Immunogenicity of therapeutic proteins

Unique challenges required reassessment and alterations to critical reagents to rescue a neutralizing antibody assay

Aim: To redevelop a neutralizing antibody (NAb) assay to be much more drug tolerant, have a large dynamic range and have high inhibition when using high levels of positive control (PC).Materials & methods: Early assay data suggested that typical biotin labeling of the capture reagent (Drug 1, produced in a human cell line) was blocking it from binding with the PC or the detection target, and that the detection target was out competing the PC. Methodical biotin labeling experiments were performed at several challenge ratios and an Fc linker was added to the detection target.Results & conclusion: A larger dynamic range, high inhibition and higher drug tolerance were achieved by adding an acid dissociation step to the assay, performing atypical biotin labeling of Drug 1 and switching to a detection target that contained an Fc linker to increase steric hinderance and decrease its binding affinity to Drug 1.

Immunogenicity of Therapeutic Biological Modalities - Lessons from Hemophilia A Therapies

The introduction and development of biologics such as therapeutic proteins, gene-, and cell-based therapy have revolutionized the scope of treatment for many diseases. However, a significant portion of the patients develop unwanted immune reactions against these novel biological modalities, referred to as immunogenicity, and no longer benefit from the treatments. In the current review, using Hemophilia A (HA) therapy as an example, we will discuss the immunogenicity issue of multiple biological modalities. Currently, the number of therapeutic modalities that are approved or recently explored to treat HA, a hereditary bleeding disorder, is increasing rapidly. These include, but are not limited to, recombinant factor VIII proteins, PEGylated FVIII, FVIII Fc fusion protein, bispecific monoclonal antibodies, gene replacement therapy, gene editing therapy, and cell-based therapy. They offer the patients a broader range of more advanced and effective treatment options, yet immunogenicity remains the most critical complication in the management of this disorder. Recent advances in strategies to manage and mitigate immunogenicity will also be reviewed.

Molecular Bases of Protein Antigenicity and Determinants of Immunogenicity, Anergy, and Mitogenicity

BACKGROUND

The immune system is able to recognize substances that originate from inside or outside the body and are potentially harmful. Foreign substances that bind to immune system components exhibit antigenicity and are defined as antigens. The antigens exhibiting immunogenicity can induce innate or adaptive immune responses and give rise to humoral or cell-mediated immunity. The antigens exhibiting mitogenicity can cross-link cell membrane receptors on B and T lymphocytes leading to cell proliferation. All antigens vary greatly in physicochemical features such as biochemical nature, structural complexity, molecular size, foreignness, solubility, and so on.

OBJECTIVE

Thus, this review aims to describe the molecular bases of protein-antigenicity and those molecular bases that lead to an immune response, lymphocyte proliferation, or unresponsiveness.

CONCLUSION

The epitopes of an antigen are located in surface areas; they are about 880-3,300 Da in size. They are protein, carbohydrate, or lipid in nature. Soluble antigens are smaller than 1 nm and are endocytosed less efficiently than particulate antigens. The more the structural complexity of an antigen increases, the more the antigenicity increases due to the number and variety of epitopes. The smallest immunogens are about 4,000-10,000 Da in size. The more phylogenetically distant immunogens are from the immunogen-recipient, the more immunogenicity increases. Antigens that are immunogens can trigger an innate or adaptive immune response. The innate response is induced by antigens that are pathogen-associated molecular patterns. Exogenous antigens, T Dependent or T Independent, induce humoral immunogenicity. TD protein-antigens require two epitopes, one sequential and one conformational to induce antibodies, whereas, TI non-protein-antigens require only one conformational epitope to induce low-affinity antibodies. Endogenous protein antigens require only one sequential epitope to induce cell-mediated immunogenicity.

Key concepts in biosimilar medicines:

Biologics’ are a class of medications produced by living cells using recombinant DNA technology. Biologics have had an important impact in many areas of medicine, and in particular in rheumatology and oncology. However, the high cost of these agents is a growing concern, particularly as more products become available and their use for the treatment of immune-mediated inflammatory diseases continues to expand. Biosimilars, also called follow-on biologics, have been viewed as a potential cost-saving alternative to traditional therapies. Currently, a product can be considered biosimilar to a reference product if there are no clinically meaningful differences in terms of safety, purity, and potency. In this review, the most important key concepts about biosimilars were summarized for physicians emphasizing the status in Turkey.

Lymphoid follicle antigen (Ag) delivery and enhanced rodent humoral immune responses mediated by Ag-containing PEGylated liposomes

Antigen (Ag) delivery to lymphoid follicles is important in achieving adaptive immunity. We recently developed a novel two-step Ag delivery system that efficiently induces cellular immune responses to Ags in mice by using priming intravenous (i.v.) injections of empty PEGylated liposomes (PEG-Lip) followed 3 days later by Ag-entrapped PEG-Lip (Ag-PEG-lip). In this study, we looked for humoral immune responses in rats and mice with IgG production specific to the encapsulated Ags. We observed that initial i.v. injections of empty PEG-Lip triggered accumulation of subsequent doses ovalbumin-PEG-Lip (OVA-PEG-lip) in splenic follicles and enhanced IgG production against OVA in both rats and mice. Anti-OVA IgG production was diminished by inhibition of splenic follicular accumulation of OVA-PEG-Lip by fingolimod (FTY720), which inhibits lymphocyte egress from lymphoid tissues. Thisindicates that the follicular accumulation of Ags that we observed is an indispensable and unique step in the production of anti-OVA IgG. Interestingly, in BALB/c nude mice, which are T cell deficient, a high follicular accumulation of OVA-PEG-Lip was observed, but anti-OVA IgG production was not observed. This suggests that T cells are also indispensable for the induction of cellular immune responses by our two-step immunization procedure. Our unique Ag delivery platform, which efficiently delivers Ags to splenic follicles, may be a useful technique for the enhancement of cellular immunity, as well as humoral immunity. Further experimental evaluation should be undertaken in relevant animal models in order for efficacy, safety and immunological correlates to be determined.

