200 Participants Needed

PTC923 for Phenylketonuria

Recruiting at 70 trial locations
PA
AK
Overseen ByAneal Khan
No Placebo GroupAll trial participants will receive the active study treatment (no placebo)
Pivotal Trial (Near Approval)This treatment is in the last trial phase before FDA approval
Prior Safety DataThis treatment has passed at least one previous human trial
Approved in 2 JurisdictionsThis treatment is already approved in other countries

Trial Summary

Will I have to stop taking my current medications?

The trial requires that you do not take any medications that inhibit folate synthesis or certain supplements like tetrahydrobiopterin (BH4) or pegvaliase-pqpz. If you're on these, you may need to stop them to participate.

What data supports the effectiveness of the drug PTC923 (sepiapterin) for treating phenylketonuria?

Research shows that PTC923 (sepiapterin) can lower high levels of phenylalanine in the blood of people with phenylketonuria, potentially more effectively than sapropterin, a similar drug. This suggests that PTC923 might help manage phenylketonuria by improving metabolic control.12345

Is PTC923 (sepiapterin) safe for humans?

PTC923, also known as sepiapterin, has been studied in humans and is generally considered safe. In a study with 24 adults with phenylketonuria, it was compared to sapropterin, which is well-tolerated and has been used safely in many patients. Most adverse events (unwanted effects) reported with sapropterin were mild or moderate, and serious events were rare.12678

How is the drug PTC923 different from other treatments for phenylketonuria?

PTC923 (sepiapterin) is unique because it is an oral drug that increases levels of tetrahydrobiopterin (BH4) more effectively than sapropterin, potentially benefiting a broader range of patients with phenylketonuria by reducing blood phenylalanine levels.1891011

What is the purpose of this trial?

This trial is testing the safety of a medication called PTC923 in people with phenylketonuria (PKU). PKU patients need to manage their blood phenylalanine levels carefully. PTC923 aims to help control these levels, making it easier for patients to manage their condition. PTC923 is a newer treatment for PKU, following earlier treatments like sapropterin and pegvaliase.

Eligibility Criteria

This trial is for individuals with Phenylketonuria (PKU) who have had high blood phenylalanine levels. They must stick to their current diet unless told otherwise, not be on certain other PKU treatments, and use effective contraception if applicable. People with significant lab abnormalities, renal disease, gastrointestinal issues that affect drug absorption, or serious uncontrolled neuropsychiatric illness cannot join.

Inclusion Criteria

I agree to use birth control and not donate sperm during and up to 90 days after the study.
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
Willing to continue current diet unchanged while participating in the study (unless specifically instructed to change diet during the study by the investigator)
See 1 more

Exclusion Criteria

I have a stomach or bowel condition that could affect how I absorb medication.
I cannot take medicine by mouth.
I have kidney problems with a GFR under 60 mL/min.
See 10 more

Timeline

Screening

Participants are screened for eligibility to participate in the trial

2-4 weeks

Treatment

Participants receive PTC923 orally once daily for a minimum of 12 months

12 months

Follow-up

Participants are monitored for safety and effectiveness after treatment

up to approximately 2.5 years

Long-term safety evaluation

Evaluation of long-term safety and changes in dietary Phe/protein consumption

up to approximately 2.5 years

Treatment Details

Interventions

  • PTC923
Trial Overview The study tests the long-term safety of a drug called PTC923 in people with PKU. It also looks at how the treatment might allow participants to change their dietary intake of phenylalanine/protein from what they usually consume.
Participant Groups
1Treatment groups
Experimental Treatment
Group I: PTC923Experimental Treatment1 Intervention
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.

PTC923 is already approved in United States, European Union for the following indications:

🇺🇸
Approved in United States as PTC923 for:
  • Phenylketonuria (PKU)
  • Hyperphenylalaninemia
🇪🇺
Approved in European Union as PTC923 for:
  • Phenylketonuria (PKU)
  • Hyperphenylalaninemia

Find a Clinic Near You

Who Is Running the Clinical Trial?

