Cumulative incidence of posttransplant leukemia relapses. (A,C) Relapses in historical controls, and (B,D) in the present cohort of Treg-Tcon patients. Relapse rates were evaluated separately for transplants from NK alloreactive (solid line) vs non–NK-alloreactive (dotted line) donors. In historical AML patients, the cumulative incidence of relapse was significantly lower for those who were transplanted from NK-alloreactive donors (0.32 vs 0.03; P = .03), whereas no difference was observed in historical ALL patients (0.31 and 0.29, respectively). In Treg-Tcon haplo transplants leukemia relapse was markedly reduced in all patients independently of NK alloreactivity (B,D).