PEGylated Granulocyte Colony-Stimulating Factor and Plerixafor Enhance Autologous Stem and Progenitor Cell Mobilization and Transplantation in Pediatric Patients

Autologous hematopoietic stem cell transplantation is used to restore bone marrow function after high-dose chemotherapy. For apheresis, granulocyte colony-stimulating factor (G-CSF) is standard of care, but obtaining sufficient stem cells can be challenging. Other mobilization agents include plerixafor and PEGylated G-CSF (PEG-G-CSF). While efficacy of these is established in adults, limited data for their use in pediatric patients are available. Here, we compare Good versus Poor Mobilizers and study success of different mobilization regimens in regard to CD34⁺cell-collection, -quality, -phenotype and hematologic reconstitution in pediatric patients. In this multi-center retrospective study, we analyzed data of 278 patients with solid tumors and lymphoma, mobilized with either G-CSF (<i>n</i> = 224), PEG-G-CSF (<i>n</i> = 34), or G-CSF/PEG-G-CSF with additional plerixafor (<i>n</i> = 20). In Poor Mobilizers (13.7% of all patients), addition of plerixafor to G-CSF augmented CD34⁺cell collection, without adverse effects on hematologic reconstitution and CD34⁺cell quality. PEG-G-CSF-aided mobilization was successful as first-line treatment in two-thirds of patients and did not impair hematological reconstitution, compared to G-CSF-only. Within the Poor Mobilizer group, G-CSF+plerixafor increased primitive (CD45RA^-CD38^-CD90⁺CD49f⁺) and CXCR4-expressing CD34⁺cells in apheresis products compared to G-CSF-only, without exceeding levels of Good Mobilizers. No plerixafor-related increase in tumor cells was observed in apheresis products. In conclusion, our comprehensive study supports the use of plerixafor and furthermore demonstrates the potential of patient-friendly PEG-G-CSF for mobilization of pediatric patients.