Alexion Pharmaceuticals is conducting this clinical trial. The objective of this study is to evaluate the safety and efficacy of eculizumab in pediatric participants (aged 2 to < 18 years) with relapsing neuromyelitis optica spectrum disorder (NMOSD).
All participants will receive open-label eculizumab by intravenous infusion during the Primary Treatment Period, starting on Day 1 and for a total of 52/53 weeks. The dosing regimen will be based on the participant’s body weight. As body weight changes during the study, the participant’s weight cohort and dose may change accordingly. After completing the 52/53-week Primary Treatment Period, participants may continue receiving eculizumab in the Extension Treatment Period for 104 weeks. Following a weight-based weekly dose of eculizumab during an induction phase, participants will receive weight-based doses of eculizumab every 2 weeks during the Primary Treatment Period and Extension Treatment Period.