Pharmacokinetic Comparison of Efanesoctocog Alfa vs Other EHL-rFVIII Products in Participants With Severe Haemophilia A

This study is designed for men aged between 18 and 65 years old. To take part, you must have severe haemophilia A. This means your doctors have confirmed that your body produces very little or no Factor VIII, which is essential for blood clotting. Your medical records should show this, or you should have a genetic test result that confirms severe haemophilia A.

You also need to have been treated for haemophilia A with similar medicines (called recombinant or plasma-derived Factor VIII) for at least 150 days in your life. Crucially, at the time you join the study, you must currently be receiving treatment with either damactocog alfa pegol or turoctocog alfa pegol.

You cannot join the study if you have ever had your body create 'inhibitors' to Factor VIII – these are antibodies that would stop your medicine from working. We will check for these at the start of the study.

If you decide to take part, the study starts with a screening period which can last up to 28 days. During this time, we'll check if you're suitable for the study, including a wash-out period where you'll stop your current medication for a short time before the main part of the study begins.

First, you'll receive a single dose of the haemophilia medicine you're currently using (either damactocog alfa pegol or turoctocog alfa pegol). Over the next few days, you'll have about 7 visits for blood tests to see how this medicine works in your body.

Once we've finished checking your current medicine, you'll then receive a single dose of the new medicine, efanesoctocog alfa. After this, you'll have another 8 visits for more blood tests, also spread over several days, to see how the new medicine works. In total, you'll have about 15 visits for blood tests in the main part of the study, plus the screening visits.