A Randomized, Double-Blind, Placebo-Controlled, First-In-Human Study of the Safety, Tolerability, Pharmacokinetics, and Preliminary Efficacy of ALN-CFB, an Investigational siRNA Therapeutic Against Complement Factor B, in Participants With Paroxysmal Nocturnal Hemoglobinuria and Persistent Anemia on Approved C5-Inhibitor Therapy
This study is researching an experimental drug called ALN-CFB. The study is focused on people with Paroxysmal Nocturnal Hemoglobinuria (PNH) who are currently taking a complement component C5 inhibitor (C5-inhibitor) and continue to have anemia (low red blood cell count). The aim of the study is to see how tolerable ALN-CFB is compared to placebo. A placebo looks like the study drug but does not contain any drug. The study is looking at several other research questions, including: * What side effects may happen from taking ALN-CFB * How much ALN-CFB is in the blood at different times * How much Complement Factor B (CFB) protein levels in the blood are affected by ALN-CFB
• Has been diagnosed with PNH confirmed by a history of high flow cytometry from prior testing
• Treated with a stable dose of C5 inhibitor (eculizumab or approved eculizumab biosimilar, ravulizumab, or crovalimab) for at least 24 weeks prior to screening visit, as described in the protocol
• Has hemoglobin ≤10.5 g/dL at screening visit 1, with evidence of anemia prior to this visit, as described in the protocol
• Has peripheral blood reticulocyte count of ≥100 x 10\^9/L at screening visit 1