Extension of human GCSF serum half-life by the fusion of albumin binding domain.

Granulocyte colony stimulating factor (GCSF) can decrease mortality of patients undergo chemotherapy through increasing neutrophil counts. Many strategies have been developed to improve its blood circulating time. Albumin binding domain (ABD) was genetically fused to N-terminal end of GCSF encoding sequence and expressed as cytoplasmic inclusion bodies within Escherichia coli. Biological activity of ABD-GCSF protein was assessed by proliferation assay on NFS-60 cells. Physicochemical properties were analyzed through size exclusion chromatography, circular dichroism, intrinsic fluorescence spectroscopy and dynamic light scattering. Pharmacodynamics and pharmacokinetic properties were also investigated in a neutropenic rat model. CD and IFS spectra revealed that ABD fusion to GCSF did not significantly affect the secondary and tertiary structures of the molecule. DLS and SEC results indicated the absence of aggregation formation. EC50 value of the ABD-GCSF in proliferation of NFS-60 cells was 75.76 pg/ml after 72 h in comparison with control GCSF molecules (Filgrastim: 73.1 pg/ml and PEG-Filgrastim: 44.6 pg/ml). Animal studies of ABD-GCSF represented improved serum half-life (9.3 ± 0.7 h) and consequently reduced renal clearance (16.1 ± 1.4 ml/h.kg) in comparison with Filgrastim (1.7 ± 0.1 h). Enhanced neutrophils count following administration of ABD-GCSF was comparable with Filgrastim and weaker than PEG-Filgrastim treated rats. In vitro and in vivo results suggested the ABD fusion as a potential approach for improving GCSF properties.

A prospective study of filgrastim pharmacokinetics in morbidly obese patients compared with non-obese controls.

INTRODUCTION: Filgrastim is a human granulocyte colony-stimulating factor (G-CSF). There are limited data on dosing filgrastim in obesity. The objective of this study was to compare filgrastim pharmacokinetic parameters for morbidly obese and non-obese patients after a single subcutaneous dose of filgrastim dosed per actual body weight. METHODS: This prospective, matched-pair study (NCT01719432) included patients ≥18 years of age, receiving filgrastim at 5 µg/kg with a weight >190% of their ideal body weight (IBW) for "morbidly obese" patients or within 80%-124% of IBW for matched-control patients. The control group was prospectively matched for age (within 10 years), degree of neutropenia, and gender. Filgrastim doses were not rounded to vial size, to allow more accurate assessment of exposure. Blood samples were collected at 0 (prior to dose), 2, 4, 6, 8, 12, and 24 h after the first subcutaneous administration of filgrastim. RESULTS: A total of 30 patients were enrolled in this prospective pharmacokinetic study, with 15 patients assigned to each arm. Non-compartmental analysis showed that the systemic clearance (Cl) was 0.111 ± 0.041 ml/min in the morbidly obese group versus 0.124 ± 0.045 ml/min in the non-obese group (p = 0.44). Additionally, the mean area under the curve (AUC0-24h ) was 49.3 ± 13.9 ng/ml × min in the morbidly obese group versus 46.3 ± 16.8 ng/mL x min in the non-obese group (p = 0.6). No differences were seen in maximum concentrations (Cmax ) between the two groups (morbidly obese: 48.1 ± 14.7 ng/ml vs. non-obese: 49.2 ± 20.7 ng/ml (p = 0.87)). The morbidly obese group had a numerically higher, but not statistically significant, increase in time to maximum concentration (Tmax ) compared to the non-obese group (544 ± 145 min vs 436 ± 156 min (p = 0.06), respectively). CONCLUSION: Calculating subcutaneous filgrastim doses using actual body weight appears to produce similar systemic exposure in morbidly obese and non-obese patients with severe neutropenia.

Pharmacokinetic and Pharmacodynamic Characteristics of Tripegfilgrastim, a Pegylated G-CSF, in Pediatric Patients with Solid Tumors.

