Comparison between granulocyte colony-stimulating factor and granulocyte-macrophage colony-stimulating factor in the mobilization of peripheral blood stem cells

Intravenous delivery of granulocyte-macrophage colony stimulating factor impairs survival in lipopolysaccharide-induced sepsis

Background

Cell-based therapies with bone marrow-derived progenitor cells (BMDPC) lead to an improved clinical outcome in animal sepsis models. In the present study we evaluated the ability of granulocyte macrophage-colony stimulating factor (GM-CSF) to mobilize BMDPC in a lipopolysaccharide (LPS)-induced sepsis model and thereby its potential as a novel treatment strategy.

Methods

Male Wistar rats received LPS (25μg/kg/h for 4 days) intravenously and were subsequently treated with GM-CSF 12.5μg/kg (0h,24h,48h,72h). As control groups, rats were infused with sodium chloride or GM-CSF only. Clinical and laboratory parameters, proinflammatory plasma cytokines as well as BMDPC counts were analyzed. Cytokine release by isolated peripheral blood mononuclear cells from rat spleen upon incubation with LPS, GM-CSF and a combination of both were investigated in vitro.

Results

In vivo, rats receiving both LPS and GM-CSF, showed a reduced weight loss and increased mobilization of BMDPC. At the same time, this regime resulted in an increased release of proinflammatory cytokines (IL-6, IL-8) and a significantly increased mortality. In vitro, the combination of LPS and GM-CSF showed a significantly increased IL-6 release upon incubation compared to incubation with LPS or GM-CSF alone.

Conclusions

GM-CSF did not have a beneficial effect on the clinical course in our LPS-induced sepsis model. It synergistically promoted inflammation with LPS and probably thereby impaired survival.

GM-CSF Enhances Mobilization of Bone Marrow Mesenchymal Stem Cells via a CXCR4-Medicated Mechanism

Background

This study was conducted to investigate the effect of granulocyte-macrophage colony-stimulating factor (GM-CSF) on the mobilization of mesenchymal stem cells (MSCs) from the bone marrow (BM) into the peripheral blood (PB) in rats.

Methods

GM-CSF was administered subcutaneously to rats at 50 μg/kg body weight for 5 consecutive days. The BM and PB of rats were collected at 1, 3, and 5 days during the administration for analysis.

Results

Upon GM-CSF administration, the number of mononuclear cells increased rapidly at day 1 both in the BM and PB. This number decreased gradually over time in the BM to below the initial amount by day 5, but was maintained at a high level in the PB until day 5. The colony-forming unit-fibroblasts were increased in the PB by 10.3-fold at day 5 of GM-CSF administration, but decreased in the BM. Compared to GM-CSF, granulocyte-colony stimulating factor (G-CSF) stimulated lower levels of MSC mobilization from the BM to the PB. Immunohistochemical analysis revealed that GM-CSF induced a hypoxic and proteolytic microenvironment and increased C-X-C chemokine receptor type 4 (CXCR4) expression in the BM. GM-CSF added to BM MSCs in vitro dose-dependently increased CXCR4 expression and cell migration. G-CSF and stromal cell derived factor-1 (SDF-1) showed similar results in these in vitro assays. Know-down of CXCR4 expression with siRNA significantly abolished GM-CSF- and G-CSF-induced MSC migration in vitro, indicating the involvement of the SDF-1-CXCR4 interaction in the mechanism.

Conclusion

These results suggest that GM-CSF is a useful tool for mobilizing BM MSCs into the PB.

Five Days Granulocyte Colony-Stimulating Factor Treatment Increases Bone Formation and Reduces Gap Size of a Rat Segmental Bone Defect: A Pilot Study

Bone is an organ with high natural regenerative capacity and most fractures heal spontaneously when appropriate fracture fixation is provided. However, additional treatment is required for patients with large segmental defects exceeding the endogenous healing potential and for patients suffering from fracture non-unions. These cases are often associated with insufficient vascularization. Transplantation of CD34+ endothelial progenitor cells (EPCs) has been successfully applied to promote neovascularization of bone defects, however including extensive ex vivo manipulation of cells. Here, we hypothesized, that treatment with granulocyte colony-stimulating factor (G-CSF) may improve bone healing by mobilization of CD34+ progenitor cells into the circulation, which in turn may facilitate vascularization at the defect site. In this pilot study, we aimed to characterize the different cell populations mobilized by G-CSF and investigate the influence of cell mobilization on the healing of a critical size femoral defect in rats. Cell mobilization was investigated by flow cytometry at different time points after five consecutive daily G-CSF injections. In a pilot study, bone healing of a 4.5-mm critical femoral defect in F344 rats was compared between a saline-treated control group and a G-CSF treatment group. In vivo microcomputed tomography and histology were applied to compare bone formation in both treatment groups. Our data revealed that leukocyte counts show a peak increase at the first day after the last G-CSF injection. In addition, we found that CD34+ progenitor cells, including EPCs, were significantly enriched at day 1, and further increased at day 5 and day 11. Upregulation of monocytes, granulocytes and macrophages peaked at day 1. G-CSF treatment significantly increased bone volume and bone density in the defect, which was confirmed by histology. Our data show that different cell populations are mobilized by G-CSF treatment in cell specific patterns. Although in this pilot study no bridging of the critical defect was observed, significantly improved bone formation by G-CSF treatment was clearly shown.

