Mobilization of blood-derived stem and progenitor cells in normal subjects by granulocyte-macrophage- and granulocyte-colony-stimulating factors

Role of myeloid-derived suppressor cells in tumor recurrence

The establishment of primary tumor cells in distant organs, termed metastasis, is the principal cause of cancer mortality and is a crucial therapeutic target in oncology. Thus, it is critical to establish a better understanding of metastatic progression for the future development of improved therapeutic approaches. Indeed, such development requires insight into the timing of tumor cell dissemination and seeding of distant organs resulting in occult lesions. Following dissemination of tumor cells from the primary tumor, they can reside in niches in distant organs for years or decades, following which they can emerge as an overt metastasis. This timeline of metastatic dormancy is regulated by interactions between the tumor, its microenvironment, angiogenesis, and tumor antigen-specific T-cell responses. An improved understanding of the mechanisms and interactions responsible for immune evasion and tumor cell release from dormancy would help identify and aid in the development of novel targeted therapeutics. One such mediator of dormancy is myeloid derived suppressor cells (MDSC), whose number in the peripheral blood (PB) or infiltrating tumors has been associated with cancer stage, grade, patient survival, and metastasis in a broad range of tumor pathologies. Thus, extensive studies have revealed a role for MDSCs in tumor escape from adoptive and innate immune responses, facilitating tumor progression and metastasis; however, few studies have considered their role in dormancy. We have posited that MDSCs may regulate disseminated tumor cells resulting in resurgence of senescent tumor cells. In this review, we discuss clinical studies that address mechanisms of tumor recurrence including from dormancy, the role of MDSCs in their escape from dormancy during recurrence, the development of occult metastases, and the potential for MDSC inhibition as an approach to prolong the survival of patients with advanced malignancies. We stress that assessing the impact of therapies on MDSCs versus other cellular targets is challenging within the multimodality interventions required clinically.

Pathways and factors regulated by bone marrow-derived stem cells in human ovarian tissue

OBJECTIVE

To describe molecular and paracrine signaling changes produced by human bone marrow-derived stem cells (BMDSC) in human ovarian cortex.

DESIGN

Experimental study.

SETTING

University hospital research laboratories.

PATIENT(S)

Ovarian cortex from poor responder women (n = 7).

ANIMALS

Immunodeficient NOD/SCID female mice (n = 18).

INTERVENTION(S)

Human ovarian cortex strips were xenografted into ovariectomized NOD/SCID female mice. A week later, mice were infused with phosphate-buffered saline, 1 × 106 BMDSC, or 3 × 105 CD133+ cells via tail vein. Gene expression changes and enriched pathways were assessed by RT2 Profiler Arrays. Several upregulated genes were validated in individual samples by real-time quantitative PCR, and transcriptomic results were reinforced by a proteomic assessment.

MAIN OUTCOME MEASURE(S)

Gene expression changes, enriched Kyoto Encyclopedia of Genes and Genomes pathways, and paracrine factors.

RESULT(S)

Seventy-four Kyoto Encyclopedia of Genes and Genomes pathways were upregulated, with the PI3K-Akt signaling pathway the most enriched after BMDSC and CD133 treatments. The greatest transcriptomic changes were seen on day 14 in the BMDSC group, affecting the regulation of paracrine factors such as KITLG, THBS1, SERPINF1, and TIMP2. Proteomics data verified changes in FoxO signaling, actin cytoskeleton remodeling, and apoptosis by BMDSC.

CONCLUSION(S)

We identified paracrine factors and pathways regulated by BMDSC that may be future targets of treatment for the increasing number of poor responder women. Our findings suggest that BMDSC upregulated soluble factors such as KITLG, THBS1, SERPINF1, and TIMP2 as well as PI3K-Akt signaling and regulation of actin cytoskeleton pathways. The identification of these putative underlying mechanisms informs future experiments aiming to optimizing clinical application of BMDSC.

Myeloid derived suppressor cells and the release of micro-metastases from dormancy

Metastasis is the primary cause of cancer mortality and an improved understanding of its pathology is critical to the development of novel therapeutic approaches. Mechanism-based therapeutic strategies require insight into the timing of tumor cell dissemination, seeding of distant organs, formation of occult lesions and critically, their release from dormancy. Due to imaging limitations, primary tumors can only be detected when they reach a relatively large size (e.g. > 1 cm³), which, based on our understanding of tumor evolution, occurs approximately 10 years and about 30 doubling times following tumor initiation. Genomic profiling of paired primary tumors and metastases has suggested that tumor seeding at secondary sites occurs early during tumor progression and frequently, years prior to clinical diagnosis. Following seeding, tumor cells may enter into and remain in a dormant state, and if they survive and are released from dormancy, they can proliferate into an overt lesion. The timeline of tumor initiation and metastatic dormancy is regulated by tumor interactions with its microenvironment, angiogenesis, and tumor-specific cytotoxic T-lymphocyte (CTL) responses. Therefore, a better understanding of the cellular interactions responsible for immune evasion and/or tumor cell release from dormancy would facilitate the development of therapeutics targeted against this critical part of tumor progression. The immunosuppressive mechanisms mediated by myeloid-derived suppressor cells (MDSCs) contribute to tumor progression and, we posit, promote tumor cell escape from CTL-associated dormancy. Thus, while clinical and translational research has demonstrated a role for MDSCs in facilitating tumor progression and metastasis through tumor escape from adoptive and innate immune responses (T-, natural killer and B-cell responses), few studies have considered the role of MDSCs in tumor release from dormancy. In this review, we discuss MDSC expansion, driven by tumor burden associated growth factor secretion and their role in tumor cell escape from dormancy, resulting in manifest metastases. Thus, the therapeutic strategies to inhibit MDSC expansion and function may provide an approach to delay metastatic relapse and prolong the survival of patients with advanced malignancies.

Role of myeloid-derived suppressor cells in metastasis

The spread of primary tumor cells to distant organs, termed metastasis, is the principal cause of cancer mortality and is a critical therapeutic target in oncology. Thus, a better understanding of metastatic progression is critical for improved therapeutic approaches requiring insight into the timing of tumor cell dissemination and seeding of distant organs, which can lead to the formation of occult lesions. However, due to limitations in imaging techniques, primary tumors can only be detected when they reach a relatively large size (e.g., > 1 cm³), which, based on our understanding of tumor evolution, is 10 to 20 years (30 doubling times) following tumor initiation. Recent insights into the timing of metastasis are based on the genomic profiling of paired primary tumors and metastases, suggesting that tumor cell seeding of secondary sites occurs early during tumor progression and years prior to diagnosis. Following seeding, tumor cells may remain in a dormant state as single cells or micrometastases before emerging as overt lesions. This timeline and the role of metastatic dormancy are regulated by interactions between the tumor, its microenvironment, and tumor-specific T cell responses. An improved understanding of the mechanisms and interactions responsible for immune evasion and tumor cell release from dormancy would support the development of novel targeted therapeutics. We posit herein that the immunosuppressive mechanisms mediated by myeloid-derived suppressor cells (MDSCs) are a major contributor to tumor progression, and that these mechanisms promote tumor cell escape from dormancy. Thus, while extensive studies have demonstrated a role for MDSCs in the escape from adoptive and innate immune responses (T-, natural killer (NK)-, and B cell responses), facilitating tumor progression and metastasis, few studies have considered their role in dormancy. In this review, we discuss the role of MDSC expansion, driven by tumor burden, and its role in escape from dormancy, resulting in occult metastases, and the potential for MDSC inhibition as an approach to prolong the survival of patients with advanced malignancies.

