PKU and the pediatrician with Suzanne Hollander, MS, RD, LDN

As the phenylketonuria (PKU) community anticipates the potential FDA approval of a new treatment, Suzanne Hollander, MS, RD, LDN, senior clinical nutrition specialist at Boston Children's Hospital, says pediatricians and primary care providers have a critical opportunity to reconnect patients to care.

“Pediatricians and primary care providers play a really important role in the healthcare and the lives of our kids with PKU,” said Hollander. “From the start, they are involved in referring those newborn screen cases to a metabolic center or a PKU clinic.” But over time, she explained, the burden of managing PKU through strict dietary restrictions can cause some patients, particularly adolescents and young adults, to disengage from follow-up care.

“We see it often in later adolescence and adulthood,” she said. “Pediatricians and primary care providers can have a huge impact in referring those individuals back to the PKU clinic, where we'll have the opportunity to offer them new treatments.”

A potential treatment is sepiapterin, an investigational oral therapy that may significantly reduce blood phenylalanine (Phe) levels and allow for dietary liberalization. Sepiapterin has a Prescription Drug User Fee Act date of July 29, 2025, for potential approval from the FDA.

“Sepiapterin is an exciting novel treatment,” Hollander said. “It works to lower levels of phenylalanine in the blood, which can improve clinical outcomes and also allow for individuals to eat more natural protein in their diet.”

PKU is caused by a deficiency in the enzyme that converts phenylalanine to tyrosine. Sepiapterin acts by enhancing the function of that enzyme, thereby reducing blood Phe and potentially easing the restrictive dietary demands of the disorder.¹

Recent results from the APHENITY trial and its open-label extension showed that 97% of participants were able to liberalize their diet while on sepiapterin, with a mean increase in protein intake of 126% and sustained control of Phe levels.¹

In a previous interview with Contemporary Pediatrics, Hollander further discussed details from the APHENITY trial, noting that 84% of individuals reached a target range of less than 360. Click here to watch this discussion.²

“In the PKU community, we're hearing a lot of excitement from people coming to the clinic and from families,” Hollander said. “So it's exciting to get the word out there—to both patients, the community, and other providers—that… we have this new data and that we can stay tuned for more details later.”

References:

1. PTC Therapeutics Presents New Sepiapterin Data from Ongoing Studies. PTC Therapeutics. Press release. March 20, 2025. Accessed May 8, 2025. https://ir.ptcbio.com/news-releases/news-release-details/ptc-therapeutics-presents-new-sepiapterin-data-ongoing-studies

2. Fitch J, Hollander S. PKU and sepiapterin data with Suzanne Hollander, MS, RD, LDN. Contemporary Pediatrics. May 7, 2025. May 8, 2025. https://www.contemporarypediatrics.com/view/pku-and-sepiapterin-data-with-suzanne-hollander-ms-rd-ldn