Management of mobilization failure in 2017

In contemporary clinical practice, almost all allogeneic transplantations and autologous transplantations now capitalize on peripheral blood stem cells (PBSCs) as opposed to bone marrow (BM) for the source of stem cells. In this context, granulocyte colony-stimulating factor (G-CSF) plays a pivotal role as the most frequently applied frontline agent for stem cell mobilization. For patients classified as high-risk, chemotherapy based mobilization regimens can be preferred as a first choice and it is notable that this also used for remobilization. Mobilization failure occurs at a rate of 10%-40% with traditional strategies and it typically leads to low-efficiency practices, resource wastage, and delayed in treatment intervention. Notably, however, several factors can impact the effectiveness of CD34⁺ progenitor cell mobilization, including patient age and medical history (prior chemotherapy or radiotherapy, disease and marrow infiltration at the time of mobilization). In recent years, main (yet largely ineffective) approach was to increase G-CSF dose and add SCF, but novel and promising pathways have been opened up by the synergistic impact of a reversible inhibitor of CXCR4, plerixafor, with G-CSF. The literature shows to its favorable results in upfront and failed mobilizers, and it is necessary to use plerixafor (or equivalent agents) to optimize HSC harvest in poor mobilizers. Different CXCR4 inhibitors, growth hormone, VLA4 inhibitors, and parathormone, have been cited as new agents for mobilization failure in recent years. In view of the above considerations, the purpose of this paper is to examine the mobilization of PBSC while focusing specifically on poor mobilizers.

Granulocyte Colony-Stimulating Factor (G-CSF) for the Treatment of Spinal Cord Injury

Spinal cord injury (SCI) is a common medical condition with a poor prognosis for recovery and catastrophic effects on a patient's quality of life. Available treatments for SCI are limited, and the evidence suggesting their harmful side effects is more consistent than any suggestion of clinical benefit. Developing novel safe and effective therapeutic options for SCI is crucial. Granulocyte colony-stimulating factor (G-CSF) is a hematopoietic cytokine with known multifaceted effects on the central nervous system. Herein, we review the accumulating preclinical evidence for the beneficial effects of G-CSF on functional and structural outcomes after SCI. Meanwhile we present and discuss multiple mechanisms for G-CSF's neuroprotective and neuroregenerative actions through the results of these studies. In addition, we present the available clinical evidence indicating the efficacy and safety of G-CSF administration for the treatment of acute and chronic traumatic SCI, compression myelopathy, and SCI-associated neuropathic pain. Our review indicates that although the quality of clinical evidence regarding the use of G-CSF in SCI is inadequate, the encouraging available preclinical and clinical data warrant its further clinical development, and bring new hope to the longstanding challenge that is treatment of SCI.

Regulation of dendritic cell development by GM-CSF: molecular control and implications for immune homeostasis and therapy

Dendritic cells (DCs) represent a small and heterogeneous fraction of the hematopoietic system, specialized in antigen capture, processing, and presentation. The different DC subsets act as sentinels throughout the body and perform a key role in the induction of immunogenic as well as tolerogenic immune responses. Because of their limited lifespan, continuous replenishment of DC is required. Whereas the importance of GM-CSF in regulating DC homeostasis has long been underestimated, this cytokine is currently considered a critical factor for DC development under both steady-state and inflammatory conditions. Regulation of cellular actions by GM-CSF depends on the activation of intracellular signaling modules, including JAK/STAT, MAPK, PI3K, and canonical NF-κB. By directing the activity of transcription factors and other cellular effector proteins, these pathways influence differentiation, survival and/or proliferation of uncommitted hematopoietic progenitors, and DC subset–specific precursors, thereby contributing to specific aspects of DC subset development. The specific intracellular events resulting from GM-CSF–induced signaling provide a molecular explanation for GM-CSF–dependent subset distribution as well as clues to the specific characteristics and functions of GM-CSF–differentiated DCs compared with DCs generated by fms-related tyrosine kinase 3 ligand. This knowledge can be used to identify therapeutic targets to improve GM-CSF–dependent DC-based strategies to regulate immunity.

The chemokine system in allogeneic stem-cell transplantation: a possible therapeutic target?

Further improvements in allogeneic stem-cell transplantation will probably depend on a better balance between immunosuppression to control graft-versus-host disease and immunological reconstitution sufficient to ensure engraftment, reduction of infection-related mortality and maintenance of post-transplant antileukemic immune reactivity. The chemokine network is an important part of the immune system, and, in addition, CXCL12/CXCR4 seem to be essential for granulocyte colony-stimulating factor-induced stem-cell mobilization. Partial ex vivo graft T-cell depletion based on the expression of specific chemokine receptors involved in T-cell recruitment to graft-versus-host disease target organs may also become a future therapeutic strategy; an alternative approach could be pharmacological inhibition (single-receptor inhibitors or dual-receptor inhibitors) in vivo of specific chemokine receptors involved in this T-cell recruitment. Future clinical studies should therefore be based on a better characterization of various immunocompetent cells, including their chemokine receptor profile, both in the allografts and during post-transplant reconstitution.

How I treat patients who mobilize hematopoietic stem cells poorly

Transplantation with 2-5 × 106 mobilized CD34+cells/kg body weight lowers transplantation costs and mortality. Mobilization is most commonly performed with recombinant human G-CSF with or without chemotherapy, but a proportion of patients/donors fail to mobilize sufficient cells. BM disease, prior treatment, and age are factors influencing mobilization, but genetics also contributes. Mobilization may fail because of the changes affecting the HSC/progenitor cell/BM niche integrity and chemotaxis. Poor mobilization affects patient outcome and increases resource use. Until recently increasing G-CSF dose and adding SCF have been used in poor mobilizers with limited success. However, plerixafor through its rapid direct blockage of the CXCR4/CXCL12 chemotaxis pathway and synergy with G-CSF and chemotherapy has become a new and important agent for mobilization. Its efficacy in upfront and failed mobilizers is well established. To maximize HSC harvest in poor mobilizers the clinician needs to optimize current mobilization protocols and to integrate novel agents such as plerixafor. These include when to mobilize in relation to chemotherapy, how to schedule and perform apheresis, how to identify poor mobilizers, and what are the criteria for preemptive and immediate salvage use of plerixafor.

