Efficacy and toxicity of a high-dose G-CSF schedule for peripheral blood progenitor cell mobilization in healthy donors

Peripheral blood stem cell harvesting in young children weighing less than 15 kg

Autologous peripheral blood stem cell (PBSC) transplantation is crucial in pediatric cancer treatment, and tandem transplantation is beneficial in certain malignancies. Collecting PBSCs in small children with low body weight is challenging. We retrospectively analyzed data of pediatric cancer patients weighing <15 kg who underwent autologous PBSC harvesting in our hospital. Collections were performed in the pediatric intensive care unit over 2 or 3 consecutive days, to harvest sufficient stem cells (goal ≥2 × 106 CD34+ cells/kg per apheresate). From April 2006 to August 2021, we performed 129 collections after 50 mobilizations in 40 patients, with a median age of 1.9 (range, 0.6-5.6) years and a body weight of 11.0 (range, 6.6-14.7) kg. The median CD34+ cells in each apheresate were 4.2 (range, 0.01-40.13) × 106/kg. 78% and 56% of mobilizations achieved sufficient cell dose for single or tandem transplantation, respectively, without additional aliquoting. The preapheresis hematopoietic progenitor cell (HPC) count was highly correlated with the CD34+ cell yield in the apheresate (r = 0.555, P < 0.001). Granulocyte colony-stimulating factor alone was not effective for mobilization in children ≥2 years of age, even without radiation exposure. By combining the preapheresis HPC count ≥20/μL and the 3 significant host factors, including age <2 years, no radiation exposure and use of chemotherapy, the prediction rate of goal achievement was increased (area under the curve 0.787).

Healing Effect of Subcutaneous Administration of Granulocyte Colony-Stimulating Factor on Acute Rotator Cuff Injury in a Rat Model

Granulocyte colony-stimulating factor (G-CSF) is a cytokine that mobilizes bone marrow-derived cells (BMDCs) to peripheral blood and has been clinically used to treat neutropenia. Previously, we reported that BMDCs migrated into the rotator cuff repair site via peripheral blood in the healing process. However, techniques to accelerate the healing process using the peripheral blood pathway have not been established. We evaluated whether G-CSF has a noteworthy effect on improving rotator cuff healing by enhancing the influx of BMDCs into the peripheral blood. We used Sprague-Dawley rats and chimeric rats, selectively expressing green fluorescent protein (GFP) in BMDCs. Their bilateral supraspinatus tendons were resected and sutured to the greater tuberosity of the humerus using the Masson-Allen technique, and G-CSF was subcutaneously injected for 5 days after surgery. Several GFP-positive cells were observed around the enthesis in the G-CSF-treated group compared with that in the Control group. Histological analysis revealed that the tendon-to-bone maturing scores and the Safranin O-stained cartilaginous areas were significantly higher in G-CSF-injected rats than in the control rats at weeks 4 and 8 after surgery. Consistently, the ultimate force to failure in the G-CSF-treated group significantly increased compared with the Control group at weeks 4 and 8 after surgery. These results suggest that BMDCs mobilized into the peripheral blood after G-CSF administration migrated to the rotator cuff repair area and effectively enhanced rotator cuff healing by promoting tenocyte and cartilage matrix production. In conclusion, the BMDC mobilization technique by G-CSF treatment via peripheral blood will provide a potential therapeutic approach for rotator cuff healing with clinically relevant applications. Impact statement As the retear rate following rotator cuff repair is high, new methods to aid its healing are required. Granulocyte colony-stimulating factor (G-CSF) has been used clinically and may represent a novel approach to treating rotator cuff tear. Herein, using a rat model, we elucidate the kinetics of bone marrow-derived mesenchymal stem cells at the repair site following G-CSF administration and describe the underlying mechanism by which G-CSF can help promote the repair of the rotator cuff.

Feasibility and cost analysis of day 4 granulocyte colony-stimulating factor mobilized peripheral blood progenitor cell collection from HLA-matched sibling donors

BACKGROUND

Guidelines recommend treatment with 4-5 days of granulocyte colony-stimulating factor (G-CSF) for optimal donor peripheral blood progenitor cell (PBPC) mobilization followed by day 5 collection. Given that some autologous transplant recipients achieve adequate collection by day 4 and the possibility that some allogeneic donors may maximally mobilize PBPC before day 5, a feasibility study was performed evaluating day 4 allogeneic PBPC collection.

METHODS

HLA-matched sibling donors underwent collection on day 4 of G-CSF for peripheral blood (PB) CD34⁺ counts ≥0.04 × 10⁶/mL, otherwise they underwent collection on day 5. Those with inadequate collected CD34⁺ cells/kg recipient weight underwent repeat collection over 2 days. Transplant and PBPC characteristics and cost analysis were compared with a historical cohort collected on day 5 per our prior institutional algorithm.

