A study of selected hematopoietic stem cell donors provided by an intermediate size registry

Abstract

Objective Planning new hematopoietic stem cell (HSC) donor recruitment strategies requires a sound understanding of the factors underlying donor selection, especially considering HLA‐matching criteria. Method A total of 182 consecutive workups of Swiss donors performed from 2014 to 2017 were analyzed for HLA match level, locus disparities, number of potentially 10/10 matched donors in the international database, donor ranking on the lists, donor date of registration, age, ABO, CMV, gender matching, patient genotype frequency, and country performing the search. Results Matching status of the selected donors was 10/10 for 38.5%, 10‐12/12 for 35.1%, and 8‐9/10 for 26.4% donors, without differences in average donor age in the three categories. HLA‐A and ‐C mismatches were most frequent and ‐DRB1 very rare. 8.2% patients were matched for HLA‐DPB1 (12/12). ABO matching was 46.3%, and CMV matching was 59.1%. Based on “HaploStat”‐derived genotype frequencies, 50.3% patients belonged to the “good,” 38.5% to the “fair,” and 11.2% to the “poor” search prognosis categories. 37.9% of transplants were gender‐mismatched, and 42.3% of donors were female. Conclusion HLA typing quality (high resolution, all loci typed), great diversity of haplotypes and donor age are main factors impacting the selection of Swiss donors, while gender and ABO matching seem to be of secondary importance.

An intermediate‐sized donor registry experience: HLA barriers in matching procedures

“…The present donor recruitment strategies are commonly focused on younger males since this type of donor is the preferred choice. Our study shows a significant difference between male and female donors in the entire studied group; female donors were selected for 42.0% of patients, which is similar to the data presented by Nicoloso et al 23 This percentage is significantly higher than the 18% (in 10/10 pairs) and 27% (in 9/10 pairs) reported for the OneMatch registry 24 . This study demonstrates that an almost equal percentage of both genders were selected from the CBMDR, as opposed to the WMDA‐registered donors where the male donors were chosen significantly more often than the female donors.…”

“…Our results, which indicate that a 9/10 MUD was selected more often in “other” (small/intermediate) registries, support our goal to increase the size of the CBMDR to 100,000 donors but also corroborate the suggestion by Nicoloso et al The authors highlighted the necessity of the continuing growth of small/intermediate‐size registries because each population has its specificities and contributes to the diversity of HLA haplotypes across Europe 23,27–30 …”

“…In contrast to the study about Swiss patients, where the gender mismatch was present in around one-third of the patient/ MUD pairs, our study revealed a much higher percentage of such mismatched pairs, half of them. 23 One of the reasons for this finding lies in the fact that choosing a MUD from the CBMDR shortens the time necessary to get a finalized donor, there is no waste of time on the transport of the transplant as is the in case when the donor is from other countries, especially in cases of the United States or Canada, but also because it offers the financial benefit for a national health care system. Additionally, the prevalence of female donors in CBMDR also implies that rare haplotypes will more often be found in female donors by chance, and female donors will therefore be chosen more frequently in cases when there is a limited or no choice at all in gender preference selection.…”

“…25,26 Our results, which indicate that a 9/10 MUD was selected more often in "other" (small/intermediate) registries, support our goal to increase the size of the CBMDR to 100,000 donors but also corroborate the suggestion by Nicoloso et al The authors highlighted the necessity of the continuing growth of small/intermediate-size registries because each population has its specificities and contributes to the diversity of HLA haplotypes across Europe. 23,[27][28][29][30] There is currently a consensus that a single HLA MM at the HLA-A, -B, -C, and -DRB1 loci is clinically relevant; however, which of these loci is the most important one has not been agreed upon. 20,31,32 Different studies reported various results, for example, Petersdorf et al reported that mortality and GvHD increase with increasing numbers of HLA MMs as well as that a single HLA-B MM increased grade III-IV aGvHD incidence.…”

HLA Linked Regional Differences in Donor Selection: A 9-Year Study of the Swiss Registry

“…The impact of regional diversity within a given registry on the effective donor selection for national and foreign patients has not been investigated so far. In a preliminary study performed on 182 WU with donors from the Swiss Registry, we could show that 50% of the donors were selected by transplant centres in Switzerland and its four neighbouring countries, albeit with significant differences in HLA-matching grades [12]. However, the limited number of donors precluded more refined analysis at the regional level.…”