Hematopoietic cell transplantation in pediatric patients with acute leukemias or myelodysplastic syndrome using unrelated adult or umbilical cord blood donors in Brazil

The choice of alternative donors for HCT for patients without an HLA-matched related donor depends on several factors. We compared major HCT outcomes in 212 consecutive children transplanted at 11 centers in Brazil for acute leukemia or MDS from an HLA-matched unrelated donor (MUD, n = 95), mismatched unrelated donor (MMUD, n = 47) or unrelated umbilical cord blood (UCB, n = 70). Most had ALL (61%), bone marrow (57%) as the graft source and 95% received a MAC regimen. The 3-year OS probability were 57, 55, and 37% after HCT from MUD, MMUD, and UCB, respectively (HR 1.68, 95%CI 1.07-2.63; P = .02). In comparison with MUD, OS was similar after transplantation of a ≥ 6/8 HLA-matched or a high cell dose (>5 × 10⁷ TNC/kg) CB unit (HR 1.41, 95%CI 0.88-2.27; P = .15). NRM was higher for UCB (HR 3.90, 95%CI 1.43-10.7; P = .01) but not for MMUD (HR 1.03, 95%CI 0.53-2.00; P > .20). Advanced disease (HR 2.05, 95%CI 1.26-3.33; P < .001) and UCB with high probability of being < 6/8 HLA-matched (HR 5.34, 95%CI 2.0-13.9; P < .001) were associated with higher mortality. Relapse and acute GVHD were similar among groups, while PGF was higher among UCB transplants (P = .002) and chronic GVHD among MMUD group (HR 2.88, 95% CI 1.05-7.88; P = .04). Our results suggest that in Brazil HCT outcomes performed with MMUD and MUD donors were comparable, while with UCB units < 6/8 HLA-matched were associated with higher NRM for children with acute leukemia or MDS.