A Long-Term Safety Study of PTC923 in Participants With Phenylketonuria

The main purpose of this study is to evaluate the long-term safety of PTC923 in participants with phenylketonuria, and to evaluate the changes from baseline in dietary phenylalanine (Phe)/protein consumption.

PTC Identifier:
PTC923-MD-004-PKU
ClinicalTrials.gov Identifier:
NCT05166161
EudraCT Identifier:
2021-000497-28
EU CT ID:
2023-509229-31-00
Recruiting

Trial Purpose

Age
N/A
Sex
Both (Female and Male)
Healthy Volunteers
No

Key Participation Requirements

Inclusion Criteria:

  • Inclusion Criteria:
  • Clinical diagnosis of PKU with hyperphenylalaninemia (HPA) documented by past medical history of at least 2 blood Phe measurements ≥600 μmol/L.

Exclusion Criteria:

Inclusion and Exclusion Criteria
Inclusion criteria
  • Inclusion Criteria:
  • Clinical diagnosis of PKU with hyperphenylalaninemia (HPA) documented by past medical history of at least 2 blood Phe measurements ≥600 μmol/L.
  • Women of childbearing potential must have a negative pregnancy test at screening and agree to abstinence or the use of at least one highly effective form of contraception for the duration of the study, and for up to 90 days after the last dose of the study drug.
  • Males who are sexually active with women of childbearing potential who have not had a vasectomy must agree to use a barrier method of birth control during the study and for up to 90 days after the last dose of study drug. Males must also refrain from sperm donations during this time period.
  • Willing to continue current diet unchanged while participating in the study (unless specifically instructed to change diet during the study by the investigator).
  • Exclusion Criteria:
  • Inability to tolerate oral medication.
  • A female who is pregnant or breastfeeding, or considering pregnancy.
  • Serious neuropsychiatric illness (for example, major depression) not currently under medical control, that in the opinion of the investigator or PTC, would interfere with the participant's ability to participate in the study or increase the risk of participation for that participant.
  • Past medical history and/or evidence of renal impairment and/or condition including moderate/severe renal insufficiency (glomerular filtration rate [GFR] <60 milliliters [mL]/minute [min] min as estimated most recently during qualifying participation in a feeder study) and/or under care of a nephrologist.
  • Any other condition that in the opinion of the investigator or PTC, would interfere with the participant's ability to participate in the study or increase the risk of participation for that participant.
  • Requirement for concomitant treatment with any drug known to inhibit folate synthesis (for example, methotrexate).
  • Concomitant treatment with tetrahydrobiopterin (BH4) supplementation (for example, sapropterin dihydrochloride, KUVAN) or pegvaliase-pqpz (PALYNZIQ).
  • Additional criteria for non-feeder participants who did not participate in a feeder study:
  • Gastrointestinal disease (such as irritable bowel syndrome, inflammatory bowel disease, chronic gastritis, and peptic ulcer disease, etc) that could affect the absorption of study drug.
  • History of gastric surgery, including Roux-en-Y gastric bypass surgery or an antrectomy with vagotomy, or gastrectomy.
  • History of allergies or adverse reactions to synthetic BH4 or sepiapterin.
  • Any clinically significant laboratory abnormality as determined by the investigator.
  • Any abnormal physical examination and/or laboratory findings indicative of signs or symptoms of renal disease, including calculated GFR <60 milliliters (mL)/minute/1.73 square meter (m^2).
  • Confirmed diagnosis of a primary BH4 deficiency as evidenced by biallelic pathogenic mutations in 6-pyruvoyltetrahydropterin synthase, recessive GTP cyclohydrolase I, sepiapterin reductase, quinoid dihydropteridine reductase, or pterin-4-alphacarbinolamine dehydratase genes.

Trial Summary

Total Participants

This is the number of individuals who are taking part in the trial.

Total Participants
200

Trial Dates

These are the start and end dates for the trial. Note that future dates are estimates that may be updated before or during the trial.

Trial Dates
Feb 2022 - Apr 2026

Phase

These are the different steps that a treatment goes through during clinical development before it is approved for use.