RESULTS

Of the 101 patient/donor pairs, 50 (49.5%) had adequate PBPC collection on day 4, with a median PB CD34⁺ cell count of 0.06 × 10⁶/mL. Day 4 donors were more likely to develop bone pain and require analgesics. Median collected CD34⁺ count was significantly greater, whereas total nucleated, mononuclear and CD3⁺ cell counts were significantly lower, at time of transplant infusion for day 4 versus other collection cohorts. There were no significant differences in engraftment or graft-versus-host disease. Cost analysis revealed 6.7% direct cost savings for day 4 versus historical day 5 collection.

DISCUSSION

Day 4 PB CD34⁺ threshold of ≥0.04 × 10⁶/mL identified donors with high likelihood of adequate PBPC collection. Day 4 may be the optimal day of collection for healthy donors, without adverse effect on recipient transplant outcomes and with expected cost savings.

Polymer conjugation of proteins as a synthetic post-translational modification to impact their stability and activity

For more than 40 years, protein-polymer conjugates have been widely used for many applications, industrially and biomedically. These bioconjugates have been shown to modulate the activity and stability of various proteins while introducing reusability and new activities that can be used for drug delivery, improve pharmacokinetic ability, and stimuli-responsiveness. Techniques such as RDRP, ROMP and "click" have routinely been utilized for development of well-defined bioconjugate and polymeric materials. Synthesis of bioconjugate materials often take advantage of natural amino acids present within protein and peptide structures for a host of coupling chemistries. Polymer modification may elicit increased or decreased activity, activity retention under harsh conditions, prolonged activity in vivo and in vitro, and introduce stimuli responsiveness. Bioconjugation has resulted to modulated thermal stability, chemical stability, storage stability, half-life and reusability. In this review we aim to provide a brief state of the field, highlight a wide range of behaviors caused by polymer conjugation, and provide areas of future work.

Peripheral blood stem cell mobilization in multiple myeloma: Growth factors or chemotherapy?

High-dose therapy followed by autologous hematopoietic stem cell (HSC) transplant is considered standard of care for eligible patients with multiple myeloma. The optimal collection strategy should be effective in procuring sufficient HSC while maintaining a low toxicity profile. Currently available mobilization strategies include growth factors alone, growth factors in combination with chemotherapy, or growth factors in combination with chemokine receptor antagonists; however, the optimal strategy has yet to be elucidated. Herein, we review the risks and benefits of each approach.

Cytokine therapy-mediated neuroprotection in a Friedreich's ataxia mouse model

OBJECTIVES

Friedreich's ataxia is a devastating neurological disease currently lacking any proven treatment. We studied the neuroprotective effects of the cytokines, granulocyte-colony stimulating factor (G-CSF) and stem cell factor (SCF) in a humanized murine model of Friedreich's ataxia.

METHODS

Mice received monthly subcutaneous infusions of cytokines while also being assessed at monthly time points using an extensive range of behavioral motor performance tests. After 6 months of treatment, neurophysiological evaluation of both sensory and motor nerve conduction was performed. Subsequently, mice were sacrificed for messenger RNA, protein, and histological analysis of the dorsal root ganglia, spinal cord, and cerebellum.

RESULTS

Cytokine administration resulted in significant reversal of biochemical, neuropathological, neurophysiological, and behavioural deficits associated with Friedreich's ataxia. Both G-CSF and SCF had pronounced effects on frataxin levels (the primary molecular defect in the pathogenesis of the disease) and a regulators of frataxin expression. Sustained improvements in motor coordination and locomotor activity were observed, even after onset of neurological symptoms. Treatment also restored the duration of sensory nerve compound potentials. Improvements in peripheral nerve conduction positively correlated with cytokine-induced increases in frataxin expression, providing a link between increases in frataxin and neurophysiological function. Abrogation of disease-related pathology was also evident, with reductions in inflammation/gliosis and increased neural stem cell numbers in areas of tissue injury.

INTERPRETATION

These experiments show that cytokines already clinically used in other conditions offer the prospect of a novel, rapidly translatable, disease-modifying, and neuroprotective treatment for Friedreich's ataxia. Ann Neurol 2017;81:212-226.

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.

An assessment of the pharmacokinetics, pharmacodynamics, and tolerability of GCPGC, a novel pegylated granulocyte colony-stimulating factor (G-CSF), in healthy subjects

INTRODUCTION

A pegylated recombinant human granulocyte colony-stimulating factor (G-CSF) is effective in reducing the severity and duration of neutropenia. This study was performed to investigate the pharmacokinetics (PK), pharmacodynamics (PD), and tolerability of GCPGC, a new formulation of pegylated G-CSF, in healthy volunteers and to compare them with those of pegfilgrastim (Neulasta®).

METHODS

Twenty-five healthy Korean male volunteers randomly received a single subcutaneous (SC) GCPGC injection at a dose of 30 (n = 10), 100 (n = 10), or 300 (n = 5) μg/kg or placebo in a 4:1 ratio in a double-blind manner. Additionally, 8 subjects received a SC dose of pegfilgrastim at 100 μg/kg. Blood samples were collected up to 14 days after both therapies. The absolute neutrophil count (ANC) and CD34(+) cell counts were the PD markers.

