Impact of Donor Age in Haploidentical-Post-Transplantation Cyclophosphamide versus Matched Unrelated Donor Post-Transplantation Cyclophosphamide Hematopoietic Stem Cell Transplantation in Patients with Acute Myeloid Leukemia.

Haploidentical hematopoietic cell transplantation (HCT) with post-transplantation cyclophosphamide (PTCy) graft-versus-host-disease (GVHD) prophylaxis is associated with inferior overall survival (OS) compared to HLA-matched unrelated donor (MUD) HCT with PTCy prophylaxis in patients receiving reduced-intensity conditioning (RIC). Given prognostic implications of donor age, we investigated the differences in outcomes of patients with acute myeloid leukemia (AML; n = 775) undergoing RIC-HCT with a younger MUD (age <35 years; n = 84) versus a younger haploidentical donor (age <35 years; n = 302) versus an older haploidentical donor (age ≥35 years; n = 389). The older MUD group was excluded from the analysis because of small numbers. The younger haploidentical donor group (median age, 59.5 years) was somewhat younger than the younger MUD group (median age, 66.8 years) and the older haploidentical donor group (median age, 64.7 years). More patients in the MUD group received peripheral blood grafts (82%) compared to the haploidentical donor groups (55% to 56%). In multivariate analysis, compared to the younger MUD group, the younger haploidentical donor group (hazard ratio [HR], 1.95; 95% confidence interval [CI], 1.22 to 3.12; P = .005) and the older haploidentical donor group (HR, 2.36; 95% CI, 1.50 to 3.71; P < .001) had a significantly inferior OS, and the younger haploidentical donor group (HR, 3.72; 95% CI, 1.39 to 9.93; P = .009) and older haploidentical donor group (HR, 6.91; 95% CI, 2.75 to 17.39; P < .001) had a significantly higher risk of nonrelapse mortality. The older haploidentical group had a significantly higher risk of grade II-IV acute GVHD (HR, 2.29; 95% CI, 1.38 to 3.80; P = .001) and grade III-IV acute GVHD (HR, 2.70; 95% CI, 1.09 to 6.71; P = .03). There were no significant differences across the groups in the incidence of chronic GVHD or relapse. Among adult AML patients in CR undergoing RIC-HCT with PTCy prophylaxis, a young MUD may be preferred over a young haploidentical donor.

Concordant acute myeloblastic leukemia in identical twins treated with allogeneic transplantation from a younger HLA-identical sibling following a single apheresis procedure.

A concordant leukemia is that which occurs in a pair of monozygotic twins; a similar genetic background suggests an in utero monoclonal origin. We present the case of a pair of monozygotic infants with concordant acute myeloid leukemia who underwent a peripheral blood hematopoietic stem-cell transplant (HSCT) from a single, younger human leukocyte antigen-identical sibling donor, using a fractioned graft collected during only one apheresis procedure. Twin A relapsed at +456 and received a second haploidentical HSCT from his father, twin B has been in complete remission since the first HSCT. Both children are in complete remission and with negative minimal residual disease at +900 (after second transplant) and +1488, respectively.