Stable colony-stimulating factor 1 fusion protein treatment increases hematopoietic stem cell pool and enhances their mobilisation in mice

Background

Prior chemotherapy and/or underlying morbidity commonly leads to poor mobilisation of hematopoietic stem cells (HSC) for transplantation in cancer patients. Increasing the number of available HSC prior to mobilisation is a potential strategy to overcome this deficiency. Resident bone marrow (BM) macrophages are essential for maintenance of niches that support HSC and enable engraftment in transplant recipients. Here we examined potential of donor treatment with modified recombinant colony-stimulating factor 1 (CSF1) to influence the HSC niche and expand the HSC pool for autologous transplantation.

Methods

We administered an acute treatment regimen of CSF1 Fc fusion protein (CSF1-Fc, daily injection for 4 consecutive days) to naive C57Bl/6 mice. Treatment impacts on macrophage and HSC number, HSC function and overall hematopoiesis were assessed at both the predicted peak drug action and during post-treatment recovery. A serial treatment strategy using CSF1-Fc followed by granulocyte colony-stimulating factor (G-CSF) was used to interrogate HSC mobilisation impacts. Outcomes were assessed by in situ imaging and ex vivo standard and imaging flow cytometry with functional validation by colony formation and competitive transplantation assay.

Results

CSF1-Fc treatment caused a transient expansion of monocyte-macrophage cells within BM and spleen at the expense of BM B lymphopoiesis and hematopoietic stem and progenitor cell (HSPC) homeostasis. During the recovery phase after cessation of CSF1-Fc treatment, normalisation of hematopoiesis was accompanied by an increase in the total available HSPC pool. Multiple approaches confirmed that CD48⁻CD150⁺ HSC do not express the CSF1 receptor, ruling out direct action of CSF1-Fc on these cells. In the spleen, increased HSC was associated with expression of the BM HSC niche macrophage marker CD169 in red pulp macrophages, suggesting elevated spleen engraftment with CD48⁻CD150⁺ HSC was secondary to CSF1-Fc macrophage impacts. Competitive transplant assays demonstrated that pre-treatment of donors with CSF1-Fc increased the number and reconstitution potential of HSPC in blood following a HSC mobilising regimen of G-CSF treatment.

Conclusion

These results indicate that CSF1-Fc conditioning could represent a therapeutic strategy to overcome poor HSC mobilisation and subsequently improve HSC transplantation outcomes.

Filgrastim induced thrombocytopenia

Drug-induced thrombocytopenia (DITP) is suggested by severe thrombocytopenia with subsequent recovery of platelet count after removal of the offending drug. The diagnosis is ascertained when there is reproducibility of thrombocytopenia with repeated exposure. Filgrastim is used during peripheral blood progenitor cell harvest during autologous stem cell transplantation in the setting of multiple myeloma to prolong event-free survival and overall mortality. The following case illustrates all of the suggestive features of DITP after filgrastim exposure during elective stem cell harvest. Due to the inability to tolerate filgrastim, autologous stem cell transplant was aborted in this patient and he was maintained on induction chemotherapy.

Rationale and design of the granulocyte-macrophage colony stimulating factor in peripheral arterial disease (GPAD-3) study

BACKGROUND

Lower extremity peripheral arterial disease (PAD) is a public health problem and many patients with PAD experience claudication despite adequate medical and/or surgical management. Mobilization of endogenous progenitor cells using Granulocyte-Macrophage Colony Stimulating Factor (GM-CSF) is a novel therapeutic option that has shown promising results in experimental models and phase I/IIA clinical trials. The GPAD-3 trial will study the effect of two successive administrations of GM-CSF at 3-month interval for improving claudication among patients with lower extremity PAD.

METHODS

We plan to recruit 176 patients in this ongoing randomized, double-blind, placebo-controlled Phase IIB trial. After screening for inclusion and exclusion criteria, eligible subjects undergo a 4-week screening phase where they perform subcutaneous placebo injections thrice weekly and walk at least three times a day until they develop claudication. After the screening phase, eligible subjects undergo baseline testing and are randomized 2:1 to receive 500 μg/day of GM-CSF subcutaneously thrice weekly for three weeks or placebo injections. After 3 months, follow-up endpoint testing is performed and subjects in the GM-CSF group receive the second administration of the drug for three weeks while subjects in placebo group receive matching placebo injections. All participants undergo endpoint testing at six-month and nine-month follow-up. The primary endpoint is change in 6-min walk distance between baseline and 6-month follow-up.

CONCLUSION

GPAD-3 explores a novel approach to address the need for alternative therapies that can alleviate symptoms among patients with lower extremity PAD. If successful, this study will pave the way for a pivotal Phase III trial.

Optimizing mobilization strategies in difficult-to-mobilize patients: The role of plerixafor

Peripheral blood stem cell collection is currently the most widely used source for hematopoietic autologous transplantation. Several factors such as advanced age, previous chemotherapy, disease and marrow infiltration at the time of mobilization influence the efficacy of CD34(+) progenitor cell mobilization. Despite the safety and efficiency of the standard mobilization protocols (G-CSF ± chemotherapy), there is still a significant amount of mobilization failure rate (10-40%), which necessitate novel agents for effective mobilization. Plerixafor, is a novel agent, has been recently approved for mobilization of hematopoietic stem cells (HSCs). The combination of Plerixafor with G-CSF provides the collection of large numbers of stem cells in fewer apheresis sessions and can salvage those who fail with standard mobilization regimens. The development and optimization of practical algorithms for the use Plerixafor is crucial to make hematopoietic stem cell mobilization more efficient in a cost-effective way. This review is aimed at summarizing how to identify poor mobilizers, and define rational use of Plerixafor for planning mobilization in hard-to-mobilize patients.

The evolving role of plerixafor in hematopoietic progenitor cell mobilization

The introduction of plerixafor as a peripheral blood stem cell mobilization agent has allowed more patients with multiple myeloma, non-Hodgkin's lymphoma, and Hodgkin's disease to mobilize sufficient hematopoietic progenitor cells (HPCs) to proceed to autologous transplantation. Because of the high cost of plerixafor, it is not routinely used in all patients undergoing HPC mobilization. If cost were not an issue, an argument could be made that plerixafor could be added to every mobilization regimen, but cost is an issue so in an attempt to be more cost-effective, many centers have limited plerixafor use to patients who have failed or who are predicted to fail collection of adequate numbers of cells by other methods. Additionally, plerixafor is now under investigation both for HPC collection of healthy donors for allogeneic stem cell transplantation and as an adjunct therapy (i.e., chemosensitizing agent) for acute leukemias. This article briefly reviews the role of plerixafor in autologous and allogeneic transplantation as well as its emerging role in the treatment of acute leukemias. Emphasis is placed on the choice of appropriate patients for plerixafor use to assure an adequate stem cell yield while maximizing the cost effectiveness of using plerixafor. The role of prophylactic collections and future areas of research are also presented.

