A Long-term Extension Study to Assess the Long-term Safety and Efficacy of Pegtibatinase Treatment in Participants ≥5 to ≤65 Years of Age With Classical Homocystinuria (HCU) (ENSEMBLE)

To be able to join this study, you must be between 5 and 65 years old. The study is specifically for people who are already taking part in another study called COMPOSE investigating pegtibatinase. Alternatively, you can join if you have completed 24 weeks of treatment in the HARMONY study, which also looked at pegtibatinase or a placebo.

Unfortunately, you cannot join this particular study if you had to stop an earlier pegtibatinase study because of a serious side effect or if your body couldn't tolerate the treatment. This is to ensure the safety of participants already known to have had difficulties with the medication.

Both males and females are welcome to participate, as long as they meet the other criteria. The researchers want to get a broad understanding of how the treatment works across different people.

If you join this study, you could be involved for at least 108 weeks, which is about two years. This period includes up to 104 weeks where you'll be taking the pegtibatinase medication. After you stop taking the medicine, there will be a 4-week follow-up period to check on your health and safety.

Most participants will give themselves the pegtibatinase injections, unless there's a good reason why they can't. Throughout the study, doctors will take blood samples to see how the medication is moving through your body. There's also an extra, optional part of the study (called a 'sub-study') that some people might be able to join, which looks at how much protein you can eat while on the treatment. This is an 'open-label' study, meaning everyone involved, including you and your doctors, will know you are receiving pegtibatinase.