Polyphosphate nanoparticles on the platelet surface trigger contact system activation.

Polyphosphate is an inorganic polymer that can potentiate several interactions in the blood coagulation system. Blood platelets contain polyphosphate, and the secretion of platelet-derived polyphosphate has been associated with increased thrombus formation and activation of coagulation factor XII. However, the small polymer size of secreted platelet polyphosphate limits its capacity to activate factor XII in vitro. Thus, the mechanism by which platelet polyphosphate contributes to thrombus formation remains unclear. Using live-cell imaging, confocal and electron microscopy, we show that activated platelets retain polyphosphate on their cell surface. The apparent polymer size of membrane-associated polyphosphate largely exceeds that of secreted polyphosphate. Ultracentrifugation fractionation experiments revealed that membrane-associated platelet polyphosphate is condensed into insoluble spherical nanoparticles with divalent metal ions. In contrast to soluble polyphosphate, membrane-associated polyphosphate nanoparticles potently activate factor XII. Our findings identify membrane-associated polyphosphate in a nanoparticle state on the surface of activated platelets. We propose that these polyphosphate nanoparticles mechanistically link the procoagulant activity of platelets with the activation of coagulation factor XII.

Quality Comparison of Biosimilar and Copy Filgrastim Products with the Innovator Product.

PURPOSE: Filgrastim, a recombinant human granulocyte-colony stimulating factor, is widely used to treat congenital and acquired neutropenia. Following patent expiration of the innovator filgrastim product, biosimilar filgrastim products have been approved in the EU and shown to be comparable with the innovator with respect to quality, safety and efficacy. In less regulated markets, copy filgrastim products are available but data about their quality are scarce. In the present study, we provide a head-to-head comparative study on the quality of biosimilar and copy filgrastim products. METHODS: Innovator filgrastim product, Neupogen®, two EU-licensed biosimilars, Zarzio® and Tevagrastim®, and two copy filgrastim products, Biocilin® and PDgrastim®, were subjected to peptide mapping, circular dichroism spectroscopy, fluorescence spectroscopy, sodium dodecyl sulfate polyacrylamide gel electrophoresis, high performance size-exclusion chromatography, reversed-phase ultra-performance liquid chromatography, endotoxin test, flow imaging microscopy and in vitro potency assay. RESULTS: Zarzio® and Tevagrastim® have comparable quality to Neupogen®, while Biocilin® showed a significantly lower and PDgrastim® a higher specific activity. Moreover, PDgrastim® showed a higher level of impurities and a lower thermo stability than the other products. CONCLUSIONS: Except for the deviating specific activities of the two copy filgrastim products, we found no substantial differences in product quality between the filgrastim products studied.

Safety and efficacy of biosimilars in oncology.

Biosimilars are considered to be one of the solutions to combat the substantially increasing costs of cancer treatment, and its imminent introduction is expected to expand affordability worldwide. However, biosimilar monoclonal antibodies provide many challenges compared with first-generation biosimilars, growth factors, and hormones, because they have shown only a modest clinical effect, and are often used in combination with other more toxic therapies, making it difficult to design studies that allow appropriate efficacy and safety assessments compared with the original products. The value of comparative clinical trials for showing clinical equivalence of biosimilars that demonstrate a high degree of similarity in physical, chemical, structural, and biological characteristics with the original product is increasingly being questioned, and advances in analytical methods that provide robust non-clinical data might reduce the need for extensive clinical comparisons. In this Series paper, the third of three papers on drug safety in oncology, we review the safety and efficacy of biosimilars in oncology, assessing biosimilar monoclonal antibodies in relation to first-generation biosimilars, the issues surrounding interchangeability and extrapolation of biosimilars to other disease and patient indications, and reassessing the safety approval pathway in light of 10 years worth of biosimilar experience.

Label-free glycoprofiling with multiplex surface plasmon resonance: a tool to quantify sialylation of erythropoietin.

