Fludarabine-based preparative protocol for unrelated donor cord blood transplantation in children: Successful engraftment with minimal toxicity

Unrelated umbilical cord blood (UCB) is a new source of hematopoietic stem cell (HSC) for allogeneic transplantation. The optimal conditioning for UCB transplant has not been defined. Intensive immunosuppression is frequently employed because of the higher risk of graft failure. Fludarabine monophosphate is shown to be an effective agent for facilitating allogeneic HSC engraftment. We have recently encountered three children who were not ideal candidates for 'conventional' conditioning protocols. TBI followed by fludarabine and melphalan were used for transplant preparation. The UCB units were one HLA-antigen (n = 1) and two HLA-antigen mismatched with the recipients. All three patients engrafted successfully. There was mild extramedullary toxicity. Two patients are alive with complete chimerism 8 and 20 months after transplant. A fludarabine-based protocol may be considered for selected cases of UCB transplants.