Equality Of Access To Transplant For Ethnic Minority Patients Through Use Of Cord Blood and Haploidentical Transplants
Authors: Lown Robert N , Marsh Steven GE , Blake Helen , Querol Sergio , Evseeva Irina , Mackinnon Stephen , Pagliuca Antonio , Potter Michael , Russell Nigel , Craddock Charles , Madrigal J. Alejandro , Shaw Bronwen E. 
Published: October 2019

It is well accepted that patients of ethnic minorities who lack a sibling donor are poorly represented on the international unrelated donor panels. As recently as 2000, only 30% of such patients were able to find an unrelated donor suitable for transplantation. Historically these patients would have either not been transplanted, or would receive transplants from unrelated donors with two or more HLA mismatches. Continued expansion of the international donor inventory, and the advent of cord blood and haploidentical transplantation has improved the prospects for transplantation for such patients and, through the expertise of search staff within donor registries and histocompatibility laboratories, transplant centres are increasingly able to identify early on those patients who are unlikely to find a well-matched unrelated adult donor. Surprisingly, however, few contemporary data have been published to show the impact of these search strategies and alternative stem cell sources on provision of transplant to those of non-white Northern European origin.

We consecutively enrolled and prospectively followed up (from search request to last contact or death) 332 patients referred by four UK transplant centres to the Anthony Nolan Graft Identification and Advisory Service (GIAS) for identification of an unrelated adult donor or cord blood unit. Of these, 248 (74.7%) were of white Northern European (WNE) descent, and 84 (25.3%) non-WNE. The underlying disease did not differ significantly between ethnicities. The median number of UK donors listed on the search report was 8 (range 0 to 3395) and 0 (0 to 42) respectively, and on BMDW 127 (0 to 38245) and 5.5 (0 to 380) respectively. 69.3% of WNE and 20.5% of non-WNE patients found a 10/10 HLA-matched donor at confirmatory typing (CT) (p<0.001); 96.3% of WNE and 61.4% of non-WNE found at least a 9/10 HLA-matched donor (p<0.001). Non-WNE patients had more cord blood transplants (21.3% vs 3.8%, p<0.001) and more haploidentical transplants (10.6% vs 1.3%, p<0.001). There was no significant difference in the number of patients reaching transplant (WNE 63.3%, non-WNE 56.0%, p=0.185) when considering all of the graft sources. Patients of non-WNE background had a significantly slower time from first CT request to identification of an unrelated donor for transplant (median 27 days vs 33.5 days, p= 0.02), and from search request to transplant with any graft source (median 110 days vs 132 days, p=0.03). However, when the cumulative incidence of transplantation with death as a competing risk was considered, there was no difference between ethnic groups (log rank p=0.185, see figure). The median time from search request to transplant by graft source was 120.5 days for adult unrelated donors (n=179), 143 days for cord blood (n=16) and 91 days for haploidentical donors (n=6) (p=0.626).

These data show that the chance of receiving a transplant for patients of a non-WNE descent has improved considerably compared to historical literature. The majority of non-WNE patients were able to find a 9 or 10/10 matched donor, and many of those who could not were afforded the option of a cord blood or haploidentical donor transplant within a similar timescale. Whilst times to transplant do remain slightly longer for non-WNE patients, mainly due to a more protracted CT stage, they now stand an equal chance of reaching transplant. However, whether survival following transplant is similar between ethnic groups remains to be seen.

Disclosures:

No relevant conflicts of interest to declare.