NRM and OS after grade 3 to 4 aGVHD, stratified by adequate CD4⁺IR within the first 100 days after HCT. Cumulative incidence plots showing NRM after grade 3 to 4 aGVHD in the UMC/PMC cohort (A) and the MSK cohort (B). Kaplan-Meier curves showing OS in patients in the UMC/PMC cohort (C) and the MSK cohort (D). CD4⁺ IR was defined as ≥50 CD4⁺ T cells per μL in 2 consecutive measurements within the first 100 days after HCT (blue lines) and with no CD4⁺ IR (red lines).