Availability of cord blood extends allogeneic hematopoietic stem cell transplant access to racial and ethnic minorities

Abstract

Allogeneic transplant access can be severely limited for patients of racial and ethnic minorities without suitable sibling donors. Whether cord blood (CB) transplantation can extend transplant access because of the reduced stringency of required HLA-match is not proven. We prospectively evaluated availability of unrelated donors (URD) and CB according to patient ancestry in 553 patients without suitable sibling donors. URDs had priority if adequate donors were available. Otherwise ≥4/6 HLA-matched CB grafts were chosen utilizing double units to augment graft dose. Patients had highly diverse ancestries including 35% non-Europeans. In 525 patients undergoing combined searches, 10/10 HLA-matched URDs were identified in 53% of those with European ancestry, but only 21% of patients with non-European origins (P < .001). However, the majority of both groups had 5-6/6 CB units. The 269 URD transplant recipients were predominantly European, with non-European patients accounting for only 23%. By contrast, 56% of CB transplant recipients had non-European ancestries (P < .001). Of 26 patients without any suitable stem cell source, 73% had non-European ancestries (P < .001). Their median weight was significantly higher than CB transplant recipients (P <.001), partially accounting for their lack of a CB graft. Availability of CB significantly extends allo-transplant access, especially in non-European patients, and has the greatest potential to provide a suitable stem cell source regardless of race or ethnicity. Minority patients in need of allografts, but without suitable matched sibling donors, should be referred for combined URD and CB searches to optimize transplant access.

Figure 1. Comparison of Ancestry Composition of URD and CB Transplant Recipients and Those Without a Graft

Greater than 50% of CB transplant recipients were non-European. Patients with African ancestry were the least likely to secure a suitable graft.

Figure 2. Comparison of Transplant Type or Lack of Graft for Individual Ancestry Groups

URD transplantation predominantly serves Europeans. CB significantly extends transplant access to patients of eastern, southern, and mixed European ancestry, as well as Asian, African, white Hispanic, and mixed non-European patients.