A long-acting granulocyte colony-stimulating factor, tripegfilgrastim, was approved in Korea for the prevention of chemotherapy-induced neutropenia in adult patients. In this study, we evaluated the pharmacokinetics, pharmacodynamics, and safety of tripegfilgrastim in pediatric patients. A phase I, open-label, single ascending-dose study was performed in pediatric patients with solid tumors or lymphoma (ClinicalTrials.gov, NCT02963389). The patients were stratified according to age groups (aged 6 to 12 or 12 to 19 years) and received a single subcutaneous dose of tripegfilgrastim 60 µg/kg or 100 µg/kg. Tripegfilgrastim was administered 24 hours after the end of the chemotherapy, and serial blood sampling and safety monitoring were conducted. Twenty-seven patients with solid tumors were enrolled in this study. Tripegfilgrastim was detectable in plasma for an extended period (terminal half-life > 40 hours), and plasma concentrations increased slightly less than dose proportionally. The mean duration of grade 4 neutropenia was reduced as the average tripegfilgrastim concentration during the initial neutrophil recovery process increased. No substantial differences in the pharmacokinetic and pharmacodynamic responses were observed between the two age groups. When stratified by body weight, weighing more than 45 kg has a higher risk of a prolonged neutropenia period when receiving the lower dose (60 µg/kg) of tripegfilgrastim. Tripegfilgrastim was generally safe and well-tolerated in the pediatric patients. These results justify further clinical investigations of tripegfilgrastim at 100 µg/kg dose in pediatric patients.

Granulocyte-colony stimulating factor (G-CSF) to treat acute-on-chronic liver failure: A multicenter randomized trial (GRAFT study).

BACKGROUND & AIMS: Based on positive results from small single center studies, granulocyte-colony stimulating factor (G-CSF) is being widely used for the treatment of patients with acute-on-chronic liver failure (ACLF). Herein, we aimed to evaluate the safety and efficacy of G-CSF in patients with ACLF. METHODS: In this multicenter, prospective, controlled, open-label phase II study, 176 patients with ACLF (EASL-CLIF criteria) were randomized to receive G-CSF (5 µg/kg daily for the first 5 days and every third day thereafter until day 26) plus standard medical therapy (SMT) (n = 88) or SMT alone. The primary efficacy endpoint was 90-day transplant-free survival analyzed by Cox regression modeling. The key secondary endpoints were overall and transplant-free survival after 360 days, the development of ACLF-related complications, and the course of liver function scores during the entire observation period. RESULTS: Patients treated with G-CSF had a 90-day transplant-free survival rate of 34.1% compared to 37.5% in the SMT group (hazard ratio [HR] 1.05; 95% CI 0.711-1.551; p = 0.805). Transplant-free and overall survival at 360 days did not differ between the 2 arms (HR 0.998; 95% CI 0.697-1.430; p = 0.992 and HR 1.058; 95% CI 0.727-1.548; p = 0.768, respectively). G-CSF did not improve liver function scores, the occurrence of infections, or survival in subgroups of patients without infections, with alcohol-related ACLF, or with ACLF defined by the APASL criteria. Sixty-one serious adverse events were reported in the G-CSF+SMT group and 57 were reported in the SMT group. In total, 7 drug-related serious adverse reactions occurred in the G-CSF group. The study was prematurely terminated due to futility after conditional power calculation. CONCLUSIONS: In contrast to previous findings, G-CSF had no significant beneficial effect on patients with ACLF in this multicenter controlled trial, which suggests that it should not be used as a standard treatment for ACLF. CLINICALTRIALS. GOV NUMBER: NCT02669680 LAY SUMMARY: Granulocyte-colony stimulating factor was considered as a novel treatment for acute-on-chronic liver failure (ACLF). We performed the first randomized, multicenter, controlled phase II trial, which showed that G-CSF did not improve survival or other clinical endpoints in patients with ACLF. Therefore, G-CSF should not be used to treat liver disease outside clinical studies.

