FDA

Palynziq now approved for phenylketonuria in adolescents

March 5, 2026

On February 27, 2026, FDA approved the supplemental biologics license application (sBLA) for Palynziq (pegvaliase-pqpz) to include pediatric patients ≥12 years of age with phenylketonuria (PKU).

Efficacy

Palynziq's expanded approval was supported by data from the phase 3, open‑label, randomized, controlled PEGASUS trial. In this study, 55 patients aged 12 to 17 years with uncontrolled PKU (blood phenylalanine levels >600 µmol/L) were randomized 2:1 to receive pegvaliase-pqpz (n=36) or continue dietary management alone (n=19). The primary endpoint was the change in blood phenylalanine (Phe) levels from baseline to week 72. Baseline Phe concentrations were similar between groups—1025 µmol/L in the pegvaliase-pqpz arm vs. 1029 µmol/L in the diet‑only arm. At week 72, treatment with pegvaliase-pqpz significantly reduced blood Phe levels from baseline compared with diet alone (–473 vs –19 µmol/L), reflecting a treatment difference of –409 µmol/L (95% CI: –579 to –240).

Nearly half of pegvaliase-pqpz‑treated patients (44.4%) achieved Phe levels below guideline targets, and within this group, 75% reached levels under 120 µmol/L, averaging an 828 µmol/L reduction from baseline. Additionally, 9 patients achieved Phe levels <30 µmol/L, allowing for substantial dietary freedom—increased natural protein intake by 318.1% and decreased medical food protein use by 55.16%. Six patients were able to stop using medical food entirely.

Safety

The safety profile of Palynziq in adolescents mirrored earlier studies in adults, with most adverse events occurring during the induction and titration phases and declining in the maintenance phase. Common adverse reactions (≥20% and greater than in control) in patients 12 to 17 years old were injection site reactions, arthralgia, headache, pyrexia, hypersensitivity reactions, dizziness, nausea, vomiting, fatigue, and pain in extremity.

Note that Palynziq is available only through a restricted program under a Risk Evaluation and Mitigation Strategy (REMS) because of the risk of anaphylaxis.

Sources:

BioMarin Pharmaceutical Inc. (2026, February 27). U.S. Food and Drug Administration Approves BioMarin’s Palynziq (pegvaliase-pqpz) for Adolescents 12 Years of Age and Older with Phenylketonuria (PKU). [Press release]. 2026. https://www.biomarin.com/news/press-releases/u-s-food-and-drug-administration-approves-biomarins-palynziq-pegvaliase-pqpz-for-adolescents-12-years-of-age-and-older-with-phenylketonuria-pku/

Palynziq (pegvaliase-pqpz). [Package insert]. BioMarin Pharmaceutical Inc. https://www.biomarin.com/wp-content/uploads/2026/02/Palynziq-prescribing-Information_Feb-2026.pdf Revised February 2026. Accessed March 4, 2026.