RESULTS

After GCPGC administration, 4 different pharmacokinetic phases were identified, indicating target-mediated drug disposition (TMDD) for the elimination of GCPGC, which was slowed down as the dose was increased, resulting in a higher than proportional dose-normalized exposure to GCPGC. Although GCPGC was cleared faster than pegfilgrastim, leading to a 19 % lower systemic exposure to pegylated G-CSF, the increase in ANC and CD34(+) were ~20 % greater by GCPGC at 100 μg/kg than pegfilgrastim. Thrombocytopenia, splenomegaly, and hemoperitoneum occurred in one subject in the 300 μg/kg GCPGC group, which resolved completely with appropriate care.

CONCLUSIONS

GCPGC showed a non-linear TMDD. The PK-PD characteristics of GCPGC at 30-100 μg/kg were comparable to those of pegfilgrastim at 100 μg/kg. GCPGC at 30-100 μg/kg was well tolerated in healthy Korean males.

Differences in the phenotype, cytokine gene expression profiles, and in vivo alloreactivity of T cells mobilized with plerixafor compared with G-CSF

Plerixafor (Mozobil) is a CXCR4 antagonist that rapidly mobilizes CD34(+) cells into circulation. Recently, plerixafor has been used as a single agent to mobilize peripheral blood stem cells for allogeneic hematopoietic cell transplantation. Although G-CSF mobilization is known to alter the phenotype and cytokine polarization of transplanted T cells, the effects of plerixafor mobilization on T cells have not been well characterized. In this study, we show that alterations in the T cell phenotype and cytokine gene expression profiles characteristic of G-CSF mobilization do not occur after mobilization with plerixafor. Compared with nonmobilized T cells, plerixafor-mobilized T cells had similar phenotype, mixed lymphocyte reactivity, and Foxp3 gene expression levels in CD4(+) T cells, and did not undergo a change in expression levels of 84 genes associated with Th1/Th2/Th3 pathways. In contrast with plerixafor, G-CSF mobilization decreased CD62L expression on both CD4 and CD8(+) T cells and altered expression levels of 16 cytokine-associated genes in CD3(+) T cells. To assess the clinical relevance of these findings, we explored a murine model of graft-versus-host disease in which transplant recipients received plerixafor or G-CSF mobilized allograft from MHC-matched, minor histocompatibility-mismatched donors; recipients of plerixafor mobilized peripheral blood stem cells had a significantly higher incidence of skin graft-versus-host disease compared with mice receiving G-CSF mobilized transplants (100 versus 50%, respectively, p = 0.02). These preclinical data show plerixafor, in contrast with G-CSF, does not alter the phenotype and cytokine polarization of T cells, which raises the possibility that T cell-mediated immune sequelae of allogeneic transplantation in humans may differ when donor allografts are mobilized with plerixafor compared with G-CSF.

[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.

Pegfilgrastim overdose: case report and review of the literature

Single-dose pegfilgrastim is commonly used for the prophylaxis of neutropenia in patients receiving myelotoxic chemotherapy. We report a case of a 69-year-old man who was treated with chemotherapy for small-cell lung cancer and mistakenly self-administered a 36 mg overdose of pegfilgrastim, a sixfold increase over the scheduled dose.

Pharmacokinetic profiles of a biosimilar filgrastim and Amgen filgrastim: results from a randomized, phase I trial

Recombinant human granulocyte colony-stimulating factor (filgrastim) has multiple hematologic and oncologic indications as Neupogen (Amgen filgrastim). Hospira has developed a biosimilar filgrastim (Nivestim). Here, results are reported from a phase I trial, primarily designed to compare the pharmacokinetic profiles of Hospira filgrastim and Amgen filgrastim. A phase I, single-center, open-label, randomized trial was undertaken to demonstrate equivalence of the pharmacokinetic characteristics of Hospira filgrastim and Amgen filgrastim. Forty-eight healthy volunteers were randomized to receive intravenous (i.v.) or subcutaneous (s.c.) dosing and then further randomized to order of treatment. Volunteers in each of the two dosing groups received a single 10microg/kg dose of Hospira filgrastim or Amgen filgrastim, with subsequent crossover. Bioequivalence was evaluated by analysis of variance; if the estimated 90% confidence intervals (CIs) for the ratio of 'test' to 'reference' treatment means were within the conventional equivalence limits of 0.80-1.25, then bioequivalence was concluded. Forty-six volunteers completed the study. Geometric mean area under the curve from time 0 to the last time point (primary endpoint) was similar in volunteers given Hospira filgrastim or Amgen filgrastim following i.v. (ratio of means: 0.96; 90% CI: 0.90-1.02) or s.c. (ratio of means: 1.02; 90% CI: 0.95-1.09) dosing; 90% CIs were within the predefined range necessary to demonstrate bioequivalence. Hospira filgrastim was well tolerated with no additional safety concerns over Amgen filgrastim. Hospira filgrastim is bioequivalent with Amgen filgrastim in terms of its pharmacokinetic properties and may provide a clinically effective alternative.

