Kaplan-Meier estimates of EFS based on HSCT donor and conditioning in the HLH-2004 study. Five-year probabilities of survival (pSu) are indicated with a 95% CI. Death or second HSCT were defined as events. P values from Cox proportional hazards models. (A) EFS for the entire cohort based on donor: MRD (n = 44, event n = 21, blue line); MUD (n = 60, event n = 24, red line, dashed); UCB (n = 53, event n = 23, black line, dotted)], P = .52. [MUD vs MRD, P = .26; UCB vs MRD, P = .61]. (B) EFS for children with verified FHL based on donor (MRD, n = 31, event n = 14, blue line; MUD, n = 45, event n = 18, red line, dashed; UCB, n = 39, event n = 14, black line, dotted; P = .65 (MUD vs MRD, P = .40; UCB vs MRD, P = .44). (C) EFS for the entire cohort based on conditioning (busulfan-based, n = 99, events n = 42, blue line; fludarabine based, n = 39, events n = 18, red line dashed; treosulfan based, n = 20, events n = 5, black line, dotted; P = .31 (fludarabine vs busulfan, P = .74; treosulfan vs busulfan, P = .16). (D) EFS for children with verified FHL based on conditioning (busulfan based, n = 69, events n = 27, blue line; fludarabine based, n = 26, events n = 12, red line, dashed; treosulfan based, n = 18, events n = 5, black line, dotted; P = .49 (fludarabine vs busulfan, P = .49; treosulfan vs busulfan, P = .43).