• 28 Feb 2026
• Admin
• News Article

FDA Expands BioMarin’s PALYNZIQ Approval to Adolescents With PKU

BioMarin Pharmaceutical Inc. has secured a major regulatory win in phenylketonuria (PKU).
The U.S. Food and Drug Administration (FDA) has approved BioMarin’s supplemental Biologics License Application (sBLA) for PALYNZIQ® (pegvaliase-pqpz), extending its use to pediatric patients aged 12 years and older.

PALYNZIQ remains the only enzyme substitution therapy approved to reduce blood phenylalanine (Phe) levels in people with PKU.

Why This Approval Matters for Adolescents With PKU?

Adolescence is one of the most challenging phases for PKU management.

• Academic and social independence increases
• Adherence to an ultra-restrictive, low-Phe diet often declines
• Poor Phe control is linked to long-term neurocognitive impairment

According to Boston Children’s Hospital, adolescence is often when dietary management becomes unsustainable.

PALYNZIQ offers a genotype-independent treatment option that can normalize Phe levels while allowing a less restrictive diet.

Clinical Evidence Behind the FDA Decision

The approval is based on results from PEGASUS, a Phase 3, multicenter, open-label randomized controlled trial.

PEGASUS Trial Design

• Adolescents aged 12 to <18 years
• Uncontrolled PKU with blood Phe >600 µmol/L
• PALYNZIQ vs diet-only management

Key Results at Week 72

• PALYNZIQ arm: Mean Phe reduction of 473 µmol/L
• Diet-only arm: Mean reduction of 19 µmol/L
• Treatment difference: −409 µmol/L (95% CI: −579 to −240)

These results demonstrate a clinically and statistically meaningful reduction in blood Phe levels with PALYNZIQ.

Longer-Term Outcomes: Diet Flexibility and Sustained Control

Additional data presented at the 15th International Congress of Inborn Errors of Metabolism highlighted further benefits:

• 44.4% of participants reached guideline-recommended Phe levels
• 75% of responders achieved Phe <120 µmol/L
• Average Phe reduction reached 94% from baseline

In patients with very low Phe levels:

• Intact protein intake increased by 318%
• Medical food protein intake dropped by 55%
• Some participants discontinued medical food entirely

Safety Profile in Adolescents

The safety profile in adolescents was consistent with prior adult studies. Most common adverse reactions (≥20%):

• Injection site reactions
• Arthralgia
• Headache
• Pyrexia
• Hypersensitivity reactions
• Dizziness, nausea, vomiting, fatigue

Reactions were most frequent during induction and titration and declined during maintenance therapy.

PALYNZIQ continues to carry a Boxed Warning for anaphylaxis and is available only through the PALYNZIQ REMS program.

Voices From the PKU Community

“This approval provides a new option for adolescents at a critical life stage,” said National PKU Alliance.

Clinical experts also emphasized that adherence may be stronger when treatment begins earlier, while patients still have family support.

Strategic Significance for BioMarin

The adolescent approval further strengthens BioMarin’s long-standing PKU franchise.

Key milestones:

• Third PKU-focused therapy introduced by BioMarin
• PALYNZIQ now approved in more than 35 countries
• EMA review underway to expand adolescent use in Europe

BioMarin continues to position itself as a leader in genetically defined rare diseases, with PKU remaining a cornerstone of its portfolio.

Bottom Line

By expanding PALYNZIQ’s label to include adolescents aged 12 and older, BioMarin is addressing a critical treatment gap in PKU.

For many families, this approval could mean better metabolic control, greater dietary freedom, and improved long-term neurological outcomes, right when patients need it most.