FDA Approves Sepiapterin for Phenylketonuria Treatment
Sepiapterin Shows Significant Promise in Managing Phenylketonuria (PKU)
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New Phase 3 Data Highlight Dietary Liberalization and Genetic Insights
New York, NY – july 28, 2025 – Groundbreaking data from the Phase 3 APHENITY clinical trial and its accompanying open-label extension study have illuminated the significant benefits of sepiapterin in managing phenylketonuria (PKU). Presented at the 2025 American College of Medical Genetics and Genomics Annual Clinical Genetics Meeting, these findings offer clinicians and pharmacists valuable insights into the efficacy of this novel agent.
Dietary Freedom Achieved for Majority of patients
The APHENITY trial’s open-label extension study revealed remarkable results regarding dietary liberalization for individuals with PKU undergoing sepiapterin treatment. According to PTC Therapeutics,the developers of sepiapterin,over 97% of participants in the Phe tolerance protocol were able to liberalize their diet. This translates to a substantial mean increase in protein intake of 126%.
even more encouraging, 66% of subjects in the Phe tolerance sub-study achieved or surpassed the age-adjusted recommended daily allowance of protein intake for individuals without PKU. Crucially, this dietary expansion was accomplished while maintaining effective control of blood phenylalanine (Phe) levels, underscoring sepiapterin’s potential to significantly improve the quality of life for PKU patients.
Genetic Variant Analysis Aids Clinical Decision-Making
Further analysis of genetic variants among subjects enrolled in the APHENITY trial provided clinicians with critical information for patient diagnosis and treatment considerations. The data indicated that over 70% of patients possessed a genotype-phenotype value consistent with the presentation of classical PKU. This genetic insight can be instrumental for healthcare providers when diagnosing PKU and assessing a patient’s potential tolerability and response to sepiapterin therapy.
Regulatory milestones Pave the Way for Broader Access
The presentation of these compelling Phase 3 data follows significant regulatory advancements for sepiapterin. PTC Therapeutics announced the FDA approval of Sephience™ (sepiapterin) for the treatment of children and adults living with PKU on July 28, 2025.This approval was preceded by a positive opinion from the European Medicines Agency’s Committee for Medicinal Products for Human Use (CHMP) on April 25, 2025, signaling a promising future for broader patient access to this innovative treatment.
The extensive data from the APHENITY trial and its extension studies, coupled with these recent regulatory approvals, position sepiapterin as a transformative therapeutic option for individuals affected by PKU, offering hope for improved dietary management and overall well-being.
References:
- PTC Therapeutics. PTC Therapeutics Announces FDA Approval of Sephience™ (sepiapterin) for the Treatment of Children and Adults Living with Phenylketonuria (PKU). News Release. Released July 28, 2025. Accessed July 28, 2025. https://ir.ptcbio.com/news-releases/news-release-details/ptc-therapeutics-announces-fda-approval-sephiencetm-sepiapterin
- PTC Therapeutics. PTC Therapeutics Receives Positive CHMP Opinion for Sephience™ (sepiapterin) for the Treatment of Children and Adults Living with Phenylketonuria (PKU). News Release. released April 25, 2025. Accessed July 28, 2025. https://ir.ptcbio.com/news-releases/news-release-details/ptc-therapeutics-receives-positive-chmp-opinion-sephiencetm
- PTC Therapeutics. PTC Therapeutics Presents New Sepiapterin Data from Ongoing Studies. News Release. Released March 20, 2025. Accessed July 28, 2025. https://ir.ptcbio.com/news-releases/news-release-details/ptc-therapeutics-presents-new-sepiapterin-data-ongoing-studies?mobile=1
- A Study of PTC923 in Participants With Phenylketonuria. National Library of Medicine*. ClinicalTrials.gov Identifier: NCT05099640.