A Study to Evaluate How Safe Pozelimab + Cemdisiran Combination Therapy is and How Well it Works in Adult Patients With Paroxysmal Nocturnal Hemoglobinuria (PNH) Who Have Not Recently Received or Have Not Received Complement Inhibitor Treatment

This study is researching a clinical treatment combination with two experimental drugs called pozelimab and cemdisiran. The study is focused on people with paroxysmal nocturnal hemoglobinuria (PNH). The aim of the study is to see how safe and effective the pozelimab + cemdisiran combination is for people with PNH and how the combination compares with 2 existing treatments: ravulizumab and eculizumab. The pozelimab + cemdisiran combination may be referred to as "study drugs". Ravulizumab and eculizumab may also be called the "comparator drug". The study is looking at several research questions, including: * How effective is the pozelimab + cemdisiran combination compared to ravulizumab? * How effective is pozelimab + cemdisiran combination compared to eculizumab? * What side effects may happen from taking the study drugs? * How much study drugs are in the blood at different times? * Whether the body makes antibodies against the study drugs (which could make the study drugs less effective or could lead to side effects)