure with different completion dates, this term refers to the date on which data collection is completed for all the primary outcome measures. The "anticipated" primary completion date is the date that the researchers think will be the primary completion date for the study.
July 31, 2024

Study Completion (Estimated)

Study Completion

The date on which the last participant in a clinical study was examined or received an intervention/treatment to collect final data for the primary outcome measures, secondary outcome measures, and adverse events (that is, the last participant's last visit). The "anticipated" study completion date is the date that the researchers think will be the study completion date.
July 31, 2024

Study Registration Dates

First Submitted

First Submitted

The date on which the study sponsor or investigator first submitted a study record to ClinicalTrials.gov. There is typically a delay of a few days between the first submitted date and the record's availability on ClinicalTrials.gov (the first posted date).
December 13, 2021

First Submitted That Met QC Criteria

First Submitted That Met QC Criteria

The date on which the study sponsor or investigator first submits a study record that is consistent with National Library of Medicine (NLM) quality control (QC) review criteria. The sponsor or investigator may need to revise and submit a study record one or more times before NLM's QC review criteria are met. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
December 13, 2021

First Posted (Actual)

First Posted

The date on which the study record was first available on ClinicalTrials.gov after National Library of Medicine (NLM) quality control (QC) review has concluded. There is typically a delay of a few days between the date the study sponsor or investigator submitted the study record and the first posted date.
December 30, 2021

Study Record Updates

Last Update Posted (Estimated)

Last Update Posted

The most recent date on which changes to a study record were made available on ClinicalTrials.gov. There may be a delay between when the changes were submitted to ClinicalTrials.gov by the study's sponsor or investigator (the last update submitted date) and the last update posted date.
December 4, 2023

Last Update Submitted That Met QC Criteria

Last Update Submitted That Met QC Criteria

The most recent date on which the study sponsor or investigator submitted changes to a study record that are consistent with National Library of Medicine (NLM) quality control (QC) review criteria. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
November 30, 2023

Last Verified

Last Verified

The most recent date on which the study sponsor or investigator confirmed the information about a clinical study on ClinicalTrials.gov as accurate and current. If a study with a recruitment status of recruiting; not yet recruiting; or active, not recruiting has not been confirmed within the past 2 years, the study's recruitment status is shown as unknown.
November 1, 2023

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

Other Study ID Numbers

Identifiers or ID numbers other than the NCT number that are assigned to a clinical study by the study's sponsor, funders, or others. These numbers may include unique identifiers from other trial registries and National Institutes of Health grant numbers.
  • LNAA for PKU

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

NO

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

No

Studies a U.S. FDA-regulated device product

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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