Successful mobilisation, harvest, and transplant of stem cells following AMD3100 in 3 paediatric patients. The australian experience

Defining "poor mobilizer" in pediatric patients who need an autologous peripheral blood progenitor cell transplantation

The definition of poor mobilizers is not clear in pediatric patients undergoing autologous peripheral blood hematopoietic progenitor cell (HPC) mobilization. Most studies conducted in children define those variables related to the collection of HPC after leukapheresis, but the information regarding exclusively the mobilization process is scarce. In our experience, most children (92.2%) reach the target CD34(+) cell dose for autologous peripheral blood progenitor cell transplantation if CD34(+) cell count was higher than 10/μL. No differences were observed between those with >20 CD34(+) cells/μL and 11-20 CD34(+) cells/μL. In this study, we analyzed the variables that influence CD34(+) cell count; we found that prior use of radiotherapy was the main variable related to poor mobilization. Patients diagnosed with Ewing sarcoma, treated with radiotherapy and mobilized with standard doses of granulocyte colony-stimulating factor (G-CSF) were also at a high risk of mobilization failure. In these patients, we should consider mobilization with high dose G-CSF and be prepared with new mobilization agents to avoid delay on their course of chemotherapy.

Priming of hematopoietic progenitor cells by plerixafor and filgrastim in children with previous failure of mobilization with chemotherapy and/or cytokine treatment

Plerixafor has been recently approved by the European Medicines Agency for adult patients who have failed other mobilization strategies. Experience in children, however, is extremely limited. We describe the experience of the use of this drug in 8 children under a compassionate-use program in 3 Italian and 2 Spanish centers. Plerixafor was generally well tolerated; only 2 of 8 children reported adverse effects, and these were mild in intensity. Peripheral blood progenitor cell priming was improved with plerixafor in 6 of 8 patients. In the remaining 2 patients, the target CD34+ cell count was below the target of 2 × 10(6) cells/kg, although in these patients cell counts before collection were good enough for leukapheresis. Plerixafor, therefore seems to be safe and effective for peripheral blood progenitor cell mobilization in children. Adverse events were comparable with those described with filgrastim alone.

Successful mobilization, harvest and transplant of peripheral blood stem cells using AMD3100 and G-CSF following high dose craniospinal irradiation for medulloblastoma in a young child

Contemporary protocols for the treatment of malignant brain tumors such as medulloblastoma (MB) in children, often involve craniospinal irradiation (CSI) at diagnosis followed by serial courses of high dose chemotherapy and autologous hematopoietic stem cell support. Patients often require several pheresis procedures in order to collect sufficient stem cells for this type of treatment, particularly if they have already had CSI. We describe the successful mobilization, collection and subsequent transplant of a 7-year-old female with medulloblastoma after recent CSI using granulocyte colony stimulating factor (G-CSF) and the CXCR4 antagonist AMD3100 after a failed previous mobilization attempt using G-CSF alone.