Safety and Efficacy of Eculizumab in High-risk TA-TMA

Inclusion Criteria: * Age ≥18 years. * Patients who have undergone hematopoietic stem cell transplantation for any indication within 12 months prior to enrollment. * Meet the diagnostic criteria for TA-TMA within ≤14 days prior to enrollment (at least 4 of the following 7 criteria present simultaneously):① Lactate dehydrogenase (LDH) above the age-adjusted upper limit of normal;② Presence of schistocytes on peripheral blood smear;③ New-onset thrombocytopenia or requirement for platelet transfusions;④ New-onset anemia or requirement for red blood cell transfusions;⑤ Hypertension;⑥ Random urine protein-to-creatinine ratio (rUPCR) ≥1 mg/mg;⑦ Elevated plasma soluble C5b-9 (sC5b-9) level (≥244 ng/mL). * Meet the criteria for high-risk TA-TMA (presence of any of the following):① Proteinuria (rUPCR ≥2 mg/mg);②Multiple organ dysfunction syndrome (MODS);③ Elevated IL-10 (≥2× upper limit of normal \[ULN\]). * Meet the following condition: TA-TMA has not resolved after ≥72 hours of management of triggering factors/conditions, including: ① Discontinuation or dose reduction of inciting medications (e.g., calcineurin inhibitors, CNI); ② Treatment of any underlying infection; ③ Treatment of underlying acute graft-versus-host disease (aGVHD). * Provide written informed consent. Exclusion Criteria: * Known hypersensitivity to eculizumab. * Uncontrolled severe infection (including meningococcal infection). * Prior treatment with complement inhibitors. * Known hereditary or acquired ADAMTS13 deficiency (activity \<10%). * Disseminated intravascular coagulation (DIC). * Respiratory failure (any cause) requiring mechanical ventilation, occurring within 72 hours prior to enrollment. * Acute and/or chronic heart failure with ejection fraction ≤40%. * Expected survival \<48 hours. * Any subject who, in the investigator's opinion, is not suitable for participation in this study.