Allogeneic stem cell transplantation from unrelated donors in acute leukaemia

To summarize the past and current knowledge of the use of unrelated donors (URDs) in allogeneic stem cell transplantation for patients with acute leukaemia.

The outcome of URD stem cell transplants in terms of treatment-related mortality, relapse rates, disease free survival and overall survival is comparable to sibling donors.

Haematopoietic stem cell transplantation (HSCT) is the therapy of choice in many haematological malignant diseases but only one-third of the patients will have an HLA-matched sibling. The possibility of finding a matched URD is more than 70% because of recent advances in HLA typing and continuous expansion of URD registries around the world. The use of URD as a source of stem cells in adult patients are steadily increasing and in the last 8 years, superseded the matched sibling donors and became the most commonly used stem cell source. There is also an increasing trend of using peripheral blood stem cells than bone marrow stem cells. Outcomes following URD transplants depend mainly upon the indication and urgency of transplant, age and comorbidities of recipients, cytomegalovirus matching/mismatching between donor and the recipient and degree of HLA matching.