Haploidentical Bone Marrow Transplantation Without T-Cell Depletion

Abstract

Approaches for haploidentical bone marrow transplantation (BMT) without T-cell depletion have been designed using new transplant strategies, including anti-thymocyte globulin (ATG) preparative regimens, granulocyte colony-stimulating factor-primed grafts, post-transplantation rapamycin, or high-dose cyclophosphamide (Cy) in combination with other immunosuppressive agents for graft-versus-host disease (GVHD) prophylaxis. These strategies ensured fast hematologic engraftment across the human leukocyte antigen (HLA) barrier with an acceptable incidence of GVHD. Long-term follow-up results from different transplant centers suggest that unmanipulated transplantation may provide an alternative strategy in the haploidentical setting without requiring the technical expertise and cost of ex vivo T-cell depletion. This review discusses immune reconstitution and factors associated with clinical outcomes following unmanipulated haploidentical hematopoietic stem cell transplantation (HSCT), and compares outcomes between unmanipulated haploidentical transplant versus HLA-matched sibling donor (MSD) transplantation, HLA-matched unrelated donor (MUD) transplantation, or unrelated double umbilical cord blood (dUCB) transplantation. Advantages and disadvantages of unmanipulated haploidentical HSCT and strategies to improve outcome after haploidentical BMT without ex vivo T-cell depletion are discussed.