Bioequivalence of two recombinant granulocyte colony-stimulating factor formulations in healthy male volunteers

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 (AUC_0-24h ) 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 (C_max ) 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 (T_max ) 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.

Biosimilarity Assessment of 2 Filgrastim Therapeutics in Healthy Volunteers

This study aimed to compare the pharmacokinetic, pharmacodynamic, and safety profiles of a proposed biosimilar and innovator filgrastim therapeutics in healthy volunteers. In a crossover design, 23 subjects received a single subcutaneous injection of 300-µg filgrastim, followed by a 7-day washout period. Assessed pharmacokinetic parameters were the maximum observed filgrastim serum concentration (C_max ), time to reach C_max (t_max ), the area under the concentration-time curve (AUC), and elimination half-life. Pharmacodynamics were assessed by the maximum observed absolute neutrophil count effect (E_max ), t_max,E (time to reach E_max ), and the area under the effect of the absolute neutrophil count -time curve. The test/reference ratio (90% confidence intervals) of C_max of 0.992 (0.860-1.143), AUC_0-inf of 0.995 (0.891-1.111), E_max of 0.952 (0.841, 1.078), and area under the effect of the absolute neutrophil count -time curve from time zero to 96 hours of 0.939 (0.854-1.032), were all well within the predefined equivalence boundaries of 80% and 125%. Obtained values for t_max (∼4 hours), t_max,E (∼15 hours), and elimination half-life (∼3.5 hours) were comparable between 2 treatment groups. The local tolerability and incidence of adverse events were comparable, with no clinically meaningful difference between biosimilar and innovator products. Altogether, the results suggested a high similarity of the proposed biosimilar to the innovator filgrastim in healthy volunteers.

Mouse Models for Drug Discovery. Can New Tools and Technology Improve Translational Power?

The use of mouse models in biomedical research and preclinical drug evaluation is on the rise. The advent of new molecular genome-altering technologies such as CRISPR/Cas9 allows for genetic mutations to be introduced into the germ line of a mouse faster and less expensively than previous methods. In addition, the rapid progress in the development and use of somatic transgenesis using viral vectors, as well as manipulations of gene expression with siRNAs and antisense oligonucleotides, allow for even greater exploration into genomics and systems biology. These technological advances come at a time when cost reductions in genome sequencing have led to the identification of pathogenic mutations in patient populations, providing unprecedented opportunities in the use of mice to model human disease. The ease of genetic engineering in mice also offers a potential paradigm shift in resource sharing and the speed by which models are made available in the public domain. Predictively, the knowledge alone that a model can be quickly remade will provide relief to resources encumbered by licensing and Material Transfer Agreements. For decades, mouse strains have provided an exquisite experimental tool to study the pathophysiology of the disease and assess therapeutic options in a genetically defined system. However, a major limitation of the mouse has been the limited genetic diversity associated with common laboratory mice. This has been overcome with the recent development of the Collaborative Cross and Diversity Outbred mice. These strains provide new tools capable of replicating genetic diversity to that approaching the diversity found in human populations. The Collaborative Cross and Diversity Outbred strains thus provide a means to observe and characterize toxicity or efficacy of new therapeutic drugs for a given population. The combination of traditional and contemporary mouse genome editing tools, along with the addition of genetic diversity in new modeling systems, are synergistic and serve to make the mouse a better model for biomedical research, enhancing the potential for preclinical drug discovery and personalized medicine.

Recombinant Human Granulocyte Colony-Stimulating Factor Promotes Preinvasive and Invasive Estrogen Receptor-Positive Tumor Development in MMTV-erbB2 Mice

PURPOSE

We investigated whether recombinant human granulocyte colony-stimulating factor (rhG-CSF) could promote the development of preinvasive and invasive breast cancer in mouse mammary tumor virus (MMTV-erbB2) mice with estrogen receptor-positive tumors.

METHODS

MMTV-erbB2 mice were randomly divided into three experimental groups with 20 mice in each group. MMTV-erbB2 mice were treated with daily subcutaneous injections of vehicle or rhG-CSF (low-rhG-CSF group, rhG-CSF 0.125 µg; vehicle-rhG-CSF group, normal saline 0.25 µg; and high-rhG-CSF group, rhG-CSF 0.25 µg) at 3 months of age. Cellular and molecular mechanisms of G-CSF action in mammary glands were investigated via immunohistochemistry and reverse transcription polymerase chain reaction.

