Successful Mobilization with the Combination of Plerixafor and G-CSF in Korean Pediatric Patients Who Failed in Previous Chemomobilization with G-CSF Alone

The classical peripheral blood stem cell mobilization (PBSCM) relies on granulocyte colony-stimulating factor (G-CSF) either as a single agent or in conjunction with chemotherapeutic agents (chemomobilization). This method however, sometimes fails in patients who have previously been heavily treated with chemotherapy or radiotherapy. PBSCM with plerixafor (AMD3100), a newly developed specific inhibitor of the CXCR4 receptor, in combination with G-CSF has been shown to enhance stem cell mobilization in adult patients, but pediatric data is scarce. We document our experiences with this drug in five pediatric patients.

Five patients (three males, two females) with a median age of 9.6 years (range 6–11 years) who have failed in chemomobilization with G-CSF alone, received plerixafor. The diagnosis of patients was medulloblastoma in 2, osteosarcoma in 2, and neuroblastoma in 1. All the patients had previously been heavily treated with chemotherapy (median 15.4 months) and two of them with medulloblastoma underwent craniospinal irradiation. Patients received G-CSF (10mcg/kg) for 4 days at 10 AM before the first plerixafor (240ug/kg) administration, which was given subcutaneously 10 hours before apheresis. Apheresis was performed thereafter on the fifth day of G-CSF administration. Patients received G-CSF at 8AM and apheresis was started at 10AM. Each apheresis was performed with plerixafor and G-CSF in the same manner.

All the patients mobilized targeted numbers of CD34⁺ cells (median 12.86×10^6/kg, range 6.34–28.97×10^6/kg) successfully with two to three cycles of apheresis, without complications (Per each apheresis: median 3.8×10^6/kg, range 1.55–14.49×10^6/kg). A total of four autologous transplantations were performed in 3 patients including one tandem transplantation in a neuroblastoma patient. Neutrophil and platelet were successfully engrafted in four transplantations within a median of 9.7 days (range 9–10 days) and 68.3 days (range 15–197 days), respectively.

Our study suggests that mobilization with plerixafor is safe and effective in Korean pediatric patients who have previously been heavily treated and have failed PBSC mobilization with classical chemomobilization with G-CSF. This is the first results of PBSCM with plerixafor in Asian pediatric patients.

No relevant conflicts of interest to declare.