Effect of donor age in patients with acute myeloid leukemia undergoing haploidentical hematopoietic cell transplantation vary by conditioning intensity and recipient age

Abstract

AbstractWe investigated the impact of donor age (younger [≤35 years] vs. older [>35 years]) after accounting for other non‐HLA and HLA factors on outcomes of patients with acute myeloid leukemia undergoing HLA‐haploidentical hematopoietic cell transplantation (n = 790). The effect differed by conditioning—partly related to the differences in the recipient age in myeloablative (MAC; median 46 years) versus reduced‐intensity/non‐myeloablative conditioning (RIC/NMA; median 61 years) groups. With MAC (n = 320), donor age had no impact on acute graft‐versus‐host disease (GVHD), but older donors were associated with a significantly higher risk of chronic GVHD (hazard ratio [HR]: 1.6, 95% confidence interval [CI]: 1.10–2.30, p = .02) independent of recipient age and other factors. Donor age had no impact on either relapse or non‐relapse mortality (NRM). The impact of donor/recipient age on overall survival changed over time. Older donors were associated with significantly higher late overall mortality (>6 months) in younger recipients (≤ 50 years; HR: 2.2, 95% CI: 1.03–4.6, p = .04) but not older recipients. With RIC/NMA (n = 470), neither recipient's nor donor's age influenced the risk of GVHD. Donor age had no significant impact on the risk of relapse, but older donors were associated with a significantly higher risk of NRM (HR: 1.6, 95% CI: 1.02–2.6, p = .04) independent of recipient age. Older donor age was associated with significantly higher late overall mortality (>9 months) in older recipients (>50 years; HR: 1.66, 95% CI: 1.0–2.67; p = .049) but not in younger recipients. Donor selection based on donor age may require a tailored approach for a particular recipient.