[Hematopoietic stem cells mobilization: state of the art in 2011 and perspectives]

High-dose chemotherapy with stem cells support has largely improved in terms of hematopoietic stem and progenitor cells harvest procedures as well as in those, which target or manipulate the cellular composition of autologous graft. Optimal preparative regimens and supportive care had lead to better use of autologous transplantation procedure. For other patients assigned to hematopoietic transplantation, availability of allogeneic donors appears to be an interesting alternative source of hematopoietic stem cells. Since three decades, hematopoietic growth factors development has allowed mobilization optimization and collection of peripheral hematopoietic stem cells leading to reduced days of hospitalization and less blood products requirements, being more cost-effective for patients in autologous transplantation settings and for stem cell collection facilities in allogeneic ones. New perspectives include, besides ex vivo manipulation of graft, development of mobilizing drugs in order to perform transplantation even in poor mobilizers patients. An important goal is achieved with the description of genetic polymorphisms related to optimal mobilization of stem cells. New approach using more promising and selective agents called chemokines, such as plerixafor the main leader among these agents are now available and appear complementary for alternative approach using cytokines alone (G-CSF, GM-CSF, SCF). The aim of this review is to assess the evolution of theses biotechnologies and their role in different steps of autologous transplantation and allogeneic stem cells collection.

Advances in mobilization for the optimization of autologous stem cell transplantation

In autologous stem cell transplantation, mobilized peripheral blood has replaced the bone marrow as the preferred source of hematopoietic stem cells (HSCs). Because HSCs normally exist in the blood in very low numbers, the use of agents to "mobilize" HSCs from the marrow niche to the peripheral blood is essential for successful transplantation. Until recently, granulocyte colony-stimulating factor (G-CSF) and granulocyte-macrophage colony-stimulating factor were the only approved agents by the US Food and Drug Administration for use as peripheral blood stem cell (PBSC)-mobilizing agents in the United States, but G-CSF has become the gold standard. Unfortunately, some patients fail to mobilize sufficient numbers of PBSCs for transplantation in response to G-CSF with or without chemotherapy. Recently, a new agent, plerixafor (AMD3100) added to G-CSF has been approved to enhance PBSC mobilization. This review will discuss the current methodologies to improve hematopoietic stem cell mobilization.

Mobilization of hematopoietic stem cells for use in autologous transplantation

Autologous hematopoietic stem cell transplantation (HSCT) is a potentially curative therapeutic approach for various malignant hematologic and lymphoid diseases. Hematopoietic stem cells (HSCs) may be collected from the blood or the bone marrow. HSCs are capable of self-renewal and give rise to progenitor cells, multipotent cells that differentiate and proliferate into the mature cells of the blood and immune system. HSCs and progenitor cells are released from the bone marrow into the peripheral blood through a process called mobilization. HSCs then are collected from the blood in a process called apheresis and cryopreserved for administration following the high-dose preparative regimen. This article reviews stem cell biology, current mobilization strategies, use of novel mobilization agents, and nursing care of patients during the mobilization phase of autologous HSCT. Understanding the biology and process of HSC mobilization is critical for transplantation nurses to deliver and coordinate care during this complex phase of autologous HSCT.

A randomized study comparing chemotherapy followed by G-CSF alone or in combination with GM-CSF for mobilization of peripheral blood stem cells in patients with non-Hodgkin's lymphomas

OBJECTIVE

Granulocyte colony-stimulating factor (G-CSF) and granulocyte-macrophage colony stimulating factor (GM-CSF) are the two most commonly used cytokines for mobilization of stem cells in patients undergoing high dose chemotherapy with stem cell support. Both cytokines increase the peripheral blood white blood cell count and the stem cell count but there are other differences in the stem cell products mobilized by G-CSF versus those mobilized with GM-CSF. Generally higher numbers of dendritic cells are mobilized with GM-CSF than by G-CSF. The primary objective of this randomized study was to evaluate the safety and efficacy of chemotherapy plus G-CSF versus chemotherapy plus G-CSF and GM-CSF in patients with B-cell non-Hodgkin's lymphoma (NHL) who were undergoing chemo-mobilization. Secondary objectives were to determine the expression of various dendritic cell subsets in the two groups and to determine the incidence of disease progression or relapse at 12 months.

METHODS

We prospectively evaluated 84 patients with relapsed NHL who were candidates for high dose therapy (HDT). All patients underwent chemo-mobilization using ifosfamide, etoposide, and rituximab. All patients were randomized in an adaptive manner to receive either G-CSF or G-CSF plus GM-CSF (G+GM) starting 24 hours after completion of chemotherapy and continuing until completion of apheresis. The stem cell yield/kg, the number of apheresis procedures needed in the two groups, and the toxicity were recorded. We also enumerated dendritic cell subsets, myeloid DCs (mDC) and plasmacytoid DCs (pDC), in apheresis products and in peripheral blood (PB) samples collected pre-chemotherapy. The data were expressed as a percentage of peripheral blood mononuclear cells.

RESULTS

A total of 84 patients were treated. Forty-three patients received G-CSF and 41 received G+GM. Both regimens were well tolerated. The median CD34+ cell dose collected was similar in the two groups. A total of 54 (G-CSF N = 25 and G+GM N = 29) paired samples from baseline and post-apheresis were available for analysis of dendritic cell subsets. There was no significant difference in the percentages of mDC subsets between baseline and post-apheresis collected with G-CSF or G+GM mobilization. However, there was a significant increase in the percentage of pDC subsets in the G-CSF alone when compared to the G+GM arm (P = 0.002). Furthermore, the ratio of mDC and pDC was significantly lower after mobilization with G-CSF versus G+GM (P = 0.029).

CONCLUSION

Addition of GM-CSF to G-CSF to the mobilization regimen resulted in lower percentages of pDC in the apheresis products when compared to those with G-CSF alone. This shifts the mDC/pDC ratio in the apheresis grafts in favor of mDC in the combination arm. However, these differences did not seem to impact the clinical outcomes in the two groups. (ClinicalTrials.gov Identifier: NCT00499343).

