Improved Iron Overload with Pegcetacoplan in Eculizumab-Experienced Patients with Paroxysmal Nocturnal Hemoglobinuria

Complement factor 5 (C5) inhibitors for paroxysmal nocturnal hemoglobinuria (PNH) may cause iron overload due to residual intravascular hemolysis (IVH) and emergent extravascular hemolysis (EVH). In PEGASUS (phase 3; NCT03500549), adults with PNH with residual anemia (hemoglobin concentration < 10.5 g/dL) after ≥3 months of eculizumab received eculizumab and pegcetacoplan for 4 weeks and were then randomized (1:1) to eculizumab or pegcetacoplan monotherapy for 16 weeks; in the following 32-week, open-label period, patients either continued pegcetacoplan or switched from eculizumab to pegcetacoplan. This post hoc analysis reports PEGASUS transfusion-related data and iron-related biomarkers to evaluate pegcetacoplan's effects on iron regulation. Of 80 patients randomized in PEGASUS, 27 (33.8%) had baseline iron overload (serum transferrin saturation ≥ 50%). Iron overload resolved within 52 weeks of pegcetacoplan treatment in 16 of 22 patients (72.7%) with baseline and postbaseline data; 10 experienced resolution after 20 weeks. With pegcetacoplan, transfusion numbers decreased for patients with and without iron overload, hepcidin concentrations increased, and absolute reticulocyte counts (ARCs) decreased to normal range. Mean ferritin concentrations were above normal throughout the study, regardless of iron overload status. Pegcetacoplan improves iron overload-related biomarkers, including increased hepcidin concentrations and decreased ARCs, by blocking IVH and EVH and preventing anemia.