Pre-HCTFLT3-ITD MRD and outcomes. (A) The majority of FLT3-ITD MRD detected by PCR-NGS pre-HCT is below the threshold of conventional CE. The limit of detection for FLT3-ITD as assessed by CE and PCR-NGS is indicated. Orange boxes indicate 2 patients positive for FLT3-ITD by PCR-NGS but without available CE data. (B) Relapse risk post-HCT is associated with FLT3-ITD PCR-NGS VAF ≥0.001%. Kaplan–Meier estimates of relapse-free survival according to pre-HCT FLT3-ITD MRD levels showing highest relapse risk for FLT3-ITD MRD ≥1%, lowest risk for FLT3-ITD MRD <0.001%, and intermediate risk for levels between 0.001 and <1%. (C-D) Pre-HCT FLT3-ITD MRD is associated with inferior clinical outcomes. Kaplan-Meier estimates of (C) cumulative incidence of relapse (with transplant-related mortality as a competing risk in 14 patients not included in this curve) and (D) overall survival according to pre-HCT FLT3-ITD PCR-NGS and CE status. Two patients with positive FLT3-ITD by PCR-NGS lacking CE data were excluded. (E-F) Pre-HCT FLT3-ITD and NPM1 MRD are prognostic for clinical outcome post-HCT. Kaplan-Meier estimates of (E) relapse-free and (F) overall survival according to pre-HCT FLT3-ITD PCR-NGS MRD and NPM1 MRD in 71 of 78 co-mutated for both FLT3-ITD and NPM1. Seven patients with insufficient material for NPM1 MRD assessment were excluded.