Donor Age Influences Graft-Versus-Host Disease Relapse-Free Survival after Allogeneic Stem Cell Transplant in Elderly Patients in Two Countries from Latin America.

ABSTRACT

BACKGROUND AND OBJECTIVES: Allogeneic stem cell transplantation (Allo-SCT) in elderly patients is a growing practice. We aimed to determine the graft-versus-host disease (GVHD) relapse-free survival (GRFS) in patients ≥65 years who underwent Allo-SCT in two countries from Latin America. PATIENTS AND METHODS: We performed a retrospective analysis of patients ≥65 years who underwent Allo-SCT in Argentina and Brazil from 2007 to 2019. RESULTS: Ninety-eight patients were evaluated, with primary diagnoses of acute myeloid leukemia and myelodysplastic syndrome; 30% of patients had a hematopoietic cell transplant-comorbidity index (HCT-CI) score ≥3 and 49% were in complete remission. Donor types included matched sibling (n = 41), matched unrelated (n = 31), and haploidentical (HID; n = 26) donors. The conditioning regimen was myeloablative in 28 patients (14 busulfan pharmacokinetically [PK]-guided) and reduced-intensity in 70 patients. The two-year non-relapse mortality (NRM) was 29%, with a higher NRM in melphalan-based compared to other conditionings (51% vs. 33%, p = 0.02). The two-year relapse rate was 24%, with a reduction in PK-guided busulfan (0% vs. 28%, p = 0.03). The two-year overall survival (OS) and GRFS was 52% and 38%, respectively, with a significant reduction in GRFS in HCT-CI ≥3 (27% vs. others 42%, p = 0.02) and donors ≥40 years (29% vs. <40 years 55%, p = 0.02). These variables remained significantly associated with GRFS after multivariate analysis. CONCLUSION: In this cohort of elderly patients from Argentina and Brazil undergoing Allo-SCT, donor age and comorbidities significantly influenced GRFS. The role of the conditioning regimen in this population deserves further investigation.