Efficacy and Safety Maintained up to 3 Years in Adults with Paroxysmal Nocturnal Hemoglobinuria Receiving Pegcetacoplan

INTRODUCTION: Pegcetacoplan, the first C3 and C3b inhibitor for paroxysmal nocturnal hemoglobinuria (PNH), demonstrated efficacy and safety in C5 inhibitor-experienced and -naive patients in the phase 3 studies PEGASUS (NCT03500549) and PRINCE (NCT04085601), respectively. This integrated analysis of PEGASUS, PRINCE, and their subsequent open-label extension study (NCT03531255) evaluated pegcetacoplan long-term efficacy and safety. METHODS: Efficacy was assessed from pegcetacoplan initiation through 2.5 years (PRINCE) and 3 years (PEGASUS) by measuring hemoglobin, lactate dehydrogenase (LDH), absolute reticulocyte count (ARC), indirect bilirubin, and Functional Assessment of Chronic Illness Therapy (FACIT)-Fatigue scores. Transfusion avoidance and safety were assessed during pegcetacoplan monotherapy. Of 133 patients in PRINCE and PEGASUS, 114 enrolled in the extension. Most patients (PRINCE, 81.1%; PEGASUS, 75.0%) were transfusion dependent at trial entry and baseline hemoglobin was below normal. RESULTS: Pegcetacoplan markedly and rapidly (within 4 weeks) improved all efficacy measures, which stabilized close to (hemoglobin, FACIT-Fatigue) or within (LDH, ARC, indirect bilirubin) normal range for up to 3 years; annual transfusion avoidance rates were 79.5-86.4% in PRINCE and 71.2-79.2% in PEGASUS. No new safety concerns were identified over 3 years. Serious adverse events were reported in 73 (55.3%) patients, deemed pegcetacoplan related in 6 (4.5%) patients. Most injection site reactions were mild, and their incidence decreased over time. Five (3.8%) deaths occurred (none deemed pegcetacoplan related); 37 (28.0%) patients experienced clinically significant and laboratory-confirmed breakthrough hemolysis; 4 thrombotic events occurred in 3 (2.3%) patients; no meningitis cases were reported. CONCLUSION: Pegcetacoplan efficacy and safety was sustained for up to 3 years in patients with PNH, with or without prior C5 inhibitor treatment, verifying the long-term favorable clinical profile of this proximal complement inhibitor. TRIAL REGISTRATION: ClinicalTrials.gov NCT03500549 (PEGASUS), NCT04085601 (PRINCE), and NCT03531255 (307 OLE).