Pre-HSCT emapalumab is associated with improved IFS and high-risk IFS. Five-year Kaplan-Meier survival estimates based on OS (A), TA-TMA status (moderate and high risk only) (B), IFS (use of any additional cellular product for low chimerism, or death) (C), and high-risk IFS (rapid taper of immunosuppression, DLI, second HSCT, or death) (D). Time for the TA-TMA survival analysis was recorded from the start of conditioning, but for all other analyses, time is relative to the day of stem cell infusion (day 0). Curves were compared using the log-rank (Mantel-Cox) test. Similar curves for GVHD free survival are shown in supplemental Figure 11. ∗P < .05. ns, not statistically significant.