Enhanced cell therapy strategy to treat chronic limb-threatening ischemia

Intermittent programmed compression of the chronically ischemic limb is associated with arteriogenesis. However, progenitor cell elements contributing to this neovascularization are typically diminished in number and function in the elderly dysvascular patient, particularly in the presence of diabetes, renal insufficiency, and cardiac disease. Granulocyte-colony stimulation factor (G-CSF) dramatically boosts the circulating progenitor cell count. G-CSF was administered in 2 patients being treated for ischemic wounds with an intermittent programmed pneumatic compression device (PPCD). Both had comorbidities associated with diminished circulating progenitor cell counts. Remarkable clinical, hemodynamic, and angiographic improvement was observed. Further study of this synergistic strategy is warranted.

Increase of SCF plasma concentration during donepezil treatment of patients with early Alzheimer's disease

Alzheimer's disease (AD) can be treated with inhibitors of the enzyme acetylcholinesterase (AChE). There is evidence that AChE inhibitors promote neuroprotective effects and neurogenesis in the central nervous system (CNS). However, the mechanisms by which AChE inhibitors mediate these effects are still not well understood. One possible mechanism could be the up-regulation of haematopoietic growth factors (HGFs), also known to promote neuroprotective effects and to stimulate neurogenesis in the CNS. In the present study we investigated the impact of a 15-month treatment with the AChE inhibitor donepezil on blood levels of the HGFs stem cell factor (SCF), stromal cell-derived factor 1 (SDF-1), granulocyte colony- stimulating factor (G-CSF) and vascular endothelial growth factor (VEGF) in 19 patients with AD and 45 age-matched healthy controls. Before treatment with donepezil we found in AD patients significantly decreased SCF plasma concentrations (661.1+/-40.0 pg/ml) compared to healthy controls (997.7+/-33.7 pg/ml, p<0.001) but no significant differences between both groups concerning blood levels of SDF-1, G-CSF and VEGF. After 15 months' treatment SCF plasma levels increased significantly in the AD patients (764.5+/-41.5 pg/ml, p=0.016). In addition, we found a significant positive correlation between SCF plasma levels at baseline and changes of cognitive functions over the 15-month period (r=0.521, p=0.022). For the other HGFs we were unable to show a significant impact of donepezil treatment. Our findings indicate that donepezil treatment of AD patients is associated with an up-regulation of SCF plasma levels, which may contribute to neuroprotection and neurogenesis in the CNS.

Peripheral blood stem cell mobilization: new regimens, new cells, where do we stand

PURPOSE OF REVIEW

Granulocyte colony-stimulating factor-mobilized peripheral blood stem cells are widely used to reconstitute hematopoiesis; however, preclinical and clinical studies show that improvements to this mobilization can be achieved. We discuss the development of new mobilizing regimens and evaluation of new findings on mobilized stem cell populations that may improve the utility and convenience of peripheral blood stem cell transplant.

RECENT FINDINGS

Chemokines and their receptors regulate leukocyte trafficking, and altering chemokine signaling pathways mobilizes stem cells. In recent trials, combination use of the chemokine (C-X-C motif) receptor 4 antagonist AMD3100 and granulocyte colony-stimulating factor mobilized more CD34 cells in fewer days than granulocyte colony-stimulating factor alone and allowed more patients to proceed to autotransplant. In preclinical studies the chemokine GRObeta synergizes with granulocyte colony-stimulating factor and when used alone or with granulocyte colony-stimulating factor mobilizes more primitive hematopoietic stem cells with less apoptosis, higher integrin activation, lower CD26 expression and enhanced marrow homing compared with granulocyte colony-stimulating factor. Hematopoietic stem cells mobilized by GRObeta or AMD3100 demonstrate superior engraftment and contribution to chimerism in primary and secondary transplant studies in mice, and peripheral blood stem cells mobilized by AMD3100 and granulocyte colony-stimulating factor in patients demonstrate enhanced engraftment capabilities in immunodeficient mice.

SUMMARY

Alternate regimens differentially mobilize stem cell populations with unique intrinsic properties with the potential to expand the utility of hematopoietic transplantation. Continued mechanistic evaluation will be critical to our understanding of mechanisms of mobilization and their use in regenerative medicine.

Improved mobilization of peripheral blood CD34+ cells and dendritic cells by AMD3100 plus granulocyte-colony-stimulating factor in non-Hodgkin's lymphoma patients

AMD3100 is a drug capable of mobilizing peripheral blood stem cells (PBSCs) in donors and in cancer patients as a single agent or in combination with granulocyte-colony-stimulating factor (G-CSF). We initiated a phase II study of 11 refractory or relapsed non-Hodgkin's lymphoma (NHL) patients, receiving 16 microg/kg daily of G-CSF for 4 days followed by 240 microg/kg of AMD3100 given subcutaneously on a new schedule of 9-10 h before apheresis collection on day 5. Our aims were to assess the effect of AMD3100 on the mobilization of CD34+ cells, dendritic cells (DCs) and lymphoma cells. Administration of G-CSF and AMD3100 were continued daily until >or=2 x 10(6) CD34+ cells/kg were collected. Adequate collection of the target of CD34+ cells was achieved in all but 1 patient within 2 days, and 10/11 patients were transplanted within 2 months. All transplanted patients engrafted with a mean of 10 and 12 days for neutrophils and platelets, respectively. Addition of AMD3100 to G-CSF resulted with >2.5-fold increase in CD34+ cells/microl (p = 0.0001) and in a >2-fold increase in pDC1 and pDC2 cells/microl (p = 0.003). Adverse events related to AMD3100 were minimal. AMD3100 was generally safe and improved PBSC and DC cell mobilization with no apparent contamination of lymphoma cells.

