This makes Palynziq the only enzyme substitution therapy that received approval to reduce blood phenylalanine (Phe) concentrations in individuals with PKU.
The approval follows data from PEGASUS, a Phase III randomised controlled, open-label, multi-centre trial assessing the efficacy and safety of Palynziq compared to dietary management alone in adolescents with uncontrolled blood Phe levels above 600µmol/L.
By the end of Part I, 44.4% of participants achieved Phe concentrations below guideline recommendations; within this group, 75% fell below 120µmol/L, and the mean Phe reduction reached 828µmol/L, corresponding to a 94% decrease from baseline.
For nine participants who reached hypophenylalaninaemia, intact protein intake increased by 318.1% from baseline while medical food protein intake fell by 55.16%. Six individuals discontinued medical food entirely.
The most common adverse reactions among adolescents included arthralgia, dizziness, fatigue, hypersensitivity reactions, nausea, pyrexia and vomiting.
Most side effects occurred during induction/titration phases and declined during maintenance.
BioMarin’s executive vice-president and chief research and development officer Greg Friberg said: “Over the past two decades, BioMarin has been working hand-in-hand with the medical and advocacy communities to improve the lives of people living with PKU, including the introduction of the first two treatment options for this inherited metabolic condition that otherwise requires lifelong adherence to a rigid medical diet.
“We are proud to build on this legacy by expanding Palynziq’s approval to adolescents aged as young as 12 [years], which will allow even more people with PKU the prospect of achieving substantially lower Phe levels.”
BioMarin is seeking European Medicines Agency (EMA) approval to broaden Palynziq’s use to adolescents aged 12 years and above in the European Union.
In May 2025, BioMarin agreed to acquire Inozyme Pharma for $4.00 per share in a $270m all-cash transaction.