Pegtibatinase as a Treatment for Participants With Classical Homocystinuria (HCU) Receiving Standard of Care Treatment

To join this study, you need to be between 12 and 65 years old and have a confirmed diagnosis of Homocystinuria (HCU). Your blood test for total homocysteine (tHcy) needs to show levels of 50 µM (micromoles per litre) or higher. It's important that you're willing to stick to a stable diet and continue your current HCU treatments (like betaine or special medical foods) throughout the study, unless your doctor says otherwise for your health.

There are also some reasons why you might not be able to join. For example, if you have certain other medical conditions (like Marfan syndrome or recent serious blood clots), or if you've had a bad reaction to similar drugs in the past. If you weigh more than 160 kg, or if you've previously taken pegtibatinase or similar study drugs, you wouldn't be able to participate. If you could become pregnant, you'll need a negative pregnancy test and to use effective contraception.

If you decide to take part, the study will last up to 38 weeks (about 9 months). It starts with a screening period of up to 10 weeks to check if you're suitable. This includes an initial check-up and a period of up to 6 weeks where your diet will be carefully monitored to make sure it's consistent. During this time, your regular HCU diet and treatments will be recorded.

After screening, you'll enter the 'blinded treatment period' for 24 weeks. This means you won't know if you're receiving pegtibatinase or the placebo, and neither will your study doctor. This helps to ensure the results are accurate. You'll have regular study visits, some at home and some possibly online, where your diet and HCU treatments will continue to be monitored. After your last dose of the study medicine, there will be a 4-week safety check-up, unless you choose to join a long-term follow-up study.