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

PHASE3RECRUITING

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.

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Study details:

Eligible participants are:. Feeder participants: those who have completed a Phase 3 PTC Therapeutics (PTC) sponsored feeder study (including Study PTC923-MD-003-PKU). Non-feeder controlled participants: those who have not completed a feeder study and have blood Phe levels \<360 μmol/L at study entry.

Non-feeder uncontrolled participants: those who have not completed a feeder study and have blood Phe levels ≥360 μmol/L at study entry.

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Eligibility criteria

Researchers look for people who fit a certain description, called eligibility criteria. See if you qualify.

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 sponsor, 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 sponsor, 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).

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Eligibility

Age eligible for study : 0 and older

Healthy volunteers accepted : No

Gender eligible for study: All

Things to know

Study dates

Study start: 2022-02-14

Primary completion: 2026-04-30

Study completion finish: 2026-04-30

Study type

TREATMENT

Phase

PHASE3

Trial ID

NCT05166161

Intervention or treatment

DRUG: PTC923

Conditions

• Phenylketonuria

Condition: Phenylketonuria
DRUG: PTC923
Westmead, New South Wales, Australia and more
Sponsor: PTC Therapeutics

You may be eligible to participate in this trial based on your search. Check eligibility by answering some questions.

Are you running this trial? If you're a clinic or sponsor, you can claim this study. Claim or learn more.

Find a site

Closest Location:

Westmead Hospital

Research sites nearby

Select from list below to view details:

Westmead Hospital
Westmead, New South Wales, Australia
Royal Children's Hospital
Parkville, Victoria, Australia
PARC Clinical Research
Adelaide, South Australia, Australia

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?

Participant Group/Arm	Intervention/Treatment
EXPERIMENTAL: PTC923 Participants will receive PTC923 7.5 mg/kg (participants 0 to \<6 months of age), 15 mg/kg (participants 6 to \<12 months of age), 30 mg/kg (participants 12 months to \<2 years of age), or 60 mg/kg (participants ≥2 years of age) orally once daily for a minimum of 12 months or until participant experiences lack of efficacy, adverse events (AEs) that lead to discontinuation, withdraws from treatment, or PTC923 is authorized and commercially available in the specific country.	DRUG: PTC923 PTC923 powder for oral use will be suspended in water or apple juice prior to administration.

Participant Group/Arm

Intervention/Treatment

EXPERIMENTAL: PTC923

Participants will receive PTC923 7.5 mg/kg (participants 0 to \<6 months of age), 15 mg/kg (participants 6 to \<12 months of age), 30 mg/kg (participants 12 months to \<2 years of age), or 60 mg/kg (participants ≥2 years of age) orally once daily for a minimum of 12 months or until participant experiences lack of efficacy, adverse events (AEs) that lead to discontinuation, withdraws from treatment, or PTC923 is authorized and commercially available in the specific country.

DRUG: PTC923

PTC923 powder for oral use will be suspended in water or apple juice prior to administration.

What is the study measuring?

Primary outcome

Primary Outcome Measure	Primary Outcome Description	Primary Outcome Time Frame
Number of Treatment-Emergent Adverse Events (TEAEs)	A TEAE is any unfavorable or unintended sign (including an abnormal laboratory finding), symptom or disease in a study participant who is administered study drug in this study	Baseline up to end of study (up to approximately 2.5 years)
Change From Baseline in Dietary Phe/Protein Consumption at Week 26, Measured During Phe Tolerance Assessment Period	Phe tolerance is defined as the total amount of dietary Phe (milligrams \[mg\]/kilogram \[kg\] per day) ingested while maintaining blood Phe levels within the range of 40 to 360 micromoles (μmol)/liter (L) (defined as ≥40 to \<360 μmol/L).	Baseline, Week 26

Secondary outcome

Secondary Outcome Measure	Secondary Outcome Description	Secondary Outcome Time Frame
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	QOL using PKU-QOL questionnaire will be assessed in the subset of participants who are able to complete the PKU-QOL (that is, participants whose primary language is English \[British or American\], Turkish, Dutch, German, Spanish, Italian, Portuguese, or French) (ages 6 to 8 years Parent PKU-QOL; ages 9 to 11 years Child PKU-QOL; ages 12 to 17 years Adolescent PKU-QOL; ages ≥18 years Adult PKU-QOL).	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	QOL will be assessed using the EQ-5D (EQ-5D-Y Proxy Version 1 \[3 to 7 years\]; EQ-5D-Y \[8 to 15 years\]; EQ-5D-5L (\[≥16 years\]).	Baseline, Months 8, 14, 20, 26, 32, and 38

Frequently Asked Questions

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You may be eligible to participate in this trial based on your search.Apply for study

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References

Clinical Trials Gov: A Long-Term Safety Study of PTC923 in Participants With Phenylketonuria