Temporal changes in plerixafor administration and hematopoietic stem cell mobilization efficacy: results of a prospective clinical trial in multiple myeloma.

Plerixafor with granulocyte colony-stimulating factor (G-CSF) is effective for hematopoietic stem cell (HSC) mobilization in patients with non-Hodgkin Lymphoma and myeloma; however, labeling requires dosing 11 hours before apheresis. Pharmacodynamic studies show peak blood CD34(+) cell counts at 10 to 14 hours; limited data are available for later time points. To address the effect of afternoon plerixafor dosing on CD34(+) cell yields, we conducted a prospective clinical trial in myeloma patients undergoing stem cell collection. Thirty-one patients received plerixafor 17 hours before apheresis; blood CD34(+) cells were measured before the first plerixafor dose and 1, 3, and 17 ± 1 hours after treatment. The target HSC number (≥10 × 106 CD34(+) cells/kg) was collected from 22 subjects (73%) in 1 day and from all subjects within 3 days. Hematopoietic engraftment after transplantation and adverse events were similar to previous studies. Plerixafor given 17 hours before apheresis yields desired HSC collection efficiencies after induction treatment in myeloma patients.