In vitro human helper T-cell assay to screen antibody drug candidates for immunogenicity

Monoclonal antibody (mAb) drugs offer a number of valuable treatments. Many newly developed mAb drugs include artificial modification of amino acid sequences from human origin, which may cause higher immunogenicity to induce anti-drug antibodies (ADA). If the immunogenicity of a new candidate can be understood in the nonclinical phase, clinical studies will be safer and the success rate of development improved. Empirically, in vitro immunogenicity assays with human cells have proved to be sufficiently sensitive to nonhuman proteins, but not to human/humanized mAb. To detect the weaker immunogenicity of human-based mAb, a more sensitive biomarker for in vitro assays is needed. The in vitro study here developed a proliferation assay (T_H cell assay) using flow cytometry analysis that can detect a slight increase in proliferating T_H cells. Samples from 218 donors treated with a low-immunogenic drug (etanercept) were measured to determine a positive threshold level. With this threshold, positive donor percentages among PBMC after treatment with higher-immunogenicity mAb drugs were noted, that is, 39.5% with humanized anti-human A33 antibody (hA33), 27.3% with abciximab, 25.9% with adalimumab, and 14.8% with infliximab. Biotherapeutics with low immunogenicity yielded values of 0% for basiliximab and 3.7% for etanercept. These data showed a good comparability with previously reported incidences of clinical ADA with the evaluated drugs. Calculations based on the data here showed that a T_H cell assay with 40 donors could provide statistically significant differences when comparing low- (etanercept) versus highly immunogenic mAb (except for infliximab). Based on the outcomes here, for screening purposes, a practical cutoff point of 3/20 positives with 20 donors was proposed to alert immunogenicity of mAb drug candidates.

Factor VIII: Perspectives on Immunogenicity and Tolerogenic Strategies

Therapeutic treatment of bleeds with FVIII can lead to an antibody response that effectively inhibits its function. Herein, we review the factors that contribute to this immunogenicity and possible ways to overcome it.

Association of Pharmacological Biomarkers with Treatment Response and Longterm Disability in Patients with Psoriatic Arthritis: Results from OUTPASS

Objective.

To identify (1) whether tumor necrosis factor inhibitor (TNFi) drug levels/anti-drug antibodies (ADAb) are associated with treatment response and disability in patients with psoriatic arthritis (PsA); and (2) the factors associated with TNFi drug levels.

Methods.

Patients were recruited from a national multicenter prospective cohort with longitudinal serum samples and 28-joint count Disease Activity Scores (DAS28)/Health Assessment Questionnaire (HAQ) measurement over 12 months.

Results.

Adalimumab (ADA) drug levels were significantly associated with ΔDAS28 (β 0.055, 95% CI 0.011–0.099; p = 0.014) and inversely with HAQ over 12 months (β −0.022, 95% CI −0.043 to −0.00063). Factors significantly associated with ADA drug levels were ADAb levels and body mass index.

Conclusion.

Drug level testing in ADA-initiated PsA patients may be useful in determining treatment response/disability over 12 months.

Drug safety and immunogenicity of tumour necrosis factor inhibitors: the story so far

TNF-α inhibitor (TNFi) therapies have transformed the treatment of several rheumatic musculoskeletal diseases. However, the majority of TNFi's are immunogenic and consequent anti-drug antibodies formation can impact on both treatment efficacy and safety. Several controversies exist in the area of immunogenicity of TNFis and drug safety. While anti-drug antibodies to TNFis have been described in association with infusion reactions; serious adverse events (AEs) such as thromboembolic events, lupus-like syndrome, paradoxical AEs, for example, vasculitis-like events and other autoimmune manifestations have also been reported. The expansion of the biologic armamentarium, new treatment strategies such as introduction/switching to biosimilars and cost-saving approaches such as TNFi tapering, may all have a potential impact on immunogenicity and clinical sequelae. In this review we evaluate how evolution of biologics relates to drug safety and immunogenicity, appraise relevant evidence from trials, spontaneous pharmacovigilance and observational studies and outline the areas of uncertainty that still exist.

Update of the Position Paper of the Spanish Society of Rheumatology on Biosimilar Drugs

In 2015 the Spanish Society of Rheumatology (Sociedad Española de Reumatología [SER]) published its position paper on biosimilar drugs. In this update, the SER, continues to manifest its unequivocal commitment to the sustainability of the health system of our country and is aligned with the measures that, without reducing quality of care, are aimed at ensuring its continuity. Since the publication of the previous position paper, the European Commission has authorized new biosimilar drugs, which provides an excellent opportunity to advance the efficiency of health care. In this new scenario of increased therapeutic offer of biologics, the SER considers it crucial to preserve the freedom of prescription of physicians who prescribe drugs based exclusively on the characteristics and individual circumstances of each patient, without forgetting the economic aspects there of.

Immunogenicity of Protein Pharmaceuticals

Protein therapeutics have drastically changed the landscape of treatment for many diseases by providing a regimen that is highly specific and lacks many off-target toxicities. The clinical utility of many therapeutic proteins has been undermined by the potential development of unwanted immune responses against the protein, limiting their efficacy and negatively impacting its safety profile. This review attempts to provide an overview of immunogenicity of therapeutic proteins, including immune mechanisms and factors influencing immunogenicity, impact of immunogenicity, preclinical screening methods, and strategies to mitigate immunogenicity.

Separation, Characterization and Discriminant Analysis of Subvisible Particles in Biologics Formulations

Background:

The presence of subvisible particles (SVPs) in parenteral formulations of biologics is a major challenge in the development of therapeutic protein formulations. Distinction between proteinaceous and non-proteinaceous SVPs is vital in monitoring formulation stability.

Methods:

The current compendial method based on light obscuration (LO) has limitations in the analysis of translucent/low refractive index particles. A number of attempts have been made to develop an unambiguous method to characterize SVPs, albeit with limited success.

Results:

Herein, we describe a robust method that characterizes and distinguishes both potentially proteinaceous and non-proteinaceous SVPs in protein formulations using Microflow imaging (MFI) in conjunction with the MVAS software (MFI View Analysis Suite), developed by ProteinSimple. The method utilizes two Intensity parameters and a morphological filter that successfully distinguishes proteinaceous SVPs from non-proteinaceous SVPs and mixed aggregates.

