Allogeneic Stem Cell Transplant Donors: Sibling or Stranger?

Allogeneic stem cell transplantation (SCT) provides a curative option for many patients with relapsed hematologic malignancies and for others with high risk of recurrence after initial therapy. Traditionally HLA-matched sibling donors were preferred as the source of stem cells, but the availability of such a donor in only about one-third of patients has led to the use of matched unrelated donors. This French multicenter study assessed the outcomes for patients with standard-risk hematologic malignancies undergoing allogeneic SCT from related versus unrelated donors, utilizing a uniform pre-transplant conditioning regimen of total body irradiation plus high-dose cyclophosphamide and uniform graft-versus-host disease (GVHD) prophylaxis with cyclosporin-A and short-course methotrexate for all patients. The study population included patients with acute leukemia in first or second complete remission, CML, and myelodysplastic syndrome. Bone marrow rather than peripheral blood was used as the source of stem cells for all patients. One hundred and eighty-one patients had an HLA-matched sibling donor, while 55 had an HLA-matched unrelated donor identical at 10/10 allelic loci. Patient characteristics in the two groups were largely comparable, and all but seven patients engrafted. With a median post-transplantation follow-up of 34.6 months, there was no significant difference in time to engraftment, acute GVHD, event-free survival, or overall survival (Figure). A retrospective review of patients in this trial showed increased occurrence of chronic GVHD in unrelated versus sibling transplants. Mortality was increased in CMV seropositive recipients, in those who developed >/= grade II acute GVHD, and in those with stem cell donors > 37 years of age.