Novel G-CSF conjugated anionic globular dendrimer: Preparation and biological activity assessment.

The most crucial role of granulocyte colony-stimulating factor (G-CSF) in the body is to increase the strength of immune system. In recent years, research on the use of nanoparticles in pharmaceuticals has been considered, most of which have been for drug-loading purposes. In this study, a novel G-CSF conjugated dendrimer was synthesized and characterized using different techniques. In vitro cytotoxicity was assessed on A549 and L929 cells, while abnormal toxicity was studied in mice. In vitro and in vivo biological activities were assessed in NFS60 cells and rats, respectively. In addition, in vivo distribution, plasma half-life, and histopathological effect were studied in rat. The characterization tests confirmed the successful conjugation. There was no difference between G-CSF cytotoxicity before and after conjugation, and no difference with the control group. No mice showed abnormal toxicity. Although in vitro biological activity revealed both conjugated and free G-CSF promote proliferation cells, biological activity decreased significantly after conjugation about one-third of the unconjugated form. Nonetheless, in vivo biological activity of conjugated G-CSF increased by more than 2.5-fold relative to the unconjugated form, totally. Fortunately, no histopathologic adverse effect was observed in vital rat tissues. Also, in vivo distribution of the conjugate was similar to the native protein with an enhanced terminal half-life. Our data revealed that G-CSF conjugated dendrimer could be considered as a candidate to improve the in vivo biological activity of G-CSF. Moreover, multivalent capability of the dendrimer may be used for other new potentials of G-CSF in future perspectives.

Pharmacokinetics and Pharmacodynamics of Two Formulations of Pegylated Recombinant Human Granulocyte Colony-Stimulating Factor in Healthy Chinese Subjects: An Open-Label, Randomized, Parallel-Design Bioavailability Study.

Pegylated recombinant human granulocyte colony-stimulating factor (PEG-rhG-CSF, pegfilgrastim) is a long-acting derivative of recombinant human granulocyte colony-stimulating factor with limited renal clearance and a longer half-life. It is used for the prevention of febrile neutropenia, owing to its capacity to promote neutrophil recovery. In this study, the pharmacokinetics, pharmacodynamics, safety, and immunogenicity of 2 formulations of PEG-rhG-CSF were evaluated in healthy Chinese subjects. Twenty-four male subjects who received a single dose of subcutaneous PEG-rhG-CSF 100 µg/kg were randomized to either treatment A (3 mg/mL) or treatment B (1 mg/mL). Noncompartmental pharmacokinetic parameters of PEG-rhG-CSF were derived from serum concentration-time data. In addition, absolute neutrophil count (ANC) as a pharmacodynamic maker, immunogenicity through antidrug antibody testing, and safety were evaluated. The mean area under the concentration-time curve from time zero to the last quantifiable concentration (AUC0-t ) and the mean maximum concentration (Cmax ) of PEG-rhG-CSF after treatment A were 5070 ng·h/mL and 125 ng/mL, respectively; these values were comparable to those measured after treatment B (5340 ng·h/mL and 123 ng/mL, respectively). The mean value of area under the △ANC (baseline-adjusted ANC)-time curve and the maximum △ANC values were 4380 × 109  h/L and 33.1 × 109 /L, respectively, in the treatment A group, and 5170 × 109  h/L and 38.6 × 109 /L, respectively, in the treatment B group. The pharmacokinetic and pharmacodynamic profiles were similar for the 2 PEG-rhG-CSF formulations following a single dose of 100 µg/kg. The safety and immunogenicity profiles were also similar, with no significant differences. The dose adjustment of PEG-rhG-CSF was not considered necessary for formulation transformation.

Commentary - A comprehensive safety understanding of granulocyte-colony stimulating factor biosimilars and Intended Copy Biologics in treating chemotherapy associated febrile neutropenia.

