A retrospective study of 582 patients with acute leukemia or myelodysplastic syndromes has shown that umbilical cord blood may be a superior graft choice for the approximately 70% of patients who lack an HLA-matched related donor, especially if they are minimal residual disease positive (MRD+). The single-center study examined patients who received a first myeloablative hematopoietic cell transplant (HCT) using an unrelated cord blood unit (n=140), an HLA-matched unrelated donor (n=344), or an HLA-mismatched unrelated donor (n=98).
The relative risks of relapse and death between the cord blood group and the two other unrelated-donor groups varied according to pre-transplant MRD status. The risk of relapse among MRD+ patients was significantly higher in the two unrelated donor groups than in the cord blood group (hazard ratio (HR) in the HLA-mismatched group, 3.01; 95% CI, 1.22-7.38; p=0.02; HR in the HLA-matched group, 2.92; 95% CI, 1.34-6.35; p=0.007).
Among MRD+ patients, the risk of death was higher in the HLA-mismatched group than in the cord blood group (hazard ratio (HR), 2.92; 95% confidence interval [CI], 1.52-5.63; p=0.001). The risk of death between a matched unrelated donor and cord blood group was similar (p=0.57). Contrary to previous reports, the MRD status of cord blood recipients did not affect their overall mortality or risk of relapse.
The researchers concluded that umbilical cord blood may be the preferred alternative graft source for MRD+ patients lacking a matched related donor. “Because cord blood can allow for greater HLA disparity, it is possible to find suitable donors for nearly all patients, regardless of their racial or ethnic group.”