Open-Label Efficacy and Safety Study of Pozelimab in Patients With CD55-Deficient Protein-Losing Enteropathy (CHAPLE Disease)

The primary objective of the study is to determine the effect of pozelimab on active CD55-deficient protein-losing enteropathy (PLE; CHAPLE). The secondary objectives of the study are: * To evaluate the safety and tolerability of pozelimab in patients with CD55-deficient PLE disease * To evaluate the effect of pozelimab on CD55-deficient PLE (both patients with active disease at baseline and those with inactive disease on eculizumab, switching to pozelimab) * To determine the effects of pozelimab on albumin and other serum proteins (total protein, immunoglobulins) * To determine the effects of pozelimab on ascites * To determine the effects of pozelimab on stool consistency * To determine the effect of pozelimab on health-related quality of life * To determine the effect of pozelimab on lab abnormalities observed in CD55-deficient PLE such as hypertriglyceridemia, thrombocytosis, and hypovitaminosis B12 * To describe the effects of pozelimab on the sparing of concomitant medications and reduction in hospitalization days * To determine the effects of pozelimab on growth * To characterize the concentration of pozelimab in patients with CD55-deficient PLE * To assess the incidence of treatment-emergent ADA for pozelimab in patients with CD55-deficient PLE disease