Racial Differences in Prognostic Factors and Outcomes in Patients Undergoing Allogeneic Hematopoietic Cell Transplant
Authors: Hamilton Betty K. , Rybicki Lisa , Sekeres Mikkael A. , Bolwell Brian J. , Kalaycio Matt , Hanna Rabi , Dean Robert M , Sobecks Ronald , Duong Hien K. , Hill Brian T. , Copelan Edward A. 
Published: October 2019

Abstract
Abstract 2020
Racial differences have been identified in a number of cancers, with African Americans (AA) having poorer survival than Caucasians (C). Disparate outcomes are attributed to racial differences in cancer biology, pharmacogenetics, environmental exposures, and/or socioeconomic and cultural factors. Disparities in outcome in patients with acute myeloid leukemia (AML) have been observed, and one study of post remission therapy in AA compared to C with AML revealed a significant delay in post-remission therapy with AA, but no differences in survival (Brady et al, Leuk Res 2011; Mar;35:346). There are limited data on the effects of race on survival after allogeneic hematopoietic cell transplantation (HCT).
From January 1997 until December 2011 we identified 789 patients, 58 AA and 731 white, that underwent allogeneic HCT for AML (n=304), myelodysplastic syndrome (n=107), acute lymphoblastic leukemia (n=107), chronic myeloid leukemia (n=87), non-Hodgkin lymphoma (n=105), myeloproliferative neoplasms, (n=26), bone marrow failure syndromes (n=23), Hodgkin lymphoma (n=15), plasma cell neoplasms (n=13), and biphenotypic leukemias (n=2). There were no significant differences between AA and C patients in gender, performance status, co-morbidity score, diagnosis, intensity of transplant, or donor type. However, AA were younger than C (median 40 (range 18–62) vs 47 (range 18–71) years, p=0.003); were more likely to: be in remission at HCT, (74.1% vs 57%, p=0.011); have an HLA mismatched donor, (35.7% vs 13.7%, p<0.001); have positive donor or recipient CMV serostatus, (89.7% vs 69.4%, p<0.001), use TBI as part of their preparative regimen (53.4% vs 39.1%, p=0.032), have a cord blood transplant (20.7% vs 5.7%, p<0.001) and have lower CD34+ cell dose (median 1.49 vs 2.49×106/kg, p=0.023). Time from diagnosis to transplant was longer in AA (median 10.7 (range 1.6–136.9) vs 7.9 (range 0.2–246.4) months, with a trend toward significance, p=0.06). Outcomes were compared using the log-rank or Pepe-Mori test and included infection, incidence and degree of graft versus host disease (GVHD), relapse, non-relapse mortality, relapse free-survival (RFS) and overall survival (OS). In univariable analysis, AA had significantly worse OS (HR 1.41, p=0.026) and RFS (HR 1.36, p=0.044) compared to C. There were no significant differences in incidence or degree of acute or chronic GVHD, infection, or relapse. In multivariable analyses, adjusted for number of prior chemotherapy regimens, prior radiation, co-morbidity score, diagnosis, disease status, donor type and source, HLA mismatch, and CMV status, the OS difference between AA and C became non-significant (HR 1.27, p=0.18). Propensity analyses was used to identify a well-matched cohort of C patients with AA patients, n=47 per group. Among these well-matched groups, CMV infection was higher in AA compared to C, p=0.029, but OS (p=0.92) and RFS (p=0.43) were not significantly different.
In conclusion, our study demonstrates important differences between racial populations undergoing allogeneic HCT. We found that AA patients coming into transplant present at a younger age, are more likely to have positive donor or recipient CMV serostatus, and are less likely to have an HLA matched donor. Despite these differences, race in and of itself did not translate into worse survival in controlled analyses.

Disclosures:
No relevant conflicts of interest to declare.