Ethnicity Affects Survival Following Stem Cell Transplant in Patients With Hematologic Disorders

Patient ethnicity has been correlated with different outcomes after hematopoietic cell transplantation (HCT), according to the authors of a UK study published in Lancet Haematology. Patients from minority ethnic backgrounds were reported to have worse outcomes compared with White patients. To date, studies investigating HCT outcomes have been predominantly conducted in the US, where health care models are different to European countries, such as the UK.^1,2

In previous studies conducted in the US, data have indicated poorer outcomes for minority ethnic patients, such as lower overall survival (OS) rates for Hispanic adults receiving unrelated cord blood transplants and higher rates of acute graft-versus-host disease (GVHD) in Black pediatric patients. However, some large cohort studies have found no significant differences in survival or relapse rates based on ethnicity. These contrasting findings highlight limitations, including small sample sizes, and socioeconomic variables, which may not apply to the UK’s demographics and unique health care context.^1,2

An illustration of stem cells. Image Credit: © venusvi - stock.adobe.com

In this study, investigators analyzed data from over 30,000 transplant patients who were registered in the British Society of Blood and Marrow Transplantation and Cellular Therapy patient registry and were analyzed as full cohorts and as separate adult (≥18 years) and pediatric (0–17·9 years) cohorts. Patients were included who had autologous or allogeneic HCT between Jan 1, 2009, and Dec 31, 2019, and the primary end point was 5-year OS, with OS defined as the time from transplantation to death from any cause. Patient ethnicity was self-defined and grouped into 4 broad categories, including Asian, Black, other, and White.^1,2

This research is the first population-wide study in the UK to examine the effect of ethnicity on HCT outcomes. The findings confirm that non-White ethnicities, particularly Asian and other groups, experience poorer outcomes after allogeneic HCT, emphasizing the urgent need for targeted research and interventions.^1,2

Higher Mortality in Minority Ethnic Groups

This study revealed that adult Black and Asian patients were 1.5 times more likely to die within 5 years of a donor stem cell transplant compared to White patients. Among children, Asian patients faced the highest risk, with a 32% chance of death within 5 years compared to 15% for White children. Black patients had a 39% risk of death within 5 years for adults and 16% for children. Similarly, Asian adults and children showed mortality rates of 39% and 32%, respectively. Patients identifying as other ethnicity had a 32% risk in adults and 15% in children, highlighting challenges across diverse groups.^1,2

According to the study authors, genetic diversity among minority ethnic groups may result in difficulties finding well-matched donors, prolonging the wait for a transplant and increasing risks. Socioeconomic factors such as income, health care access, and language barriers may exacerbate these inequalities. The study found no impact of ethnicity on survival for patients using their own cells for transplantation, suggesting the disparities are specific to donor transplants. These findings align with international studies, but the precise causes of these disparities remain unclear. Potential explanations include genetic factors affecting drug metabolism, socioeconomic barriers, and systemic inequities in health care delivery.^1,2 Future research should address these gaps and provide actionable insights to improve equity in care.¹

Addressing the Problem

Enhanced Research Funding

UK stem cell transplant charity Anthony Nolan Foundation and other organizations are calling for government investment to investigate the genetic and systemic factors contributing to disparities. Alternative transplant strategies, such as the use of umbilical cord blood cells, which require less precise genetic matching, are also being explored.

Expanding the Donor Register

Anthony Nolan Foundation emphasizes the need for increased recruitment of donors from minority ethnic backgrounds to improve the likelihood of finding matches for all patients. Initiatives such as collaborations with international registries, like DATRI in India, aim to diversify the global pool of donors.

Addressing Socioeconomic Barriers

The SEQoL study, spearheaded by Anthony Nolan Foundation, seeks to understand how socioeconomic factors impact transplant outcomes. Insights from this research will guide policy changes to reduce inequities in care.

Advocacy and Public Awareness

Health care professionals play a vital role in educating patients about the importance of donor diversity and advocating for systemic changes to address unconscious bias and improve equity in health care delivery.

Patient Case

Zara Kundra, an 11-year-old of Indian origin, highlights the personal impact of these disparities. Diagnosed with acute myeloid leukemia in 2019, Zara underwent a donor stem cell transplant but faced complications due to GVHD and a suboptimal donor match. While she has returned to a mostly normal life, her family’s experience underscores the urgent need for better outcomes for patients of all ethnicities.¹

“It’s difficult to hear that patients like my daughter are less likely to respond well to a stem cell transplant because of their ethnicity. We come from Indian origin, and unfortunately, Zara didn’t have the best donor-match in the world. It meant she had a lot of complications afterwards,” said Zara’s mother Taruna Kundra in a press release. “Zara is doing well now and has returned to a mostly normal life. But it’s vital more research is carried out in this area so that more children like her have the best chance when undergoing life-changing treatment.”¹

REFERENCES

1. Ethnicity affects survival following donor stem cell transplant, according to new research. Anthony Nolan. December 3, 2024. Accessed December 17, 2024. https://www.anthonynolan.org/blog/2024/11/28/new-anthony-nolan-research-ethnicity-affects-survival-after-donor-stem-cell

2. Mayor NP, Szydlo RM, Sheikh Y, et al. The impact of patient ethnicity on haematopoietic cell transplantation outcome: a retrospective cohort study on the UK experience. Lancet Haematol. 2024;11(12):e916-e926. doi:10.1016/S2352-3026(24)00312-0