Filgrastim, human white cell growth factor, Granulocyte colony-stimulating factor (G-CSF), is a core medicine in the WHO list of Essential Medicines. For this reason, recent reporting of statistically significant safety and efficacy differences between reference and Biosimilar brands of filgrastim by Rastogi and the Indian Pharmacopoeia Commission in Toxicology and Applied Pharmacology in 2020 is of great concern [Shruti Rastogi et al. Towards a comprehensive safety understanding of granulocyte-colony stimulating factor biosimilars in treating chemotherapy associated febrile neutropenia: Trends from decades of data. Toxicology and Applied Pharmacology Volume 395, 15 May 2020, 114,976. https://doi.org/10.1016/j.taap.2020.114976]. This commentary shows that the alarming report is a result of incorrect statistical tests misapplied to inappropriate data sets compounded by a further problem relating to the strict regulatory definition of a Biosimilar Medicine as opposed that of an Intended Copy Biologic. In contrast, the body of evidence from more than seven and a half thousand participants in Confirmatory Clinical Studies and Post Approval Clinical Studies as well as the Periodic Safety Update Reports confirms that European approved filgrastim Biosimilars show no meaningful difference in quality, safety or efficacy compared to the reference brand.

Characterization of a Long-Acting Site-Specific PEGylated Murine GM-CSF Analog and Analysis of Its Hematopoietic Properties in Normal and Cyclophosphamide-Treated Neutropenic Rats.

Previously we reported that site-specific modification of the human granulocyte-macrophage colony-stimulating factor (GM-CSF) A3C analog with polyethylene glycol (PEG) dramatically improved the pharmacokinetic properties of the protein in rats. However, we could not evaluate the hematological properties of the PEG-A3C protein in rats because human GM-CSF is inactive in rodents. To study the biological effects of PEGylated GM-CSF analogs in rodents we created a homologous site-specific PEGylated murine (mu) GM-CSF (T3C) protein. muGM-CSF and the T3C protein were expressed in Escherichia coli and purified by column chromatography. The purified T3C protein was covalently modified with a linear 20 kDa- or a branched 40 kDa-maleimide-PEG, and the monoPEGylated proteins purified by column chromatography. muGM-CSF, T3C and the two PEG-T3C proteins had comparable in vitro biological activities, as measured by stimulation of proliferation of the murine FDC-P1 cell line. The PEG-T3C proteins had 10- to 25-fold longer circulating half-lives than muGM-CSF and stimulated greater and longer lasting increases in neutrophils and white blood cells than muGM-CSF following a single intravenous or subcutaneous administration to rats. Treatment of rats made neutropenic with cyclophosphamide with the PEG-T3C proteins shortened the time for recovery of neutrophils to normal levels from 9 or 10 days to 5 or 6 days, whereas muGM-CSF showed no benefit versus vehicle solution. Acceleration of neutrophil recovery in cyclophosphamide-treated rats required a minimum of three PEG-T3C treatments over five days. The PEG-T3C proteins should prove useful for evaluating the potential therapeutic benefits of GM-CSF and long-acting GM-CSF proteins in rodent disease models.

Albumin Modifies Responses to Hematopoietic Stem Cell Mobilizing Agents in Mice.

Albumin, the most abundant plasma protein, not only controls osmotic blood pressure, but also serves as a carrier for various small molecules, including pharmaceuticals. Its impact on pharmacological properties of many drugs has been extensively studied over decades. Here, we focus on its interaction with the following mobilizing agents: Granulocyte-colony stimulating factor (G-CSF) and AMD3100, where such analyses are lacking. These compounds are widely used for hematopoietic stem cell mobilization of healthy donors or patients. Using albumin-deficient (Alb-/-) mice, we studied the contribution of albumin to mobilization outcomes. Mobilization with the bicyclam CXCR4 antagonist AMD3100 was attenuated in Alb-/- mice compared to wild-type littermates. By contrast, mobilization with recombinant human G-CSF (rhG-CSF), administered twice daily over a five-day course, was significantly increased in Alb-/- mice. In terms of a mechanism, we show that rhG-CSF bioavailability in the bone marrow is significantly improved in Alb-/- mice, compared to wild-type (WT) littermates, where rhG-CSF levels dramatically drop within a few hours of the injection. These observations likely explain the favorable mobilization outcomes with split-dose versus single-dose administration of rhG-CSF to healthy donors.