Stem cell transplantation for neuroblastoma

High-risk neuroblastoma is a childhood malignancy with a poor prognosis. Gradual improvements in survival have correlated with therapeutic intensity, and the ability to harvest, process and store autologous hematopoietic stem cells has allowed for dose intensification beyond marrow tolerance. The use of high-dose chemotherapy with autologous hematopoietic stem cell rescue in consolidation has resulted in improvements in survival, although further advances are still needed. Newer approaches to SCT and supportive care, most notably the transition to PBSC, have resulted in further improvement in survival and decreases in treatment-related mortality. Research into experimental approaches to hematopoietic SCT is ongoing.

The Use of Stem Cells’ Hematopoietic Stimulating Factors Therapy Following Spinal Cord Injury

Spinal cord injury (SCI) remains one of the most devastating conditions in medicine, particularly due to the loss of productive life years and the high economic burden it places on our society. There are limited therapeutic options available to reduce the morbidity and mortality related to SCI. However, recent work with stem cells in repairing SCI appears to be promising, making this one of the most exciting frontiers in medicine. A brief review of the mechanisms of SCI is presented. Stem cells from a variety of sources have shown effectiveness in improving motor function after SCI in animals. The pre-clinical use of stem cells in SCI and methods of delivery are discussed. The potential use of granulocyte-colony stimulating factor (G-CSF) to increase the number of stem cells engrafting at the site of injury in order to improve neurological and motor function recovery following SCI is introduced. G-CSF, through stimulation of lymphohemopoietic stem cells in peripheral blood, can potentially cause repopulation of the SCI region with neural progenitor cells. This allows for improved functional outcomes. More pre-clinical and translational research exploring this possibility is required.

AMD3100: CXCR4 antagonist and rapid stem cell-mobilizing agent

As hematopoietic stem cells collected from peripheral blood are increasingly used for autologous and allogeneic stem cell transplantation, new approaches for the mobilization of stem cells are needed. These should have the goal of improving stem cell collection and reducing the duration and toxicity of the mobilization process. AMD3100, a specific inhibitor of CXCR4, one of the key molecules that tethers hematopoietic stem cells to the bone marrow microenvironment, is a promising new agent currently in clinical development for autologous and allogeneic stem cell mobilization. Early clinical trials have demonstrated that AMD3100 rapidly mobilizes stem cells to the peripheral blood, with minimal side effects. In Phase II trials, mobilization with the combination of AMD3100 and granulocyte colony-stimulating factor (G-CSF) results in the collection of more progenitor cells than G-CSF alone.

Mobilizing stem cells from normal donors: is it possible to improve upon G-CSF?

Currently, granulocyte colony stimulating factor (G-CSF) remains the standard mobilizing agent for peripheral blood stem cell (PBSC) donors, allowing the safe collection of adequate PBSCs from the vast majority of donors. However, G-CSF mobilization can be associated with some significant side effects and requires a multi-day dosing regimen. The other cytokine approved for stem cell mobilization, granulocyte-macrophage colony stimulating factor (GM-CSF), alters graft composition and may reduce the development of graft-versus-host disease, but a significant minority of donors fails to provide sufficient CD34+ cells with GM-CSF and some experience unacceptable toxicity. AMD3100 is a promising new mobilizing agent, which may have several advantages over G-CSF for donor mobilization. As it is a direct antagonist of the interaction between the chemokine stromal-derived factor-1 and its receptor CXCR4, AMD3100 mobilizes PBSCs within hours rather than days. It is also well tolerated, with no significant side effects reported in any of the clinical trials to date. Studies of autologous and allogeneic transplantation of AMD3100 mobilized grafts have demonstrated prompt and stable engraftment. Here, we review the current state of stem cell mobilization in normal donors and discuss novel strategies for donor stem cell mobilization.

Stromal Derived Growth Factor-1α: Another Mediator in Neural-Emerging Immune System throughTac1Expression in Bone Marrow Stromal Cells

Stromal cell-derived growth factor-1alpha (SDF-1alpha) is a member of the CXC chemokines and interacts with the G protein, seven-transmembrane CXCR4 receptor. SDF-1alpha acts as a chemoattractant for immune and hemopoietic cells. The Tac1 gene encodes peptides belonging to the tachykinin family with substance P being the predominant member. Both SDF-1alpha and Tac1 peptides are relevant hemopoietic regulators. This study investigated the effects of SDF-1alpha on Tac1 expression in the major hemopoietic supporting cells, the bone marrow stroma, and addresses the consequence to hemopoiesis. Reporter gene assays with the 5' flanking region of Tac1 showed a bell-shaped effect of SDF-1alpha on luciferase activity with 20 ng/ml SDF-1alpha acting as stimulator, whereas 50 and 100 ng/ml SDF-1alpha acted as inhibitors. Gel shift assays and transfection with wild-type and mutant IkappaB indicate NF-kappaB as a mediator in the repressive effects at 50 and 100 ng/ml SDF-1alpha. Northern analyses and ELISA showed correlations among reporter gene activities, mRNA (beta-preprotachykinin I), and protein levels for substance P. Of relevance is the novel finding by long-term culture-initiating cell assays that showed an indirect effect of SDF-1alpha on hemopoiesis through substance P production. The results also showed neurokinin 1 and not neurokinin 2 as the relevant receptor. Another crucial finding is that substance P does not regulate the production of SDF-1alpha in stroma. The studies indicate that SDF-1alpha levels above baseline production in bone marrow stroma induce the production of substance P to stimulate hemopoiesis. Substance P, however, does not act as autocrine stimulator to induce the production of SDF-1alpha. This study adds SDF-1alpha as a mediator within the neural-immune-hemopoietic axis.

