FDA Approves PTC Therapeutics’ Sephience for Rare Genetic Disorder PKU

The U.S. Food and Drug Administration (FDA) has approved PTC Therapeutics’ (NASDAQ:PTCT) oral drug Sephience to treat phenylketonuria (PKU), a rare inherited metabolic disorder affecting the body’s ability to break down the amino acid phenylalanine. PKU, detected in about 1 in 15,000 U.S. newborns, can lead to toxic phenylalanine buildup, causing irreversible brain damage and intellectual disability if untreated.

Sephience enhances the activity and stability of the phenylalanine hydroxylase (PAH) enzyme, allowing patients to manage the condition more effectively and, in some cases, relax strict dietary restrictions. The approval is expected to bolster PTC’s revenue as sales of its Duchenne muscular dystrophy therapies, Translarna and Emflaza, decline due to patent expirations and regulatory challenges.

The FDA approval follows a late-stage clinical trial where Sephience reduced blood phenylalanine levels by an average of 63%, with most patients achieving guideline-recommended targets. The therapy, suitable for both children and adults, provides an alternative to existing treatments such as BioMarin’s Kuvan and Palynziq, which are effective only for certain patient populations.

PTC anticipates strong market potential, with Jefferies analyst Kelly Shi projecting peak annual sales of $741 million by 2030. Sephience was also approved in Europe last month and is under regulatory review in Japan, Brazil, and other countries.

All U.S. newborns are routinely screened for PKU shortly after birth, ensuring early diagnosis and intervention. Current treatments primarily involve lifelong low-phenylalanine diets and specialized medical formulas, underscoring the significance of new drug options like Sephience in improving patient quality of life and expanding therapeutic choices.