Immunogenicity evaluation of viral peptides via nonspecific interactions between anti-peptide IgYs and non-cognate peptides

Immunogenicity can be evaluated by detecting antibodies (Abs) induced by an antigen. Presently deployed assays, however, do not consider the negative impacts of Ab poly-specificity, which is well established at the monoclonal antibody level. Here, we studied antibody poly-specificity at the serum level (i.e. nonspecific Ab-probe interactions, NSIs), and ended up establishing a new platform for viral peptide immunogenicity evaluation. We first selected three peptides of high, medium and low immunogenicity, using a 'vaccine serum response rate'-based approach (i.e. the gold standard). These three peptides (Pi) in the bovine serum albumin-Pi form were used to immunize chickens, resulting in longitudinal serum samples for screening with a non-cognate peptide library. The signal intensity of Ab-peptide specific binding and 'NSI count' was used to evaluate the viral peptides' immunogenicity. Only the NSI count agreed with the gold standard. The NSI count also provides more informative data on antibody production than the aggregated signal intensity by whole-protein-based indirect enzyme-linked immunosorbent assay.

In vitro immunogenicity prediction: bridging between innate and adaptive immunity

Development of antidrug antibodies (ADAs) is an undesirable potential outcome of administration of biotherapeutics and involves the innate and adaptive immune systems. ADAs can have detrimental clinical consequences: they can reduce biotherapeutic efficacy or produce adverse events. Because animal models are considered poor predictors of immunogenicity in humans, in vitro assays with human innate and adaptive immune cells are commonly used alternatives that can reveal cell-mediated unwanted immune responses. Multiple methods have been developed to assess the immune cell response following exposure to biotherapeutics and estimate the potential immunogenicity of biotherapeutics. This review highlights the role of innate and adaptive immune cells as the drivers of immunogenicity and summarizes the use of these cells in assays to predict clinical ADA.

Laboratory Testing in the Context of Biologics and Cellular Therapies

"With the increasing application of biotechnology to the realm of pharmacology and therapeutics, the types of biological treatments available have significantly expanded. Currently, recombinant proteins, humanized antibodies, or rationally engineered monoclonal antibodies are used on a regular basis in the clinical setting. Moreover, cell-based therapeutics with molecularly rewired antigenic specificities are becoming increasingly common in oncology and are actively being developed for a broad range of diseases. Nonetheless, there has been a significant lag between the development of these technologies and the emergence of assays that can monitor these novel interventions."

ASP2409, A Next-Generation CTLA4-Ig, Versus Belatacept in Renal Allograft Survival in Cynomolgus Monkeys

Belatacept is the first costimulatory blockade agent approved for maintenance immunosuppression in kidney transplant recipients. Clinical results have indicated that belatacept is associated with superior renal function and improved metabolic profile; however, higher incidence of acute rejection and posttransplant lymphoproliferative disorder are the shortcomings of this agent. In this study, ASP2409, a new cytotoxic T-lymphocyte associated protein 4-immunoglobulin possessing 14-fold higher in vitro CD86 binding affinity than belatacept, was tested for renal allograft survival in cynomolgus monkeys. ASP2409 monotherapy dose-dependently prolonged renal allograft survival. Low-dose ASP2409 in combination with a subtherapeutic dose of tacrolimus showed much longer median survival time than monotherapy. Similar allograft survival results were observed in regimens based on high-dose ASP2409, belatacept, and therapeutic-dose tacrolimus. The results of renal allograft histopathology with high-dose ASP2409-based regimens were not inferior to the belatacept-based regimen. Moreover, higher frequencies of FoxP3-positive regulatory T cells in renal allografts were observed in ASP2409- and belatacept-based regimens compared with tacrolimus-based regimens. No serious side effects related to ASP2409 administration were found during the study. These data suggest that ASP2409 is a promising candidate for calcineurin inhibitor-sparing or -avoidance regimens.

Characterization of the interaction of staphylococcal enterotoxin B with CD1d expressed in human renal proximal tubule epithelial cells

Background

Participation of renal cells in the pathogenesis of staphylococcal enterotoxin B (SEB) is critical for late cleansing and sequestration of the antigens facilitated by CD1d mediated antigen sensing and recognition. This is a noted deviation from the typical antigen recognition process that recruits the major histocompatibility complex class II (MHC II) molecules. The immunological importance of CD1d is underscored by its influences on the performances of natural killer T-cells and thereby mediates the innate and adaptive immune systems.