Protein glycosylation is among the most common and well-defined post-translational modifications due to its vital role in protein function. Monitoring variation in glycosylation is necessary for producing more effective therapeutic proteins. Glycans attached to glycoproteins interact highly specific with lectins, natural carbohydrate-binding proteins, which property is used in the current label-free methodology. We have established a lectin microarray for label-free detection of lectin-carbohydrate interactions allowing us to study protein glycosylation directly on unmodified glycoproteins. The method enables simultaneous measurement of up to 96 lectin-carbohydrate interactions on a multiplex surface plasmon resonance imaging platform within 20 min. Specificity determination of lectins succeeded by analysis of neoglycoproteins and enzymatically remodeled glycoproteins to verify carbohydrate binding. We demonstrated the possibilities for glycosylation fingerprinting by comparing different Erythropoietin sources without the need for any sample pretreatment and we were able to accurately quantify relative sialylation levels of Erythropoietin.

How bio-questionable are the different recombinant human erythropoietin copy products in Thailand?

PURPOSE: The high prevalence of pure red cell aplasia in Thailand has been associated with the sharp increase in number of recombinant human erythropoietin (rhEPO) copy products, based on a classical generic regulatory pathway, which have entered the market. This study aims to assess the quality of rhEPO copy products being used in Thailand. METHODS: Twelve rhEPO copy products were purchased from pharmacies in Thailand, shipped under controlled cold chain conditions to the Netherlands and characterized using (1) high performance size-exclusion chromatography, (2) asymmetrical flow field-flow fractionation, (3) sodium dodecyl sulfate polyacrylamide gel electrophoresis in combination with (4) Western blotting and additionally tested for (5) host cell protein impurities as well as (6) endotoxin contamination. RESULTS: Some of the tested rhEPO copy products showed high aggregate levels and contained a substantial amount of protein fragments. Also, one of rhEPO copy products had a high endotoxin level, exceeding the FDA limit. CONCLUSIONS: Our observations show that some of the tested copy products on the Thai market differ significantly from the originator rhEPO product, Epogen®. This comparison study supports a link between the quality attributes of copy rhEPO products and their immunogenicity.

Effect of arginine on pre-nucleus stage of interferon beta-1b aggregation.

Understanding the mechanism of aggregation of a therapeutic protein would not only ease the manufacturing processing but could also lead to a more stable finished product. Aggregation of recombinant interferon (IFNß-1b) was studied by heating, oxidizing, or seeding of unformulated monomeric solution. The formation of aggregates was monitored by dynamic light scattering (DLS) and UV spectroscopy. The autocatalytic monomer loss model was used to fit the data on aggregation rates. The influence of pre-nucleation on aggregation step was demonstrated by inducing the liquid samples containing a monomer form of folded IFNß-1b by heat and also an oxidizing agent. Results tend to suggest that the nucleus includes a single protein molecule which has been probably deformed. Seeding tests showed that aggregation of IFNß-1b was probably initiated when 1.0% (w/w) of monomers converted to nucleus form. Chemiluminescence spectroscopy analysis of the sample indicated the generation of 3.0 µM of hydrogen peroxide (H2O2) during nucleation stage of IFNß-1b aggregation. Arginine with a concentration of 200 mM was sufficient to suppress aggregation of IFNß-1b by decreasing the rate of pre-nucleation step. We proposed the formation of pre-nucleus structures prior to nucleation as the mechanism of aggregation of IFNß-1b. Furthermore, we have showed the positive anti-aggregation effect of arginine on pre-nucleation step.

Antibody response against Betaferon® in immune tolerant mice: involvement of marginal zone B-cells and CD4+ T-cells and apparent lack of immunological memory.