Preclinical evaluation of a biobetter candidate: Pharmacokinetics and pharmacodynamics of GX-G3 in healthy and neutropenia-induced rats.

Neutropenia is a condition of an abnormally low number of neutrophils which render patients more susceptible to infections, especially to bacterial infections, as the condition may become life threatening and deadly without prompt medical attention. Various factors such as, anticancer drugs, radiotherapy, infectious diseases, congenital defects, or vitamin B12/B9 deficiency can trigger neutropenia. GX-G3, a human hybrid (hy) Fc-fused granulocyte colony stimulating factor (G-CSF), was developed as next-generation G-CSF for the treatment of cancer therapy-induced neutropenia. In this study, with the aim of investigating this promising potential next-generation G-CSF, comparative pharmacokinetic and pharmacodynamic studies were conducted in healthy and neutropenia-induced rats. It was found that t1/2 of GX-G3 is longer than same mass injection of filgrastim and pegfilgrastim and AUEClast (area under theeffect-time curve from time zero to the last measurable ANC level) of absolute neutrophil count showed a significant increase after GX-G3 injection compared with filgrastim and pegfilgrastim in healthy rats. Besides, in duration of neutropenia after the same mass injection GX-G3 showed about 3.3 days of reduction effect compared with that of filgrastim, and 1.3 days of reduction effect compared with that of pegfilgrastim in neutropenia-induced rats. These results demonstrate that the half-life of GX-G3 is longer than pegfilgrastim and GX-G3 is more effective than filgrastim and pegfilgrastim in neutropenia-induced rats.

Granulocyte Colony-Stimulating Factor Combined with Methylprednisolone Improves Functional Outcomes in Rats with Experimental Acute Spinal Cord Injury.

OBJECTIVES: To evaluate the effects of combined treatment with granulocyte colony-stimulating factor (G-CSF) and methylprednisolone in rats subjected to experimental spinal cord injury. METHODS: Forty Wistar rats received a moderate spinal cord injury and were divided into four groups: control (no treatment); G-CSF (G-CSF at the time of injury and daily over the next five days); methylprednisolone (methylprednisolone for 24 h); and G-CSF/Methylprednisolone (methylprednisolone for 24 h and G-CSF at the time of injury and daily over the next five days). Functional evaluation was performed using the Basso, Beattie and Bresnahan score on days 2, 7, 14, 21, 28, 35 and 42 following injury. Motor-evoked potentials were evaluated. Histological examination of the spinal cord lesion was performed immediately after euthanasia on day 42. RESULTS: Eight animals were excluded (2 from each group) due to infection, a normal Basso, Beattie and Bresnahan score at their first evaluation, or autophagy, and 32 were evaluated. The combination of methylprednisolone and G-CSF promoted greater functional improvement than methylprednisolone or G-CSF alone (p<0.001). This combination also exhibited a synergistic effect, with improvements in hyperemia and cellular infiltration at the injury site (p<0.001). The groups displayed no neurophysiological differences (latency p=0.85; amplitude p=0.75). CONCLUSION: Methylprednisolone plus G-CSF promotes functional and histological improvements superior to those achieved by either of these drugs alone when treating spinal cord contusion injuries in rats. Combining the two drugs did have a synergistic effect.

Model-based optimization of G-CSF treatment during cytotoxic chemotherapy.