Mobilization of hematopoietic progenitors from normal donors using the combination of granulocyte-macrophage colony-stimulating factor and granulocyte colony-stimulating factor results in fewer plasmacytoid dendritic cells in the graft and enhanced donor T cell engraftment with Th1 polarization: results from a randomized clinical trial

Granulocyte colony-stimulating factor (G-CSF) and granulocyte-macrophage colony-stimulating factor (GM-CSF) both mobilize CD34(+) stem cells into the blood when administered before apheresis but have distinct effects on dendritic cell (DC) differentiation. We previously demonstrated that the combination of GM+G-CSF results in fewer plasmacytoid DCs (pDCs) when used to mobilize peripheral blood stem cells for autologous transplantation. To test the hypothesis that the content of pDCs in an allograft can be modulated with the cytokines used for mobilization, we randomized the human leukocyte antigen-matched sibling donors of 50 patients with hematological malignancies to a mobilization regimen of either GM+G-CSF (n = 25) or G-CSF alone (n = 25). Primary and secondary endpoints included the cellular constituents of the mobilized grafts, the kinetics of posttransplantation immune reconstitution, and clinical outcomes of the transplantation recipients. Grafts from donors receiving GM+G-CSF contained equivalent numbers of CD34(+) cells with fewer pDCs and T cells, with a higher fraction of Th1-polarized donor T cells than G-CSF mobilized grafts. Immune recovery was enhanced among recipients of GM+G-CSF. Survival was not significantly different between transplantation recipients in the two arms. The use of GM+G-CSF modulates immune function and recovery after allogeneic transplantation and should be explored in larger studies powered to evaluate clinical outcomes.

Advances in stem cell mobilization

The use of mobilized peripheral blood stem cells (PBSCs) has largely replaced the use of bone marrow as a source of stem cells for both allogeneic and autologous stem cell transplantation. G-CSF with or without chemotherapy is the most commonly used regimen for stem cell mobilization. Some donors or patients, especially the heavily pretreated patients, fail to mobilize the targeted number of stem cells with this regimen. A better understanding of the mechanisms involved in hematopoietic stem cell (HSC) trafficking could lead to the development of newer mobilizing agents and therapeutic approaches. This review will cover the current methods for stem cell mobilization and recent developments in the understanding of the biology of stem cells and the bone marrow microenvironment.

Cell-based therapy for urinary incontinence

Urinary incontinence has become a societal problem that affects millions of people worldwide. Although numerous therapeutic modalities are available, none has been shown to be entirely satisfactory. Consequently, cell-based approaches using regenerative medicine technology have emerged as a potential solution that would provide a means of correcting anatomical deficiencies and restoring normal function. As such, numerous cell-based investigations have been performed to develop systems that are focused on addressing clinical needs. While most of these attempts remain in the experimental stages, several clinical trials are being designed or are in progress. This article provides an overview of the cell-based approaches that utilize various cell sources to develop effective treatment modalities for urinary incontinence.

Bone marrow mobilization with granulocyte macrophage colony-stimulating factor improves endothelial dysfunction and exercise capacity in patients with peripheral arterial disease

BACKGROUND

We hypothesized that granulocyte macrophage colony-stimulating factor (GM-CSF) administration will be safe and will improve endothelial dysfunction and exercise capacity by mobilizing progenitor cells in patients with peripheral arterial disease (PAD).

METHODS

Forty-five patients with PAD received thrice-weekly injections for 2 weeks of 3, 6, or 10 microg/kg per day of GM-CSF or placebo in successive cohorts of 15 subjects randomized 2:1 to drug or placebo. CD34+ mononuclear cell subsets and colony formation assay, endothelial function, ankle-brachial index, and walking capacity were measured.

RESULTS

Granulocyte macrophage colony-stimulating factor administration was safe. After pooling data from GM-CSF cohorts, at 2 weeks, there was a significant increase in total leukocytes (43%, P < .0001), CD34+ cells (46%, P = .035), and colony-forming units (31%, P = .026, week 1). At 12 weeks, endothelial function improved with GM-CSF (flow-mediated vasodilation increased by 59%, P < .01) as did pain-free treadmill walking time (38 seconds, P = .008) and total treadmill walking time (55 seconds, P = .016). Corresponding changes were not observed in the placebo group.

CONCLUSIONS

Granulocyte macrophage colony-stimulating factor therapy in patients with PAD was associated with mobilization of progenitor cells, improvement of endothelial dysfunction, and exercise capacity. The efficacy of strategies designed to mobilize bone marrow progenitors warrants further study in patients with PAD.

Sequential administration of sargramostim and filgrastim in pediatric allogeneic stem cell transplantation recipients undergoing myeloablative conditioning

G-CSF and GM-CSF both hasten myeloid engraftment post-MA-alloSCT; however, GM-CSF is earlier acting and less expensive. The objective was to evaluate efficacy/safety of sequential administration of GM-CSF followed by G-CSF in children post-MA-alloSCT. From January 2001 to June 2005, 31 children received 32 MA-alloSCT: mean age 6.65 yr; MRD BM or PBSC vs. related or unrelated UCB 11:21; malignant vs. non-malignant disorders 22:10. GM-CSF (250 microg/m(2) IV QD) began on day of stem cell infusion. GM-CSF was switched to G-CSF (10 microg/kg IV QD) when WBC >or= 300/mm(3) x 2 days. G-CSF continued until ANC >or= 2500/mm(3) x 2 days, then tapered to maintain ANC >or= 1000/mm(3). Median time to myeloid engraftment (ANC >or= 500/mm(3) x 3 days) was 17 days [13 days vs. 24 days, MRD BM/PBSC vs. UCB (p < 0.0001)], occurring at a median time of two days after switch to G-CSF. Clinically relevant adverse events were bone pain (n = 8) and large pleural effusion (n = 1). It was estimated that sequential GM-CSF/G-CSF was cost-effective compared with G-CSF alone [cost-savings of $1311/patient ($41,952/study), 2007 Red Book Average Wholesale Price]. In summary, it was demonstrated that sequential administration of GM-CSF/G-CSF post-MA-alloSCT was safe, cost-effective and resulted in prompt myeloid engraftment.

Is a boosting dose of granulocyte-colony-stimulating factor necessary for healthy PBSC donors undergoing secondary apheresis? An institute's experience

Successful allogeneic PBSC transplantation depends upon the infusion of an adequate number of CD34+ cells to patients. Granulocyte-colony-stimulating factors (G-CSF) mobilized PBSC were harvested on 5th day after stimulation from donors. When the CD34+ cell target yield was not achieved; secondary apheresis was performed the following day. Before September 2006, 67 donors (Group A) received five doses of G-CSF. After September 2006, a sixth dose of G-CSF was administered to 35 donors (Group B) to improve CD34+ yield. The mean CD34+-cell concentration of the second PBSC harvest was significantly higher in Group B (1,087 x 10(6)/l vs. 767 x 10(6)/l; P = 0.031).

Allogeneic peripheral blood stem cell collection as of 2008

The rapid growth of the use of recombinant human granulocyte colony-stimulating factor (rhG-CSF) to mobilize and collect allogeneic peripheral blood stem cells (PBSCs) for transplantation has made it a new international standard. While the procedure remains safe, older donors, donors with significant comorbidities and pediatric donors are now often employed. This brings a new set of challenges in the donor evaluation, medical clearance, informed consent and collection process. Rare and unexpected severe adverse events related to rhG-CSF administration and PBSC apheresis have been described. Proper PBSC donor counseling, evaluation and care have become even more important.

