Real-world data confirms that all racial and ethnic backgrounds have a suitable mismatched unrelated HCT donor
May 2024
A study of real-world data focused on the availability of 5/8 to 7/8 mismatched unrelated donors (MMUDs) on the NMDP Registry for a diverse cohort in the Bronx, New York. Data show that all patients have a suitable donor when considering 5/8 to 7/8 MMUDs for allogeneic hematopoietic cell transplant (alloHCT). Results reinforce the potential of MMUDs to overcome barriers in donor availability for diverse patients in need of alloHCT as a curative treatment option.
Download a PDF of the study highlights and citation here.
Background
Recent advances in graft-versus-host disease (GVHD) prophylaxis, such as post-transplant cyclophosphamide (PTCy) and abatacept, have significantly improved outcomes for patients undergoing HLA-mismatched alloHCT. These advances hold great promise for reducing racial disparities in donor availability. The NMDP-sponsored and CIBMTR-supported 15-MMUD trial using bone marrow as the source of stem cells demonstrated similar outcomes for 7/8 versus 5-6/8 HLA matches. This approach has been extended to a larger study using peripheral blood stem cells (ACCESS trial). A recent CIBMTR registry modeling analysis suggested that all patients have a potential match at the ≥5/8 match level on the NMDP Registry. However, this has not been validated in an ethnically diverse real-world setting. This study aimed to examine real-world MMUD options for a predominantly ethnically diverse cohort in the Bronx.
Methods
This study involved a retrospective review of electronic medical records of adult patients who underwent high-resolution HLA typing at Montefiore Medical Center between January 2019 and December 2022. The cohort included 241 patients from 37 countries, with an ethnic/racial distribution of 38.5% Hispanic, 30.8% Non-Hispanic White, 26.1% Black, and 4.7% Asian. The median age was 58 years (range 20-80), and the majority were male (56.4%). Patient diagnoses were primarily leukemia (56%), lymphoma (17%), and myelodysplastic syndromes (10%).
Results
The study found that all patients had at least 1 donor at the 5/8 and 6/8 HLA match levels, compared to 91% at 7/8 and 52% at 8/8. Over 80% of patients had more than 100 potential 5/8 and 6/8 HLA-matched donors. Non-Hispanic White patients were more likely to have an available 7/8 or 8/8 match compared to other racial/ethnic groups (p=0.002). Match levels by race/ethnicity are shown in the Figure below. Among the 71 patients who proceeded to alloHCT, 35.2% had a matched unrelated donor, 28.2% had a matched related donor, and 36.6% had a haploidentical related donor.
Key Takeaways
This study confirms the findings of the previous CIBMTR modeling analysis, demonstrating that patients from all racial/ethnic backgrounds have a suitable donor at the 5/8 and 6/8 match levels. These real-world data highlight the potential to reduce donor availability barriers to alloHCT using MMUDs. Continued research through initiatives like NMDP’s Donor For All will further expand access and accelerate progress toward potential cures for all patients.
Figure
This figure shows the percentage of patients from different racial and ethnic backgrounds who have 1 or more available donors at each HLA-match level.