Hepatocyte growth factor mobilizes and recruits hematopoietic progenitor cells into liver through a stem cell factor-mediated mechanism

AIMS

Although bone marrow cells are reported to migrate to the liver under circumstances of severe liver injury, the bone marrow cell type and the mechanisms in this process, remain to be clarified. We examined the involvement of hepatocyte growth factor (HGF) in this process and the cell type of migrated hematopoietic cells by HGF.

METHODS

The CD34(+) cells and colony forming cells in the peripheral blood were examined in HGF transgenic, recombinant HGF-administered, and HGF-expressing adenovirus-administered mice. The cell type mobilized by HGF was examined by the percentages of donor cells in the peripheral blood of the recipient mice transplanted with Lin(-)c-kit(+)Sca-1(+)CD34(+) cells and those with Lin(-)c-kit(+)Sca-1(+)CD34(-) cells. Expression of stem cell factor (SCF) was examined after the addition of HGF in MS-5 stromal cells. The numbers of the cells which were mobilized from bone marrow and recruited into liver by HGF were assessed using green fluorescence fluorescent (GFP)-chimera mice.

RESULTS

Mobilized CD34+ cells and colony forming cells in the peripheral blood were increased by HGF treatment. The cells mobilized by HGF were mostly Lin(-)c-kit(+)Sca-1(+)CD34(+) cells. Recruitment of bone marrow cells into liver was not suppressed in MMP-9-/- mice. Expression of SCF was induced by HGF in MS-5 stromal cells. However, expression of CXCR4, SDF-1, MMP-9 or VCAM-1 was not changed. The numbers of GFP-positive cells in liver 1 month after treatment by HGF was greater than that by G-CSF.

CONCLUSION

The results of the present study suggest that HGF mobilizes and recruits hematopoietic progenitor cells from bone marrow into the liver through SCF-mediated mechanism.

Comparison of the pharmacodynamic profiles of a biosimilar filgrastim and Amgen filgrastim: results from a randomized, phase I trial

Further to the patent expiry of Neupogen (Amgen filgrastim), Hospira has developed a biosimilar filgrastim (Nivestim) that may offer a clinically effective alternative for multiple hematologic and oncologic indications. Here results are reported from a phase I trial, primarily designed to compare the pharmacodynamic profiles of Hospira filgrastim and Amgen filgrastim. A phase I, single-center, double-blind, randomized trial was undertaken to demonstrate equivalence of the pharmacodynamic characteristics of Hospira filgrastim and Amgen filgrastim. Fifty healthy volunteers were randomized to receive 5 or 10 microg/kg dosing, before further randomization to treatment sequence. All volunteers received five daily subcutaneous doses of Hospira filgrastim or Neupogen, with subsequent crossover to the alternative treatment. Bioequivalence was evaluated by analysis of variance; if the estimated 90% confidence intervals (CIs) for the ratio of 'test' to 'reference' treatment means were within the conventional equivalence limits of 0.80-1.25, then bioequivalence was concluded. Forty-eight volunteers completed the study. Geometric mean absolute neutrophil count area under the curve from time 0 to the last time point at day 5 (primary endpoint) was comparable in volunteers given Hospira filgrastim or Amgen filgrastim at 5 microg/kg (ratio of means, 0.98; 90% CI, 0.92-1.05) or 10 microg/kg (ratio, 0.97; 90% CI, 0.93-1.01); 90% CIs were within the predefined range necessary to demonstrate bioequivalence. Hospira filgrastim was well tolerated with no additional safety concerns over Amgen filgrastim. Hospira filgrastim is bioequivalent with Amgen filgrastim with regard to its pharmacodynamic characteristics.

Stem cell bioprocessing: fundamentals and principles

In recent years, the potential of stem cell research for tissue engineering-based therapies and regenerative medicine clinical applications has become well established. In 2006, Chung pioneered the first entire organ transplant using adult stem cells and a scaffold for clinical evaluation. With this a new milestone was achieved, with seven patients with myelomeningocele receiving stem cell-derived bladder transplants resulting in substantial improvements in their quality of life. While a bladder is a relatively simple organ, the breakthrough highlights the incredible benefits that can be gained from the cross-disciplinary nature of tissue engineering and regenerative medicine (TERM) that encompasses stem cell research and stem cell bioprocessing. Unquestionably, the development of bioprocess technologies for the transfer of the current laboratory-based practice of stem cell tissue culture to the clinic as therapeutics necessitates the application of engineering principles and practices to achieve control, reproducibility, automation, validation and safety of the process and the product. The successful translation will require contributions from fundamental research (from developmental biology to the 'omics' technologies and advances in immunology) and from existing industrial practice (biologics), especially on automation, quality assurance and regulation. The timely development, integration and execution of various components will be critical-failures of the past (such as in the commercialization of skin equivalents) on marketing, pricing, production and advertising should not be repeated. This review aims to address the principles required for successful stem cell bioprocessing so that they can be applied deftly to clinical applications.