RESULTS

Low, but not high, rhG-CSF doses significantly accelerated mammary tumorigenesis in MMTV-erbB2 mice. Short-term treatment with rhG-CSF could significantly promote the development of preinvasive mammary lesions. The cancer prevention effect was associated with reduced expression of proliferating cell nuclear antigen, cluster of differentiation 34, and signal transducers and activators of transcription 3 in mammary glands by >80%.

CONCLUSION

We found that G-CSF was regulated by rhG-CSF both in vitro and in vivo. Identification of G-CSF genes helped us further understand the mechanism by which G-CSF promotes cancer. Low doses of rhG-CSF could significantly increase tumor latency and increase tumor multiplicity and burden. Moreover, rhG-CSF effectively promotes development of both malignant and premalignant mammary lesions in MMTV-erbB2 mice.

Comparison of the pharmacokinetic and pharmacodynamic properties of two recombinant granulocyte colony-stimulating factor formulations after single subcutaneous administration to healthy volunteers

BACKGROUND AND OBJECTIVE

The aim of this randomized, single dose, two-period crossover study with two weeks wash-out period was the demonstration of bioequivalence of two recombinant human granulocyte colony-stimulating factor (rG-CSF) formulations after subcutaneous administration of 300μg comparing their pharmacokinetic (primary endpoints AUC0-24, AUC0-∞ and Cmax) and pharmacodynamic (primary endpoints ANC AUC0-72, ANC AUC0-∞ and ANCmax) profiles in healthy male subjects.

MATERIALS AND METHODS

A total of 36 (23.0±6.0 years, 76.6±7.2kg) healthy subjects were recruited. Using a 1:1 randomization ratio, subjects were randomly assigned to one of two possible treatment-sequence groups to receive the single dose of test formulation (Gp-02) and reference product (Neupogen™) concentrations were measured by enzyme-linked immunosorbent assay (ELISA) up to 24h and the Absolute Neutrophil Count (ANC) was determined using hematology analyzer Coulter STKS™ (Beckman Coulter) up to 72h after injection. The geometric mean of primary pharmacokinetic and pharmacodynamic variables were considered bioequivalent if the 90% confidence intervals (CI) would fall in the bioequivalence range of 80%-125%.

RESULTS

AUC0-24 (ratio of means 103.4, 90% CI: 95.6-111.9), AUC0-∞ (103.4, 90% CI: 95.7-111.7), Cmax (99.6, 90% CI: 89.0-111.4), ANC AUC0-72 (100.0, 90% CI: 96.6-103.5), ANC AUC0-∞ (100.8, 90% CI: 96.5-105.3), and ANCmax (100.2, 90% CI: 95.4-105.1) were determined. Single doses of test and reference formulations were well tolerated. The incidence of AEs was equally distributed across treatment groups with the most frequent AEs being headache, fever, and back pain.

CONCLUSIONS

The study results demonstrated the bioequivalence of Gp-02, a new formulation of filgrastim, and the reference product Neupogen™.

Application of human FcRn transgenic mice as a pharmacokinetic screening tool of monoclonal antibody

1. For drug discovery, useful screening tools are essential to select superior candidates. Here, we evaluated the applicability of transgenic mice expressing human neonatal Fc receptor (FcRn) (hFcRn Tgm) as a pharmacokinetic screening tool of therapeutic monoclonal antibodies (mAbs) and Fc-fusion proteins that overcomes the species difference in FcRn binding. 2. Marketed 11 mAbs and 2 Fc-fusion proteins were intravenously administered to hFcRn Tgm and WT mice. The half-lives in hFcRn Tgm and WT mice were compared with those in human obtained from literature. The linear half-lives in human and monkey were also calculated by nonlinear pharmacokinetic analysis. For comparison, correlations of half-lives between monkey and human were also evaluated. 3. The half-lives of mAbs and Fc-fusion proteins after intravenous administration ranged from 1.1 to 13.2 days in hFcRn Tgm and from 1.2 to 30.3 days in WT mice. The half-lives in human correlated more closely with those in hFcRn Tgm than in WT mice and monkey. 4. Our results suggest that hFcRn Tgm are a valuable and useful tool for pharmacokinetic screening of mAbs and Fc-fusion proteins in the preclinical stage. Furthermore, we believe that hFcRn Tgm are broadly applicable to preclinical pharmacokinetic screening of mAbs-based therapeutics.

