New PKU drug could loosen strict diet restrictions

NCT ID NCT05166161

Ongoing Disease control Sponsor: PTC Therapeutics Source: ClinicalTrials.gov ↗

First seen Jun 26, 2026 · Last updated Jun 27, 2026 · Updated 1 time

Summary

This phase 3 study tests a drug called PTC923 (sepiapterin) in 200 people with phenylketonuria (PKU), a genetic condition that requires a strict low-protein diet. The main goal is to see if the drug is safe over the long term and whether it allows people to eat more protein without harmful side effects. Participants take the drug daily as a powder mixed in water or apple juice.

What this could mean

Our plain-language read of the trial. This is informational only — not medical advice or a prediction.

Active substance

PTC923 (sepiapterin), a powder taken by mouth mixed with water or apple juice

What this could lead to

If successful, this could provide a new treatment option that helps people with PKU tolerate more protein in their diet, potentially easing dietary restrictions.

What could go wrong

This is an open-label study without a placebo group, so results may be less reliable. The main focus is safety, and it is not designed to prove the drug works better than existing treatments.

Disclaimer Read more

This is a summary of the original study . Summaries may miss details or leave out important information. Before applying or accepting participation, make sure you have read and understood the full study. Curemydisease.com takes no responsibility whatsoever for anything missed, misunderstood, or acted upon as a result of our summary — we know it does not capture everything.

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Conditions

The condition(s) this trial relates to.

phenylketonuria

As listed by the trial registrant

The condition terms exactly as the trial's registrant entered them.

PHENYLKETONURIA

Contacts and locations

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Locations

Azienda Ospedaliera-Universita Padova

Padua, Veneto, 35129, Italy
Birmingham Children's Hospital NHS Foundation Trust

Birmingham, B4 6NH, United Kingdom
Boston Children's Hospital

Boston, Massachusetts, 02115, United States
CENTRO HOSPITALAR UNIVERSITÁRIO LISBOA NORTE Hospital de Santa Maria

Lisbon, Estremadura, 1649-035, Portugal
CENTRO HOSPITALAR UNIVERSITÁRIO LISBOA NORTE Hospital de Santa Maria,

Lisbon, Estremadura, 1649-035, Portugal
Centro Hospitalar Universitário Do Porto, Epe

Porto, 4099-001, Portugal
Children's Hospital Colorado

Aurora, Colorado, 80045, United States
Copenhagen University Hospital, Rigshospitalet

Copenhagen, DK-2100, Denmark
Department of Human Neuroscience, Child and Adolescent Neuropsychiatry, Policlinico Umberto I

Rome, 00185, Italy
Ege University Faculty of Medicine Children Hospital

Bornova, İzmir, 35100, Turkey (Türkiye)
Fakultní nemocnice Královské Vinohrady Klinika dětí a dorostu Ambulance pro léčbu PKU a HPA

Prague, 100 34, Czechia
Gazi Üniversitesi Tıp Fakültesi

Yenimahalle, Ankara, 06500, Turkey (Türkiye)
Great Ormond Street Hospital

London, WC1N 3JH, United Kingdom
Hacettepe University Medical Faculty

Altındağ, Ankara, 06230, Turkey (Türkiye)
Hospital Sant Joan de Déu

Barcelona, Esplugues de Llobregat, 08950, Spain
Hospital Universitario Ramón y Cajal

Madrid, 28034, Spain
Hospital Universitario Virgen del Rocío

Seville, 41013, Spain
Hospital das Clínicas da Faculdade de Medicina de Ribeirão Preto da Universidade de São Paulo

Ribeirão Preto, São Paulo, 14051-140, Brazil
Hospital de clinicas de Porto Alegre

Porto Alegre, Rio Grande do Sul, 90035-903, Brazil
Hôpital Necker-Enfants Malades - Centre de Référence des Maladies Héréditaires du Métabolisme

Paris, 75015, France
Icahn School of Medicine at Mount Sinai (ISMMS)

New York, New York, 10009, United States
Indiana University School of Medicine Department of Medical and Molecular Genetics

Indianapolis, Indiana, 46202, United States
McMaster Children's Hospital Hamilton Health Sciences

Hamilton, Ontario, L8N 3Z5, Canada
Medical Genetics and Laboratory Diagnostics Center

Tbilisi, 0159, Georgia
Metabolics and Genetics in Calgary (MAGIC) Clinic, Ltd.

Calgary, Alberta, T2E 7Z4, Canada
PARC Clinical Research

Adelaide, South Australia, SA 5000, Australia
PTC Clinical Site 1

Multiple Locations, Japan
PTC Clinical Site 2

Multiple Locations, Japan
PTC Clinical Site 3

Multiple Locations, Japan
PanAmerican Clinical Research

Guadalajara, Jalisco, 44670, Mexico
Pomorski Uniwersytet Medyczny w Szczecinie Centrum Wsparcia Badań Klinicznych

Szczecin, 71-252, Poland
Royal Children's Hospital

Parkville, Victoria, 3052, Australia
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, M5G 1X8, Canada
The Queensland Children's Hospital

South Brisbane, Brisbane, Australia
UF College of Medicine, Department of Pediatrics Division of Genetics and Metabolism

Gainesville, Florida, 32610, United States
UMCG Beatrix Children's Hospital

Groningen, 9713 GZ, Netherlands
UNIVERSITY HOSPITALS BIRMINGHAM NHS Foundation Trust

Birmingham, United Kingdom
UPMC Children's Hospital of Pittsburgh

Pittsburgh, Pennsylvania, 15224, United States
University Children's Hospital Hamburg Eppendorf (Kinder-UKE) Klinik für Kinder- und Jugendmedizin (Kinder-UKE)

Hamburg, 20246, Germany
University of Utah

Salt Lake City, Utah, 84108, United States
Universitätsklinikum Heidelberg / Zentrum für Kinder- und Jugendmedizin / Sektion für Neuropädiatrie & Stoffwechselmedizin

Heidelberg, 69120, Germany
Universitätsklinikum Münster

Münster, 48149, Germany
Univerzitetni klinicni center Ljubljana

Ljubljana, 1000, Slovenia
Westmead Hospital

Westmead, New South Wales, 2145, Australia
Çukurova Üniversitesi Tıp Fakültesi Balcalı Hastanesi

Adana, 01330, Turkey (Türkiye)
İstanbul Üniversitesi Cerrahpaşa Tıp Fakültesi

Fatih, Istanbul, 34098, Turkey (Türkiye)