Soluble human leucocyte antigen-G molecules in peripheral blood haematopoietic stem cell transplantation: a specific role to prevent acute graft-versus-host disease and a link with regulatory T cells

Haematopoietic stem cell transplantation is often complicated by the life-threatening graft-versus-host disease (GVHD) which consists of an allogeneic reaction of the graft cells against the host organs. The aim of this study was to investigate the putative involvement of soluble human leucocyte antigen (sHLA) class I molecules, and particularly sHLA-G molecules, in the occurrence and/or prevention of acute GVHD (aGVHD) in allogeneic peripheral blood stem cell (PSC) transplantation. Whole sHLA class I molecules seem to be involved in aGVHD pathogenesis because detection of a high concentration of these molecules in the first month post allograft is correlated with aGVHD occurrence. Conversely, a high level of sHLA-G molecules before and after allograft could indicate good prognosis in PSC allograft transplantation. sHLA-G molecules seem to be involved in aGVHD prevention, not only because they are enriched in plasma of patients without aGVHD, but also because: (i) a positive correlation has been found between sHLA-G level and CD4+ CD25+ CD152+ natural regulatory T cell (T(reg)) frequency in the blood of transplanted patients; and (ii) the presence of CD4+ CD25+ CD152+ natural T(reg) is correlated with increased sHLA-G expression in in vitro mixed leucocyte reaction cultures. Altogether, these results support the immunomodulatory function of sHLA-G molecules that might create a regulatory network together with the natural T(reg) to foster the induction of a tolerogenic environment and improve PSC transplantation favourable outcome.

Peripheral blood progenitor cell mobilization with intermediate-dose cyclophosphamide, sequential granulocyte-macrophage-colony-stimulating factor and granulocyte-colony-stimulating factor, and scheduled commencement of leukapheresis in 225 patients undergoing autologous transplantation

BACKGROUND

Interpatient variability in the kinetics of peripheral blood progenitor cell (PBPC) mobilization is commonly seen with conventional chemotherapy-based mobilization regimens. This necessitates the availability of leukapheresis (LP) facilities 7 days a week.

STUDY DESIGN AND METHODS

The efficacy of an approach where LP was invariably commenced on Day 11 after intermediate-dose cyclophosphamide followed by sequential administration of granulocyte-macrophage-colony-stimulating factor (CSF) and granulocyte-CSF (Cy/GM/G) was retrospectively analyzed in 225 consecutive, unselected patients undergoing autologous hematopoietic stem cell transplantation for all diagnoses other than acute leukemia at our center. Cy/GM/G was scheduled to avoid weekend LP.

RESULTS

After Cy/GM/G, a CD34+ cell yield of at least 2.0x10(6) per kg was achieved in 90.7 percent of patients. Optimal yield (OY; >or=5x10(6) or 10x10(6) CD34+ cells/kg depending on diagnosis) was achieved in 67.6 percent of patients. Only three patients (1.3%) required LP on Saturday or Sunday. Febrile neutropenia (FN) was encountered in 5.3 percent. PBPC yield was highest on Day 1 of LP (p<0.001). In multivariate analyses, platelet (PLT) count on Day 1 of LP (PLT-D1LP) was positively associated with achievement of OY (p<0.001). PLT-D1LP and diagnosis of myeloma were associated with a shorter time to achieve a CD34+ cell yield of at least 5x10(6) per kg (p<0.001 and p=0.002, respectively).

CONCLUSION

Cy/GM/G with scheduled LP commencement on Day 11 enables optimal CD34+ cell yields in most patients undergoing autologous transplantation, despite a low risk of FN and avoidance of weekend LP.

Hematopoietic growth factors for hematopoietic stem cell mobilization and expansion

During inflammation and cytopenia, increased levels of hematopoietic growth factors (HPGFs) induce mobilization and proliferation of hematopoietic stem cells and hematopoietic progenitor cells (HPCs), resulting in spatial and quantitative in vivo expansion of the hematopoietic tissue. Exogenous administration of recombinant HPGFs, particularly granulocyte colony-stimulating factor (G-CSF), is routine for mobilization of stem cells, followed by collection and transplantation of autologous or allogeneic stem cells. In this review, we summarize experience using different HPGFs and HPGF combinations for stem cell mobilization, such as G-CSF, granulocyte-macrophage colony-stimulating factor (GM-CSF), interleukin-3 (IL-3), stem cell factor (SCF), and others. Preclinical and clinical studies of so-called early- and late-acting HPGFs for ex vivo expansion of HPCs are discussed, also with respect to the unresolved question whether expansion of repopulating stem cells can be achieved in vitro.

Neovasculogenic Therapy to Augment Perfusion and Preserve Viability in Ischemic Cardiomyopathy

BACKGROUND

Ischemic cardiomyopathy is a global health concern with limited therapy. We recently described endogenous revascularization utilizing granulocyte-macrophage colony stimulating factor (GMCSF) to induce endothelial progenitor cell (EPC) production and intramyocardial stromal cell-derived factor-1alpha (SDF) as a specific EPC chemokine. The EPC-mediated neovascularization and enhancement of myocardial function was observed. In this study we examined the regional biologic mechanisms underlying this therapy.

METHODS

Lewis rats underwent left anterior descending coronary artery (LAD) ligation and developed ischemic cardiomyopathy over 6 weeks. Three weeks after ligation, the animals received either subcutaneous GMCSF and intramyocardial SDF injections or saline injections as control. Six weeks after LAD ligation circulating EPC density was studied by flow cytometry. Quadruple immunofluorescent vessel staining for mature, proliferating vasculature was performed. Confocal angiography was utilized to identify fluorescein lectin-lined vessels to assess perfusion. Ischemia reversal was studied by measuring myocardial adenosine triphosphate (ATP) levels. Myocardial viability was assayed by terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick-end labeling detection of apoptosis and quantitation of myofilament density.

RESULTS

The GMCSF/SDF therapy enhanced circulating leukocyte (13.1 +/- 4.5 x 10(6) vs 3.1 +/- 0.5 x 10(6)/cc, p = 0.001, n = 6) and EPC (14.2 +/- 6.6 vs 2.2 +/- 2.1/cc, p = 0.001, n = 6) concentrations. Tetraimmunofluorescent labeling demonstrated enhanced stable vasculature with this therapy (39.2 +/- 8.1 vs 25.4 +/- 5.1%, p = 0.006, n = 7). Enhanced perfusion was shown by confocal microangiography of borderzone lectin-labeled vessels (28.2 +/- 5.4 vs 11.5 +/- 3.0 vessels/high power field [hpf], p = 0.00001, n = 10). Ischemia reversal was demonstrated by enhanced cellular ATP levels in the GMCSF/SDF borderzone myocardium (102.5 +/- 31.0 vs 26.9 +/- 4.1 nmol/g, p = 0.008, n = 5). Borderzone cardiomyocyte viability was noted by decreased apoptosis (3.2 +/- 1.4% vs 5.4 +/- 1.0%, p = 0.004, n = 10) and enhanced cardiomyocyte density (40.0 +/- 5.6 vs 27.0 +/- 6 myofilaments/hpf, p = 0.01, n=10).

CONCLUSIONS

Endogenous revascularization for ischemic cardiomyopathy utilizing GMCSF EPC upregulation and SDF EPC chemokinesis upregulates circulating EPCs, enhances vascular stability, and augments myocardial function by enhancing perfusion, reversing cellular ischemia, and increasing cardiomyocyte viability.

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.

Growth factors in haematological cancers

Since their discovery just under a century ago, growth factors (GFs) have been used almost ubiquitously in haematology. Many haematological cancers are associated with bone marrow failure, either as a direct consequence of the disease or its treatment. Colony stimulating factors (CSFs) have been used to address the problems associated with the resulting cytopenias, however, concerns about the potential leukaemogenic effects of some of these CSFs led to a degree of initial hesitancy in usage, particularly in the management of acute myeloid leukaemia (AML). This has now been largely overcome. Other limitations have included cost and side effect profiles (the latter particularly with the multilineage factors). There has been wide variation locally, nationally and internationally in the usage of GFs. The American Society of Clinical Oncologists (ASCO) attempted to rationalise the usage of GFs by producing a consensus document enumerating the evidence-based indications for use of GFs. There is little information on cost effectiveness, this remains an important issue for the future. Peripheral blood stem cell transplantation (PBSCT) has revolutionised the management of many malignant conditions and has contributed to the increased use of growth factors. Many other indications are emerging for GFs used singly or in combination. Current clinical applications of GFs include: i) amelioration of cytopenias following chemotherapy and stem cell transplantation, ii) chemotherapy dose maintenance and escalation, iii) chemosensitisation and modification of disease states, iv) optimisation of methods for mobilisation of progenitor stem cells, v) immunotherapy, and vi) as therapeutic targets for treatment of haematolgical malignancies.

