Survival probability for recipient of HCT with hrTMA. (A) Kaplan-Meier estimate of survival probability in recipients of HCT with hrTMA treated with the terminal complement blocker eculizumab (n = 21) starting at hrTMA diagnosis. Survival at 6 months after hrTMA diagnosis was 71% (solid line; 95% confidence interval [CI], 55-94 [dotted lines]). (B) Kaplan-Meier estimate of survival in recipients of HCT with hrTMA treated with the terminal complement blocker eculizumab (n = 21) and untreated controls with the same risk TA-TMA (n = 12) starting at hrTMA diagnosis. Survival 6 months after hrTMA diagnosis in participants treated with eculizumab was 71%, and 18% in untreated historical controls. A P value for the comparison between the historical and treated cohorts is not provided because the 2 cohorts were not accrued concurrently. (C) Kaplan-Meier estimate of survival probability in recipients with HCT with hrTMA treated with the terminal complement blocker eculizumab (n = 21) starting at stem cell infusion (day 0). Survival at 1 year after HCT was 61.9% (solid line; 95% CI, 45-87 [dotted lines]).