Peripheral Blood Stem Cell Mobilization by G-CSF Alone and Engraftment Kinetics Following Autologous Transplantation in Children and Adolescents with Solid Tumor.

The purpose of this study was to examine the yield of PBSC, mobilized with G-CSF alone, and engraftment kinetics after autologous transplantation in pediatric cancer patients. In 55 patients (median age; 7 years, range 0–21) with various pediatric and adolescent solid tumors, PBSC were mobilized with G-CSF alone, and the yields of PBSC and engraftment following autologous PBSCT were evaluated retrospectively. Patients were categorized according to prior treatment; patients who had received less than 4 or 4 cycles of chemotherapy with/without local irradiation (Group 1: N= 21), patients who received more than 4 cycles of chemotherapy or 3 or more cycles of chemotherapy with extended irradiation (Group 2: N= 23), and patients who received high-dose chemotherapy with stem cell support (Group 3: N= 11). Ten microgram per kg of G-CSF was injected subcutaneously for mobilization when patients showed no influence of previous chemotherapy, and administration was continued for five days. The peaks of CD34⁺ cells and CFU-GM were observed on day 5 of G-CSF administration essentially in all patients. Aphereses were performed on days 5 and 6 of G-CSF treatment. Mobilization failure was observed in four patients in all groups. Compared with the results in patients mobilized by chemotherapy plus G-CSF (N=18), the progenitor cell yields were lower in those mobilized with G-CSF alone. However, there were no significant differences in WBC engraftment speed compared to the chemotherapy plus G-CSF mobilization group, although platelet recovery was delayed in patients with G-CSF alone, especially in patients in Group 3. The median time taken for ANC and platelet counts to reach 500 and 20K was 12 days (range 8–28) and 15 days (8–55), respectively, in all patients who were mobilized by G-CSF alone except for patients with progressive disease. In summary, mobilization with G-CSF alone can mobilize a sufficient number of CD34⁺ cells for successful autografting and sustained hematological reconstitution in pediatric patients with cancer, even in heavily pre-treated patients. Mobilization with G-CSF alone might offer some advantages, such as ease of determining a collection schedule without a daily determination of CD34⁺ cells in the blood, and the avoidance of neutropenic fever and additional transfusion.