Mobilization of Peripheral Blood Progenitor Cells (PBPC) with G-CSF and GM-CSF in Autologous and Allogeneic Pediatric Transplants.

BACKGROUND: Chemotherapy and/or use of single or multiple growth factors have simplified the mobilization and collection of PBPC for autologous and allogeneic transplantation following high-dose chemotherapy. Nevertheless, the best method for PBPC mobilization continues uncertain. In children, mobilizations for CD34+ cells for autologous or allogeneic PBPC has been almost exclusively done with G-CSF. We conducted a phase III study to evaluate the results achieved using the combination of G-CSF + GM-CSF mobilizing CD34+ cells in children undergoing autologous or allogeneic PBPC transplantation.

METHOD: A total of 34 pediatric patients participated in the study. Seven healthy donors and 27 pediatric patients with different types of cancer participated in the mobilization study. They included patient with acute lymphoblastic leukemia, acute myelogenous leukemia, advanced stage neuroblastoma, Hodgkin’s lymphoma and rhabdomyosarcoma. Mobilization with G-CSF and GM-CSF (10μg/Kg/day each) was administered for 5 consecutive days in all patients, followed by PBPC harvesting until a threshold of 2.0 x 10^6/Kg CD34+ cells was obtained. A total of 19 PBPC transplants were performed (15 autologous and 5 allogeneic). Neutrophil engraftment was defined as ANC> 500/mm³ and, platelet engraftment was defined as a platelet count > 30,000/mm³ (transfusion independent) for more than 48 hours.

RESULTS: Table 1. The engraftment kinetics for neutrophils and platelets were 9.87 and 12.6 days respectively for the autologous transplants, and 9.4 and 12.2 days for the allogeneic. The mean number of days to achieve a higher or equal to 2 x 10^6 count of CD34+ cells in cancer patients was 2 days and 1 day for healthy donors. Side effects during mobilizations were mild and included nausea or vomiting, and tingling sensations in one individual. No secondary side effects like bone pain, headaches, or flu-like symptoms were experienced or documented. No infections were documented in the transplanted population, both autologous and allogeneic. Acute Graft versus Host Disease (GVHD) was documented in 2 patients that underwent an allogeneic PBPC transplants.

CONCLUSIONS: This study suggest that the combination of G-CSF + GM-CSF (10μ/Kg/day x 5 days) is well tolerated. It seems to be cost effective and adequate to mobilize more than average numbers of PBPC in a shorter period of time (from 1–3 apheresis) to perform allogeneic/autologous hematopoietic transplants in the pediatric population. It furnished a clinical reduction in the degree and duration of severe neutropenia in both allogeneic and autologous transplants as compared with other reports, without added increase incidence of GVHD.

Mobilizations