Effects of granulocyte-colony stimulating factor and the expression of its receptor on various malignant cells

Background

Granulocyte-colony stimulating factor (G-CSF) is extensively used to improve neutrophil count during anti-cancer chemotherapy. We investigated the effects of G-CSF on several leukemic cell lines and screened for the expression of the G-CSF receptor (G-CSFR) in various malignant cells.

Methods

We examined the effects of the most commonly used commercial forms of G-CSF (glycosylated lenograstim and nonglycosylated filgrastim) on various leukemic cell lines by flow cytometry. Moreover, we screened for the expression of G-CSFR mRNA in 38 solid tumor cell lines by using real-time PCR.

Results

G-CSF stimulated proliferation (40-80% increase in proliferation in treated cells as compared to that in control cells) in 3 leukemic cell lines and induced differentiation of AML1/ETO+ leukemic cells. Among the 38 solid tumor cell lines, 5 cell lines (hepatoblastoma, 2 breast carcinoma, squamous cell carcinoma of the larynx, and melanoma cell lines) showed G-CSFR mRNA expression.

Conclusion

The results of the present study show that therapeutic G-CSF might stimulate the proliferation and differentiation of malignant cells with G-CSFR expression, suggesting that prescreening for G-CSFR expression in primary tumor cells may be necessary before using G-CSF for treatment.

[Biosimilar filgrastim: from development to record]

Ratiograstim® is the first filgrastim biosimilar approved by EMEA. The reference medicinal product is Neupogen®. The active substance is filgrastim (the manufacturing laboratory, ratiopharm, is using the name XM02). Filgrastim is a non glycosylated recombinant methionyl human granulocyte colony stimulating factor expressed in E. coli. Differences with human granulocyte-colony stimulating factor (G-CSF) are a N-terminal methionyl extension and be a non-glycosylated protein. Ratiograstim® has the same indications as the reference product: — Cytotoxic chemotherapy induced neutropenia. — Neutropenia caused by myeloablative therapy followed by BMT. — Mobilisation of peripheral blood progenitor cells (PBPC). — Congenital, cyclic or idiopathic neutropenia. — Persistant neutropenia in HIV-patients. Authorisation according to the EMEA guidelines for biosimilars by centralized approval procedure, to demonstrate quality, efficacy and safety compared to the reference product Neupogen®. Comprehensive phase I and phase III clinical studies involving 880 subjects and patients have been completed (table 1).

Biologic and molecular effects of granulocyte colony-stimulating factor in healthy individuals: recent findings and current challenges

Recombinant human granulocyte colony-stimulating factor (rhG-CSF) is widely used in healthy donors for collection of peripheral blood progenitor cells (PBPCs) for allogeneic transplantation and granulocytes for transfusion. The spectrum of its biologic and molecular activities in healthy individuals is coming into sharper focus, creating a unique set of challenges and clarifying the need to monitor and safeguard donor safety. Accumulating evidence indicates that rhG-CSF effects are not limited to the myeloid cell lineage. This may reflect the presence of functional G-CSF receptors on other cell types and tissues, as well as rhG-CSF-induced modulation of cytokine networks. While most rhG-CSF-induced effects are transient and self-limiting, preliminary, provocative data have suggested the possibility of a more durable effect on the chromosomal integrity of lymphocytes. While these reports have not been validated and have been subject to criticism, they are prompting prospective studies and monitoring efforts to determine whether there is a significant risk of long-term adverse events (eg, hematologic malignancies) in healthy PBPC and granulocyte donors. Based on the totality of information that is currently available, the administration of rhG-CSF to healthy donors for the purpose of PBPC donation continues to have a favorable risk-benefit profile.