Phase I/II Study of Intravenous Plerixafor Added to a Mobilization Regimen of Granulocyte Colony–Stimulating Factor in Lymphoma Patients Undergoing Autologous Stem Cell Collection

Plerixafor, given subcutaneously with granulocyte colony–stimulating factor (G-CSF), improves autologous stem cell collection in patients with lymphoma and multiple myeloma. Intravenous (i.v.) administration of plerixafor allows administration of plerixafor on the same day as pheresis and it may improve stem cell collection. The primary objectives of this phase I/II study were to determine the maximum tolerated dose of i.v. plerixafor and the efficacy of i.v. plerixafor + G-CSF to mobilize ≥ 2 × 10⁶ CD34⁺ cells/kg from patients with lymphoma. In phase I, 25 patients were treated with G-CSF + i.v. plerixafor at escalating doses; in phase II, 36 patients were treated with G-CSF + plerixafor .40 mg/kg. The treatment was well tolerated. Fifty-nine of 61 patients (98%) met the collection goal and 47 of 61 patients (77%) collected ≥ 5.0 × 10⁶ CD34⁺ cells/kg in a median of 2 pheresis days. Analysis of CD34⁺ hematopoietic stem and progenitor cells (HSPCs) revealed that G-CSF–mobilized grafts were enriched with CD34⁺CD45RA^-CD123^+/- primitive HSPCs whereas plerixafor preferentially mobilized CD34⁺CD45RA⁺CD123⁺⁺ plasmacytoid dendritic cell precursors. In conclusion, i.v. plerixafor is well tolerated and effective when added to G-CSF for the mobilization of stem cells from patients with lymphoma, with mobilization kinetics and stem cell collections that compare favorably with subcutaneous dosing.