Haploidentical haematopoietic stem cell transplantation for acute leukaemia in adults: experience in Europe and the United States.

Work on one haplotype-mismatched transplants has been proceeding for over 20 years all over the world and novel transplant techniques have been developed. Some centres have focused on the conditioning regimens and post transplant immune suppression; others have concentrated on manipulating the graft. Haploidentical transplant modalities are based mainly on high-intensity conditioning regimen, but reduced intensity regimens have recently been introduced. The graft may be a megadose of extensively T cell-depleted or unmanipulated progenitor cells. Excellent engraftment rates are associated with a very low incidence of GVHD- and regimen-related mortality even in patients who are over 50 years old. Overall, event-free survival and transplant-related mortality compare favourably with reports on transplants from sources of stem cells other than the matched sibling. Improvements will come with successful implementation of strategies to accelerate and strengthen post transplant immune reconstitution as well as transplantation of patients in early stage disease.