Conclusion:

he MFI generated raw data of a protein sample is processed through Lumetics LINK software that applies an in-house developed filter to separate proteinaceous from the rest of the particulates.

Flow Microscopy Imaging Is Sensitive to Characteristics of Subvisible Particles in Peginesatide Formulations Associated With Severe Adverse Reactions

The presence of subvisible particles in formulations of therapeutic proteins is a risk factor for adverse immune responses. Although the immunogenic potential of particulate contaminants likely depends on particle structural characteristics (e.g., composition, size, and shape), exact structure-immunogenicity relationships are unknown. Images recorded by flow imaging microscopy reflect information about particle morphology, but flow microscopy is typically used to determine only particle size distributions, neglecting information on particle morphological features that may be immunologically relevant. We recently developed computational techniques that utilize the Kullback-Leibler divergence and multidimensional scaling to compare the morphological properties of particles in sets of flow microscopy images. In the current work, we combined these techniques with expectation maximization cluster analyses and used them to compare flow imaging microscopy data sets that had been collected by the U.S. Food and Drug Administration after severe adverse drug reactions (including 7 fatalities) were observed in patients who had been administered some lots of peginesatide formulations. Flow microscopy images of particle populations found in the peginesatide lots associated with severe adverse reactions in patients were readily distinguishable from images of particles in lots where severe adverse reactions did not occur.

Correlation between HLA haplotypes and the development of antidrug antibodies in a cohort of patients with rheumatic diseases

Introduction

The aim of this study was to investigate the correlation between human leukocyte antigen (HLA) haplotypes and the development of antidrug antibodies (ADAs) in a cohort of patients with rheumatic diseases.

Patients and methods

We evaluated the presence of ADAs in 248 patients with inflammatory rheumatic diseases after 6 months of treatment with anti-TNF drugs: 26 patients were treated with infliximab (IFX; three with rheumatoid arthritis [RA], 13 with ankylosing spondylitis [AS], 10 with psoriatic arthritis [PsA]); 83 treated with adalimumab (ADA; 24 with RA, 36 with AS, 23 with PsA); 88 treated with etanercept (ETA; 35 with RA, 27 with AS, 26 with PsA); 32 treated with certolizumab (CERT; 25 with RA, two with AS, five with PsA); and 19 treated with golimumab (GOL; three with RA, seven with AS, nine with PsA). Serum drug and ADA levels were determined using Lisa-Tracker Duo, the ADA-positive samples underwent an inhibition test, and the true-positive samples underwent genetic HLA typing. To have a homogeneous control population, we also performed genetic HLA typing of 11 ADA-negative patients.

Results

After inhibition test, the frequency of ADAs was 2/26 patients treated with IFX (7.69%), 4/83 treated with ADA (4.81%), 0/88 treated with ETA (0%), 4/32 treated with CERT (12.5%), and 1/19 treated with GOL (5.26%). The frequency of HLA alleles in the examined patients was HLA-DRβ-11 0.636, HLA-DQ-03 0.636, and HLA-DQ-05 0.727. The estimated relative risks between the ADA-positive patients and the ADA-negative patients were HLA-DRβ-11 2.528 (95% CI 0.336-19.036), HLA-DQ-03 1.750 (95% CI 0.289-10.581), and HLA-DQ-05 2.424 (95% CI 0.308-15.449).

Conclusion

This is the first study that shows an association between HLA and genetic factors associated with the occurrence of ADAs in patients with rheumatic diseases, but the number of samples is too small to draw any definite conclusion.

Non-surgical interventions for treating heavy menstrual bleeding (menorrhagia) in women with bleeding disorders

BACKGROUND

Heavy menstrual bleeding without an organic lesion is mainly due to an imbalance of the various hormones which have a regulatory effect on the menstrual cycle. Another cause of heavy menstrual bleeding with no pelvic pathology, is the presence of an acquired or inherited bleeding disorder. The haemostatic system has a central role in controlling the amount and the duration of menstrual bleeding, thus abnormally prolonged or profuse bleeding does occur in most women affected by bleeding disorders. Whereas irregular, pre-menarchal or post-menopausal uterine bleeding is unusual in inherited or acquired haemorrhagic disorders, severe acute bleeding and heavy menstrual bleeding at menarche and chronic heavy menstrual bleeding during the entire reproductive life are common. This is an update of a previously published Cochrane Review.

OBJECTIVES

To determine the efficacy and safety of non-surgical interventions versus each other, placebo or no treatment for reducing menstrual blood loss in women with bleeding disorders.

SEARCH METHODS

We searched the Cochrane Cystic Fibrosis Haemoglobinopathies Trials Register (25 August 2016), Embase (May 2013), LILACS (February 2013) and the WHO International Clinical Trial registry (February 2013).

SELECTION CRITERIA

Randomised controlled studies of non-surgical interventions for treating heavy menstrual bleeding (menorrhagia) in women of reproductive age suffering from a congenital or acquired bleeding disorder.

DATA COLLECTION AND ANALYSIS

Two authors independently assessed studies for inclusion, extracted data and assessed the risk of bias.

MAIN RESULTS

Three cross-over studies, with 175 women were included in the review. All three studies had an unclear risk of bias with regards to trial design and overall, the quality of evidence generated was judged to be poor.Two of the studies (n = 59) compared desmopressin (1-deamino-8-D-arginine vasopressin) with placebo. Menstrual blood loss was the primary outcome for both of these studies. Neither study found clear evidence of a difference between groups. The first of these reported a mean difference in menstrual blood loss in the desmopressin versus placebo group of 21.20 mL (95% confidence interval -19.00 to 61.50)The second study reported that even though there was an improvement of pictorial bleeding assessment chart scores with desmopressin and placebo when compared to pretreatment assessment, there was no clear evidence of difference in these scores when the two were compared to each other (results presented graphically, P = 0.51). The data from these studies could not be combined.The third study (n = 116) compared desmopressin with tranexamic acid (n = 116). This study found a decrease in pictorial bleeding assessment chart scores after both treatments as compared to baseline. The decrease in these scores was greater for tranexamic acid than for desmopressin, with a mean difference of 41.6 mL (95% confidence interval 19.6 to 63) (P < 0.0002).In relation to adverse events, across two studies, there was no clear evidence of a difference when placebo was compared to desmopressin, risk ratio 1.17 (95% confidence interval 0.41 to 3.34) . The same was also true when desmopressin was compared to tranexamic acid, risk ratio 1.17 (95% confidence interval 0.41 to 3.34).Only the study that compared desmopressin to tranexamic acid assessed quality of life. However, we are unable to present any data from this study, since no differences in this outcome between the two intervention groups were reported.

