Use of plerixafor for peripheral blood stem cell mobilization failure in children

Background: Peripheral blood stem cell mobilization is usually performed following chemotherapy plus G-CSF in children. This standard approach may not be successful in some heavily pretreated patients undergoing mobilization. Plerixafor (AMD3100) has been used in adults as a second line mobilizing agent. Our aim is to analyze our experiences with plerixafor in children. Methods: We retrospectively evaluated three children who received plerixafor as a second line stem cell mobilizing agent in our department in the 2010-2012 period. Data including age, sex, diagnosis, previous chemotherapy, radiotherapy details, previous harvest attempts, adverse reaction, and harvest outcome were analyzed. Results: We used plerixafor in combination with G-CSF and chemotherapy or with only G-CSF seven times in three patients. All three patients were treated with different multiple chemotherapy regimens prior to stem cell harvest and failed earlier mobilization with chemotherapy plus G-CSF. The diagnoses were relapsed Hodgkin lymphoma in two and recurrent Ewing's sarcoma in one patient. We used plerixafor in combination with G-CSF and chemotherapy or with only G-CSF seven times in three patients. The harvest was successful in four of seven attempts. No adverse reaction was observed in the patients. Conclusion: The success rate is four out of seven attempts (57%) in our group. Although the data regarding the use of plerixafor in children is scarce, our experience also supports its use in poor mobilizer children. The use of plerixafor in children results in effective increases in peripheral stem cell counts and reduces the risk of mobilization failure.