First Line Haploidentical Stem Cell Transplantation in Children and Adolescents with Severe Aplastic Anemia Using Mobilized Peripheral Blood As Source of CD34+ Cells

Introduction The only curative treatment for severe aplastic anemia in children is allogenic stem cell transplantation, but only few patients have a matched related or unrelated donor. Haploidentical stem cell transplantation (haplo-SCT) using bone marrow (BM) and peripheral blood stem cells (PBSC) has been recently described as effective and safe. In this study, we retrospectively describe the outcome of nine pediatric patients who underwent haplo-SCT using only PBSC. Patients and methods The father was the selected donor for seven of the nine patients. Donor specific anti-HLA antibodies were ruled out. Stem cells mobilization was performed with filgrastim 10 mcg/kg/d for five days, and CD34+ were recollected by peripheral blood apheresis on day 0. The conditioning regimen consisted on rabbit anti-thymocyte globulin 2.5 mg/kg/d on days -7, -6, -5, and -4, and cyclophosphamide 50 mg/kg/d on days -3 and -2. We used cyclophosphamide 50 mg/kg/d on days +3 and +4, tacrolimus and mycophenolic acid as graft versus host disease prophylaxis. Results The median follow up was 253 days (range 45-765 days). The median infused CD34+ was 10 × 10^6/kg (range 2.7 to 43 × 10^6/kg). The median myeloid engraftment was day +15 (range 11-30 days), and median platelet engraftment was day +16 (range 12-30 days). In eight of the nine patients, a sustained graft was achieved. One patient never achieved platelet engraftment and died because of cytomegalovirus infection. There was not treatment related toxicity reported. None of the patients had GVHD. The overall survival up to date is 88.8%. The eight surviving patients remain free of transfusions. Conclusions Haplo-SCT could be established as first line treatment when there is no matched related or unrelated donor. According to this short sample and previous reports, PBSC is a feasible option to be effectively used as only source of stem cells.