PURPOSE: Although G-CSF is widely used to prevent or ameliorate leukopenia during cytotoxic chemotherapies, its optimal use is still under debate and depends on many therapy parameters such as dosing and timing of cytotoxic drugs and G-CSF, G-CSF pharmaceuticals used and individual risk factors of patients. METHODS: We integrate available biological knowledge and clinical data regarding cell kinetics of bone marrow granulopoiesis, the cytotoxic effects of chemotherapy and pharmacokinetics and pharmacodynamics of G-CSF applications (filgrastim or pegfilgrastim) into a comprehensive model. The model explains leukocyte time courses of more than 70 therapy scenarios comprising 10 different cytotoxic drugs. It is applied to develop optimized G-CSF schedules for a variety of clinical scenarios. RESULTS: Clinical trial results showed validity of model predictions regarding alternative G-CSF schedules. We propose modifications of G-CSF treatment for the chemotherapies 'BEACOPP escalated' (Hodgkin's disease), 'ETC' (breast cancer), and risk-adapted schedules for 'CHOP-14' (aggressive non-Hodgkin's lymphoma in elderly patients). CONCLUSIONS: We conclude that we established a model of human granulopoiesis under chemotherapy which allows predictions of yet untested G-CSF schedules, comparisons between them, and optimization of filgrastim and pegfilgrastim treatment. As a general rule of thumb, G-CSF treatment should not be started too early and patients could profit from filgrastim treatment continued until the end of the chemotherapy cycle.

Granulocyte Colony-Stimulating Factor Nanocarriers for Stimulation of the Immune System (Part I): Synthesis and Biodistribution Studies.

In the field of cancer immunotherapy, an original approach consists of using granulocyte colony-stimulating factor (G-CSF) to target and activate neutrophils, cells of the innate immune system. G-CSF is a leukocyte stimulating molecule which is commonly used in cancer patients to prevent or reduce neutropenia. We focused herein on developing a G-CSF nanocarrier which could increase the in vivo circulation time of this cytokine, keeping it active for targeting the spleen, an important reservoir of neutrophils. G-CSF-functionalized silica and gold nanoparticles were developed. Silica nanoparticles of 50 nm diameter were functionalized by a solid phase synthesis approach. The technology enabled us to incorporate multiple functionalities on the surface such as a PEG as hydrophilic polymer, DTPA as 111In chelating agent and G-CSF. The gold nanocarrier consisted of nanoparticles of 2-3 nm diameter elaborated with DTPA groups on the surface and functionalized with G-CSF. We studied the particle biodistribution in mice with special attention to organs involved in the immune system. The two nanocarriers with similar functionalization of surface showed different pathways in mice, probably due to their difference in size. Considering the biodistribution after G-CSF functionalization, we confirmed that the protein was capable of modifying the pharmacokinetics by increasing the nanocarrier concentration in the spleen, a reservoir of G-CSF receptor expressing cells.

Granulocyte-Colony Stimulating Factor Nanocarriers for Stimulation of the Immune System (Part II): Dose-Dependent Biodistribution and In Vivo Antitumor Efficacy in Combination with Rituximab.

The purpose of immuno-modulation is to increase or restore the action of immunocompetent cells against tumors with or without the use of monoclonal antibodies. The innate immune system is a key player in various pathological situations, but cells of this system appear to be inhibited or insufficiently active in malignancy or severe infectious diseases. The present study was designed to investigate therapeutic value of nanoparticles (NPs) coupled with bioactive hematopoietic growth factors acting on the innate immune system. The use of nanoparticles (NPs) allowing multimodal detection and multifunctional grafting are currently of great interest for theranostic purposes. In the present work, we have evaluated the impact of the number of granulocyte-colony stimulating factor (G-CSF) grafted on the surface on the NPs on the biodistribution in mice thanks to indium 111 radiolabeling. Furthermore, we have investigated whether grafted G-CSF NPs could stimulate the immune innate system and enhance the therapeutic efficacy of the monoclonal antibody rituximab in mice bearing human lymphoma xenografts. Following intravenous (i.v.) administration of NP-DTPA and NP-DTPA/G-CSF-X high levels of radioactivity were observed in the liver. Furthermore, spleen uptake was correlated with the number of G-CSF molecules grafted on the surface of the NPs. Combining NP-DTPA/G-CSF-34 with rituximab strongly reduced RL tumor growth compared to rituximab alone or in combination with conventional G-CSF + rituximab. The use of highly loaded G-CSF NPs as immune adjuvants could enhance the antitumor activity of therapeutic monoclonal antibodies by amplifying tumor cell destruction by innate immune cells.