PURPOSE: The immunological processes underlying immunogenicity of recombinant human therapeutics are poorly understood. Using an immune tolerant mouse model we previously demonstrated that aggregates are a major trigger of the antidrug antibody (ADA) response against recombinant human interferon beta (rhIFNß) products including Betaferon®, and that immunological memory seems to be lacking after a rechallenge with non-aggregated rhIFNß. The apparent absence of immunological memory indicates a CD4+ T-cell independent (Tind) immune response underlying ADA formation against Betaferon®. This hypothesis was tested. METHODS: Using the immune tolerant mouse model we first validated that rechallenge with highly aggregated rhIFNß (Betaferon®) does not lead to a subsequent fast increase in ADA titers, suggesting a lack of immunological memory. Next we assessed whether Betaferon® could act as Tind antigen by inactivation of marginal zone (MZ) B-cells during treatment. MZ B-cells are major effector cells involved in a Tind immune response. In a following experiment we depleted the mice from CD4+ T-cells to test their involvement in the ADA response against Betaferon®. RESULTS: Inactivation of MZ B-cells at the start of Betaferon® treatment drastically lowered ADA levels, suggesting a Tind immune response. However, persistent depletion of CD4+ T-cells before and during Betaferon® treatment abolished the ADA response in almost all mice. CONCLUSION: The immune response against rhIFNß in immune tolerant mice is neither a T-cell independent nor a classical T-cell dependent immune response. Further studies are needed to confirm absence of immunological memory (cells).

Effect of treatment regimen on the immunogenicity of human interferon Beta in immune tolerant mice.

PURPOSE: Interferon beta is commonly used as therapeutic in the first line of therapy for multiple sclerosis. However, depending on the product, it induces an antibody response in up to 60% of patients. This study evaluated the impact of therapy related factors like dose, route of administration and administration frequency on the immunogenicity of one of the originator interferon beta drugs (Betaferon®) in an immune tolerant transgenic mouse model. METHODS: Immune tolerant transgenic mice received injections with Betaferon® via different routes, doses and injection frequencies. Anti-drug antibody (ADA) production was measured by ELISA to assess immunogenicity. RESULTS: A single injection of Betaferon® was found to be sufficient for the induction of ADAs. The antibody titer was enhanced with increasing dose and treatment frequency. Among the tested administration routes, the intravenous route was the most immunogenic one, which is in contradiction with one of the dogma in immunogenicity research according to which subcutaneous administration is the most immunogenic route. Intramuscular, intraperitoneal and subcutaneous injections resulted in comparable immunogenicity. CONCLUSION: This study shows that treatment related factors affect significantly immunogenicity of Betaseron® and therefore substantiate the need for further studies on these factors in patients.

The immunogenicity of polyethylene glycol: facts and fiction.

An increasing number of pegylated therapeutic proteins and drug targeting compounds are being introduced in the clinic. Pegylation is intended to increase circulation time and to reduce an immunogenic response. Recently however a number of publications have appeared claiming that the polyethylene glycol (PEG) moiety of these products in itself may be immunogenic and that the induced anti-PEG antibodies are linked to enhanced blood clearance and reduced efficacy of the products. A critical review of the literature shows that most, if not all assays for anti-PEG antibodies are flawed and lack specificity. Also the biological effects induced by anti-PEG antibodies lack the characteristics of a bona fide antibody reaction. Standardization of the anti-PEG assays and the development of reference sera are urgently needed.

The role of Periodic Safety Update Reports in the safety management of biopharmaceuticals.

PURPOSE: To describe and assess the outcomes of Periodic Safety Update Report (PSUR) evaluations of biopharmaceuticals. METHODS: A cross-sectional analysis was performed of follow-up requirements of PSURs submitted for centrally approved biopharmaceuticals in the European Union between 1 July 2008 and 30 June 2010. A follow-up analysis on a subset of products that submitted multiple PSURs within the study period was also performed. RESULTS: The cross-sectional analysis included 70 PSURs. Potential safety concerns occurred in 57 (83 %) of all PSURs, and 26 (37 %) concluded a need to change the Summary of Product Characteristics (SPC). In comparison to newer products, products authorized for more than 10 years contained significantly fewer potential safety concerns (60 vs. 92 %; p < 0.01) and required fewer SPC changes (15 vs. 46 %; p = 0.03). For 45 products, multiple PSURs were submitted that could be included in a follow-up analysis. For this subset of products, of the 106 newly identified safety potential safety issues, 7 (7%) resulted in requirements for label changes in the following PSUR. CONCLUSIONS: PSURs facilitate communication between regulators and marketing authorization holders. Potential safety concerns occur for the majority of biopharmaceuticals and throughout their lifecycle, but for established products PSUR evaluations rarely lead to regulatory actions.

