Extension of Minority Transplant Access Using Domestic Units Supports the Importance of Public CB Bank Funding: An 884 Patient Analysis

Background: Availability of suitably HLA-matched unrelated donors (URD) is a major barrier to allogeneic transplantation especially in minorities & patients with acute leukemia & lymphoma requiring urgent transplant. The extent that cord blood (CB) extends transplant access, however, is not established. Moreover, the contribution of the domestic U.S. & international CB inventories to minority patients is an important factor in public CB Bank funding considerations. Methods: We prospectively analyzed the availability of 7-8/8 HLA-matched URDs or 4-6/6 HLA-A,-B antigen, -DRB1 allele matched CB units in patients with hematologic malignancies between 10/2005-8/2014. 8 HLA-allele matched URDs were given priority if available; otherwise HLA-mismatched URDs or double-unit CB (dCB) grafts were chosen. Results: Of 884 patients, 623 (70%) received a 7-8/8 URD transplant, 218 (25%) underwent dCBT & 43 (5%) had no URD/dCB graft. The distribution of 8/8 URD, 7/8 URD, dCB & no URD/dCB grafts is shown (Table). The majority (66%) of Europeans received an 8/8 URD whereas the majority of non-Europeans received either a mismatched URD or dCB graft. 35/43 (81%) of patients without URD/ CB grafts had non-European origins, & no URD/ dCB grafts were seen in 1% of Europeans versus 12.5% of non-Europeans. When non-Europeans were subdivided into the largest minority groups we found African, White Hispanic & Asian patients were very unlikely to have a matched URD, were most likely to receive dCB grafts, & African ancestry patients were the most likely (one quarter) to have no URD or dCB graft. Interestingly, there was no difference in 8 allele donor recipient HLA-match grade of European (median 5/8, range 2/8-8/8) & non-European (median 5/8, range 1/8-8/8) dCBT recipients. When the origin of dCB grafts was analyzed we found that overall 71% of units for European ancestry patients were domestic as compared to 78% of units for non-Europeans. However, in African & white Hispanic patients 86% & 83% of CB units were obtained from the domestic inventory, respectively. Conclusion: CB extends transplant access to all patients & is especially important for minorities who are unlikely to have a matched URD. The fact that over 80% of units used in African & white Hispanic patients were domestic, that these patients will be very unlikely to identify a matched URD regardless of the size of the global volunteer donor registry, & that some minority patients do not have suitable CB grafts emphasizes the critical importance of the funding of US public CB banks.