Finding the needle in the hay stack: hematopoietic stem cells in Fanconi anemia

Fanconi anemia is a rare bone marrow failure and cancer predisposition syndrome. Childhood onset of aplastic anemia is one of the hallmarks of this condition. Supportive therapy in the form of blood products, androgens, and hematopoietic growth factors may boost blood counts temporarily. However, allogeneic hematopoietic stem cell transplantation (HSCT) currently remains the only curative treatment option for the hematologic manifestations of Fanconi anemia (FA). Here we review current clinical and pre-clinical strategies for treating hematopoietic stem cell (HSC) failure, including the experience with mobilizing and collecting CD34+ hematopoietic stem and progenitor cells as target cells for somatic gene therapy, the current state of FA gene therapy trials, and future prospects for cell and gene therapy.

Granulocyte colony-stimulating factor administration: adverse events

Recombinant human granulocyte colony-stimulating factor (G-CSF) has been in clinical use for approximately 2 decades. In healthy donors, it has been used to mobilize peripheral blood progenitor cells for hematopoietic stem cell transplantation and granulocytes for apheresis collection. In patients, it has been used to decrease the duration of neutropenia after chemotherapy and to offset the neutropenia due to myelodysplasia, acquired immunodeficiency syndrome, and genetic disorders of granulocyte production. As the number of uses of G-CSF in clinical practice grows, more side effects of this generally safe pharmaceutical agent are being recognized. Our objective in this article is to provide an in-depth review of the reported adverse events associated with the use of G-CSF.

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.

An analysis of the optimal timing of peripheral blood stem cell harvesting following priming with cyclophosphamide and G-CSF

Increasing demand on the apheresis service makes efficient harvesting of peripheral blood stem cells (PBSCs) essential. A total of 168 adult patients with haematological malignancy were primed using low-moderate dose cyclophosphamide (1.5-3 g/m(2)) with G-CSF 5-10 microg/kg per day. Harvesting was booked and peripheral blood (PB) counts first checked between 6 and 10 days post-priming. One hundred and thirty (77%) patients harvested successfully (total harvest yield > or =2 x 10(6) CD34(+)/kg) and the median PBSC collection per procedure was 2.18 x 10(6)/kg (range 0.1-14.5). Only more lines of prior chemotherapy predicted failure to harvest in multivariate analysis (P=0.003). The PB CD34(+) cell count correlated significantly with harvest yield (r=0.8448, P<0.0001). A PB CD34(+) count > or =10/microl predicted a collection of > or =2 x 10(6)/kg (positive-predictive value of 61%, negative-predictive-value 100%). Patients first attending day 9 required significantly fewer visits to achieve a successful harvest than those first attending days 6-8 without increasing the risk of failure. No significant difference in failure rates, number of days attending and total harvest yield was found between days 9 and 10 attendees. Collection from day 9 may however enable higher target yields to be achieved. PB CD34(+) count monitoring should commence and harvesting booked from day 9 to optimize both the harvest and the efficiency of the PBSC harvesting service.

Risk assessment in haematopoietic stem cell transplantation: Stem cell source

Bone marrow (BM) has been used for many years as the unique source of progenitor cells for allogeneic transplantation. However, two other sources of progenitor cells, peripheral blood (PB) and umbilical cord (UC), are being increasingly used. The type of graft is one of the most important factors in determining the speed and robustness of the reconstitution after the transplant of monocytes, T lymphocytes, B lymphocytes, NK cells, and dendritic cells. This fact is of especial relevance since the most important reactions after allogeneic transplants - e.g. graft-versus-host disease (GVHD), graft-versus-leukaemia effect (GvL), achievement of full donor chimerism, and fight against infections - are strongly influenced by a rapid and robust reconstitution of these cells. For this reason, the choice of the type of graft for allogeneic transplantation will influence the clinical outcome.

Peripheral blood stem cell yield in 400 normal donors mobilised with granulocyte colony-stimulating factor (G-CSF): impact of age, sex, donor weight and type of G-CSF used

Mobilised peripheral blood is now the main source of stem cells collected from normal donors. We report our experience of mobilising and collecting 400 normal healthy donors using standardised procedures and techniques. Target recipient doses were reached with one aphaeresis in 63% of donors and with two aphereses in 81% of donors. Approximately 2% of donors yielded such low progenitor values that they were termed 'poor mobilisers'. There were minor effects of donor age, weight and sex and where possible, larger male donors under the age of 55 years should be selected. Two forms of granulocyte colony-stimulating factor (G-CSF) were used at the same dose and no significant difference was seen in the yield of CD34+ cells collected/l of blood processed. However, a greater number of granulocyte-macrophage colony-forming cells were harvested using lenograstim (glycosylated G-CSF) compared with filgrastim (non-glycosylated G-CSF; P = 0.002). CD34+ cell yields were also measured halfway through the aphaeresis procedure. This was found to be highly predictive of final yield and facilitated distribution of the stem cell product to other centres. The observation that CD34+ yields did not decline in the second half compared with the first half of aphaeresis suggests that the circulating cell numbers are not static.

