PTC Therapeutics To Present New Sephience Data At The 2026 Society For The Study Of Inborn Errors Of Metabolism Annual Symposium, August 25-28

The presentations include new data from clinical trials and real-world evidence which 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) including those with classical PKU. In addition, Sephience studies continue to show a consistent and favorable safety profile.

"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. "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. These impressive data support the potential benefits Sephience can deliver for individuals affected by PKU."

Highlights of the data to be presented at SSIEM 2026 include:

• 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.
• 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.