Low doses of GM-CSF (molgramostim) and G-CSF (filgrastim) after cyclophosphamide (4 g/m2) enhance the peripheral blood progenitor cell harvest: results of two randomized studies including 120 patients

The use of a combination of G-CSF and GM-CSF versus G-CSF alone, after cyclophosphamide (4 g/m2) was compared in two randomized phase III studies, including 120 patients. In study A, 60 patients received 5 x 2 microg/kg/day of G-CSF and GM-CSF compared to 5 mug/kg/day of G-CSF. In study B, 60 patients received 2.5 x 2 microg/kg/day G-CSF and GM-CSF compared to G-CSF alone (5 microg/kg/day). With the aim to collect at least 5 x 10(6)/kg CD34 cells in a maximum of three large volume leukapherises (LK), 123 LK were performed in study A, showing a significantly higher number of patients reaching 10 x 10(6)/kg CD34 cells (21/29 in G+GM-CSF arm vs 11/27 in G-CSF arm, P=0.00006). In study B, 109 LK were performed, with similar results (10/27 vs 15/26, P=0.003). In both the study, the total harvest of CD34 cells/kg was twofold higher in G-CSF plus GM-CSF group (18.3 x 10(6) in study A and 15.85 x 10(6) in study B) than in G-CSF group (9 x 10(6) in study A and 8.1 x 10(6) in study B), a significant difference only seen in multiple myeloma, with no significant difference in terms of mobilized myeloma cells between G-CSF and GM-CSF groups.

Chemokines in multiple myeloma

OBJECTIVE

In this article we focus on the role that chemokines and chemokine receptors play in the pathogenesis of multiple myeloma and the associated bone destructive process, and consider their utility as novel therapeutic targets for treating this devastating disease.

METHODS

Current research on the role that chemokine and chemokine receptors play in the pathogenesis of myeloma is reviewed.

RESULTS

The chemokines, MIP-1alpha, MCP-1, IL-8, and SDF-1, and their receptors play important roles in homing of MM cells, tumor growth, and bone destruction in myeloma. They are attractive therapeutic targets for treating myeloma patients.

CONCLUSION

Addition of chemokine antagonists to current treatment regimens for myeloma should result in better therapeutic responses because of the loss of both the protective effect of the marrow microenvironment on the MM cells and the induction of osteoclast activity.

Granulocyte Colony-Stimulating Factor Mobilizes More Dendritic Cell Subsets Than Granulocyte-Macrophage Colony-Stimulating Factor with No Polarization of Dendritic Cell Subsets in Normal Donors

Dendritic cells (DCs) are effective antigen-presenting cells. We hypothesized that increasing the DC populations in donor lymphocyte infusions (DLIs) may augment the graft versus malignancy effect, particularly if granulocyte-macrophage colony-stimulating factor (GM-CSF) mobilization resulted in increased precursor dendritic cell (pDC) 1 cells. Mature DCs, pDC1 cells, pDC2 cells, and CD34(+) cells from the same donor were compared after granulocyte colony-stimulating factor (G-CSF) mobilized peripheral blood stem cell collections and GM-CSF mobilized DLI collections. Mobilization with G-CSF resulted in up to a 10-fold larger number of CD34(+) cells per kg and a 3-5-fold larger number of mature DCs, pDC1 cells, and pDC2 cells within the same donor compared with GM-CSF. The ratio of pDC1 to pDC2 in each donor remained constant with either cytokine. In this small sample of normal donors, it appears that G-CSF mobilizes more CD34(+) cells, mature DCs, pDC1 cells, and pDC2 cells within the same donor than does GM-CSF, with no significant polarization by G-CSF or GM-CSF for either pDC1 or pDC2 cells.

No Polarization of Type 1 or Type 2 Precursor Dendritic Cells in Peripheral Blood Stem Cell Collections of Non-Hodgkin's Lymphoma Patients Mobilized with Cyclophosphamide Plus G-CSF, GM-CSF, or GM-CSF Followed by G-CSF

Dendritic cells (DCs) are the most efficient antigen-presenting cells and play a role in immune reconstitution after autologous transplantation. Recent reports suggest that mobilization with granulocyte colony-stimulating factor (G-CSF) containing regimens polarizes DCs into pDC2, which could potentially result with increased Th2 response and decreased graft-versus-host disease (GVHD) in allogeneic transplantation and with decreased cytotoxic Th1 response and graft versus tumor effect, which in autologous transplantation could translate into increased relapse rate. Previously, we have shown that non-Hodgkin's lymphoma (NHL) patients receiving cyclophosphamide (CTX) plus granulocyte- macrophage (GM)-CSF, G-CSF or GM-CSF followed by G-CSF for stem cell collection, mobilize up to five-fold more mature CD80(+) DCs compared to CTX plus G-CSF mobilized patients. Here, we analyzed samples from the same study for the number of pDC1 and pDC2 subsets in blood and apheresis products obtained from these patients. Samples from 29 patients were collected. Patients mobilized with CTX plus G-CSF collected a mean of 1.2 +/- 0.4 x 10(6) pDC1/kg per day and 2.2 +/- 1 x 10(6) pDC2/kg per day, whereas patients mobilized with CTX plus GM-CSF collected a mean of 1.1 +/- 0.5 x 10(6) pDC1 and 1.5 +/- 0.9 x 10(6) pDC2/kg per day. Patients mobilized with CTX plus GM-CSF followed by G-CSF collected 2.5 +/- 1.1 x 10(6) pDC1 and 2 +/- 0.5 x 106 pDC2/kg per day, with significantly higher levels of pDC1 +/- pDC2 cells. No significant difference was observed in pDC1/pDC2 ratio between the three mobilization arms. Patients mobilized with the GM-CSFcontaining regimen had a higher probability for survival compared to patients receiving G-CSF alone (median of 55 months vs. 15 months; p = 0.02). These results support the hypothesis that higher levels of DCs in the graft might be associated with prolonged survival of autotransplanted NHL patients. Further similar studies are merited in a larger population of NHL patients.

