A new study indicates similar survival outcomes for patients with hematologic malignancies undergoing hematopoietic stem cell transplantation (HSCT) using either haploidentical (haplo) HSCT with posttransplant cyclophosphamide or umbilical cord blood (UCB) HSCT. Study results were reported in the journal Blood Advances.

Haplo-HSCT utilization has traditionally been limited by poor outcomes such as mortality, graft vs host disease, and graft failure. However, conditioning regimens have evolved that have enabled some improvements in outcomes with this treatment approach. The researchers conducting this study aimed to compare outcomes between haplo-HSCT and UCB HSCT in patients who had received myeloablative conditioning. Prior research had indicated similar outcomes between these approaches in patients with nonmyeloablative or reduced intensity conditioning.

Data used in this prospective analysis were obtained from the Center for International Blood and Marrow Transplant Research. Patients had been treated with HSCT for either acute myeloid leukemia or acute lymphoblastic lymphoma between 2012 and 2017. Patients receiving haplo-HSCT had 4/8 human leukocyte antigen (HLA)-matched grafts, while patients receiving UCB HSCT had ≥6/8 or ≤5/8 HLA-matched grafts.

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There were 375 patients in the haplo-HSCT group, 188 in the ≤5/8 HLA-matched UCB HSCT group, and 145 in the ≥6/8 HLA-matched UCB HSCT group. Overall, patients receiving UCB HSCT more often were transplanted during second complete remission and were more likely to have acute lymphoblastic leukemia, in addition to better performance status, compared with haplo-HSCT recipients. Compared with the other groups, patients with ≥6/8 HLA-matched UCB HSCT transplants more often were young and with fewer comorbidities.

Median follow-ups occurred at 24 months for the haplo-HSCT group, at 46 months for the ≤5/8 HLA-matched UCB HSCT group, and at 36 months for the ≥6/8 HLA-matched UCB HSCT group. Three-year survival rates adjusted for age, comorbidities, and disease status were 66% for the haplo-HSCT group, 61% for the ≤5/8 HLA-matched UCB HSCT group, and 58% for the ≥6/8 HLA-matched UCB HSCT group.

The 3-year nonrelapse mortality rates were 10% with haplo-HSCT, 26% with ≤5/8 HLA-matched UCB HSCT, and 23% with ≥6/8 HLA-matched UCB HSCT, which reflected significant differences between haplo- and UCB HSCT donor types. However, the 3-year relapse rates were 36% in the haplo-HSCT group, 21% in the ≤5/8 HLA-matched UCB HSCT group, and 30% in the ≥6/8 HLA-matched UCB HSCT group.

“In summary, our results demonstrate that both haplo- and UCB HSCT are efficacious,” the study investigators wrote in their report. “The effect of a higher risk of nonrelapse mortality after UCB HSCT is tempered by lower risk of relapse (although not always statistically significant) negating an adverse effect on leukemia-free survival,” they concluded.


Wagner, Jr JE, Ballen KK, Zhang MJ, et al. Comparison of haploidentical and umbilical cord blood transplantation after myeloablative conditioning. Blood Adv. 2021;5(20):4064-4072. doi:10.1182/bloodadvances.2021004462