Factors affecting PBSC mobilization and collection in healthy donors

Peripheral blood stem cells are widely used as stem cell source for allografting. Progenitor cells can be effectively mobilized into peripheral blood in majority of healthy donors with a brief administration of G-CSF. A mobilization course in 111 donors (median age 40years) was retrospectively studied and the factors influencing the efficacy of mobilization were analyzed. The median number of CD34+ cells per kg recipient weight 5.1x10(6) was obtained after a median of two aphereses. The target cell dose (4.0x10(6)/kg) was reached in 69% of donors. Circulating CD34+ count and CD34+ yield were negatively associated with donor's age. Other independent factors associated with superior yield were precollection platelet and WBC counts. In multivariate analysis only CD34+ precount predicted for CD34+ yield. G-CSF had an acceptable short-term safety profile. Our data confirm that apheresis is a safe procedure in healthy including aged donors and suggest that older donors could be poorer mobilizers than younger.

A prospective randomized study on the mobilization of CD34+ cells comparing continuous intravenous vs subcutaneous administration of rhG-CSF in normal donors

The efficacy of mobilizing peripheral blood progenitor cells (PBPC) with continuous intravenous (c.i.v.) administration of rhG-CSF was randomly compared to subcutaneous (s.c.) administration, in 15 normal donors in each arm of the study for 6 days. The percentage and absolute numbers of CD34+ cells in the c.i.v. and s.c. groups increased maximally at day 3 and 5, respectively, when compared with the steady-state (day 0) level. Peak CD34+ cell levels were achieved on day 3 in the c.i.v. group, with more rapid results than in the s.c. group (49.3/microl vs 35.9/microl, P=0.043). Plasma rhG-CSF levels declined progressively during mobilization in each group as the WBC increased. The serum level of rhG-CSF did not correlate with CD34+ cell counts in the peripheral blood. Toxicity profiles in the c.i.v. and s.c. groups were similar. Each regimen was effective in successfully mobilizing the target CD34 cell number.

The effect of peptide stimulation on haematopoietic stem cell mobilisation including engraftment characteristics and a note on donor side effects

Aplasia or irreversible bone marrow failure and a variety of haematologic malignancies, as well as an increasing number of solid tumours, currently include various forms of marrow or equivalent transplantation in routine management. In both allogeneic and autologous procedures stable recipient immunohaematopoietic reconstitution depends upon infusing the requisite population harvested at a precise time following commencement of a stimulatory peptide. In a first step this prospective study documented the safety of apheresis, defined side effects and enumerated mononuclear, CD34+ and CD3+ cells obtained. In the second stage delivery of the graft, characterised in this way and with the additional measurement of in vitro growth in clonogenic assay, to the suitably conditioned patient was correlated with recovery of neutrophil and platelet numbers appearing in the circulation. In a third and ongoing analysis the influence of passenger T-lymphocytes is being evaluated for impact on infection and a potential anti-tumour effect. The conclusion is that this technology is reliable, has a high degree of patient acceptability without untoward complications, and that local results correspond to international experience thereby providing an important and relevant measure of quality control.

Analysis of remobilization success in patients undergoing autologous stem cell transplants who fail an initial mobilization: risk factors, cytokine use and cost

Inadequate stem cell mobilization is seen in approximately 25% of patients undergoing autotransplantation for hematologic malignancies. Remobilization strategies include chemotherapy/cytokine combinations or high-dose cytokines alone or in combination. From 1/1997 to 7/2002, we remobilized 86 patients who failed an initial mobilization (median total CD34=0.72 x 10(6)/kg) in sequential cohorts using high-dose G-CSF (32 microg/kg/day) or G-CSF(10 microg/kg/day)+GM-CSF (5 microg/kg/day). No difference in CD34/kg yields were seen (G-CSF alone: 2.2 x 10(6) and G-CSF+GM-CSF 1.6 x 10(6)) in the median 3 aphereses performed (P=0.333). Of the 86, 23 (27%) failed the second mobilization; 14 were remobilized again (yield=1.5 x 10(6) CD34/kg; three aphereses). Of the 86, 93% went to transplant: three progressed, and three had inadequate stem cells. Significant risk factors for a failed remobilization were: number of stem-cell-damaging regimens (P=0.015), time between last chemotherapy and first mobilization (P=0.028), and higher WBC at initiation of first mobilization (P=0.04). High-dose G-CSF (32 microg/kg/day) was more costly @ USD $9,016, vs $5,907 for the G-CSF+GM-CSF combination (P<0.001). Most patients failing an initial mobilization benefit from a cytokine only remobilization. Lower cost G-CSF+GM-CSF is as effective as high-dose G-CSF.

