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

NCT ID: NCT05174559

Last Updated: 2023-12-04

Basic Information

• Recruitment Status: ACTIVE_NOT_RECRUITING
• Clinical Phase: NA
• Total Enrollment: 10 participants
• Study Classification: INTERVENTIONAL
• Study Start Date: 2023-09-01
• Study Completion Date: 2024-07-31

Brief Summary

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.

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.

Conditions

Phenylketonurias

Keywords

N-of-1 randomized controlled trials

Study Design

• Allocation Method: RANDOMIZED
• Intervention Model: CROSSOVER
• Primary Study Purpose: TREATMENT
• Blinding Strategy: TRIPLE

Study Groups

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.

Group Type: ACTIVE_COMPARATOR

PreKUnil® LNAA Medical Food for PKU

Intervention Type: OTHER

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.

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.

Group Type: PLACEBO_COMPARATOR

PreKUnil® LNAA Medical Food for PKU

Intervention Type: OTHER

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.

Interventions

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.

Intervention Type: OTHER

Eligibility Criteria

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

• Minimum Eligible Age: 18 Years
• Eligible Sex: ALL
• Accepts Healthy Volunteers: No

Sponsors

National PKU Alliance

UNKNOWN

Sponsor Role: collaborator

University of Southern California

OTHER

Sponsor Role: lead

Responsible Party

Shoji Yano

Director, Genetics Division, Department of Pediatrics, Associate Professor of Clinical Pediatrics and Medicine, Keck School of Medicine

Responsibility Role: PRINCIPAL_INVESTIGATOR

Principal Investigators

Shoji Yano, MD, PhD

Role: PRINCIPAL_INVESTIGATOR

Keck School of Medicine at USC

Locations

University of Southern California

Los Angeles, California, United States

Countries

United States

Other Identifiers

LNAA for PKU

Identifier Type: -

Identifier Source: org_study_id