AUTHORS' CONCLUSIONS

Evidence from randomised controlled studies on the effect of desmopressin when compared to placebo in reducing menstrual blood loss is very limited and inconclusive. Two studies, each with a very limited number of participants, have shown uncertain effects in menstrual blood loss and adverse effects. A non-randomised comparison in one of the studies points to the value of combining desmopressin and tranexamic acid, which needs to be tested in a formal randomised controlled study comparison.When tranexamic acid was compared to desmopressin, a single study showed a reduction in menstrual blood loss with tranexamic acid use compared to desmopressin.There is a need to evaluate non-surgical methods for treating of menorrhagia in women with bleeding disorders through randomised controlled studies. Such methods would be more acceptable than surgery for women wishing to retain their fertility. Given that women may need to use these treatments throughout their entire reproductive life, long-term side-effects should be evaluated.

Effect of vaccine administration modality on immunogenicity and efficacy

The many factors impacting the efficacy of a vaccine can be broadly divided into three categories: features of the vaccine itself, including immunogen design, vaccine type, formulation, adjuvant and dosing; individual variations among vaccine recipients and vaccine administration-related parameters. While much literature exists related to vaccines, and recently systems biology has started to dissect the impact of individual subject variation on vaccine efficacy, few studies have focused on the role of vaccine administration-related parameters on vaccine efficacy. Parenteral and mucosal vaccinations are traditional approaches for licensed vaccines; novel vaccine delivery approaches, including needless injection and adjuvant formulations, are being developed to further improve vaccine safety and efficacy. This review provides a brief summary of vaccine administration-related factors, including vaccination approach, delivery route and method of administration, to gain a better understanding of their potential impact on the safety and immunogenicity of candidate vaccines.

Dose levels in particulate-containing formulations impact anti-drug antibody responses to murine monoclonal antibody in mice

Dosage levels and particulate contents of therapeutic protein formulations are potential factors that impact immunogenicity of protein therapeutics. Here, we evaluated the effect of dose levels on the immunogenicity of protein particulates formed by adsorbing a murine monoclonal IgG2c/κ antibody (mAb1) onto silicone oil microdroplets, glass, or aluminum hydroxide (Alhydrogel) microparticles. Immune responses to these particulate-containing preparations were compared against responses to solutions of mAb1 that had been ultracentrifuged to minimize particle levels. Formulations containing 5 or 500 μg of adsorbed mAb1 were administered subcutaneously to C57BL/6J or BALB/c mice. Antidrug antibodies (ADAs) were detected using an isotype-specific enzyme-linked immunosorbent assay (ELISA) method or a chemiluminescence method. Sera from BALB/c mice showed greater ADA responses to administration of particles at the 5-μg dose level than at the 500-μg dose level. In sera from C57BL/6J mice, ADA levels detected by ELISA were independent of the particle dose levels tested. ADAs were not detected in sera from C57BL/6J mice performing the chemiluminescence technique. In conclusion, mice administered formulations of a murine antibody adsorbed onto silicone oil microdroplets, glass microparticles, or Alhydrogel(®) showed greater ADA responses that those that received particle-free mAb1 preparations, and responses were greater for formulations containing lower doses of antibody. .

Clinical Manifestations of an Anti-Drug Antibody Response: Autoimmune Reactions

Antibodies can be generated against a therapeutic protein upon administration to human subjects. When the therapeutic protein closely mimics one of the subject's endogenous proteins, those antibodies might bind to the endogenous protein in addition to the therapeutic protein. This scenario results when tolerance to the endogenous protein is broken. The consequences of breaking tolerance include an autoimmune response where antibodies are generated against the endogenous protein. These autoantibodies could have significant clinical relevance depending on several factors, including the redundancy of action of the endogenous protein as well as the concentration, binding affinity, and neutralizing potential of the antibodies. The consequences of a therapeutic-protein-induced autoimmune reaction can be challenging to manage as the stimulus for further perpetuation of the immune response can shift from the therapeutic protein to the endogenous protein. The potential for inducing an autoimmune response is one of the reasons that the immune response to a therapeutic protein should be monitored if it persists through the end of the study.

Non-surgical interventions for treating heavy menstrual bleeding (menorrhagia) in women with bleeding disorders

BACKGROUND

Heavy menstrual bleeding without an organic lesion is mainly due to an imbalance of the various hormones which have a regulatory effect on the menstrual cycle. Another cause of heavy menstrual bleeding with no pelvic pathology, is the presence of an acquired or inherited bleeding disorder. The haemostatic system has a central role in controlling the amount and the duration of menstrual bleeding, thus abnormally prolonged or profuse bleeding does occur in most women affected by bleeding disorders. Whereas irregular, pre-menarchal or post-menopausal uterine bleeding is unusual in inherited or acquired haemorrhagic disorders, severe acute bleeding and heavy menstrual bleeding at menarche and chronic heavy menstrual bleeding during the entire reproductive life are common.

OBJECTIVES

To determine the efficacy and safety of non-surgical interventions versus each other, placebo or no treatment for reducing menstrual blood loss in women with bleeding disorders.

SEARCH METHODS

We searched the Cochrane Cystic Fibrosis Haemoglobinopathies Trials Register (13 March 2014), Embase (May 2013), LILACS (February 2013) and the WHO International Clinical Trial registry (February 2013).