Nature of the Interaction of Alpha-D-Mannose and Escherichia coli Bacteria, and Implications for its Regulatory Classification. A Delphi Panel European Consensus Based on Chemistry and Legal Evidence.

The nature of alpha-D-mannose-natural aldohexose sugar, C-2 glucose epimer, whose intended use is for preventing urinary tract infections-in the interaction with E. coli is addressed in order to drive the issue of its regulatory classification as a medicinal product or medical device. PRISMA systematic review approach was applied; Delphi Panel method was used to target consensus on statements retrieved from evidence. Based on regulatory definitions and research evidence, the mechanism of D-mannose does not involve a metabolic or immunological action while there is uncertainty regarding the pharmacological action. Specific interaction between the product and the bacteria within the body occurs, but its nature is inert: it does not induce a direct response activating or inhibiting body processes. Moreover, the action of D-mannose takes place, even if inside the bladder, outside the epithelium on bacteria that have not yet invaded the urothelial tissue. Therefore, its mechanism of action is not directed to host structures but to structures (bacteria) external to the host's tissues. On the basis of current regulation, the uncertainty as regard a pharmacological action of alpha-D-mannose makes possible its medical device classification: new regulations and legal judgments can add further considerations. From a pharmacological perspective, research is driven versus synthetic mannosides: no further considerations are expected on alpha-D-mannose.

Translatability of preclinical to early clinical tolerable and pharmacologically active dose ranges for central nervous system active drugs.

The primary purpose of this study was to assess the translatability of preclinical to early clinical tolerable and pharmacologically active dose ranges for central nervous system (CNS) active drugs. As a part of this, IBs were reviewed on reporting quality. Investigator's Brochures (IBs) of studies performed at the Centre for Human Drug Research (CHDR) reporting statistically significant results of CNS activity related to the drug's mechanism of action were included. The quality of IBs was assessed based on the presence of a rationale for the chosen animal model, completeness of pharmacokinetic (PK) results in reporting and internal validity information of the preclinical evidence. The IB-derisk tool was used to generate preclinical and early clinical data overviews data. For each compound, the overlap between pharmacologically active dose ranges and well-tolerated levels was calculated for three pharmacokinetic (PK) parameters: human equivalent dose (HED), maximum plasma concentration (Cmax) and area under the curve (AUC). Twenty-five IBs were included. In general, the quality of reporting in IBs was assessed as poor. About a third of studies did not explore the entire concentration-effect curve (pre)clinically. Single dose tolerability ranges were most accurately predicted by Cmax. Human equivalent dose and AUC were the best predictors of pharmacologically active ranges. Tolerable and pharmacologically active dose ranges in healthy volunteers can be reasonably well predicted from preclinical data with the IB-derisk tool. The translatability of preclinical studies can be improved by applying a higher reporting standard in IBs including comparable PK measurements across all preclinical and clinical studies.

Antibody-mediated pure red cell aplasia in chronic kidney disease patients receiving erythropoiesis-stimulating agents: new insights.

Antibody-mediated pure red cell aplasia is a very rare but devastating condition affecting patients receiving treatment with erythropoiesis-stimulating agents. New cases continue to emerge, generally in clusters, consistent with an 'environmental' trigger to its pathogenesis. Defining the causes of antibody-mediated pure red cell aplasia is clearly of importance for patients with chronic kidney disease, but any developments in this area may also have relevance to other disease areas as therapeutic delivery of endogenous proteins rapidly increases. This review focuses on the current knowledge regarding the etiology of antibody-mediated pure red cell aplasia and the current approach to therapy.

