Racial Disparity in Myeloablative Hematopoietic Cell Transplantation Outcomes in Patients with Hematological Malignancies Older Than 45 Years

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Introduction The impact of race on outcomes of allogeneic hematopoietic cell transplants (HCT) has long been a field of research. The Center for International Blood and Marrow Transplant Research (CIBMTR) studies have shown worse survival for Blacks and Hispanics within the first year after HCT but evened out for one-year survivors. These studies included all adult patients aged >18 years. We hypothesize that the outcomes of South Asians (age ≥ 45 years) receiving myeloablative conditioning (MAC) are worse compared to other races. Objective To compare the outcomes after MAC-HCT for hematological malignancies among different racial groups (age ≥ 45 years) Methods This was a single-center retrospective study conducted at the Leukemia/ BMT Program of BC. All patients (Age ≥ 45 years) undergoing MAC-HCT for hematological malignancies from 2011 - 2022 were included. The primary outcome was overall survival (OS). Secondary outcomes were non-relapse mortality (NRM), incidence of grade 2-4 acute graft versus host disease (GVHD), moderate-severe chronic GVHD and relapse incidence (RI). The survival analysis was done using Kaplan-Meier analysis and log-rank test. The GVHD , NRM and RI rates were calculated using the cumulative incidence (CI) of competing events and the Gray test. EZR was used for statistical analysis. Results Of the 504 patients, there were 28 (5.5%) South Asians (SA), 73 (14.5%) Other Asians (East Asians (EA)/Southeast Asians (SEA), and 382 (75.8%) Whites (W). There was a lower proportion of recipients ≥ 60 years of age in Asians than the Whites (SA 21%, EA/SEA 14%, W 34%, p =0.001). The proportion of donors ≥30 years of age was higher in the Asians compared to the Whites (SA 78.5%, EA/SEA 70%, W 61%, p =0.02). There was a lower proportion of MUD-HCT in the Asians (SA 21%, EA/SEA 30%, W 45%, p =0.009). The three groups were comparable regarding the recipient and donor sex, body mass index , and performance status. The proportion of SA with HCT-CI ≥ 3 was significantly higher (SA 50%, EA/SEA 37%, W 31%, p =0.002). There were fewer CMV mismatches among the Asians (SA 25%, EA/SEA 26%, W 43%, p =0.009). There was no difference in the conditioning type and CD34 cell dose. However, fewer Asians received ATG/PTCy as GVHD prophylaxis (SA 39%, EA/SEA 42%, W 45%, p =0.0009). The median OS was significantly shorter in SA (SA 19, EA/SEA 103, W 65 months, p =0.04). The 2-year NRM was significantly higher in SA (SA 35.7%, EA/SEA 13.7%, W 16%, p =0.03). The CI of grade 2-4 acute and moderate-severe chronic GVHD was not significantly different ( p =0.7 & 0.6). The 2-year RI was also not significantly different ( p =0.8). Conclusion Our study confirms that South Asians aged ≥45 have worse survival after MAC-HCT. Supportive care is unable to overcome the differences in the outcomes. The high NRM is probably due to differences in comorbidities, frailty and pharmacogenetics and needs to be studied prospectively in multicenter studies.

Ce résumé expose les affirmations des auteurs. BNTIC ne l’interprète pas comme une validation indépendante des résultats.