Efficacy and safety of a reduced dose of plerixafor in combination with granulocyte colony-stimulating factor in healthy haploidentical stem cell donors

Background and Objectives Implementation of the technique of immunomagnetic selection requires the procurement of a large number of CD34+ cells from haploidentical donors within a single apheresis procedure. The release of stem cells with granulocyte colony-stimulating factor (G-CSF) alone is unsatisfactory in a number of donors, and plerixafor, a CXCR4 chemokine receptor antagonist, could be used as an additional mobilization agent. The aim of our study was to examine whether a lower dose of plerixafor (0.12 mg/kg) can provide sufficient increase in CD34+ cells in the peripheral blood of allogeneic healthy donors in comparison with a historical control group. In addition, we assessed the risk of inability to provide the recipient with a transplant containing the optimal dose of 8-10 x 10(6) CD34+ cells/kg body weight of the recipient. Materials and Methods In a prospective, single-arm study, we examined the results of 105 mobilizations in healthy adult haploidentical donors with G-CSF and plerixafor at a dose of 0.12 mg/kg. The historical control group consisted of 106 mobilizations with G-CSF and plerixafor at 0.24 mg/kg. Results The median increase in the number of CD34+ cells from day 4 to day 5 of mobilization was 69 cells/mu l (range, 28-240) versus 77 cells/mu l (24-217) in the groups of 0.12 and 0.24 mg/kg of plerixafor, respectively (p-value 0.255). The apheresis products contained a median of 14.4 x 10(6)/kg recipient body weight CD34+ cells versus 12.9 x 10(6)/kg in the groups that received 0.12 and 0.24 mg/kg of plerixafor, respectively (p-value 0.118). The obtained differences were not significant, which means the application of a decreased dose of plerixafor did not affect the results of mobilization. Conclusion The obtained differences in collection were not significant, and thus the application of a decreased dose of plerixafor did not affect the results of mobilization.