SELECTION CRITERIA

Randomised controlled studies of non-surgical interventions for treating heavy menstrual bleeding (menorrhagia) in women of reproductive age suffering from a congenital or acquired bleeding disorder.

DATA COLLECTION AND ANALYSIS

Two authors independently assessed studies for inclusion, extracted data and assessed the risk of bias.

MAIN RESULTS

Three cross-over studies, with 175 participants were included in the review. All three studies had an unclear risk of bias with regards to trial design and overall, the quality of evidence generated was judged to be poor.Two of the studies (n = 59) compared desmopressin (1-deamino-8-D-arginine vasopressin) with placebo. Menstrual blood loss was the primary outcome for both of these studies. Neither study found clear evidence of a difference between groups. The first of these reported a mean difference in menstrual blood loss in the desmopressin versus placebo group of 21.20 mL (95% confidence interval -19.00 to 61.50)The second study reported that even though there was an improvement of pictorial bleeding assessment chart scores with desmopressin and placebo when compared to pretreatment assessment, there was no clear evidence of difference in these scores when the two were compared to each other (results presented graphically, P = 0.51). The data from these studies could not be combined.The third study (n = 116) compared desmopressin with tranexamic acid (n = 116). This study found a decrease in pictorial bleeding assessment chart scores after both treatments as compared to baseline. The decrease in these scores was greater for tranexamic acid than for desmopressin, with a mean difference of 41.6 mL (95% confidence interval 19.6 to 63) (P < 0.0002).In relation to adverse events, across two studies, there was no clear evidence of a difference when placebo was compared to desmopressin, risk ratio 1.17 (95% confidence interval 0.41 to 3.34) . The same was also true when desmopressin was compared to tranexamic acid, risk ratio 1.17 (95% confidence interval 0.41 to 3.34).Only the study that compared desmopressin to tranexamic acid assessed quality of life. However, we are unable to present any data from this study, since no differences in this outcome between the two intervention groups were reported.

AUTHORS' CONCLUSIONS

Evidence from randomised controlled studies on the effect of desmopressin when compared to placebo in reducing menstrual blood loss is very limited and inconclusive. Two studies, each with a very limited number of participants, have shown uncertain effects in menstrual blood loss and adverse effects. A non-randomised comparison in one of the studies points to the value of combining desmopressin and tranexamic acid, which needs to be tested in a formal randomised controlled study comparison.When tranexamic acid was compared to desmopressin, a single study showed a reduction in menstrual blood loss with tranexamic acid use compared to desmopressin.There is a need to evaluate non-surgical methods for treating of menorrhagia in women with bleeding disorders through randomised controlled studies. Such methods would be more acceptable than surgery for women wishing to retain their fertility. Given that women may need to use these treatments throughout their entire reproductive life, long-term side-effects should be evaluated.

Transmission electron microscopy as an orthogonal method to characterize protein aggregates

Aggregation of protein-based therapeutics is a challenging problem in the biopharmaceutical industry. Of particular concern are implications for product efficacy and clinical safety because of potentially increased immunogenicity of the aggregates. We used transmission electron microscopy (TEM) to characterize biophysical and morphological features of antibody aggregates formed upon controlled environmental stresses. TEM results were contrasted with results obtained in parallel by independent methods, including size-exclusion chromatography, dynamic light scattering, microflow imaging, and nanoparticle tracking. For TEM, stressed samples were imaged by negative staining and in the frozen-hydrated state. In both cases, aggregates appeared amorphous but differed in fine structural detail. Specifically, negatively stained aggregates were compact and consisted of smaller globular structures that had a notable three-dimensional character. Elements of the native IgG structure were retained, suggesting that the aggregates were not assembled from denatured protein. In contrast, aggregates in frozen-hydrated samples appeared as extended, branched protein networks with large surface area. Using multiple scales of magnification, a wide range of particle sizes was observed and semiquantitatively characterized. The detailed information provided by TEM extended observations obtained with the independent methods, demonstrating the suitability of TEM as a complementary approach to submicron particle analysis.

Investigation of the immunogenicity of different types of aggregates of a murine monoclonal antibody in mice

PURPOSE

The potential contribution of protein aggregates to the unwanted immunogenicity of protein pharmaceuticals is a major concern. In the present study a murine monoclonal antibody was utilized to study the immunogenicity of different types of aggregates in mice. Samples containing defined types of aggregates were prepared by processes such as stirring, agitation, exposure to ultraviolet (UV) light and exposure to elevated temperatures.

METHODS

Aggregates were analyzed by size-exclusion chromatography, light obscuration, turbidimetry, infrared (IR) spectroscopy and UV spectroscopy. Samples were separated into fractions based on aggregate size by asymmetrical flow field-flow fractionation or by centrifugation. Samples containing different types and sizes of aggregates were subsequently administered to C57BL/6 J and BALB/c mice, and serum was analyzed for the presence of anti-IgG1, anti-IgG2a, anti-IgG2b and anti-IgG3 antibodies. In addition, the pharmacokinetic profile of the murine antibody was investigated.

RESULTS

In this study, samples containing high numbers of different types of aggregates were administered in order to challenge the in vivo system. The magnitude of immune response depends on the nature of the aggregates. The most immunogenic aggregates were of relatively large and insoluble nature, with perturbed, non-native structures.

CONCLUSION

This study shows that not all protein drug aggregates are equally immunogenic.

Structural characterization of IgG1 mAb aggregates and particles generated under various stress conditions

IgG1 mAb solutions were prepared with and without sodium chloride and subjected to different environmental stresses. Formation of aggregates and particles of varying size was monitored by a combination of size-exclusion chromatography, Nanoparticle Tracking Analysis, Micro-flow Imaging (MFI), turbidity, and visual assessments. Stirring and heating induced the highest concentration of particles. In general, the presence of NaCl enhanced this effect. The morphology of the particles formed from mAb samples exposed to different stresses was analyzed from transmission electron microscopy and MFI images. Shaking samples without NaCl generated the most fibrillar particles, whereas stirring created largely spherical particles. The composition of the particles was evaluated for covalent cross-linking by SDS-PAGE, overall secondary structure by FTIR microscopy, and surface apolarity by extrinsic fluorescence spectroscopy. Freeze-thaw and shaking led to particles containing protein with native-like secondary structure. Heating and stirring produced IgG1-containing aggregates and particles with some non-native disulfide cross-links, varying levels of intermolecular beta sheet content, and increased surface hydrophobicity. These results highlight the importance of evaluating protein particle morphology and composition, in addition to particle number and size distributions, to better understand the effect of solution conditions and environmental stresses on the formation of protein particles in mAb solutions.