Role of CXCR4 chemokine receptor blockade using AMD3100 for mobilization of autologous hematopoietic progenitor cells

G-CSF mobilization of hematopoietic progenitor cells (HPCs) is mediated through enzyme release from maturing myeloid cells, leading to digestion of adhesion molecules, trophic chemokines and their receptors, and the extracellular matrix. HPCs traffic to and are retained in the marrow through the trophic effects of the chemokine SDF-1alpha/CXCL12 binding to its receptor, CXCR4. AMD3100 reversibly inhibits SDF-1alpha/CXCR4 binding, and AMD3100 administration mobilizes CD34+ cells into the circulation. AMD3100 has been tested in several clinical trials which demonstrate that it improves the number of CD34+ cells mobilized including patients failing to mobilize with G-CSF alone. Engraftment of AMD3100-mobilized cells is prompt and durable. Toxicities are mild and infrequent. Lymphoma and myeloma cells do not appear to be mobilized. AMD3100 appears to be a promising agent for HPC mobilization.

Reduced risk of acute GVHD following mobilization of HLA-identical sibling donors with GM-CSF alone

We retrospectively reviewed the results of transplanting peripheral blood progenitor cell (PBPC) allografts from HLA-matched sibling donors mobilized using various hematopoietic cytokines. Patients had received allografts mobilized with Granulocyte colony-stimulating factor (G-CSF) (G, N = 65) alone, G plus Granulocyte-macrophage colony stimulating factor (GM-CSF) (G/GM, N = 70), or GM-CSF alone at 10 or 15 microg/kg/day (GM, N = 10 at 10 microg/kg/day and 21 at 15 microg/kg/day). The CD34+ and CD3+ cell content of grafts were significantly lower following GM alone compared to G alone (P < 0.001 and 0.04, respectively). Nonhematopoietic toxicity observed in donors precluded dose escalation of GM-CSF beyond 10 microg/kg/day. Hematopoietic recovery was similar among all three groups. Grades II-IV acute graft-versus-host disease (GVHD) was observed in only 13% of patients in the GM alone group compared to 49 and 69% in the G alone or G/GM groups, respectively (P < 0.001). In a multivariate analysis, receipt of PBPC mobilized with GM alone was associated with a lower risk of grades II-IV acute GVHD (hazard ratio 0.21; 95% CI 0.073, 0.58) compared to G alone or G/GM. There were no differences in relapse risk or overall survival among the groups. Donor PBPC grafts mobilized with GM-CSF alone result in prompt hematopoietic engraftment despite lower CD34+ cell doses and may reduce the risk of grades II-IV acute GVHD following HLA-matched PBPC transplantation.

Cellular Immunotherapy with Dendritic Cells in Cancer: Current Status

Dendritic cells (DCs) are specialized antigen-presenting cells whose immunogenicity leads to the induction of antigen-specific immune responses. DCs can easily be generated ex vivo from peripheral blood monocytes or bone marrow/circulating hematopoietic stem cells cultured in the presence of cytokine cocktails. DCs have been used in numerous clinical trials to induce antitumor immune responses in cancer patients. The studies carried out to date have demonstrated that DCs pulsed with tumor antigens can be safely administered, and this approach produces antigen-specific immune responses. Clinical responses have been observed in a minority of patients. It is likely that either heavy medical pretreatment or the presence of large tumor burdens (or both) is among the causes that impair the benefits of vaccination. Hence, the use of DCs should be considered in earlier stages of disease such as the adjuvant setting. Prospective applications of DCs extend to their use in allogeneic adoptive immunotherapy to specifically target the graft versus tumor reaction. DCs continue to hold promise for cellular immunotherapy, and further investigation is required to determine the clinical settings in which patients will most benefit from the use of this cellular immune adjuvant.

Phase I/II clinical trial of a nonreplicative vaccinia virus expressing multiple HLA-A0201-restricted tumor-associated epitopes and costimulatory molecules in metastatic melanoma patients

We performed a phase I/II clinical trial in metastatic melanoma patients with an ultraviolet (UV)-inactivated nonreplicating recombinant vaccinia virus enabling the expression, from a single construct, of endoplasmic reticulum-targeted HLA-A0201-restricted Melan-A/MART-1(27-35), gp100(280-288), and tyrosinase(1-9) epitopes, together with CD80 and CD86 costimulatory proteins. Corresponding soluble peptides were used to boost responses and granulocyte-macrophage colony-stimulating factor was used as systemic adjuvant. Safety and immunogenicity, as monitored with in vitro-restimulated peripheral blood mononuclear cells by cytotoxic T lymphocyte precursor (CTLp) frequency analysis and tetramer staining, were specifically addressed. Of 20 patients entering the protocol, 2 had to withdraw because of rapidly progressing disease. Immune responses were evaluated in 18 patients (stage III, n = 5; stage IV, n = 13) and increases in specific CTLp frequencies were observed in 15. In 16 patients responsiveness against all 3 antigens could be analyzed: 7 (43%), including all stage III cases, showed evidence of induction of CTLs specific for the three epitopes, and 2 (12%) and 4 (25%), respectively, showed reactivity against two or one tumor-associated antigen. In three stage IV patients no specific CTL reactivity could be induced. Increases in CTLp frequency were detected mostly after viral vaccine injections. However, in a majority of patients final CTLp levels were comparable to initial levels. Tetramer characterization of Melan-A/MART-1(27-35)-specific CTLs during the protocol also suggested preferential expansion after recombinant virus administration. Vector-specific humoral responses, frequently undetectable in stage IV patients, did not appear to prevent tumor-associated antigen-specific CTL induction. Aside from a single occurrence of transient grade 3 leukopenia, no major clinical toxicity was reported. Seventeen of 18 patients completed the 3-month trial (one patient died before the last delayed-type hypersensitivity test). Three displayed regression of individual metastases, seven had stable disease, and progressive disease was observed in seven patients. This is the first report on the administration of a UV-inactivated recombinant vaccinia virus coexpressing five transgenes in cancer patients. The results described here, in terms of safety and immunogenicity, support the use of this reagent in active specific immunotherapy.

