RecruitingPhase 2Drug trialEfficacy and Safety Study of Narsoplimab in Pediatric Patients With High-Risk Hematopoietic Stem Cell Transplant TMAThe purpose of this study is to evaluate the safety and efficacy of narsoplimab in pediatric patients with thrombotic microangiopathies (TMA) following hematopoietic stem cell transplant (HSCT).