PTC Therapeutics

Lead Sponsor

Trials
75
Recruited
6,300+

Dr. Matthew B. Klein

PTC Therapeutics

Chief Executive Officer since 2023

BA from the University of Pennsylvania, MD from Yale University School of Medicine, MS in Epidemiology from the University of Washington School of Public Health

Dr. Stuart W. Peltz

PTC Therapeutics

Chief Medical Officer since 2023

MD from Harvard Medical School

Findings from Research

In a Phase 2 study involving 24 adults with phenylketonuria (PKU), PTC923 at 60 mg/kg significantly reduced blood phenylalanine (Phe) levels more effectively than sapropterin, with a mean reduction of -206.4 μmol/L compared to -91.5 μmol/L for sapropterin.
PTC923 not only showed a faster onset of action but also demonstrated efficacy in classical PKU subjects, indicating its potential as a superior treatment option for managing elevated Phe levels in PKU patients.
PTC923 (sepiapterin) lowers elevated blood phenylalanine in subjects with phenylketonuria: a phase 2 randomized, multi-center, three-period crossover, open-label, active controlled, all-comers study.Bratkovic, D., Margvelashvili, L., Tchan, MC., et al.[2023]
In a study involving 46 children aged 4 to 12 with phenylketonuria (PKU), sapropterin dihydrochloride significantly increased the amount of phenylalanine (Phe) they could tolerate while keeping their blood Phe levels under control.
The treatment was well-tolerated with no severe or serious adverse events reported, indicating that sapropterin has a good safety profile for children with PKU.
Efficacy of sapropterin dihydrochloride in increasing phenylalanine tolerance in children with phenylketonuria: a phase III, randomized, double-blind, placebo-controlled study.Trefz, FK., Burton, BK., Longo, N., et al.[2023]
A survey of 166 healthcare professionals revealed that long-term responsiveness to tetrahydrobiopterin (BH4) in phenylketonuria (PKU) patients is commonly defined by factors such as natural protein tolerance (95.6%) and improvement in metabolic control (73.5%).
There is significant variability in the definitions of BH4 responsiveness, with different cut-off values for phenylalanine reduction and protein tolerance reported, indicating a need for a standardized, evidence-based definition to enhance treatment quality.
Defining tetrahydrobiopterin responsiveness in phenylketonuria: Survey results from 38 countries.Evers, RAF., van Wegberg, AMJ., Ahring, K., et al.[2023]

References

PTC923 (sepiapterin) lowers elevated blood phenylalanine in subjects with phenylketonuria: a phase 2 randomized, multi-center, three-period crossover, open-label, active controlled, all-comers study. [2023]
Efficacy of sapropterin dihydrochloride in increasing phenylalanine tolerance in children with phenylketonuria: a phase III, randomized, double-blind, placebo-controlled study. [2023]
Defining tetrahydrobiopterin responsiveness in phenylketonuria: Survey results from 38 countries. [2023]
Assessment of tetrahydrobiopterin (BH4) responsiveness in phenylketonuria. [2023]
Recommendations for the use of sapropterin in phenylketonuria. [2023]
Safety and efficacy of 22 weeks of treatment with sapropterin dihydrochloride in patients with phenylketonuria. [2023]
Long-term safety and efficacy of sapropterin: the PKUDOS registry experience. [2023]
Optimizing the use of sapropterin (BH(4)) in the management of phenylketonuria. [2023]
Sapropterin dihydrochloride: a new drug and a new concept in the management of phenylketonuria. [2023]
10.United Statespubmed.ncbi.nlm.nih.gov
Genotype-predicted tetrahydrobiopterin (BH4)-responsiveness and molecular genetics in Croatian patients with phenylalanine hydroxylase (PAH) deficiency. [2023]
New era in treatment for phenylketonuria: Pharmacologic therapy with sapropterin dihydrochloride. [2022]
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