Addressing Ethnically Diverse Patient Representation in Hematopoietic Cell Transplant Clinical Trials: Insights Gained through the Access Trial

Abstract

Background

The NMDP-sponsored, CIBMTR-led ACCESS (NCT04904588) trial studied safety and efficacy of peripheral blood stem cell allografts from mismatched unrelated donors (MMUD) in adults with hematologic malignancies using post-transplant cyclophosphamide-based graft-versus-host disease prophylaxis. Analysis from the initial reduced intensity conditioning (RIC) cohort showed that 51% (n=36) of patients were ethnically diverse (ED) and had a 1-year overall survival of 79% (Al Malki et al. ASCO 2024). ED patients were younger and had higher financial toxicity and social vulnerability index (SVI) than non-Hispanic White (NHW) patients (Yusuf et al. 2024 Tandem Meetings). As adult enrollment on both RIC and myeloablative conditioning strata was completed in February 2024, we defined study patient profiles that might inform social needs and trial participation of ED patients.

Methods

To enroll on ACCESS, patients required an unrelated donor (URD) matched at 4-7/8 HLA alleles (HLA-A, B, C, and DRB1) and aged 18-35 years. Recipients without an available 8/8 related or URD and lacking HLA-specific antibody (anti-HLA Ab) to any mismatched allele/antigen were eligible. ED patients had any race and ethnicity besides NHW. Donor ancestry and recipient utilization of patient services were collected through NMDP operations. COmprehensive Score for financial Toxicity (COST), SVI, and patient reported outcomes (PRO) were compared between NHW and ED subjects (significance p<0.05).

Results

Of 268 adult patients, 51% were males, 69% had acute leukemia, and 51% were ED (Figure 1A). Most patients received RIC (n=193, 72%) using 7/8 MMUD (n=183, 68%). No differences in HCT comorbidity indices between NHW and ED patients were seen (p=0.42).

Median donor age was 25 years (18-35y). Of 153 patients with anti-HLA Ab (Figure 1B), 58% were female with higher incidence of anti-HLA-Ab noted in patients utilizing MMUD with higher degree of HLA mismatch: 7/8 (n=96) 58%; 6/8 (n=45) 67%; 5/8 (n=9) 75%; and 4/8 (n=3) 100%.

Compared to NHW patients (Figure 1C), ED patients were younger, had higher overall SVI, and lived closer to a transplant center. More ED patients reported lower educational attainment, lower personal income, higher financial toxicity, and acknowledged needing a caregiver versus NHW patients.

Of 162 (60%) patients receiving support services, 90 (56%) were ED and most frequently received patient navigation and financial assistance. Compared to those who did not receive support services, patients who did lived in an area (ZIP code) associated with a lower percentage of the population having a bachelor or graduate degree and lower median income.

Conclusions

Half of adult patients enrolled on the ACCESS trial were ED and had high social vulnerability, highlighting the need for patient support strategies to ensure representation of ED patients in HCT clinical trials.