44 Success of stem cell collection and neutrophil recovery in pediatric patients with brain tumours

Abstract

BACKGROUND: The use of high-dose chemotherapy (HDC) and autologous hematopoietic stem cell transplant (HSCT) has been used in certain pediatric patients with brain tumours to delay/spare radiotherapy. We aimed to study factors predicting a successful stem cell collection (SCC) and correlate stem cell dose infused with HSCT outcomes. METHODS: A retrospective chart review was undertaken for pediatric patients with brain tumours treated at our centre with HDC/HSCT between 2004-2016. RESULTS: Fifty-five patients were identified (32 male) with median age of 6.3 years at time of SCC (range 0.4-18.7). Patients' diagnoses were medulloblastoma (62%), ATRT (20%), and PNET (18%). Most patients (82%) underwent a single/1-day SCC, while the remaining required 2 SCC procedures. Peripheral blood stem cells were the source in most collections (95%). Successful SCC (CD34 collected greater-than-or-equal-to 2 x10^6/kg/transplant) and ideal SCC (greater-than-or-equal-to 5 x10^6/kg/transplant) was achieved in 85% and 45% of patients, respectively. Use of mobilizing chemotherapy with G-CSF was the only factor associated with achieving an ideal collection, while gender, age, stem cell source, and pre-apheresis peripheral blood CD34 count were not significant. Higher CD34/kg infused was associated with faster neutrophil engraftment in the first 3 courses of HDC/HSCT and platelet engraftment in the first course. CONCLUSIONS: The majority of SCC for autologous HSCT can be successfully completed with a single apheresis session. Mobilization with both chemotherapy and G-CSF yields higher CD34 compared to G-CSF alone. Higher dose of CD34/kg infused was associated with faster neutrophil and to a more limited scale platelet recovery post-HSCT.