A Study in Adult Patients With Paroxysmal Nocturnal Hemoglobinuria (PNH) to Evaluate How Safe Long-term Treatment With Pozelimab + Cemdisiran Combination Therapy is and How Well it Works

This study is looking for adult patients (aged 18 and over) with PNH. Generally, there are two main groups of people who might be able to join. One group includes patients who have already been taking part in a similar earlier study (called the 'parent study') and completed it without stopping the treatment.

The second group includes PNH patients who have a specific gene change (called a 'C5 polymorphism') that means their current PNH treatments (like eculizumab or ravulizumab) might not be working as well as expected. For these patients, doctors would need to confirm their PNH diagnosis with a special blood test and show that their condition is currently active, with certain blood markers being high.

There are also some reasons why someone might not be able to join. For example, if they have had an organ or bone marrow transplant, or if the research doctors believe that joining the study might not be safe for them or might interfere with the study's goals. Also, all participants must be up-to-date with specific vaccinations, such as for meningococcal disease.

If you join this study, you will receive the experimental combination of pozelimab and cemdisiran. The study involves regular visits to the clinic, where the research team will monitor your health, check for any side effects, and take blood samples to see how the drugs are working and how much of them are in your blood. You will also need to comply with specific vaccination requirements, particularly for meningococcal disease. The exact number of visits, assessments, and the total duration will be carefully explained to you by the study team if you are considered for participation.