Does your adolescent have phenylketonuria (PKU)?

PEGASUS is a clinical research study evaluating the safety and effectiveness of an investigational drug in adolescents aged 12 to 17 years with PKU.

If you think your adolescent may be eligible to take part in this study, please contact your nearest study center for more information.

Find a study center

The aim of the PEGASUS Study is to see whether an investigational drug, called pegvaliase, is a safe and effective treatment for adolescents with PKU (12 to 17 years of age).

Group 1 – adolescents will be receiving pegvaliase during the study (while maintaining a stable protein diet).

Group 2 – adolescents will be managing their PKU with diet-only (maintaining a stable protein diet) for the first 72 weeks of the study. Following 72 weeks, adolescents will start treatment with pegvaliase.

All adolescents randomized to the diet-only treatment arm will receive pegvaliase treatment after 72 weeks.

Your adolescent is twice as likely to be assigned to Group 1 than to Group 2.

The study will enroll around 54 adolescents across the US and Germany.

The study duration is approximately 3 years.

What does the study involve?

Adolescent participants will be asked to visit the study center to have their health monitored and to see how they are responding to the investigational drug. There is the opportunity for virtual telemedicine visits for some selected sites.

The study is composed of:

  • Screening (4 weeks) – adolescents will be evaluated to determine whether they are eligible to participate in the study. If eligible, they will be randomized to either pegvaliase treatment or diet-only for the first 72 weeks of the study.
  • Part 1: Study Treatment Period (72 weeks) – Adolescents in Group 1 will receive pegvaliase treatment while maintaining same level of dietary protein. The first 8 weeks of pegvaliase treatment will be given at the study center. The remaining doses will be given at the study center or at home by a trained parent/guardian and/or adolescent participant. A trained observer (adult) is required to be present during home administration and for at least one hour following administration throughout the study. 
    • Adolescents in Group 2 will be managing PKU by diet only. The adolescents will receive pegvaliase treatment after 72 weeks of diet only.
  • Part 2: Extension Period (up to an additional 80 weeks) – Adolescent participants receiving pegvaliase will continue to receive pegvaliase during the extension part of the study. Adolescents randomized to diet-only in Part 1 (72 weeks), will start pegvaliase treatment in the extension part of the study. 

Can my adolescent join?

Your adolescent must meet several criteria to join the PEGASUS Study. Key eligibility criteria include: 

  • Aged 12 to 17 years.
  • Diagnosed with PKU and have difficulty maintaining recommended levels of blood Phe on their current prescribed treatment (must have prior sapropterin dihydrochloride use).
  • Willing and able to adjust their diet (such as the level of protein they eat) under the supervision of a dietician or their physician throughout the duration of the study.
  • Have an adult (aged 18 years and older) who is willing and able to be present during all home injections and for a minimum at least one-hour following injections throughout the study.

There are additional criteria to enroll in the study – the study team will assess these and discuss them with you and your adolescent. 

If you think your adolescent may be eligible, please contact the nearest study center for more information. The PEGASUS site investigator and/or site team will discuss the study with you and your adolescent in detail and perform tests and assessments to confirm whether your adolescent is eligible to join. 

By joining a clinical research study your adolescent might:

Help advance healthcare understanding – they would be contributing to medical research that may help other adolescents with PKU in the future.

Useful links

Find a study center near you Visit the clinicaltrials.gov website for more information