Second mobilization and collection of peripheral blood progenitor cells in healthy donors is associated with lower CD34(+) cell yields

We have retrospectively evaluated the results of two cycles of mobilization and collection of peripheral blood progenitor cells (PBPC) from 46 healthy donors included in the Spanish National Donor Registry. Mobilization involved the administration of granulocyte colony-stimulating factor (G-CSF) at a median dose of 10 microg/kg per day, and apheresis was begun after the fourth dose of G-CSF in both cycles. The median interval between both mobilizations was 187 days (range, 7-1428 days). The incidence and types of side-effects were similar after both donations, with 25 and 26 donors developing some toxicity after the first and second donations, respectively. The median number of CD34(+) cells collected was higher after the first mobilization than after the second (5.15 versus 3.16 x 10(6)/kg, respectively; p = 0.05), and 29 donors yielded fewer CD34(+) cells after the second mobilization (p = 0.018). A lower proportion of donors yielded CD34(+) cell counts >4 x 10(6)/kg after the second cycle than after the first (52% versus 76%, respectively; p = 0.057). Our study shows that second rounds of PBPC collection from normal donors are well tolerated but are associated with a significantly reduced number of CD34(+) cells collected when the same mobilization scheme is used.

Dose and schedule effect of G-GSF for stem cell mobilization in healthy donors for allogeneic transplantation

In the present review, we analyze the literature regarding the dose and schedule effects of granulocyte stimulating factor (G-CSF) for stem cell mobilization of healthy donors for allogeneic stem cell transplantation. There is now evidence for a dose and schedule dependency of G-CSF in mobilizing peripheral blood progenitor cells (PBSC) in healthy donors for allogeneic stem cell transplantation. In general, a dose between 10 and 16 microg/kg split into two doses is recommended. Leukapheresis should be performed on day 4 or 5. A higher dose of G-CSF might be appropriate in donors with low CD34+ baseline cell count (< 2000/ml) or if a high CD34+ cell number is required. However, a higher dose of G-CSF results in a higher acute toxicity like bone and muscle pain or headache. Severe adverse events like thromboembolic events, cerebrovascular incidents, anaphylactoid reactions and an atraumatic splenic rupture have been rarely reported. A prolonged follow-up of the donors is needed to rule out late toxicity of the donors.

Stem cell mobilisation with 16 microg/kg vs 10 microg/kg of G-CSF for allogeneic transplantation in healthy donors

We compared two doses of recombinant human granulocyte-stimulating factor (G-CSF) for stem cell mobilisation in 90 healthy donors for allogeneic stem cell transplantation in a retrospective analysis. Group I (n = 46) received 10 microg/kg G-CSF (filgrastim) given as 5 microg/kg twice daily, and group II (n = 44) received 16 microg/kg, given as 8 microg/kg twice daily with a 12-h interval. The groups were well-balanced for age and body-weight. G-CSF application was performed on an out-patient basis, and leukapheresis was started in all donors on day 5. The most frequent side-effects of G-CSF were grade I/II, bone pain, headache and fatigue in both groups, whereas grade III of bone pain, headache and fatigue occurred in the 2 x 8 microg/kg group only. One serious non-fatal event with non-traumatic spleen rupture occurred in the 2 x 5 microg/kg group. The CD34(+)cell count in the first apheresis of all donors was 5.1 x 10(6)/kg donor weight (range, 1.5-19.3). The CD34(+) cell harvest was higher in the 2 x 8 microg/kg group than in the 2 x 5 microg/kg group (7.1 x 10(6)/kg vs 4.9 x 10(6)/kg; P = 0.09). The target of collecting >5.0 x 10(6) CD34(+) cells/kg donor weight with one apheresis procedure was achieved in 45% of group I and in 61% of group II, respectively. Administering G-CSF at a dosage of 8 microg/kg twice daily leads to a higher CD34(+) cell yield than a dosage of 2 x 5 microg/kg, but is associated with increased toxicity and higher cost.

Donation of stem cells from blood or bone marrow: results of a randomised study of safety and complaints

Biological consequences and physical complaints were compared for donors randomly assigned either to blood stem cell (BSC) or bone marrow (BM) donation. In the period 1994-1999, 61 consecutive donors were included. The BSC donors were given G-CSF 10 microg/kg s.c., daily during 5 days before the first leukapheresis. Nineteen donors had one leukapheresis, 10 required two and one donor needed three leukaphereses in order to reach the target cell number of 2 x 10(6) CD34(+) cells/kg bw of the recipient. A median platelet nadir of 102 x 10(9)/l was reached shortly after the last leukapheresis. Three weeks post harvest, 17 of 30 BSC donors had a mild leukopenia. Six had a leukopenia lasting more than a year before returning to normal values. Both groups were monitored prospectively through a standardised questionnaire completed by the donors. BSC donation was significantly less burdensome than BM donation and was preferred by the donors. The short-term risks of BSC mobilisation and harvest seem negligible. The potential long-term effects of G-CSF are unresolved and the donors must be followed closely.