The ability of animal studies to detect serious post marketing adverse events is limited.

The value of animal studies to assess drug safety is unclear because many such studies are biased and have methodological shortcomings. We studied whether post-marketing serious adverse reactions to small molecule drugs could have been detected on the basis of animal study data included in drug registration files. Of 93 serious adverse reactions related to 43 small molecule drugs, only 19% were identified in animal studies as a true positive outcome, which suggests that data from animal studies are of limited value to pharmacovigilance activities. Our study shows that drug registration files can be used to study the predictive value of animal studies and that the value of animal studies in all stages of the drug development should be investigated in a collaborative endeavour between regulatory authorities, industry, and academia.

Immunogenicity of therapeutic proteins: the use of animal models.

Immunogenicity of therapeutic proteins lowers patient well-being and drastically increases therapeutic costs. Preventing immunogenicity is an important issue to consider when developing novel therapeutic proteins and applying them in the clinic. Animal models are increasingly used to study immunogenicity of therapeutic proteins. They are employed as predictive tools to assess different aspects of immunogenicity during drug development and have become vital in studying the mechanisms underlying immunogenicity of therapeutic proteins. However, the use of animal models needs critical evaluation. Because of species differences, predictive value of such models is limited, and mechanistic studies can be restricted. This review addresses the suitability of animal models for immunogenicity prediction and summarizes the insights in immunogenicity that they have given so far.

Oxidized and aggregated recombinant human interferon beta is immunogenic in human interferon beta transgenic mice.

PURPOSE: To study the effect of oxidation on the structure of recombinant human interferon beta-1a (rhIFNß-1a) and its immunogenicity in wild-type and immune-tolerant transgenic mice. METHODS: Untreated rhIFNß-1a was degraded by metal-catalyzed oxidation, H(2)O(2)-mediated oxidation, and guanidine-mediated unfolding/refolding. Four rhIFNß-1a preparations with different levels of oxidation and aggregation were injected intraperitoneally in mice 15× during 3 weeks. Both binding and neutralizing antibodies were measured. RESULTS: All rhIFNß-1a preparations contained substantial amounts of aggregates. Metal-catalyzed oxidized rhIFNß-1a contained high levels of covalent aggregates as compared with untreated rhIFNß-1a. H(2)O(2)-treated rhIFNß-1a showed an increase in oligomer and unrecovered protein content by HP-SEC; RP-HPLC revealed protein oxidation. Guanidine-treated rhIFNß-1a mostly consisted of dimers and oligomers and some non-covalent aggregates smaller in size than those in untreated rhIFNß-1a. All degraded samples showed alterations in tertiary protein structure. Wild-type mice showed equally high antibody responses against all preparations. Transgenic mice were discriminative, showing elevated antibody responses against both metal-catalyzed oxidized and H(2)O(2)-treated rhIFNß-1a as compared to untreated and guanidine-treated rhIFNß-1a. CONCLUSIONS: Oxidation-mediated aggregation increased the immunogenicity of rhIFNß-1a in transgenic mice, whereas aggregated preparations devoid of measurable oxidation levels were hardly immunogenic.

Quality of original and biosimilar epoetin products.

PURPOSE: To compare the quality of therapeutic erythropoietin (EPO) products, including two biosimilars, with respect to content, aggregation, isoform profile and potency. METHODS: Two original products, Eprex (epoetin alpha) and Dynepo (epoetin delta), and two biosimilar products, Binocrit (epoetin alpha) and Retacrit (epoetin zeta), were compared using (1) high performance size exclusion chromatography, (2) ELISA, (3) SDS-PAGE, (4) capillary zone electrophoresis and (5) in-vivo potency. RESULTS: Tested EPO products differed in content, isoform composition, and potency. CONCLUSION: Of the tested products, the biosimilars have the same or even better quality as the originals. Especially, the potency of originals may significantly differ from the value on the label.

