Prospective Evaluation of Alternative Donor Availability in 708 Patients: Improved Allograft Access with Enlarging Cord Blood (CB) Inventory for All Patients Including Racial and Ethnic Minorities

Background: Availability of suitably HLA-matched unrelated donors (URD) is a major barrier to allogeneic transplantation and CB can extend transplant access. We evaluated if URD/ CB access has improved with increased size of URD registries & global CB inventories. Methods: We prospectively collected ancestry data on patients undergoing searches between 10/2005-6/2013, & analyzed the availability of 9-10/10 HLA-matched URDs or 4-6/6 HLA-A,-B antigen, -DRB1 allele matched CB units by recipient ancestry. 10 HLA-allele matched URDs were given priority if available; otherwise HLA-mismatched URDs or double-unit CB grafts were chosen. This analysis was restricted to CB units with a cryo. TNC dose > 2.0. Availability of CB units by 10-allele match was also evaluated. Results: Of 708 patients, 223 (31%) were non-European. URD recipients were predominantly European (400/511, 78%) whereas only 77/159 (48%) of CB recipients had European origins. 30/38 (79%) “no graft” patients were non-European (including 20 African ancestry patients), and they had a higher weight (median 93 kg) than CB recipients, p < 0.001. Graft availability during early (10/2005-12/2010) vs recent (1/2011-6/2013) periods is shown (Table). Ancestry distribution was equal during the periods. Of all early vs late period patients, less than two-thirds of Europeans received a 10/10 URD in both eras (59% vs 61%) but very few had no graft (< 1% recently). However, of non-Europeans in the early period overall, only 29/129 (22%) had a 10/10 URD, & this has not improved [28/94 (30%), p = 0.28]. While only 28% of non-Europeans received ≥ 6/10 CB units in the early period, this match rate improved to 69% recently (p < 0.001). The percentage of non-Europeans with no graft has decreased from 17% to 8.5% recently (p = 0.08). Of African patients without an URD, 16/31 (52%) had a CB graft in the early period vs 15/20 (75%) recently, p = 0.14. Conclusion: Less than two-thirds of Europeans have a 10/10 URD, but very few do not have an URD &/or CB graft. CB, unlike URDs, is a critically important donor source for minorities, & transplantation of CB units with higher rates of 10 HLA-allele match is possible. Improved CB availability in non-Europeans is suggested but an enlarged inventory is required to extend access, especially for African ancestry patients.

Early Time Period (n = 424, 60% of total)	Recent Time Period (n = 284, 40% of total)
Europeans (n = 485)
N = 295 URD: 246 (71% 10/10) CB: 42 (48% ≥ 6/10) No graft: 7 (2%)	N = 190 URD: 154 (76% 10/10) CB: 35 (54% ≥ 6/10) No graft: 1 (0.5%)
Non-Europeans (n = 223)
N = 129 URD: 61 (48% 10/10) CB: 46 (28% ≥ 6/10) No graft: 22 (17%)	N = 94 URD: 50 (56% 10/10) CB: 36 (69% ≥ 6/10) No graft: 8 (8.5%)