Mobilization of peripheral blood progenitor cells using 16 versus 10 mg/kg/d G-CSF in children with malignancies

Administration of hematopoietic growth factors, with or without chemotherapy, can augment progenitor cell numbers available for collection. The dose of granulocyte colony stimulating factor (G-CSF) used for mobilization of peripheral blood progenitor cells (PBPC) is controversial, and doses between 5 and 32 microg/kg/d have been reported in adults. In order to determine the dose-response effect for G-CSF in mobilizing PBPC in children, we randomized 30 children with malignancies to receive either 16 or 10 microg/kg/d subcutaneously starting on the day after the disease-oriented chemotherapy regimen and continuing until the completion of leukapheresis. Leukapheresis commenced after threshold WBC > 1 x 10(9)/L was achieved and continued until 10 x 10(6) CD34+ cells/kg were obtained or for 6 procedures. Both treatment groups achieved an adequate yield of CD34+ cells with an average of 4 leukapheresis procedures. The numbers of CD34+ cells/kg were 8.3 x 10(6) and 11.7 x 10(6) in patients receiving 16 and 10 microg/kg/d doses of G-CSF, respectively, or 2.1 x 10(6) and 3.7 x 10(6) cells/kg per leukapheresis. The levels of CD34+ cells in peripheral blood had a wide interindividual variation, and were not significantly different after 16 or 10 microg/kg doses of daily G-CSF. We conclude that there is no advantage to using 16 microg/kg/d of G-CSF post-chemotherapy for PBPC mobilization in children.