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.

Analysis of factors associated with low peripheral blood progenitor cell collection in normal donors

BACKGROUND

Predictive factors of the response to rHuG-CSF in normal donors have not been extensively studied.

STUDY DESIGN AND METHODS

We analyzed factors influencing CD34+ cell yield in the 1st day of collection in 261 healthy donors from the Spanish National Donor Registry. The median age was 38 years (range, 2-72). The median dose of rHuG-CSF was 10 microg per kg per day (range, 5-20) over 4 days. In 103 donors (40%), <4 x 10(6) per kg CD34+ cells were collected. The variables that were analyzed included age, sex, weight, basal complete blood cell count, dose, type of rHuGCSF and schedule of administration, and maximum WBC count before apheresis.

RESULTS

By univariate analysis, the maximum WBC count (<50 vs. >or=50 x 10(9)/L, p = 0.004), advanced age (p = 0.008), and number of daily rHuG-CSF doses (one vs. two; p = 0.01) correlated with the number of CD34+ cells collected. By multivariate analysis, donors age (<38 vs. >or=38 years; p = 0.014) and a single daily dose of rHuG-CSF (p = 0.005) were the two variables that significantly predicted a low CD34+ cell yield.

CONCLUSION

Donors' age, with a threshold of 38 years or more, and the rHuG-CSF schedule are the factors that significantly affected CD34+ cell mobilization and collection in healthy donors.

Allogeneic transplantation using peripheral blood stem cells

Over the past 9 years there has been a remarkable increase in the use of peripheral blood stem cells (PBSC) for allogeneic transplantation, primarily for matched sibling transplants but also increasingly for unrelated donor transplantation. In 1999 over 50% of all sibling transplants and over 25% of unrelated donor transplants reported to the European Group for Blood and Marrow Transplantation (EBMT) used PBSC. The major reason for this increasing use of PBSC relates to the rapid haemopoietic recovery seen which mirrors the advantages of using PBSC in autologous transplantation. This improvement in engraftment is a consequence of the larger number of stem cells that can be collected from G-CSF-mobilized peripheral blood compared to bone marrow. Evidence from randomized trials now shows a survival advantage for the use of PBSC in patients with advanced leukaemia. The reason for this improved survival appears primarily to relate to a reduced risk of transplant-related mortality and, possibly, a reduced risk of relapse, However, these randomized studies have also confirmed that there is an increased risk of chronic graft-versus-host disease associated with PBSC transplantation and further follow-up is required to determine the long-term impact on outcome.

Allogeneic peripheral blood stem cell transplantation

Granulocyte colony stimulating factor (G-CSF)-mobilized peripheral blood stem cells (PBSC) are now widely used instead of bone marrow for autologous transplantation due to earlier hematopoietic recovery after transplant. The low toxicity of G-CSF has prompted phase I and II studies to evaluate PBSC for allogeneic transplantation; these studies have demonstrated that engraftment of neutrophils, red blood cells and platelets is faster with peripheral blood cells compared to marrow. In randomized studies comparing mobilized PBSC and marrow for allogeneic transplantation, most trials have confirmed significantly earlier engraftment with PBSC and similar risks of acute graft-vs.-host disease (GVHD). In some trials, an increase of 10-15% in grade II-IV GVHD has been noted with PBSC. All studies showed a trend towards more chronic GVHD with PBSC. Some randomized studies have shown improved survival and disease-free survival with the use of PBSC due to lowered transplant-related mortality and fewer relapses in recipients of PBSC as a result of improved immune reconstitution and a graft-vs.-leukemia (GVL) effect. This survival benefit is most apparent in patients with more advanced hematologic malignancies, but further studies are needed to define the relative benefits of PBSC for patients with less advanced disease. The GVL effect of PBSC is currently being exploited with the use of non-ablative allografts.

Safety of granulocyte colony-stimulating factor in normal donors

Granulocyte colony-stimulating factor (G-CSF), which is widely used to mobilize peripheral blood stem cells (PBSC) from normal donors, has led to the use of PBSC as a major alternative to bone marrow for patients undergoing allogeneic transplants. Safety issues related to the administration of G-CSF to normal donors, however, are still under study. The short-term effects after G-CSF administration are well known and manageable. G-CSF induces a hypercoagulable state, which may predispose certain donors to thrombotic complications. A dose of 10 microg/kg/d for 5 days has been recommended for routine clinical use, but the optimal dose and schedule for PBSC collection are still being defined. Small studies to date have shown no late effects of G-CSF administration but there is insufficient information regarding any long-term adverse effects or risks. Although the administration of G-CSF to normal donors for PBSC collection appears safe, longer follow-up is required.