A combination of granulocyte-colony-stimulating factor (G-CSF) and plerixafor mobilizes more primitive peripheral blood progenitor cells than G-CSF alone: results of a European phase II study

Background aimsPrevious studies in xenograft models have shown that human peripheral blood progenitor cells (PBPC) mobilized with the CXCR4 antagonist plerixafor (AMD3100) have a higher bone marrow (BM) reconstitution potential than granulocyte–colony-stimulating factor (G-CSF)-mobilized PBPC.MethodsPBPC obtained during G-CSF-supported mobilization before and after a supplementary administration of AMD3100 from patients with multiple myeloma and non-Hodgkin's lymphoma (n = 15; phase II study) were investigated for co-expression of primitive and lineage-associated markers, their proliferative activity in vitro and repopulation potential after clinical transplantation.ResultsA significant increase in primitive CD34+ CD38− cells was observed in intraindividual comparisons of all patients after administration of G-CSF+AMD3100 (peripheral blood: median 8-fold, range 2,4-fold - 39-fold) compared with G-CSF alone. Using a long-term culture-initiating cell assay, this increase was confirmed. After transplantation of G-CSF+AMD3100-mobilized PBPC, the time to leukocyte reconstitution >1 × 103/μL and platelet reconstitution >2 × 104/μL was 14 (10–19 days) and 13 days (10–15 days), respectively. A complete and stable hematologic reconstitution (platelets >1.5 × 105/μL) was observed in 91% of all patients within 35 days.ConclusionsAn additional application of AMD3100 to a standard G-CSF mobilization regimen leads to a significant increase in primitive PBPC with high repopulation capacity.