Hematopoietic stem cell transplantation from full-haplotype mismatched donors.

Until a decade ago, hematopoietic stem cell transplantation from related donor mismatched at two or three HLA-A, -B or DR loci was largely unsuccessful in leukemia patients because of severe graft-versus-host disease in unmanipulated bone marrow transplants and graft failure in extensively T-cell-depleted transplants. The breakthrough came with the use of a megadose of T-cell-depleted hematopoietic progenitor cells. Donor-vs-recipient natural killer cell alloreactivity also plays a role in facilitating engraftment and in preventing relapse of acute myeloid leukemia. Event-free survival and transplant-related mortality for high risk acute leukemia patients treated at less advanced stages of disease compare favourably with reports from unrelated matched transplants.