Granulocyte colony-stimulating factor combined with Methylprednisolone improves functional outcomes in rats with experimental acute spinal cord injury

OBJECTIVES: To evaluate the effects of combined treatment with granulocyte colony-stimulating factor (G-CSF) and methylprednisolone in rats subjected to experimental spinal cord injury. METHODS: Forty Wistar rats received a moderate spinal cord injury and were divided into four groups: control (no treatment); G-CSF (G-CSF at the time of injury and daily over the next five days); methylprednisolone (methylprednisolone for 24 h); and G-CSF/Methylprednisolone (methylprednisolone for 24 h and G-CSF at the time of injury and daily over the next five days). Functional evaluation was performed using the Basso, Beattie and Bresnahan score on days 2, 7, 14, 21, 28, 35 and 42 following injury. Motor-evoked potentials were evaluated. Histological examination of the spinal cord lesion was performed immediately after euthanasia on day 42. RESULTS: Eight animals were excluded (2 from each group) due to infection, a normal Basso, Beattie and Bresnahan score at their first evaluation, or autophagy, and 32 were evaluated. The combination of methylprednisolone and G-CSF promoted greater functional improvement than methylprednisolone or G-CSF alone (p<0.001). This combination also exhibited a synergistic effect, with improvements in hyperemia and cellular infiltration at the injury site (p<0.001). The groups displayed no neurophysiological differences (latency p=0.85; amplitude p=0.75). CONCLUSION: Methylprednisolone plus G-CSF promotes functional and histological improvements superior to those achieved by either of these drugs alone when treating spinal cord contusion injuries in rats. Combining the two drugs did have a synergistic effect.

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

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

Synthesis and characterization of heparosan-granulocyte-colony stimulating factor conjugates: a natural sugar-based drug delivery system to treat neutropenia.

Many injectable drugs require delivery strategies for enhancing their pharmacokinetics due to rapid loss via renal filtration if possess low molecular weight (<60-70 kDa) and/or clearance by the body's components (e.g., proteases, antibodies, high-efficiency receptors) in their native form. FDA-approved polyethylene glycol (PEG) is a vehicle for improving therapeutics, but artificial polymers have potential biocompatibility and immunogenicity liabilities. Here, we utilized a natural vertebrate carbohydrate, heparosan (HEP), the biosynthetic precursor of heparan sulfate and heparin, to enhance performance of a biologic drug. The HEP polysaccharide was stable with a long half-life (~8 days for 99-kDa chain) in the nonhuman primate bloodstream, but was efficiently degraded to very short oligosaccharides when internalized by cells, and then excreted into urine and feces. Several HEP-modified human granulocyte-colony stimulating factor (G-CSF) conjugates were synthesized with defined quasi-monodisperse HEP polysaccharide chains. Single dosing of 55- or 99-kDa HEP-G-CSF in rats increased blood neutrophil levels comparable to PEG-G-CSF conjugates. Repeated dosing of HEP-G-CSF or HEP alone for 2 weeks did not cause HEP-specific toxic effects in rats. HEP did not possess the anticoagulant behavior of its daughter, heparin, based on testing in rats or clinical diagnostic assays with human plasma. Neither anti-HEP IgG nor IgM antibodies were detected in a long-term (9 doses over 7 months) immunogenicity study of the HEP-drug conjugate with rats. These proof-of-concept experiments with HEP-G-CSF indicate that it is a valid drug candidate for neutropenia and suggest the potential of this HEP-based platform as a safe alternative delivery vehicle for other therapeutics.

