Haploidentical SCT in children: an update and future perspectives

Transplantation of haploidentical stem cells has become a well-established approach, which makes a potential donor available for almost all patients. This review focuses on current results and new strategies, especially in pediatric patients with malignant diseases. CD34(+) positive selection was the most common procedure for graft manipulation in the past years, whereas T and B cell depletion is a promising new method. GVHD could herewith be effectively reduced and primary engraftment was reported in 83-100% of patients after transplantation of high stem cell doses. For patients with ALL in remission, disease-free survival at 3 years ranged between 22 and 48%. TRM, mainly because of viral infections, was improved by the use of reduced-intensity conditioning (which helped to speed up T cell recovery) and by close monitoring of viral loads and prophylactic/preemptive therapy. The role of donor-derived Ag-specific T cells against viral and fungal antigens is currently under investigation. Patients with active disease at the time of transplantation had a poor outcome and several attempts to improve these results are currently evaluated, such as co-infusion of natural killer cells, co-transplantation of MSC, use of new antileukemic drugs and post-transplant immunotherapy.