Autologous peripheral blood stem cell transplantation for acute leukaemias

Initial interest in autologous blood stem cell transplants (ABSCT) in acute myeloid leukaemia (AML) was based on the postulate that there might be less malignant contamination than with bone marrow transplants. Although this remains presently uncertain, other advantages of ABSCT, such as a rapid haematopoietic recovery, were immediately recognized. In pilot studies, peripheral blood stem cells (PBSC) were collected after standard induction and consolidation courses of chemotherapy. The actuarial disease-free survival (DFS) and relapse rates (RR) at 2-3 years ranged from 28 to 39% and 57 to 60%, respectively. Recently, PBSC collection after high-dose cytarabine, with or without G-CSF, has been associated with DFS ranging from 47 to 57%. Thus, the timing of stem cell collection seems to be crucial in AML and it should be performed following an efficient in vivo purging but before the haematopoietic reserve is exhausted. Clinical results with ABSCT are similar to those seen after autologous bone marrow transplant (ABMT), although important issues such as potential contamination of stem cell collections and optimal timing of PBSC harvest remain to be clarified. Prospective randomized studies comparing ABMT and ABSCT are needed for definitive evaluation of the role of the source of stem cells in AML treatment.