Phase
Phase 3

Placebo Controlled

In this type of study, some participants receive a “placebo,” which looks like the study treatment, but does not actually contain the active treatment.

Placebo Controlled
No

Product

This is any type of drug, device, or other treatment that is being studied in the trial.

Product
N/A

Accepts Healthy Volunteers

Healthy volunteers are individuals who participate in the trial and do not have that specific disease or condition.

Accepts Healthy Volunteers
No
Discuss with the trial center for details

Trial Design

Trial Type

This is the general nature of the study.

Trial Type
Interventional

Interventional

Participants in these studies are subject to an intervention by researchers. These trials are used to understand the effects of a particular intervention.

Discuss with the trial center for details

Blinding

Study participants know which treatments they might get if they join the trial, however during a trial they may not be informed which treatment they are actually taking. The act of not disclosing this information to the participant is known as “blinding.”

Blinding
N/A
Discuss with the trial center for details

Intervention Type

This is a medicine, device, or other type of treatment that is being studied or is already approved for use. Interventions can also include behavior changes, like diet and exercise.

Intervention Type
Drug

Allocation

This determines how study participants are assigned their treatment.

Allocation
N/A

Trial Purpose

This is the rationale behind why the clinical trial is being performed.

Trial Purpose
Treatment

Trial Arms

These are the groups of participants in a clinical study. Each different “arm” is assigned a different treatment to use. Different types of trial arms in studies can include:

Trial Arms
Experimental

Experimental arm

Experimental arm: The group assigned to use the study treatment

Primary Outcome

Primary Outcome

This is the most important measurement of the study and is used to help researchers evaluate the effect of a treatment.

Number of Treatment-Emergent Adverse Events (TEAEs)

Timeframe: Baseline up to end of study (up to 4 years)

Change From Baseline in Dietary Phe/Protein Consumption at Week 26, Measured During Phe Tolerance Assessment Period

Timeframe: Baseline, Week 26

Secondary Outcome

Secondary Outcome

This measurement is a secondary measurement and is still important in helping researchers evaluate the effect of a treatment.

Change From Baseline in Quality of Life (QOL) Using Phenylketonuria-Quality of Life (PKU-QOL) Questionnaire at Months 8, 14, 20, 26, 32, and 38

Timeframe: Baseline, Months 8, 14, 20, 26, 32, and 38

Change From Baseline in QOL Using the European Quality of Life - 5 Dimensions (EQ-5D) at Months 8, 14, 20, 26, 32, and 38

Timeframe: Baseline, Months 8, 14, 20, 26, 32, and 38

Palatability of PTC923

Timeframe: Month 1 Day 1

Acceptability/Ease of Administration of PTC923

Timeframe: Month 1 Day 1

Taste/Flavor Assessment Using a Facial Hedonic Scale

Timeframe: Month 1 Day 1

Plasma Sepiapterin Concentration

Timeframe: Month 1 Day 1 up to Month 11 Day 1

Plasma BH4 Concentration

Timeframe: Month 1 Day 1 up to Month 11 Day 1

Contact Information

Location
Status
Location
Copenhagen University Hospital, Rigshospitalet
Copenhagen, Denmark, DK-2100
Status
Recruiting
Location
Universitätsklinikum Münster
Münster, Germany, 48149
Status
Recruiting
Location
University Children's Hospital Hamburg Eppendorf (Kinder-UKE) Klinik für Kinder- und Jugendmedizin (Kinder-UKE)
Hamburg, Germany, 20246
Status
Recruiting
Location
PARC Clinical Research
Adelaide, South Australia, Australia, SA 5000
Status
Recruiting
Location
Westmead Hospital
Westmead, New South Wales, Australia, 2145
Status
Recruiting
Location
The Hospital for Sick Children University of Toronto Adult Clinic: The Fred A Litwin Family Centre in Genetic Medicine University Health Network & Mt. Sinai Hospital
Toronto, Ontario, Canada, M5G 1X8
Status
Recruiting
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