BioMarin's PALYNZIQ Shows Efficacy in Phase 3 Study for PKU Adolescents at ICIEM

BioMarin's Latest Developments in PKU Treatment: PALYNZIQ's Phase 3 Success

In a significant breakthrough, BioMarin Pharmaceutical Inc. has unveiled promising results from the Phase 3 PEGASUS study on PALYNZIQ® (pegvaliase-pqpz), focusing on its effectiveness in treating adolescents suffering from phenylketonuria (PKU). The study results were presented at the 15th International Congress of Inborn Errors of Metabolism (ICIEM) held on September 2-6, 2025, in Kyoto, Japan. This pivotal research aims to improve the quality of life for young individuals who struggle with this genetic disorder.

The Phase 3 PEGASUS trial included 55 participants aged 12 to 17, who were randomly assigned to receive either PALYNZIQ or diet alone. The results are remarkable: adolescents receiving PALYNZIQ exhibited a 49.7% reduction in mean blood phenylalanine (Phe) levels compared to those adhering strictly to dietary controls. Prior to the study, the adolescents had an average blood Phe concentration of 1026.4 µmol/L, with about 49% exceeding dangerous levels above 1000 µmol/L. After 72 weeks in the treatment group, 45.2% managed to achieve reductions of over 50% in their blood Phe levels, showcasing the remarkable potential of PALYNZIQ in managing PKU.

Efficacy and Safety Profile

The efficacy of PALYNZIQ was not just in the statistical significance, but also in the tangible outcome improvements where over half of the participants saw their blood Phe levels drop to 600 µmol/L or lower. This is a critical threshold for effective PKU management, enabling these adolescents to have greater control over their health. Notably, while the study reported a small percentage (5.6%) of serious adverse events, featuring anaphylaxis leading to study withdrawal, the overall safety profile aligns with previous studies that have predominantly shown manageable side effects.

Dr. Greg Friberg, BioMarin's Executive Vice President, emphasized the importance of these findings. “These data from the PEGASUS study underscore the impact PALYNZIQ can have in enabling adolescents to experience more freedom from the burden of their condition, particularly during this pivotal period of transition to adulthood,” he stated. This commitment to improving patient outcomes has been a focal point for BioMarin, especially in light of the scientific advancements made throughout the last two decades regarding PKU treatment.

Future Directions

BioMarin is scheduled to submit these Phase 3 results to global health authorities in the latter half of 2025, with the goal of expanding PALYNZIQ’s current adult-only indication to include treatment for adolescents. The ongoing extension phase of the PEGASUS trial will continue to monitor the long-term effects and safety of PALYNZIQ treatment in this demographic, reinforcing the commitment to enhancing the lives of those with PKU.

About PALYNZIQ and PKU

PALYNZIQ is a revolutionary therapy, representing the first and only enzyme substitution treatment available for adults with PKU, targeting blood Phe levels that don't respond to traditional dietary management. PKU itself is a genetic disorder where the body cannot break down phenylalanine, an amino acid found in most protein-rich foods. If not managed correctly, PKU can lead to severe neurological complications, including intellectual disability and psychological issues, making effective treatment solutions essential.

To further enhance treatment adherence, PALYNZIQ is engineered to be administered in a way that maximizes tolerability, addressing the usually strict dietary requirements that patients face. The innovative medicational design is seen as a critical breakthrough which reflects BioMarin’s ethos of pursuing cutting-edge treatments that fundamentally change patient life.

The PEGASUS study’s outcomes give hope to countless families and adolescents challenged by PKU, demonstrating that effective treatment is not just a dream but a developing reality. As BioMarin continues to share these findings globally, the future for PKU management is becoming increasingly optimistic, with PALYNZIQ leading the charge.