Impact of ABO incompatibility on outcome after allogeneic peripheral blood stem cell transplantation

Few studies have addressed the incidence of graft-versus-host disease (GVHD) or survival after ABO-incompatible allogeneic peripheral blood stem cell transplantation (PBSCT). We analyzed the clinical outcome of ABO incompatibility after allogeneic PBSCT. A total of 89 consecutive adult patients with hematological diseases including 49 ABO-identical, 20 major, 15 minor, and five bidirectional ABO-incompatible transplants were enrolled from four medical centers in Korea. No significant difference in engraftment times, graft failure, or transfusion requirements between groups was noted. A clinical diagnosis of severe immune hemolysis or pure red cell aplasia was not made for any patient after transplantation. The incidence of acute or chronic GVHD did not statistically differ between groups. With a median follow-up duration of 13 months (range, 0.5-61 months), the 3-year overall survival estimates for the ABO-identical, major/bidirectional, and minor group were 44.6.0+/-9.0, 43.1+/-11.6, and 43.8+/-13.5%, respectively (P=0.8652), while the 3-year disease-free survival estimates were 33.8+/-7.6, 39.9+/-11.4, and 45.7+/-13.1%, respectively (P=0.8546). We observed that time to neutrophil, platelet, and red blood cell engraftment, transfusion requirements, incidence of acute or chronic GVHD, relapse, and survival were not influenced by ABO incompatibility after allogeneic PBSCT from HLA-matched sibling donors.

Augmented mobilization and collection of CD34+ hematopoietic cells from normal human volunteers stimulated with granulocyte-colony-stimulating factor by single-dose administration of AMD3100, a CXCR4 antagonist

BACKGROUND

AMD3100, a selective antagonist of CXCR4, rapidly mobilizes CD34+ hematopoietic progenitor cells (HPCs) from marrow to peripheral blood with minimal side effects.

STUDY DESIGN AND METHODS

To further investigate potential clinical utility of AMD3100 for CD34+ cell mobilization and collection, a Phase I study in normal volunteers was performed examining single-dose administration of AMD3100 alone and in combination with a standard 5-day granulocyte-colony-stimulating factor (G-CSF) regimen.

RESULTS

AMD3100 (160 microg/kg x 1 on Day 5) significantly increased both G-CSF-stimulated (10 microg/kg/day) mobilization of CD34+ cells (3.8-fold) and leukapheresis yield of CD34+ cells. Moreover, collection of CD34+ cells was comparable between individuals mobilized by a single-dose regimen of AMD3100 (240 microg/kg) and individuals mobilized with a 5-day regimen of G-CSF. AMD3100-mobilized leukapheresis products contained significantly greater numbers of T and B cells compared to G-CSF-stimulated leukapheresis products.

CONCLUSION

These findings indicate that AMD3100 can be used alone or as an adjunct to G-CSF to mobilize cells for HPC transplantation.

Factors for PBPC collection efficiency and collection predictors

Factors affecting collection efficiency of peripheral blood stem cells (PBSCs) include patient's age, diagnosis, preceding chemoradiotherapy, disease invasion of the bone marrow and mobilizing chemotherapy in PBSC collection for autologous transplants. Mobilizing cytokines, timing for apheresis, machines and operating software would affect mobilization and collection of PBSCs both for autologous and allogeneic transplantation. Also donor's age and gender would affect PBSC yield for allogeneic transplantation. Surrogate markers including peripheral blood CD34+ cell counts before mobilization and on day of collection have been reported to predict the yield of PBSC harvest. A number of standard procedures have been developed based on these findings. Newer agents for PBSC mobilization are being evaluated and still other factors affecting mobilization are being sought to better predict and cope with poor mobilization.

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.

Mobilization of hematopoietic progenitor cells in healthy volunteers by AMD3100, a CXCR4 antagonist

Stromal cell-derived factor 1 (SDF1/CXCL12) and its cognate receptor, CXCR4, play key regulatory roles in CD34+ cell trafficking. We investigated whether AMD3100, a selective CXCR4 antagonist, could mobilize hematopoietic progenitor cells from marrow to peripheral blood in healthy human volunteers. Initially, 10 persons each received a single dose of AMD3100 (80 microsubcutaneously), which induced rapid, generalized leukocytosis associated with an increase in peripheral blood CD34+ cells, representing pluripotent hematopoietic progenitors by in vitro colony-forming unit assays, from 3.8 +/- 0.5/microL to 20.7 +/- 3.5/microL at 6 hours. Subsequent dose-response studies showed a maximum increase in circulating CD34+ cells from 2.6 +/- 0.3/microL to 40.4 +/- 3.4/microL at 9 hours after 240 micro/kg AMD3100. Serial administration of AMD3100 (80 microg/kg/d for 3 days) resulted in consistent, reversible increases in peripheral blood CD34+ cells. AMD3100 was well tolerated and caused only mild, transient toxicity. These findings suggest potential clinical application of AMD3100 for CD34+ cell mobilization and collection for hematopoietic stem cell transplantation.

Lack of dendritic cell mobilization into the peripheral blood of cancer patients following standard- or high-dose chemotherapy plus granulocyte-colony stimulating factor

BACKGROUND

Dendritic cells (DC), the most specialized antigen-presenting cells, can be detected in the peripheral blood (PB) and divided into two subsets of populations, DC1 and DC2, endowed with different functions. The aim of this study was to evaluate the effect on DC release and on their subsets of three regimens utilized to mobilize CD34+ cells into the PB in cancer patients and in normal CD34+ cell donors.

PATIENTS AND METHODS

The mobilizing sequences were: standard-dose epirubicin+taxol+granulocyte-colony-stimulating factor (G-CSF; 15 patients with advanced breast cancer), high-dose cyclophosphamide (CTX)+G-CSF (10 patients with breast cancer patients and 7 with non-Hodgkin's lymphoma, NHL), and G-CSF alone (5 normal donors of CD34+ cells for allogeneic transplantation). Comparative data were obtained from the steady-state PB of 20 healthy volunteers. For flow cytometric analysis, DC were gated as negative for specific lineage markers (CD3, CD11b, CD14, CD16, CD56, CD19, CD20, CD34) and positive for HLA-DR. The DC1 and DC2 subsets were defined as CD11c and CDw123 positive, respectively.

RESULTS

The percentages of DC at baseline and the time of CD34+ cell peak were: 0.48 and 0.51 for standard-dose chemotherapy (CT); 0.55 and 0.63 for breast cancer after high-dose CTX+G-CSF; 0.53 and 0.71 for NHL after high-dose CTX+G-CSF; and 0.51 and 0.54 for normal donors of CD34+ cells after G-CSF alone (all p=n.s.). Mean DC1/DC2 ratios in each study group at the time of CD34+ cell peak were 0.10, 0.12, and 0.18, respectively. Finally, in the group of healthy volunteers, the percentage of circulating DC was 0.95 and the mean DC1/DC2 ratio was 1.28.

