Comparison of haploidentical and umbilical cord blood transplantation after myeloablative conditioning.

Abstract

Haploidentical hematopoietic stem cell transplantation (haplo HSCT) has emerged as an important treatment modality. Most reports comparing haplo HSCT with post-transplant cyclophosphamide (PTCy) and other donor sources have focused on outcomes in older adults treated with reduced intensity conditioning. Therefore, in the current study, we evaluated outcomes in patients with hematological malignancy treated with myeloablative conditioning prior to haplo (n=375) or umbilical cord blood (UCB, n=333) HSCT. All haplo recipients received a 4 of 8 HLA matched graft while recipients of UCB were matched at 6-8/8 (n=145) or ≤5/8 (n=188) HLA antigens. Recipients of 6-8/8 UCB transplants were younger (14 years vs. 21 and 29 years) and more likely to have lower co-morbidity scores compared to recipients of ≤5/8 UCB and haplo HSCT (81% vs. 69% and 63%, respectively). UCB recipients were more likely to have acute lymphoblastic leukemia and transplanted in second complete remission (CR) whereas haplo HSCT recipients were more likely to have acute myeloid leukemia in first CR. Other characteristics, including cytogenetic risk were similar. Survival at 3 years was similar for the donor sources (66% haplo and 61% after ≤5/8 and 58% after 6-8/8 UCB). Notably, relapse at 3 years was lower in recipients of ≤5/8 UCB (21%, p=0.03) compared to haplo (36%) and 6-8/8 UCB (30%). However, non-relapse mortality was higher in ≤5/8 UCB (21%) compared to other groups (p<0.0001). These data suggest that haplo HSCT with PTCy after myeloablative conditioning provides an overall survival outcome comparable to that after UCB regardless HLA match group.