Significant associations of antidrug antibody levels with serum drug trough levels and therapeutic response of adalimumab and etanercept treatment in rheumatoid arthritis

OBJECTIVE

To evaluate the associations between (1) antidrug antibody (ADAb) and therapeutic response, (2) ADAb and serum drug trough levels and (3) serum drug levels and therapeutic responses in rheumatoid arthritis (RA) patients receiving adalimumab or etanercept. Secondarily, we aim (1) to evaluate the concordance between radioimmunoassay and bridging ELISA for ADAb assessment and to evaluate the correlation between two different ELISA methods for detecting drug levels, and (2) to determine the optimal cut-off drug levels for good European League Against Rheumatism (EULAR) response.

METHODS

ADAb levels were determined by bridging ELISA and radioimmunoassay, and drug levels evaluated using sandwich ELISA among 36 adalimumab-treated patients and 34 etanercept-treated patients at the 6th and 12th month. The optimal cut-off drug levels for EULAR responses were determined by receiver-operating characteristic curve analysis.

RESULTS

ADAb was detected in 10 (27.8%) and 13 (36.1%) of adalimumab-treated patients after 12-month therapy using bridging ELISA and radioimmunoassay respectively, but not detected in any of etanercept-treated patients. The presence of ADAb was associated with lower EULAR response and lower drug levels compared with those without ADAb (both p<0.001). Drug trough levels were positively associated with DAS28 decrement (ΔDAS28) (all p<0.001). The optimal cut-off trough levels for adalimumab were 1.274 μg/mL and 1.046 μg/mL, and those for etanercept were 1.242 μg/mL and 0.800 μg/mL for good EULAR response assessed at the 6th and 12th month, respectively.

CONCLUSIONS

ADAb levels were inversely correlated with therapeutic response and drug levels. The positive correlation between drug levels and ΔDAS28 indicates that drug monitoring would be useful to evaluate therapeutic response of TNF-α inhibitors.

Immunogenicity of subcutaneously administered therapeutic proteins--a mechanistic perspective

The administration of therapeutic proteins via the subcutaneous route (sc) is desired for compliance and convenience, but could be challenging due to perceived immunogenic potential or unwanted immune responses. There are clinical and preclinical data supporting as well as refuting the generalized notion that sc is more immunogenic. We provide a mechanistic perspective of immunogenicity of therapeutic proteins administered via the sc route and discuss strategies and opportunities for novel therapeutic approaches to mitigate immunogenicity.

Immunogenicity of anti-TNF biologic therapies for rheumatoid arthritis

Currently, five anti-TNF biologic agents are approved for the treatment of rheumatoid arthritis (RA): adalimumab, infliximab, etanercept, golimumab and certolizumab pegol. Formation of anti-drug antibodies (ADA) has been associated with all five agents. In the case of adalimumab and infliximab, immunogenicity is strongly linked to subtherapeutic serum drug levels and a lack of clinical response, but for the other three agents, data on immunogenicity are scarce, suggesting that further research would be valuable. Low ADA levels might not influence the efficacy of anti-TNF therapy, whereas high ADA levels impair treatment efficacy by considerably reducing unbound drug levels. Immunogenicity is not only an issue in patients treated with anti-TNF biologic agents; the immunogenicity of other therapeutic proteins, such as factor VIII and interferons, is well known and has been investigated for many years. The results of such studies suggest that investigations to determine the optimal treatment regimen (drug dosing, treatment schedule and co-medication) required to minimize the likelihood of ADA formation might be an effective and practical way to deal with the immunogenicity of anti-TNF biologic agents for RA.

Immunogenicity issues in drug development

Immunogenicity is an important factor that manufacturers must consider as they develop new protein therapeutics. It is important to understand the immunogenicity of new proteins both at the preclinical phase and in the clinical phase of development. This paper provides an overview of the issues that manufacturers should consider including some of the potential reasons that some proteins induce an immune response, a discussion regarding current methodology used to understand immunogenicity, and some examples of marketed protein therapeutics with immunogenicity issues. Given the increasing scrutiny from regulatory agencies around the way immunogenicity is assessed by manufacturers, the strategy of detecting and characterizing antibodies that are formed against protein therapeutics is becoming an important topic. Screening assays are typically performed first on all serum samples collected in the course of a trial to detect the presence of antibodies that can bind to the protein therapeutic. There are several platforms in use: radioimmune precipitation assays (RIP), enzyme linked immunosorbent assays (ELISA), electrochemiluminescent assays (ECL), and biosensor-based assays. Each has its advantages and disadvantages, and needs to be evaluated to identify the optimal platform for a specific therapeutic protein. Once antibodies are identified, a confirmatory assay is performed to verify and characterize the antibodies. A biological assay should be used next to test if these antibodies are capable of neutralizing the biological effect of the drug. Any sample that is positive for neutralizing antibodies, indicates that the antibody is probably having an impact on the patient's ability to derive full benefit from the therapeutic protein, and may be critical for patient safety.