CONCLUSION

To our knowledge, this is the first report that demonstrates that both standard-dose or high-dose CT, when utilized together with G-CSF, do not induce DC mobilization into the PB, whereas a reversed DC1/DC2 ratio is observed. Furthermore, a lack of significant DC mobilization after G-CSF alone was also seen, in contrast to what was previously observed by others. These data should be taken in account when evaluating clinical correlations between DC number and CPC engraftment in both the transplantation setting, when monitoring the effects on the immune system of combinations of new drugs and/or cytokines, and when high numbers of DC are required for both experimental and clinical applications.

Isolation and therapeutic potential of human haemopoietic stem cells

The haemopoietic stem cell (HSC) has long been regarded as an archetypal, tissue specific, stem cell, capable of completely regenerating haemopoiesis after myeloablation. It has proved relatively easy to harvest HSC, from bone marrow or peripheral blood. In turn, isolation of these cells has allowed therapeutic stem cell transplantation protocols to be developed, that capitalise on their prodigious self renewal and proliferative capabilities. Ex vivo approaches have been described to isolate, genetically manipulateand expand pluripotent stem cell subsets. These techniques have been crucial to the development of gene therapy, and may allow adults to enjoy the potential advantages of cord blood transplantation. Recently, huge conceptual changes have occurred in stem cell biology. In particular, the dogma that, in adults, stem cells are exclusively tissue restricted has been questioned and there is great excitement surrounding the potential plasticity of these cells, with the profound implications that this has, for developing novel cellular therapies. Mesenchymal stem cells, multipotent adult progenitor cells and embryonic stem cells are potential sources of cells for transplantation purposes. These cells may be directed toproduce HSC, in vitro and in the future may be used for therapeutic, or drug development, purposes.

Adaptive decision making in a lymphocyte infusion trial

We describe an adaptive Bayesian design for a clinical trial of an experimental treatment for patients with hematologic malignancies who initially received an allogeneic bone marrow transplant but subsequently suffered a disease recurrence. Treatment consists of up to two courses of targeted immunotherapy followed by allogeneic donor lymphocyte infusion. The immunotherapy is a necessary precursor to the lymphocyte infusion, but it may cause severe liver toxicity and is certain to cause a low white blood cell count and low platelets. The primary scientific goal is to determine the infusion time that has the highest probability of treatment success, defined as the event that the patient does not suffer severe toxicity and is alive with recovered white blood cell count 50 days from the start of therapy. The method is based on a parametric model accounting for toxicity, time to white blood cell recovery, and survival time. The design includes an algorithm for between-patient immunotherapy dose de-escalation based on the toxicity data and an adaptive randomization among five possible infusion times according to their most recent posterior success probabilities. A simulation study shows that the design reliably selects the best infusion time while randomizing greater proportions of patients to superior infusion times.

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

Peripheral blood stem cells (PBSC) have become the preferred source of stem cells for autologous transplantation because of the technical advantage and the shorter time to engraftment. Mobilization of CD34+ into the peripheral blood can be achieved by the administration of granulocyte colony-stimulating factor (G-CSF), granulocyte-macrophage colony-stimulating factor (GM-CSF), or both, either alone or in combination with chemotherapy. G-CSF and GM-CSF differ somewhat in the number and composition of PBSCs and effector cells mobilized to the peripheral blood. The purpose of this review is to give a recent update on the type and immunologic properties of CD34+ cells and CD34+ cell subsets mobilized by G-CSF or GM-CSF with emphasis on (1) relative efficacy of CD34+ cell mobilization; (2) relative toxicities of G-CSF and GM-CSF as mobilizing agents; (3) mobilization of dendritic cells and their subsets; (4) delineation of the role of adhesion molecules, CXC receptor 4, and stromal cell-derived factor-1 signaling pathway in the release of CD34+ cell to the peripheral blood after treatment with G-CSF or GM-CSF.

Mobilization of allogeneic peripheral blood progenitor cells

It is possible to reliably obtain sufficient PBSC from most normal donors to perform allogeneic transplantation. The mobilization regimen, usually administration of a single daily dose of G-CSF at 7.5 to 10 micrograms/kg subcutaneously for 4 to 6 days, is tolerable with acceptable side effects. However, there is wide variability among individuals with respect to the extent of mobilization achieved by the regimen and the optimal timing of apheresis. Studies suggest that the likelihood of obtaining an adequate harvest of CD34+ cells, as defined locally may be enhanced by employing higher doses or different schedules of G-CSF, monitoring the mobilization and/or collection of PBPC, and using apheresis procedures processing 2 or more times blood volume. However, an optimal regimen for mobilization and harvesting for all donors has not yet been identified and a small percentage of donors may not mobilize adequately with G-CSF. Alternative regimens employing combinations of G-CSF and GM-CSF are available that may prove useful in such cases and novel cytokines that are even more effective than G-CSF in mobilizing stem cells are eagerly awaited. Based on currently available experience with normal donors, the short-term safety of G-CSF appears to be acceptable, however there exist several scenarios in which marrow harvesting may be preferable to G-CSF mobilization and apheresis collection of PBPC.

Economic evaluation of filgrastim, sargramostim, and sequential sargramostim and filgrastim after myelosuppressive chemotherapy

Filgrastim alone and sequential sargramostim and filgrastim have been shown to be more effective than sargramostim alone in the mobilization of CD34(+) cells after myelosuppressive chemotherapy (MC). We sought to compare costs and resource use associated with these regimens. Data were collected prospectively alongside a multicenter, randomized trial of filgrastim, sargramostim, and sequential sargramostim and filgrastim. Direct medical costs were calculated for inpatient and outpatient visits and procedures, including administration of growth factors and MC. We followed 156 patients for 30 days or until initiation of high-dose chemotherapy. The main outcome measures were resource use and costs of inpatient and outpatient visits, platelet and red blood cell transfusions, antibiotic use, and apheresis procedures. Hospital admissions, red blood cell transfusions, and use of i.v. antibiotics were significantly more common in the sargramostim group than in the other treatment arms. In univariate and multivariable analyses, total costs were higher for patients receiving sargramostim alone than for patients in the other groups. Mean costs in multivariable analysis for the filgrastim and sequential sargramostim and filgrastim arms were not significantly different. Filgrastim alone and sequential sargramostim and filgrastim are less costly than sargramostim alone after MC, as well as therapeutically more beneficial.

Peripheral blood stem cell versus bone marrow allotransplantation: does the source of hematopoietic stem cells matter?

Hematopoietic stem cells from 4 different sources have been or are being used for the reconstitution of lymphohematopoietic function after myeloablative, near-myeloablative, or nonmyeloablative treatment. Bone marrow (BM)-derived stem cells, introduced by E. D. Thomas in 1963, are considered the classical stem cell source. Fetal liver stem cell transplantation has been performed on a limited number of patients with aplastic anemia or acute leukemia, but only transient engraftment has been demonstrated. Peripheral blood as a stem cell source was introduced in 1981, and cord blood was introduced as a source in 1988. The various stem cell sources differ in their reconstitutive and immunogenic characteristics, which are based on the proportion of early pluripotent and self-renewing stem cells to lineage-committed late progenitor cells and on the number and characteristics of accompanying "accessory cells" contained in stem cell allografts.

