Effect of related donor availability on outcome of AML in the context of related and unrelated hematopoietic cell transplantation

Although allogeneic hematopoietic cell transplantation (HCT) from a related donor is effective therapy for younger patients with AML, it remains unknown how the availability of a related donor affects the outcome when unrelated HCT is a treatment option for patients without a related donor. To address this issue, we retrospectively analyzed 605 cytogenetically non-favorable AML patients younger than 50 years for whom a related donor search was performed during first CR (CR1). The 4-year OS was 62% in 253 patients with a related donor and 59% in 352 patients without a related donor (P=0.534). Allogeneic HCT was performed during CR1 in 62% and 41% of patients with and without a related donor, respectively. Among patients transplanted in CR1, the cumulative incidence of non-relapse mortality was significantly higher in patients without a related donor (P=0.022), but there was no difference in post-transplant OS between the groups (P=0.262). These findings show the usefulness of unrelated HCT in younger patients with cytogenetically non-favorable AML who do not have a related donor. The extensive use of unrelated HCT for such patients may minimize the potential disadvantage of lacking a related donor.