Comparison of outcomes of unrelated bone marrow and umbilical cord blood transplants in children with acute leukemia

In order to compare the outcomes of unrelated umbilical cord blood transpla nts (UCBTs) or bone marrow transplants, 541 children with acute leukemia (A L) transplanted with umbilical cord blood (n = 99), T-cell-depleted unrelat ed bone marrow transplants (T-UBMT) (n = 180), or nonmanipulated (UBMT) (n = 262), were analyzed in a retrospective multicenter study. Comparisons wer e performed after adjustment for patient, disease, and transplant variables . The major difference between the 3 groups was the higher number in the UC BT group of HLA mismatches (defined by serology for class I and molecular t yping for DRB1). The donor was HLA mismatched in 92% of UCBTs, in 18% of UB MTs, and in 43% of T-UBMTs (P<.001). Other significant differences were obs erved in pretransplant disease characteristics, preparative regimens, graft -versus-host disease (GVHD) prophylaxis, and number of cells infused. Nonad justed estimates of 2-year survival and event-free survival rates were 49% and 43%, respectively, in the UBMT group, 41% and 37% in the T-UBMT group, and 35% and 31% in the UCBT group. After adjustment, differences in outcome s appeared in the first 100 days after the transplantation. Compared with U BMT recipients, UCBT recipients had delayed hematopoietic recovery (Hazard ratio [HR] = 0.37; 95% confidence interval [95CI]: 0.27-0.52; P<.001), incr eased 100 day transplant-related mortality (HR = 2.13; 95CI: 1.20-3.76; P<. 01) and decreased acute graft-versus-host disease (aGVHD) (HR = 0.50; 95CI: 0.34-0.73; P<.001). T-UBMT recipients had decreased aGVHD (HR = 0.25; 95CI : 0.17-0.36; P<.0001) and increased risk of relapse (HR = 1.96; 95CI: 1.11- 3.45; P =.02). After day 100 posttransplant, the 3 groups achieved similar results in terms of relapse. Chronic GVHD was decreased after T-UBMT (HR = 0.21; 95CI: 0.11-0.37; P<.0001) and UCBT (HR = 0.24; 95CI: 0.01-0.66; P =.0 02), and overall mortality was higher in T-UBMT recipients (HR = 1.39; 95CI : 0.97-1.99; P<.07). In conclusion, the use of UCBT, as a source of hematop oietic stem cells, is a reasonable option for children with AL lacking an a cceptably matched unrelated marrow donor. (Blood. 2001;97:2962-2971) (C) 20 01 by The American Society of Hematology.