Mobilization of peripheral blood stem cells following myelosuppressive chemotherapy: a randomized comparison of filgrastim, sargramostim, or sequential sargramostim and filgrastim

Myelosuppressive chemotherapy is frequently used for mobilization of autologous CD34(+) progenitor cells into the peripheral blood for subsequent collection and support of high-dose chemotherapy. The administration of myelosuppressive chemotherapy is typically followed by a myeloid growth factor and is associated with variable CD34 cell yields and morbidity. The two most commonly used myeloid growth factors for facilitation of CD34 cell harvests are granulocyte colony-stimulating factor (G-CSF) and granulocyte-macrophage colony-stimulating factor (GM-CSF). We performed a randomized phase III clinical trial comparing G-CSF, GM-CSF, and sequential administration of GM-CSF and G-CSF following administration of myelosuppressive chemotherapy. We evaluated CD34 yields, morbidity, and cost-effectiveness of the three cytokine schedules. One hundred and fifty-six patients with multiple myeloma, breast cancer, or lymphoma received cyclophosphamide with either paclitaxel or etoposide and were randomized to receive G-CSF 6 microg/kg/day s.c., GM-CSF 250 microg/m(2)/day s.c., or GM-CSF for 6 days followed by G-CSF until completion of the stem cell harvest. Compared with patients who received GM-CSF, patients who received G-CSF had faster recovery of absolute neutrophil count to 0.5 x 10(9) per liter (median of 11 vs14 days, P = 0.0001) with fewer patients requiring red blood cell transfusions (P= 0.008); fewer patients with fever (18% vs 52%, P = 0.001); fewer hospital admissions (20% vs 42%, P = 0.13); and less intravenous antibiotic therapy (24% vs 59%, P = 0.001). Patients who received G-CSF also yielded more CD34 cells (median 7.1 vs 2.0 x 10(6) kg per apheresis, P = 0.0001) and a higher percentage achieved 2.5 x 10(6) CD34 cells per kilogram (94% vs 78%, P = 0.21) and 5 x 10(6) CD34 cells per kilogram (88% vs 53%, P = 0.01) or more CD34 cells per kilogram with fewer aphereses (median 2 vs 3, P = 0.002) and fewer days of growth factor treatment (median 12 vs 14, P = 0.0001). There were no significant differences in outcomes between groups receiving G-CSF alone and the sequential regimen. After high-dose chemotherapy, patients who had peripheral blood stem cells mobilized with G-CSF or the sequential regimen received higher numbers of CD34 cells and had faster platelet recovery with fewer patients requiring platelet transfusions than patients receiving peripheral blood stem cells mobilized by GM-CSF. In summary, G-CSF alone is superior to GM-CSF alone for the mobilization of CD34(+) cells and reduction of toxicities following myelosuppressive chemotherapy. An economic analysis evaluating the cost-effectiveness of these three effective schedules is ongoing at the time of this writing.

Peripheral blood progenitor cell collection after epirubicin, paclitaxel, and cisplatin combination chemotherapy using EPO-based cytokine regimens: a randomized comparison of G-CSF and sequential GM-/G-CSF

BACKGROUND

The peripheral blood progenitor cell (PBPC) mobilization capacity of EPO in association with either G-CSF or sequential GM-CSF/G-CSF was compared in a randomized fashion after epirubicin, paclitaxel, and cisplatin (ETP) chemotherapy.

STUDY DESIGN AND METHODS

Forty patients with stage IIIB, IIIC, or IV ovarian carcinoma were enrolled in this randomized comparison of mobilizing capacity and myelopoietic effects of G-CSF + EPO and GM-/G-CSF + EPO following the first ETP chemotherapy treatment. After ETP chemotherapy (Day 1), 20 patients received G-CSF 5 microg per kg per day from Day 2 to Day 13 and 20 patients received GM-CSF 5 microg per kg per day from Day 2 to Day 6 followed by G-CSF 5 microg per kg per day from Day 7 to Day 13. EPO (150 IU per kg) was given every other day from Day 2 to Day 13 to all patients in both arms of the study. Apheresis (two blood volumes) was performed during hematologic recovery.

RESULTS

The magnitude of CD34+ cell mobilization and the abrogation of patients' myelosuppression were comparable in both study arms; however, GM-/G-CSF + EPO patients had significantly higher CD34+ yields because of a higher CD34+ cell collection efficiency (57.5% for GM-/G-CSF + EPO and 46.3% for G-CSF + EPO patients; p = 0.0009). Identical doses of PBPCs mobilized by GM-/G-CSF + EPO and G-CSF + EPO drove comparable hematopoietic recovery after reinfusion in patients treated with identical high-dose chemotherapy.

CONCLUSION

The sequential administration of GM-CSF and G-CSF in combination with EPO is feasible and improves the PBPC collection efficiency after platinum-based intensive polychemotherapy, associating high PBPC mobilization to high collection efficiency during apheresis.

Donor age-related differences in PBPC mobilization with rHuG-CSF

BACKGROUND

Data on the administration of rHuG-CSF to normal donors <18 years old are very limited.

STUDY DESIGN AND METHODS

The results of rHuG-CSF administration to 61 donors <18 years old (Group A) were retrospectively evaluated and compared with results from 353 donors > or = 18 years old (Group B) who are included in the Spanish National Donor Registry. The mean age (range) in Group A and B was 14 (1-17) and 38 (18-71) years, respectively (p<0.001). The mean dose of rHuG-CSF was 10 microg per kg per day (range, 9-16) during a mean of 5 days (range, 4-6). Central venous access was placed more frequently in younger donors (25% vs. 6%; p<0.001).

RESULTS

The mean number of CD34+ cells collected was 7.6 and 6.9 x 10(6) per kg of donor's body weight in Group A and B, respectively. Fifty-six percent of Group A donors needed only one apheresis to achieve > or = 4 x 10(6) CD34+ cells per kg versus 39 percent of Group B donors (p = 0.01). Side effects were more common in Group B (71% vs. 41%; p<0.001).

CONCLUSION

The administration of rHuG-CSF to donors <18 years old leads to CD34+ cell mobilization in a pattern similar to that observed in adults. Greater age was associated with a more frequent requirement for more than one apheresis to achieve a similar number of CD34+ cells.

Is there any difference in PBPC mobilization between cyclophosphamide plus G-CSF and G-CSF alone in patients with non-Hodgkin's Lymphoma?

We attempted to analyze whether the use of high-dose cyclophosphamide (CTX 7g/m2, group A) plus hematopoietic growth factor (G-CSF) or G-CSF alone (10 microg/Kg, group B) as a mobilizing regimen, could result in harvesting different numbers of CD34+ cells, committed progenitors and CD34+ cells subsets. The number of CD34+ cells considered as the target for each high-dose chemotherapy was > or = 2 x 10(6) /Kg/bw. Fifteen leukaphereses procedures were necessary in group A, while 16 procedures were performed in group B. We did not observe any difference between the two groups in terms of CD34+ cells/microl in the peripheral blood (117 vs 78; p = NS), whereas in the aphereses product we found a significant difference between the two groups of patients in terms of CD34+ cells (6.41 vs 2.89 x 10(6) /Kg/bw; p = .009), CFU-GM (82.5 vs 52.3 x 10(4) /Kg/bw; p = .04). Interestingly, we noted a different distribution of CD34+/33- cells between the 2 groups (mean value 39% vs 65%; p < .05), whereas we did not find any differences regarding CD34+/38-, CD34+/Thy1+, CD34+/HLADR-. The higher number of CFU-GM/Kg/bw collected in the former group did not translate into a superior plating efficiency (27.75 vs 30.29). Furthermore, we observed a strong correlation between CD34+ cells/microl in the peripheral blood and the total number of CD34+ cells in the leukaphereses product (r = 0.97), whereas this correlation was not found in group B (r = 0.15). In both groups of patients the number of CD34+ cells collected correlated well with CFU-GM (r = 0.93; r = 0.94), but definitely we did not observe any correlation between CD34+ cells/microl and CFU-GM in patients mobilized with G-CSF alone and this did not allow us to predict the harvest accurately. Finally, we evaluated the engraftment kinetics and we did not observe any statistically significant difference between the two groups of patients.

