The primary objective of the study is to demonstrate a reduction in intravascular hemolysis by REGN3918 over 26 weeks of treatment in patients with active PNH who are treatment-naive to complement inhibitor therapy or have not recently received complement inhibitor therapy. The secondary objectives of the study are: - To evaluate the safety and tolerability of REGN3918. - To evaluate the effect of REGN3918 on parameters of intravascular hemolysis - To assess the concentrations of total REGN3918 in serum. - To evaluate the incidence of treatment-emergent anti-drug antibodies to REGN3918 over time - To evaluate the effect of REGN3918 on patient-reported outcomes (PROs) measuring fatigue and health-related quality of life

NCT03946748

Conditions

1. Paroxysmal Nocturnal Hemoglobinuria (PNH)

Interventions

1. Drug: REGN3918

MeSH:Hemoglobinuria Hemoglobinuria, Paroxysmal

HPO:Hemoglobinuria Paroxysmal nocturnal hemoglobinuria

Key Exclusion Criteria: - Prior treatment with a complement inhibitor either within 6 months prior to screening visit or at any time where the patient was refractory to complement inhibitor therapy, in the opinion of the investigator (with the exception of eculizumab refractory patients due to the C5 variant R885H/C) - History of bone marrow transplantation - Body weight < 40 kilograms at screening visit - Peripheral blood absolute neutrophil count (ANC) <500/μL [<0.5 x 109/L] or peripheral blood platelet count <50,000/μL - Documented history of systemic fungal disease or unresolved tuberculosis, or evidence of active or latent tuberculosis infection (LTBI) during screening period - Any contraindication for receiving Neisseria meningitidis vaccination and antibiotic prophylaxis therapy as recommended in the study - Any active, ongoing infection within 2 weeks of screening or during the screening period - Any clinically significant abnormality identified at the time of screening that in the judgment of the Investigator or any sub-Investigator would preclude safe completion of the study or constrain endpoints assessment such as major systemic diseases, or patients with short life expectancy - Women who are pregnant, breastfeeding, or who have a positive pregnancy test at screening visit or day 1 NOTE: Other protocol defined Inclusion/Exclusion criteria apply. --- R885H ---