The therapeutic equivalence of complex drugs.

When the patent of a small molecule drug expires generics may be introduced. They are considered therapeutically equivalent once pharmaceutical equivalence (i.e. identical active substances) and bioequivalence (i.e. comparable pharmacokinetics) have been established in a cross-over volunteer study. However this generic paradigm cannot be applied to complex drugs as biologics and a number of other therapeutic modalities. For copies of biologics the European Medicine Agency and other regulatory agencies have introduced a new regulatory biosimilar pathway which mandates clinical trials to show therapeutic equivalence. However for other complex drugs such as the iron-carbohydrate drugs, low molecular weight heparins (LMWHs), liposomal drugs and the glatiramoids regulatory guidance is still mostly lacking. In this paper we will discuss (therapeutic) experience obtained so far with these different classes of 'complex drugs' and their specifics to provide scientific arguments and criteria for consideration for a regulatory framework for the market authorization for these type of drugs.

Tradition, not science, is the basis of animal model selection in translational and applied research.

National and international laws and regulations exist to protect animals used for scientific purposes in translational and applied research, which includes drug development. However, multiple animal models are available for each disease. We evaluated the argumentation behind the selection of a specific animal model using thematic content analysis in project applications issued in 2017-2019 in the Netherlands. In total, 125 animal models for translational and applied research from 110 project applications were assessed. Explanations to select a specific model included: the model's availability (79%); the availability of expertise (62%); and the model showing similar disease pathology/symptoms (59%) to humans. Therefore, current selection of a specific animal model seems to be based on tradition rather than its potential predictive value for clinical outcome. The applicants' explanations for the implementation of the 3R prin­ciples (replacement, reduction and refinement) as to the animal model were unspecific. Replacement was achieved by using data from prior in vitro studies, reduction by optimal experimental design and statistics, and refinement by reducing discomfort. Additionally, due to the stated need for a test model with high complexity (47%) and intactness (30%), the full replacement of animal models with alternative (non-live animal) approaches was thought unachievable. Without a clear, systematic and transparent justification for the selection of a specific animal model, the likelihood of poorly trans­latable research remains. It is not only up to the researcher to demonstrate this, as ethical committees and funding bodies can provide positive stimuli to drive this change.

Aggregated recombinant human interferon Beta induces antibodies but no memory in immune-tolerant transgenic mice.

PURPOSE: To study the influence of protein aggregation on the immunogenicity of recombinant human interferon beta (rhIFNbeta) in wild-type mice and transgenic, immune-tolerant mice, and to evaluate the induction of immunological memory. METHODS: RhIFNbeta-1b and three rhIFNbeta-1a preparations with different aggregate levels were injected intraperitoneally in mice 15x during 3 weeks, and the mice were rechallenged with rhIFNbeta-1a. The formation of binding (BABs) and neutralizing antibodies (NABs) was monitored. RESULTS: Bulk rhIFNbeta-1a contained large, mainly non-covalent aggregates and stressed rhIFNbeta-1a mainly covalent, homogeneous (ca. 100 nm) aggregates. Reformulated rhIFNbeta-1a was essentially aggregate-free. All products induced BABs and NABs in wild-type mice. Immunogenicity in the transgenic mice was product dependent. RhIFNbeta-1b showed the highest and reformulated rhIFNbeta-1a the lowest immunogenicity. In contrast with wild-type mice, transgenic mice did not show NABs, nor did they respond to the rechallenge. CONCLUSIONS: The immunogenicity of the products in transgenic mice, unlike in wild-type mice, varied. In the transgenic mice, neither NABs nor immunological memory developed. The immunogenicity of rhIFNbeta in a model reflecting the human immune system depends on the presence and the characteristics of aggregates.