Immunogenicity of different stressed IgG monoclonal antibody formulations in immune tolerant transgenic mice

The presence of protein aggregates in biopharmaceutical formulations is of great concern for safety and efficacy reasons. The aim of this study was to correlate the type and amount of IgG monoclonal antibody aggregates with their immunogenic potential. IgG degradation was obtained by freeze-thawing cycles, pH-shift cycles, heating, shaking and metal-catalyzed oxidation. The size, amount, morphology and type of intermolecular bonds of aggregates, as well as structural changes and epitope integrity were characterized. These formulations were injected in mice transgenic (TG) for human genes for Ig heavy and light chains and their non-transgenic (NTG) counterparts. Anti-drug antibody (ADA) titers were determined by bridging ELISA. Both unstressed IgG and freeze-thawed formulation did not induce measurable ADA levels. A mild antibody response was obtained in a fairly small percentage of mice, when injected with shaken, pH-shifted and heated formulations. The metal-catalyzed oxidized IgG formulation was the most immunogenic one, in both ADA titers and number of responders. The overall titers of NTG responders were significantly higher than the ones produced by TG mice, whereas there was no significant difference between the overall number of TG and NTG responders. This study reinforces the important role of protein aggregates on immunogenicity of therapeutic proteins and provides new insight into the immunogenic potential of different types of IgG aggregates. The results indicate that the quality of the IgG aggregates has more impact on the development of an immune response than their quantity or size.

Immunogenicity to biologics: mechanisms, prediction and reduction

Currently, there is a significant rise in the development and clinical use of a unique class of pharmaceuticals termed as Biopharmaceuticals or Biologics, in the management of a range of disease conditions with, remarkable therapeutic benefits. However, there is an equally growing concern regarding development of adverse effects like immunogenicity in the form of anti-drug antibodies (ADA) production and hypersensitivity. Immunogenicity to biologics represents a significant hurdle in the continuing therapy of patients in a number of disease settings. Efforts focussed on the identification of factors that contribute towards the onset of immunogenic response to biologics have led to reductions in the incidence of immunogenicity. An in-depth understanding of the cellular and molecular mechanism underpinning immunogenic responses will likely improve the safety profile of biologics. This review addresses the mechanistic basis of ADA generation to biologics, with emphasis on the role of antigen processing and presentation in this process. The article also addresses the potential contribution of complement system in augmenting or modulating this response. Identifying specific factors that influences processing and presentation of biologic-derived antigens in different genotype and disease background may offer additional options for intervention in the immunogenic process and consequently, the management of immunogenicity to biologics.

Immunogenicity of protein aggregates--concerns and realities

Protein aggregation is one of the key challenges in the development of protein biotherapeutics. It is a critical product quality issue as well as a potential safety concern due to the increased immunogenicity potential of these aggregates. The overwhelming safety concern has led to an increased development effort and regulatory scrutiny in recent years. The main purposes of this review are to examine the literature data on the relationship between protein aggregates and immunogenicity, to highlight the linkage and existing inconsistencies/uncertainties, and to propose directions for future investigations/development.

Fabry disease, enzyme replacement therapy and the significance of antibody responses

Fabry disease is an X-linked disorder caused by a deficiency of α-galactosidase A. This leads to a progressive accumulation of globotriaosylceramide in tissues throughout the body. Cardiac, renal and neurological manifestations are common and life expectancy is significantly reduced relative to the general population. Management of Fabry disease involves the administration of intravenous enzyme replacement therapy (ERT). Two forms - agalsidase alfa and agalsidase beta - have been licensed in certain jurisdictions and are generally well tolerated; however, some patients develop antibodies to the infused enzyme, which may impair the efficacy and safety of treatment. Agalsidase alfa and agalsidase beta are produced in different systems; this leads to certain differences in post-translational modification that may affect immunogenicity. Immunoglobulin (Ig) G antibodies have frequently been reported in patients with Fabry disease receiving ERT; IgG responses are reported in a greater proportion of patients receiving agalsidase beta than in patients receiving agalsidase alfa. IgE antibodies are less common than IgG antibodies, and have not been observed in patients receiving agalsidase alfa. However, these data are difficult to interpret due to methodological differences in the assessment of seropositivity, and in the doses of enzyme used. The clinical impact of the development of IgG antibodies to ERT in patients with Fabry disease remains unclear, due to lack of data and to the marked heterogeneity of patients both in terms of disease manifestations and response to therapy. Further studies that examine the development of antibodies in patients with Fabry disease and the potential impact of such antibodies on the outcome of ERT are necessary.

Safety and Efficacy of Thrombin-JMI: A Multidisciplinary Expert Group Consensus

Background: The use of bovine thrombin has been an effective approach to aiding hemostasis during surgery for over 60 years. Its use has a reported association with the development of antibodies to coagulation factors with limited evidence to the clinical significance. Methods: The Collaborative Delphi survey methodology was used to develop a consensus on specified topic areas from a panel of 12 surgeons/scientists who have had experience with topical thrombins; it consisted of 2 rounds of a Web-based survey and a final live discussion. Results: Some key issues that reached consensus included: bovine, human plasma-derived and recombinant human thrombin are equally effective hemostatic agents with similar adverse event rates, and immunogenicity to a topical protein rarely translate into adverse events. Conclusions: Although a risk of immunogenicity is associated with all topical thrombins, no conclusive clinical evidence is available that these antibodies have any significant effect on short- and long-term clinical consequences.

n-Dodecyl-β-D-maltoside inhibits aggregation of human interferon-β-1b and reduces its immunogenicity

The development of neutralizing antibodies to the protein drug interferon-β is a significant impediment to its use in the treatment of multiple sclerosis. Neutralizing antibodies to interferon-β arise from aggregation of the peptide during manufacturing and storage. We tested the ability of dodecylmaltoside, a nontoxic alkylsaccharide surfactant, to reduce aggregation of interferon-β in vitro and to reduce its immunogenicity in vivo. Interferon-β, in solution with and without dodecylmaltoside, was periodically evaluated for aggregation by light scatter for 1 month. Interferon-β, with and without dodecylmaltoside, was given 3 days/week for 1 month to mice; the sera of these mice were analyzed for anti-interferon-β antibodies by ELISA. Dodecylmaltoside reduces the aggregation of interferon-β in vitro and its immunogenicity in vivo. Our positive findings warrant additional tests of dodecylmaltoside as a therapeutic adjuvant in rodent models of multiple sclerosis.

