Pre-HSCT emapalumab is associated with higher donor chimerism. (A) Cumulative incidence of mixed chimerism (donor chimerism <95% on 2 consecutive occasions) and severe mixed chimerism (donor chimerism <25%). (B) Minimum donor chimerism obtained within 1 year after HSCT and most recent donor chimerism within the study period (up to 5 years after HSCT, truncated at the time of second HSCT or death when applicable). Cumulative incidence was compared via the log-rank (Mantel-Cox) test with death included as a competing risk. Chimerism levels were treated as continuous variables and compared via the Mann-Whitney U test. ∗∗P < .01; ∗P < .05.