American Society of Hematology Annual Meeting

PTCy Equalizes Transplant Outcomes for HCT Recipients Across Racial, Ethnic Groups

Jennifer Larson
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Apheresis machine collecting stem cells for transplant
Apheresis machine collecting stem cells for transplant
A research team investigated whether use of posttransplant cyclophosphamide would mitigate outcomes disparity in racial and ethnic minority patients.

Achieving more equitable outcomes for racial and ethnic minority patients with hematologic malignancies undergoing allogeneic hematopoietic cell transplantation (HCT) could be achieved by the use of mismatched donor HCT with posttransplant cyclophosphamide (PTCy) for graft-versus-host disease (GVHD) prophylaxis.

In comparison to non-Hispanic White (NHW) patients, racial and ethnic minority patients are less likely to get an HCT referral, less likely to find a human leukocyte antigen (HLA) matched unrelated donor, and more likely to have worse outcomes, explained Teresa Caprice, PA-C, of Moffit Cancer Center in Tampa, Florida, in her presentation at the ASH Annual Meeting 2023.

Therefore, a research team based in Tampa, Florida, investigated if disparities in outcomes still exist between racial and ethnic minority HCT recipients and non-Hispanic White (NHW) transplant recipients if they received a HLA mismatched transplant with PTCy.

According to research, haploidentical or mismatched unrelated donor (MMUD) HCT with PTCy outcomes are similar to matched donor HCT, which has expanded the donor pool for racial and ethnic minority patients. But data that evaluate the outcomes among minority and NHW patients are lacking.

This retrospective analysis consisted of 302 consecutive adult patients who underwent haploidentical or MMUD HCT with PTCy between 2014 and 2022. Of the 302 patients, 178 (59%) were NHW, 41 (14%) were Hispanic White, 48 (16%) were Black, 21 were multiracial/biracial (7%), and 11 (4%) were Asian. The median patient age was 58. The primary endpoint was relapse free survival (RFS). 

No significant differences in clinical outcomes were observed between the racial/ethnic minority and NHW patients. 

At the 100-day posttransplant mark, the cumulative incidence of grade 2-4 acute GVHD was 37% for NHW patients, 32% for Hispanic White patients, 29% for Black patients, and 24% for patients of other races. 

No statistically significant differences among groups were observed when it came to chronic GVHD, even when adjusted for patient age, conditioning intensity, and donor relation. At 24 months, the rates for moderate to severe chronic GVHD were 20% for NHW patients, 23% for Hispanic White patients, 16% for Black patients, and 26% for patients of other races.  

However, the rate of relapse was 26% for both NHW and Hispanic White patients, 30% for Black patients and 19% for patients of other races.  Race and ethnicity were not associated with risk of relapse, when the data were adjusted. At 100 days posttransplant, the incidence of nonrelapse mortality was also very similar among the various patient groups. 

The probability of relapse-free survival at 24 months was similar for all the groups: 54% for NHW patients, 59% for Hispanic White patients, 49% for Black patients, and 57% for patients of other races. In multivariate analysis, a higher disease risk index and donor age older than 40 were associated with a greater risk.

“These results show that the use of HLA mismatched donor transplant with PTCy can achieve comparable clinical outcomes between racial and ethnic minority patients and non-Hispanic White patients,” concluded Ms Caprice, adding that further studies should determine if the results could be replicated at other centers. 

Reference

Caprice T, Fan W, Kim J, et al. Post-transplant cyclophosphamide equalizes clinical outcomes of allogeneic hematopoietic cell transplantation across racial and ethnic populations. Presented at ASH 2023. December 9-12, 2023. San Diego, CA. Abstract 390.