Haploidentical stem cell transplantation for the treatment of leukemia: current status

Haploidentical stem cell transplantation (haplo-SCT), either with T-cell depletion or T-cell replete, has been a reliable source of stem cells for patients with high-risk leukemia who do not have matched donors because it provides comparable outcomes to human leukocyte antigen-matched sibling donor transplantation, unrelated donor transplantation and umbilical cord blood transplantation. Factors, such as the Hematopoietic Cell Transplantation-Specific Comorbidity Index, associated with transplant outcomes may help us design risk-stratification-directed intervention to improve the prognosis of leukemia patients. Preliminary results of novel protocols, including co-transplant of haploidentical allografts and cord blood, as well as human leukocyte antigen-mismatched stem cell microtransplantation, for leukemia have shown that these approaches are feasible. Several strategies for enhancing the graft-versus-leukemia effects significantly decreased the relapse rate after haplo-SCT. Future direction of research will focus on perfecting available haplo-SCT protocols and determining the optimal time of haplo-SCT for leukemia and 'fit' haploidentical transplant candidates.