PTC Therapeutics' Sephience (sepiapterin) Data Reinforce Broad PKU Benefits, Including Diet Liberalization and Sustained Metabolic Control
核心洞察
PTC Therapeutics announced 17 abstracts and presentations on Sephience (sepiapterin) (搜索) at the 2026 SSIEM Annual Symposium in Helsinki, Finland, from Aug. 25-28.
New analyses from the AMPLIPHY study show Sephience produced a 100% greater blood Phe reduction versus sapropterin in participants switching therapies.
Real-world evidence demonstrates significant diet liberalization in adolescents while maintaining target blood Phe levels, including in classical/non-BH4-responsive PKU.
PTC Therapeutics, Inc. (NASDAQ: PTCT) announced that multiple Sephience (sepiapterin) (搜索) scientific data presentations will be featured at the 2026 Society for the Study of Inborn Errors of Metabolism (SSIEM) Annual Symposium, taking place in Helsinki, Finland, from Aug. 25-28. The presentations include new data from clinical trials and real-world evidence that reinforce the clinically meaningful benefits of Sephience on lowering phenylalanine (Phe), significant diet liberalization, and sustained metabolic control for the full spectrum of individuals living with phenylketonuria (PKU) (搜索), including those with classical PKU.
"The SSIEM presentations further demonstrate the broad clinical benefits of Sephience across the full spectrum of individuals living with PKU," said Matthew B. Klein, M.D., Chief Executive Officer of PTC Therapeutics. "In addition, new data to be presented at the PTC symposium show treatment with Sephience led to a large number of responsive participants achieving normalization of blood Phe levels (<120 µmol/L) in a rapid timeframe, including those with classical or non-BH4-responsive PKU."
Key Findings Presented at SSIEM 2026
New analyses from the AMPLIPHY study demonstrate that Sephience treatment resulted in a 100% greater reduction in blood Phe for participants on sapropterin at screening after switching to Sephience. This finding underscores the enhanced efficacy of Sephience relative to existing therapy in patients who transition from sapropterin.
In an analysis of participants in Sephience studies with high baseline Phe levels (≥900 µmol/L), Sephience treatment resulted in clinically meaningful reductions in blood Phe levels within 14 days, with response rates comparable to the overall study population and a safety profile consistent with prior studies. These findings support a trial of Sephience treatment in individuals with PKU regardless of severity or baseline Phe.
An analysis of real-world data performed by a leading global key opinion leader shows that Sephience enabled significant dietary liberalization in adolescents, supporting greater independence, reduced dietary burden, and maintained metabolic control within recommended targets. These results were observed in individuals with both BH4-responsive and classical/non-BH4 responsive PKU mutations.
Mechanism of Action and Indication
Sephience is indicated for the treatment of hyperphenylalaninemia (HPA) (搜索) in adult and pediatric patients 1 month of age and older with sepiapterin-responsive phenylketonuria (PKU) (搜索), to be used in conjunction with a phenylalanine (Phe)-restricted diet. Sephience is a natural precursor of the enzymatic co-factor BH4, a critical co-factor for phenylalanine hydroxylase (PAH) (搜索). Through its unique dual mechanism of action, Sephience is able to effectively reduce blood Phe levels and has the potential to treat a broad range of PKU patients. Sephience is approved in the United States, the European Union/European Economic Area region, Japan, and other countries.
Safety Profile
Sephience studies continue to show a consistent and favorable safety profile. The most common adverse reactions with Sephience (≥2% and > placebo) were diarrhea, headache, abdominal pain, hypophenylalaninemia, feces discoloration, and oropharyngeal pain.
Important safety considerations include an increased risk of bleeding, with events such as superficial hematomas, prolonged bleeding, and heavy menstrual bleeding reported in treated patients. Some pediatric patients receiving Sephience experienced hypophenylalaninemia, warranting monitoring of blood Phe levels and dosage or dietary adjustment. Clinicians should also monitor patients receiving levodopa for changes in neurological status, and avoid concomitant use of drugs that inhibit dihydrofolate reductase (DHFR), such as methotrexate or trimethoprim, which may reduce sepiapterin metabolism to BH4.
Disease Background
Phenylketonuria (PKU) (搜索) is a rare, inherited metabolic disease characterized by the body's inability to break down the essential amino acid phenylalanine (Phe), which can result in neurological and other symptoms. If left untreated or poorly managed, Phe can build up to harmful levels, causing severe and irreversible disabilities such as permanent intellectual disability, seizures, delayed development, memory loss, and behavioral and emotional problems. Diagnosis of PKU usually takes place during newborn screening programs, and there are an estimated 58,000 people living with PKU globally.