Determination of Critical Quality Attributes for a Biotherapeutic in the QbD Paradigm: GCSF as a Case Study.

Estimating impact of the various product-related variants and impurities on a biotherapeutic's safety and efficacy is an essential requirement in the quality by design paradigm. In view of the limited role that clinical studies offer in this regard, we demonstrate a preclinical approach to achieve this for granulocyte colony-stimulating factor (GCSF). While our repeated-dose toxicity data suggest that these variants do not elicit any adverse effects or histopathological changes, aggregated GCSF impurity caused sluggishness in animal behavior manifested by a possible muscular injury. Cell assay data revealed that the cys-64-cys74 disulfide bond in reduced GCSF imparts stabilization in absence of the cys-36-cys42 bond. PK data demonstrate variability in half lives of different species when compared to the native GCSF. PD data along with differential expression of JAK-2 and STAT5a genes show that all the tested variants triggered the required signal transduction pathways for neutrophil proliferation and activation.

A pharmacokinetic study of lipegfilgrastim in children with Ewing family of tumors or rhabdomyosarcoma.

PURPOSE: Neutropenia is a common complication from chemotherapy, limiting optimal dosing and treatment. Lipegfilgrastim is a long-acting granulocyte colony-stimulating factor developed for the management of chemotherapy-induced neutropenia. The objectives of this phase 1, multinational, open-label, single-arm study were to characterize the pharmacokinetics (PK) and pharmacodynamics (PD) of a single body weight-adjusted dose of lipegfilgrastim and to evaluate the efficacy, safety, and tolerability of the drug in children with Ewing family of tumors or rhabdomyosarcoma treated with myelosuppressive chemotherapy. METHODS: Enrolled patients received lipegfilgrastim (100 µg/kg) 24 h after the last chemotherapy treatment in week 1. Patients were stratified into three age groups: 2 to <6, 6 to <12, and 12 to <18 years. Blood samples for PK analyses were obtained at baseline and at 3, 8, 24, 30, 48, 72, 96, 144, and 240 h postdose for the two oldest groups and up to 144 h in the youngest group. RESULTS: Twenty-one patients were enrolled and received lipegfilgrastim, seven in each age group. Lipegfilgrastim exposure levels were comparable across age groups, with concentrations maintained over a prolonged period after a single injection. Differences in PD were mainly associated with chemotherapy type. Most investigator-reported adverse events were attributed to chemotherapy and not to lipegfilgrastim. Severe adverse events were noted in 57% of patients; febrile neutropenia, leukopenia, neutropenia, and thrombocytopenia were more frequent among the oldest patients. CONCLUSIONS: Results support the use of a body weight-adjusted dose to achieve equivalent initial peak exposure levels of lipegfilgrastim in children of various ages.

When Hydromorphone Is Not Working, Try Loratadine: An Emergency Department Case of Loratadine as Abortive Therapy for Severe Pegfilgrastim-Induced Bone Pain.

BACKGROUND: Intractable bone pain is a notorious adverse effect of granulocyte-colony stimulating factors (G-CSFs), such as pegfilgrastim and filgrastim, which are given to help prevent neutropenia in patients who are undergoing chemotherapy. G-CSF-induced bone pain is surprisingly common and often refractory to treatment with conventional analgesics. CASE REPORT: This article describes an emergency department case of opiate and nonsteroidal anti-inflammatory drug-resistant pegfilgrastim-induced bone pain that was successfully alleviated with 10 mg of oral loratadine, allowing for discharge home. WHY SHOULD AN EMERGENCY PHYSICIAN BE AWARE OF THIS?: This case suggests that loratadine may be an easy to implement, safe, and effective therapy in the emergency department management of intractable bone pain caused by G-CSF use. Emergency physicians should be aware that loratadine may successfully relieve otherwise intractable G-CSF-induced bone pain and allow for discharge home.