Granulocyte colony-stimulating factor versus granulocyte-macrophage colony-stimulating factor for collection of peripheral blood progenitor cells from healthy donors

The harvesting of peripheral blood progenitor cells (PBPCs) after granulocyte colony-stimulating factor or granulocyte-macrophage colony-stimulating factor stimulation instead of bone marrow in healthy donors has become increasingly popular. Donors, given the choice between bone marrow and PBPC donation, often prefer cytapheresis because of the easier access, no necessity for general anesthesia, and no multiple bone marrow punctures. In addition, accelerated engraftment and immunomodulation by granulocyte colony-stimulating factor-mobilized PBPCs are advantageous for the recipient. However, because of donor inconvenience and poor mobilization, there is a need to develop improved procedures. Aspects such as durability of hematopoietic engraftment, characterization of the earliest stem cell, and composition of PBPCs are not yet well defined, and international donor registration and follow-up must be considered when evaluating long-term safety profiles in healthy donors. This review concentrates on the most significant developments on mobilization of PBPCs published during the past year.

Hematological recovery and peripheral blood progenitor cell mobilization after induction chemotherapy and GM-CSF plus G-CSF in breast cancer

In order to determine the effect of GM-CSF plus G-CSF in combination in breast cancer patients receiving an effective induction regimen, we compared hematological recovery and peripheral blood progenitor cell (PBPC) mobilization according to colony-stimulating factor (CSF) support. Forty-three breast cancer patients were treated by TNCF (THP-doxorubicin, vinorelbine, cyclophosphamide, fluorouracil, D1 to D4) with CSF support: 11 patients received GM-CSF (D5 to D14); 16 patients G-CSF (D5 to D14) and 16 patients GM-CSF (D5-D14) plus G-CSF (D10-D14). Between two subsequent cycles, progenitor cells were assessed daily, from D13 to D17. The WBC count was similar for patients receiving G-CSF alone or GM-CSF plus G-CSF, but significantly greater than that of patients receiving GM-CSF alone (P<0.001). The GM-CSF plus G-CSF combination led to better PBPC mobilization, with significantly different kinetics (P<0.001) and optimal mean values of CFU-GM, CD34+ cells and cells in cycle, at D15 compared to those obtained with G-CSF or GM-CSF alone. The significantly greater PBPC mobilization obtained with a CSF combination by D15 could be of value for PBPC collection and therapeutic reinjection after high-dose chemotherapies.

Return of granulocyte transfusions

Recently, several groups have begun to administer granulocyte colony-stimulating factor (G-CSF), a hematopoietic growth factor, with or without dexamethasone to mobilize peripheral blood neutrophils. Granulocyte colony-stimulating factor (600 microg subcutaneously) and dexamethasone (8 mg orally) given 12 hours before standard leukapheresis routinely results in the collection of approximately 80 x 10(9) granulocytes. This number of cells is sufficient to increase the neutrophil count of a severely neutropenic patient to normal and restore the recipients' ability to develop a neutrophil response in tissues. Several trials are ongoing to establish the clinical benefit of this new approach to supportive care for neutropenic patients.

Randomized trial of filgrastim, sargramostim, or sequential sargramostim and filgrastim after myelosuppressive chemotherapy for the harvesting of peripheral-blood stem cells

PURPOSE

The purpose of this study was to compare the effects of filgrastim, sargramostim, or sequential sargramostim and filgrastim on CD34(+) cell yields and morbidity after myelosuppressive mobilization chemotherapy (MC).

PATIENTS AND METHODS

One hundred fifty-six patients were randomized to receive filgrastim (n = 51), sargramostim (n = 52), or sargramostim for 5 days followed by filgrastim (n = 53) after MC with either cyclophosphamide and etoposide (n = 75) or paclitaxel and cyclophosphamide (n = 81).

RESULTS

Compared with those who received sargramostim, patients who received filgrastim had faster recovery of an absolute neutrophil count of 0.5 x 10(9)/L or greater (a median of 11 v 14 days; P =. 0001), with fewer patients requiring RBC transfusions (P =.008), fewer patients with fever (18% v 52%; P = 0.001), fewer hospital admissions (20% v 42%; P =.013), and less intravenous antibiotic therapy (24% v 69%; P =.001). Patients who received filgrastim yielded more CD34(+) cells (median, 7.1 v 2.0 x 10(6)/kg/apheresis; P =.0001), and a higher fraction achieved 2.5 x 10(6) (94% v 78%; P =.021) and 5 x 10(6) (88% v 53%; P =.001) or more CD34(+) cells/kg with fewer aphereses (median, 2 v 3; P =.002) and fewer days of growth-factor treatment (median, 12 v 14; P =.0001). There were no major differences in outcomes between the filgrastim alone and the sequential regimens. After high-dose chemotherapy, patients who had peripheral-blood stem cells (PBSCs) mobilized with filgrastim or the sequential regimen received higher numbers of CD34(+) cells and had faster platelet recovery (P =.015), with fewer patients (P =.014) receiving fewer platelet transfusions (P =.001) than patients receiving sargramostim-mobilized PBSCs.

CONCLUSION

It was concluded that filgrastim alone or sequential sargramostim and filgrastim were superior to sargramostim alone for the mobilization of CD34(+) cells and reduction of toxicities after MC.

Correlation between IL-3 receptor expression and growth potential of human CD34+ hematopoietic cells from different tissues

CD123 (alpha-subunit of IL-3 receptor) expression on primitive and committed human hematopoietic cells was studied by multicolor sorting and single-cell culture. The sources of cells included fetal liver (FLV), fetal bone marrow, umbilical cord blood, adult bone marrow and mobilized peripheral blood. Three subsets of CD34+ cells were defined by the levels of surface CD123: CD123negative, CD123low, and CD123bright. Coexpression of lineage markers showed that a majority of CD34+CD123bright cells were myeloid and B-lymphoid progenitors, while erythroid progenitors were mainly in the CD34+CD123negative subset. The CD34+CD123low subset contained a heterogeneous distribution of early and committed progenitor cells. Single CD34+ cells from the CD123 subsets were cultured in a cytokine cocktail of stem cell factor, interleukin 3 (IL-3), IL-6, GM-CSF, erythropoietin, insulin-like growth factor-1, and basic fibroblast growth factor. After 14 days of incubation, a higher cloning efficiency (CE) was observed in the CD34+CD123negative and CD34+CD123low fractions (37+/-23% and 44+/-23%, respectively) than in the CD34+CD123bright fraction (15+/-21%). Using previously published criteria that colonies containing dispersed, translucent cells (dispersed growth pattern, DGP) were derived from primitive cells and that colonies composed solely of clusters were from committed cells, early precursors were distributed evenly in the CD34+CD123negative and CD34+CD123low subsets. When CD38 and CD90 (Thy-1) were used for further characterization of CD34+ cells from FLV, CE increased from 37+/-23% in CD123negative to 70+/-19% in CD123negativeCD38- and from 44+/-23% in CD123low to 66+/-19% in CD123lowCD38-. No significant increase in CE or DGP progenitors was observed when CD34+ cells were sorted by CD90 and CD123. We concluded that: A) high levels of CD123 were expressed on B-lymphoid and myeloid progenitors; B) early erythroid progenitors had little or no surface CD123, and C) primitive hematopoietic cells are characterized by CD123negative/low expression.