Homing and mobilization of hematopoietic stem cells and hematopoietic cancer cells are mirror image processes, utilizing similar signaling pathways and occurring concurrently: circulating cancer cells constitute an ideal target for concurrent treatment with chemotherapy and antilineage-specific antibodies

Adhesion molecules and stromal cell-derived factor-1 (SDF-1)/CXCR4 signaling play key role in homing and mobilization of hematopoietic progenitor (HPC) and hematopoietic cancer clonogenic cells (HCC). High expression of VLA-4 is required for homing of HPC and HCC, whereas downregulation of these molecules is required for successful mobilization of HPC and HCC. Upregulation and activation of the SDF-1/CXCR4 signaling is required for homing of HPC and HCC, whereas disruption of the SDF-1 signaling is required for mobilization of HPC and HCC. Hence, mobilizations of HPC and HCC occur concurrently. It is proposed that drug resistance evolves as a result of repeated cycles of chemotherapy. Following each cycle of chemotherapy, HCC lose adhesion molecules and SDF-1 signaling. Surviving cells, released from tumor sites, circulate until re-expression of adhesion molecules and CXCR4 occurs, then homing to stroma of distal tissues occurs. Cytokines secreted by cells in the new microenvironment induce proliferation and drug resistance of HCC. This process is amplified in each cycle of chemotherapy resulting in disease progression. A novel model for treatment is proposed in which circulating HCC are the target for clinical intervention, and concurrent treatment with chemotherapy and antilineage-specific antibodies will result in abrogation of the 'vicious cycle' of conventional anticancer therapy.

Mobilization of Myeloma Cells Involves SDF-1/CXCR4 Signaling and Downregulation of VLA-4

Adhesion molecules and stromal cell-derived factor-1 (SDF-1)/CXCR4 signaling play key roles in homing and mobilization of hematopoietic stem cells (HSC). Active signaling through SDF-1/CXCR4 and upregulation of adhesion molecules are required for homing, whereas downregulation of adhesion molecules and disruption of SDF-1/CXCR4 signaling are required for mobilization of HSC. We studied the surface expression of CXCR4 very late activation antigen (VLA)-4 and VLA-5 on myeloma cells mobilized with cyclophosphamide and GM-CSF in 12 multiple myeloma patients undergoing HSC mobilization for autologous transplantation. We also studied the plasma levels of SDF-1 in apheresis collection of these patients. We observed a statistically significant decrease in the levels of SDF-1 and surface expression of CXCR4 on myeloma cells in four consecutive apheresis collections compared with premobilization bone marrow specimens. We also observed a statistically significant decrease in surface expression of VLA-4 in myeloma cells in the apheresis collections compared with premobilization bone marrow samples. Furthermore, myeloma cells derived from apheresis collections had decreased adhesion and trans-stromal migration in response to SDF-1, which could be reversed by short incubation with interleukin-6. Hence, mobilization of myeloma cells involves SDF-1/CXCR4 signaling and downregulation of VLA-4.

Impact of chemotherapy regimen and hematopoietic growth factor on mobilization and collection of peripheral blood stem cells in cancer patients

Various chemotherapy regimens, combined with recombinant human granulocyte colony-stimulating factor(rhG-CSF) or recombinant granulocyte-macrophage CSF (rhGM-CSF) are used in cancer patients to mobilize and collect peripheral blood stem cells (PBSC). In this retrospective study, we evaluated and compared the efficacy of such regimens in 262 patients with different types of malignant diseases. The following chemotherapy regimens were applied: ifosfamide-etoposide-cisplatin or bleomycin (n = 96; mainly patients with testicular cancer); ifosfamide-etoposide plus or minus cytosine arabinoside (Ara-C) or vincristine (VCR)(n = 52; mainly patients with lymphoma); cyclophosphamide-anthracycline (n = 53; mainly patients with breast cancer); intermediate to high dose (ID-HD) cyclophosphamide (n = 37; mainly patients with breast or ovarian cancer. or multiple myeloma; and others (n = 24). rhG-CSF or rhGM-CSF, each at an average daily dose of 5 microg/kg body weight, were used in 166 and 96 patients, respectively. The study evaluated and compared the efficacy of these two cytokines. In patients receiving rhG-CSF, CD34+ cells could be collected earlier (median: day 14 versus day 16) and there was a significantly higher white blood cell count (WBC)(median 11,350 versus 5550/microl) and CD34+ cell count (median 88 versus 43/microl) at the start of apheresis, and a significantly higher CD34+ cell yield (median 7.4 x 10(6) versus 4.6 x 10(6)/kg) than in patients who receivedrhGM-CSF. Among the various chemotherapeutic regimens used, each combined with rhG-CSF, ifosfamide-etoposide plus or minus Ara-C or VCR mobilized a significantly higher number of CD34+ cells (median 119/microl) and produced a significantly higher harvest of these cells (median 13 x 10(6)/kg) than cyclophosphamide-anthracycline (median 87/microl and 7 x 10(6)/kg, respectively) or ID-HD cyclophosphamide (median 59/microl and 5 x I 0(6)/kg, respectively). Ifosfamide-etoposide plus or minus Ara-C or VCR was also superior to ifosfamide-etoposide-cisplatin or bleomycin (median 78/microl and 9 x 10(6)/kg, respectively), but at borderline significance. The outcome of PBSC mobilization and collection appeared to be negatively influenced by the number of relapses before the current salvage treatment. These data indicate that mobilization and collection of PBSCstrongly depend on the type of hematopoietic growth factor and chemotherapeutic regimen used. The data further show rhG-CSF is a more effective growth factor than rhGM-CSF and ifosfamide-etoposide-based regimens, particularly ifosfamide-etoposide plus or minus Ara-C or VCR, are highly effective regimens in mobilizing and collecting CD34+ cells.