Peripheral Blood Hematopoietic Progenitor Cell Mobilization Using Granulocyte Colony Stimulating Factor (G-CSF) Combined With AMD3100 Mozobil (Plerixafor) in Healthy Volunteers

Peripheral blood progenitor cells (PBPC) are the most popular source of hematopoetic stem cells for allogeneic transplantation because of technical ease of collection and faster engraftment. Traditionally, granulocyte-colony stimulating factor (G-CSF) has been used to procure the peripheral blood stem cell graft. Although regimens using G-CSF usually succeed in collecting adequate numbers of PBPC from healthy donors, 5%-10% of the donors will mobilize stem cells poorly and may require multiple large volume apheresis or bone marrow harvesting. AMD3100 reversibly inhibits CXC- chemokine receptor 4 (CXCR4) binding to stromal cell derived factor (SDF) - 1 and was recently discovered to be an effective agent to mobilize cluster of differentiation 34 (CD34)+ cells into the peripheral blood. In normal volunteers, administering AMD3100 after 4-5 days of G-CSF resulted in a 3-3.5 fold increase in circulating CD34 cells compared to G-CSF alone. Recent data has suggested that the combination of G-CSF and AMD3100 is superior to G-CSF alone for mobilizing hematopoietic progenitor cells in heavily pretreated patients with multiple myeloma or non-Hodgkin's lymphoma undergoing autologous hematopoietic transplantation. Combining AMD3100 with G-CSF could be an effective strategy to improve the yield of PBPC collected from allogeneic donors who mobilize poorly with G-CSF alone. However, the biological impact of AMD3100 in this context on T cells and other cellular populations contained within the allograft that mediate graft versus host disease (GVHD) and graft-versus-leukemia (GVL) effects are unknown.

We propose to collect peripheral progenitor cell (PBPC) from healthy volunteers following 5 days of G-CSF (10 mcg/kg/day) and a single dose of AMD3100 (240 mcg/kg subcutaneous given 12 hours before starting apheresis) to study the impact of combining these two mobilizing agents on the immunological properties of the mobilized cells. A single 15 liter apheresis will be conducted on day 5 following the 5th dose of G-CSF. The immunological studies conducted on these mobilized cells will be the same as our parallel study which is investigating the immune properties of PBPCs mobilized with G-CSF or AMD3100 alone. If combining AMD3100 with G-CSF has no negative impact on the immune populations involved in GVHD and graft-vs-leukemia effects, this regimen could be used for allogeneic donors who fail to mobilize sufficient peripheral blood stem cell (PBSC) using G-CSF alone.

Primary objective: To determine the cytokine polarization status of cluster of differentiation 4 (CD4+) T-cells collected by apheresis following combination of AMD3100 and G-CSF compared to G-CSF mobilization.

Primary endpoint: the ratio of Th1 [intracellular interferon (IFN-g) +] versus Th2 [intracellular interleukin (IL-4+)] T-cells in the apheresis products collected from individual donors undergoing mobilization with combination of G-CSF and AMD3100 to the ratio in apheresis product collected with G-CSF alone (ratio published in literature).

Secondary endpoints: To examine 1) the cellular content and other immune properties of mobilized cells; 2) yields of hematopoietic progenitor cells, immune cells, and other cellular subsets collected by apheresis; and the 3) safety profile of AMD3100.