LAUSR

There are few more devastating conversations than telling a patient that their best – or only – chance of cure is an allogeneic bone marrow transplant, but that they have no suitably matched donor available. In some cases, this means dashing their hope of cure altogether, and in other cases it can mean adopting an inferior treatment option. In an era where international borders are increasingly opaque, the logistics of international travel more challenging, and the global geopolitical landscape fraught with complexity, we cannot continue to rely almost exclusively on overseas donors for Australian bone marrow transplants. Our present population of bone marrow donors is small and rapidly dwindling, and does not match the diversity of our population. Thus, we must grow our bone marrow donor registry, instead of letting it decline through lack of funding and awareness. The need to recruit large numbers of diverse young Australian donors has never been greater. Patients with life-threatening conditions including acute leukaemias, myelodysplastic syndrome and myelofibrosis, some lymphomas, and bone marrow failure syndromes benefit from allogeneic stem cell transplantation (alloSCT) as curative treatment for their otherwise challenging to treat conditions. Crucial to the success of alloSCT is the match between donor and recipient human leukocyte antigen (HLA) type, with better-matched donors leading to significantly improved survival. Access to alloSCT is limited by the availability of suitably matched donors; only one-third of candidates will have an HLA-matched sibling as a potential donor. Of the 691 Australian patients who underwent alloSCT in 2019, 358 received a volunteer unrelated donor (VUD) SCT facilitated through the Australian Bone Marrow Donor Registry (ABMDR), making unrelated donor the most common donor source. However, more than 80% of Australian recipients of unrelated-donor transplants now receive their transplants from international donors, whereas this was just 47% in 2009. Other countries import on average just 48% of stem cell donations. Both the number of patients searching for a donor and the number of unrelated donor transplants undertaken are increasing; in 2020, each increased by 7% year-onyear in Australia. Additionally, outcomes for recipients of VUD transplants are now equivalent to those receiving matched sibling transplants and remain superior to those receiving haploidentical transplants. Younger male donors are typically thought superior due to their likelihood of producing more stem cells during donation and a reduced risk of graft-versus-host disease, but a younger male donor is more likely to be found in an overseas donor pool than in Australia. Whereas the most populated age group in the global donor pool is aged 26–35 years, the average age of a donor registered with the ABMDR is 47 years. Just over half of the 170 000 registered donors in the ABMDR are actually contactable, due to the passage of time since many were recruited. This represents <0.5% of Australia’s population, compared with the 2–3% of population recruited by many similar overseas registries. In the COVID-19 era, international donors are more difficult to access. Instead of hand-delivered fresh cells, they must be cryopreserved and air-freighted in liquid nitrogen at 196 C, which comes with added delays and risks of processing. In turn, the COVID-19 pandemic has led to a higher proportion of patients relying on the ABMDR and a lower proportion of young male donors. For historical reasons, the two largest bone marrow donor registries in the world, hosted in Germany and the United States, are both made up of largely White, NorthWest European donors. Due to significant variation in HLA, patients from an ethnic group that is poorly represented on donor registries are much less likely to find a suitable donor, as the probability of finding a donor is higher within the recipient’s ethnic group. In the United States, for example, 60% of White but only 20–45% of Black and other minority patients will be able to find a matched donor. In Australia, although 26% of registry searches were for ethnically diverse people, only 19% of transplants were for this group (L. Davis, pers. comm., 2021), suggesting a lower rate of success finding a matched donor, corroborated by our clinical experience. Access to donors for Aboriginal and Torres Strait Islander patients and those of other ethnic minorities still poses significant clinical challenges, resulting in an inequity of access to alloSCT in these groups. Until 2019, the ABMDR was shrinking, losing more donors who retire compulsorily at the age of 60 than it was recruiting each year, where recruitment occurred predominantly through the Red Cross Lifeblood service, which excludes some potential donors. From 2019 to May 2021, the ABMDR ran a successful pilot programme called ‘Strength to Give’, using convenient mail-out cheek swabs to recruit and HLA-type 12 000 donors. In its first year,