Erythropoiesis Equivalence, Pharmacokinetics and Immune Response following Repeat Hematide™ Administration in Cynomolgus Monkeys

Hematide™ is a synthetic PEGylated peptidic erythropoiesis stimulating agent (ESA) that is presently being developed for the correction of anemia in patients with chronic renal failure. Unlike currently marketed ESAs, Hematide does not possess any sequence homology to erythropoietin (EPO) and has not elicited moribund immune responses in animal safety studies thereby allowing the generation of a robust safety package. Animals administered marketed ESAs develop anti-EPO antibodies that null the effect of the administered ESA and neutralize endogenous EPO, resulting in severe anemia that precludes the interpretation of chronic safety studies. The primary objective of this study is to determine whether Hematide-specific antibodies are generated when male monkeys are exposed to high Hematide doses (10 mg/kg, intravenous [IV] and subcutaneous [SC]) administered at frequent dosing intervals (every two weeks) for a total of 9 doses; secondary objectives are to evaluate whether developed antibodies impact pharmacokinetics (PK) and pharmacology. In this study, no Hematide-specific antibodies were detected. Hematide exhibits a prolonged plasma half-life and slow clearance by either IV or SC administration. Hematide induced significant erythropoiesis with reticulocytosis and subsequent increases in red blood cells, hematocrit and hemoglobin (Hgb) levels. No erythropoietic differences were noted between the IV and the SC dosed groups with mean ± SD Hgb levels of 20.9 ± 2.5 and 20.3 ± 2.1 g/dL, respectively, occurring on Day 48, corresponding to Hgb increases of 6.5 and 6.7 g/dL, respectively, over pre-dose levels. In conclusion, Hematide is a potent erythropoiesis stimulating agent that exhibits plasma persistence in monkeys. Similar erythropoietic responses were produced following IV and SC administration. The absence of antibody development suggests that Hematide, at the doses and regimen described, has a low immunogenic potential in cynomolgus monkeys.

Effect of route of administration of human recombinant factor VIII on its immunogenicity in Hemophilia A mice

Factor VIII is a multi-domain glycoprotein and is an essential cofactor in the blood coagulation cascade. Its deficiency or dysfunction causes Hemophilia A, a bleeding disorder. Replacement using exogenous recombinant Factor VIII (FVIII) is the first line of therapy for Hemophilia A. Immunogenicity, the development of binding (total) and neutralizing (inhibitory) antibody against administered protein is a clinical complication of the therapy. There are several product related factors such as presence of aggregates, route and frequency of administration and glycosylation have been shown to contribute to immunogenicity. The effect of route of administration of FVIII on antibody development in Hemophilia A is not completely understood. Here we investigated the effect of route of administration (s.c. or i.v.) on immunogenicity in Hemophilia A mice. The total and inhibitory titers were determined using ELISA and modified Bethesda Assay respectively. The results indicated that s.c. is more immunogenic compared to i.v. route in terms of total antibody titer development (binding antibodies) but no significant differences in inhibitory titer levels could be established.

Immunogenicity of bone morphogenetic proteins

Object

The object of this paper is to review the immunogenicity of bone morphogenetic proteins (BMPs) and to compare the results of the immunogenicity characterization and clinical consequences between recombinant human (rh)BMP-2 and recombinant human osteogenic protein-1 (rhOP-1/BMP-7).

Methods

The immunogenicity of therapeutic proteins and its clinical effects were reviewed. The characteristics of BMPs were also described in terms of immunogenicity. The methods and results of antibody detection in various clinical trials of rhBMP-2 and rhOP-1 were compared, including the most recent studies using a systematic characterization strategy with both a binding assay and bioassay.

Results

Similar to all recombinant human proteins, rhBMPs induce immune responses in a select subgroup of patients. Adverse effects from this response in these patients, however, have not been reported with antibody formation to either rhBMP-2 or rhOP-1. Overall, the incidence of antibody formation was slightly higher in rhOP-1 trials than in rhBMP-2 trials.

Conclusions

Although they occur in a subgroup of patients, the immune responses against rhBMPs have no correlation with any clinical outcome or safety parameter. Clinicians, however, must be aware of the potential complications caused by the immunogenicity of BMPs until more studies clearly elucidate their safety.

Polymer-based sustained-release dosage forms for protein drugs, challenges, and recent advances

While the concept of using polymer-based sustained-release delivery systems to maintain therapeutic concentration of protein drugs for extended periods of time has been well accepted for decades, there has not been a single product in this category successfully commercialized to date despite clinical and market demands. To achieve successful systems, technical difficulties ranging from protein denaturing during formulation process and the course of prolonged in vivo release, burst release, and incomplete release, to low encapsulation efficiency and formulation complexity have to be simultaneously resolved. Based on this updated understanding, formulation strategies attempting to address these aspects comprehensively were reported in recent years. This review article (with 134 citations) aims to summarize recent studies addressing the issues above, especially those targeting practical industrial solutions. Formulation strategies representative of three areas, microsphere technology using degradable hydrophobic polymers, microspheres made of water soluble polymers, and hydrophilic in vivo gelling systems will be selected and introduced. To better understand the observations and conclusions from different studies for different systems and proteins, physicochemical basis of the technical challenges and the pros and cons of the corresponding formulation methods will be discussed.

Immune response to lytic peptides conjugated to a betaCG fragment in treated BALB/C mice

Hecate-betaCG and Phor14-betaCG(ala) are relatively short, amphipathic alpha-helical cationic peptides with the ability to destroy selectively breast, prostate and ovarian cancer cells. Treatment with proteins and peptides frequently initiated antibody formation. Short peptides may minimize the risk of the immune system mobilization after treatment but it is necessary to investigate whether Hecate-betaCG and Phor14-betaCG(ala) induce the immune system to produce antibody and whether they affect the reproductive organs in normal wild-type mice. The results of our experiments showed that specific antibodies, tested by the enzyme-immunoassay, were not detected in the group treated with Hecate-betaCG and Phor14-betaCG(ala). The blood concentrations of both peptides begun to decrease from 60 minutes after injection and after 240 minutes its levels were undetectable. Histopatho-logical examination exhibited degenerative changes in the prostate glands and testes in males and in the ovaries and uteri of females treated with both peptides. In conclusion, our results indicate that both relatively small and rapidly metabolized peptides are not immunogenic and can be used for further investigation as a potential cancer treatment.