LAUSR

In this issue of Blood Advances, through a multicenter analysis of 367 pediatric patients, Horgan et al have reported that T-replete umbilical cord stem cell (TRCB) transplants against myeloid disease provide superior disease-free survival and event-free survival (EFS) compared with that provided by all other donor sources, including matched unrelated donor, matched sibling donor, mismatched unrelated donor, haploidentical, and T-depleted cord. Similar to other reports, in young and adult patients from single institutions, the power of cord-derived T cells during transplantation appeared greatest in those children with measurable residual disease (MRD) before transplant. Horgan et al found similar EFS and overall survival in patients from all groups who had no MRD before transplant, including those who received transplants using other alternative donor sources, including haploidentical grafts. This last finding supports that of others in which the absence of this MRD positive cord-derived graftversus-leukemia (GVL) benefit normalizes TRCB overall efficacy when compared with other donor stem cell sources. These results beg the question of why cord-derived T cells have such robust antitumor reactivity in patients with positive MRD and what are we willing to pay for it?