Current haploidentical HSCT strategy for pediatric patients at AMCCH. The donor will receive G-CSF for a minimum of four consecutive days and peripheral blood mononuclear cells (PBMCs) will be collected on days -1 and 0. The αβ⁺ T cells will be depleted by negative depletion using the CliniMACS system (Miltenyi-BioTec, Bergisch-Gladbach, Germany). The final dose of αβ⁺ T cells is targeted ≤5×10⁴/kg by adding back αβ⁺ T cells from the negative selection product. The patient will receive conditioning regimen consisting of fludarabine (FLU), cyclophosphamide (CY), rabbit ATG (r-ATG), and low-dose total body irradiation (LD-TBI). After that, stem cells will be infused on day 0 without any post-transplant immunosuppressants. The patient will also receive rituximab post-transplant to deplete B cells at approximately day +28 or earlier if EBV was detected with PCR. For cytomegalovirus (CMV) prophylaxis, the CMV-seropositive patient will receive ganciclovir prior to transplant and foscarnet after transplantation up until engraftment. After engraftment, ganciclovir or valganciclovir will be administered until 100 days post-transplantation with CD4⁺ cells at >100/µL.

Abbreviations: HSC, hematopoietic stem cells; αβ, αβ⁺ T cells; γδ, γδ⁺ T cells; DC, dendritic cells; B, B cells; HR, high-risk.