Study of the Oral Factor D (FD) Inhibitor ALXN2050 in PNH Patients as Monotherapy

Experimental: Open-label ALXN2050 Monotherapy orally Group 1: Patients with PNH who are treatment naïve Group 2: Patients with PNH who have received complement component 5 (C5) inhibition with eculizumab for at least 6 months, who continue to experience anemia and reticulocytes above the upper limit of normal (ULN) who will switch to ALXN2050 monotherapy Group 3: Patients with PNH receiving danicopan monotherapy in study ACH471-103 will switch to ALXN2050 monotherapy After signing the informed consent form, participants will enter the screening period. During the Screening Period, eligibility and screening assessments will be performed. Screening assessments may be spread over more than one visit if necessary. At the baseline visit, screened participants who continue to meet eligibility criteria will enter the Treatment Period. The treatment phase will be followed by a long-term extension phase, where ALXN2050 will continue to be administered. Blood will be collected to assess the efficacy endpoints, such as, change in hemoglobin (Hgb), lactate dehydrogenase (LDH), and other measures of hemolysis. Safety and transfusion requirements will also be assessed. Participants will continue on treatment past 12 weeks in a long-term extension portion of the trial.