Results

Using diffraction-based dotReady™ immunoassays, the present study showed that SEB directly and specifically conjugated to CD1d. The specificity of the conjugation between SEB and CD1d expressed on human renal proximal tubule epithelial cells (RPTEC) was further established by selective inhibition of CD1d prior to its exposure to SEB. We found that SEB induced the expression of CD1d on the cell surface prompting a rapid conjugation between them. The mRNA transcripts encoding CD1d remained elevated potentially after completing the antigen cleansing process.

Conclusion

Molecular targets associated with the delayed pathogenic response have essential therapeutic values. Particularly in the event of bioterrorism, the caregivers are typically able to intervene much later than the toxic exposures. Given circumstances mandate a paradigm shift from the conventional therapeutic strategy that counts on targeting the host markers responding to the early assault of pathogens. We demonstrated the role of CD1d in the late stage of pathogen recognition and cleansing, and thereby underscored its clinical potential in treating bioweaponizable antigens, such as Staphylococcal enterotoxin B (SEB).

Electronic supplementary material

The online version of this article (doi:10.1186/s12866-015-0344-5) contains supplementary material, which is available to authorized users.

The challenging definition of naïve patient for biological drug use

Biosimilar is defined by The European Medical Agency as a biological medicinal product, which is similar but not identical to the biological drug already authorized. The biosimilar and its reference product are expected to display the same safety and efficacy profile and are generally used to treat the same conditions. The Italian Medicines Agency considers biosimilars as a valid therapeutic option with an economic advantage, especially in primary naïve patients with no previous exposure to the originator or with a sufficiently long wash-out period ("secondary naïve"). The identification of "secondary naïve" is not well defined and can be subjected to different variables, mainly the drug biologic effect and its immunogenicity. The first one depends on the type of biologics and on their mechanism of action. The second one is related to the fact that biologicals may be immunogenic and can trigger an anti-drug antibody response (ADA). ADA may behave as neutralizing antibodies blocking the active site of the biological but can also recognize other epitopes favoring the formation of immune-complexes that eventually affect the pharmacodynamics. Moreover, the concomitant immune-suppressive treatment can affect the immunogenicity, even if the exact mechanism remains unknown. In conclusion, the development and use of biosimilars represent a tool for increasing health system sustainability. However it is of paramount importance to distinguish between the pharmacodynamics of a given drug and its immunogenicity being the two aspects unrelated. Thus a detailed definition of "secondary naïve" patients is challenging, and may be related to both the two parameters.

Pharmacokinetics, pharmacodynamics, and immunogenicity of belatacept in adult kidney transplant recipients

BACKGROUND AND OBJECTIVES

Belatacept is a first-in-class, selective co-stimulation blocker recently approved for the prophylaxis of organ rejection in adult kidney transplant recipients. The objective of this study was to report the pharmacokinetics, pharmacodynamics, and immunogenicity of belatacept.

METHODS

The pharmacokinetics, pharmacodynamics (CD86 receptor occupancy), and immunogenicity of belatacept were studied in de novo adult kidney transplant recipients in phase II and III clinical studies.

RESULTS

Following multiple doses of 5 or 10 mg/kg, the geometric mean (percentage coefficient of variation) maximum serum concentration and area under the serum concentration-time curve over one dosing interval of belatacept were 136 (20%) and 238 (27%) μg/mL, and 13,587 (27%) and 21,241 (35%) μg·h/mL, respectively. The median belatacept elimination half-life was 8-9 days. Belatacept exhibited concentration-dependent binding to CD86 receptors. The pre-dose CD86 receptor occupancy by belatacept decreased from 94 to 65% between day 5 and 1 year post-transplant, with corresponding pre-dose trough serum concentrations of belatacept decreasing from ~35 to 4 μg/mL during this period. The cumulative incidence of developing anti-belatacept antibodies was 5.3% up to 3 years post-transplant and had no impact on belatacept exposure.

CONCLUSIONS

Belatacept in adult kidney transplant demonstrated linear pharmacokinetics with low variability, concentration-dependent pharmacodynamics, and a low incidence of anti-drug antibodies.

Detection of anti-cytokine antibodies and their clinical relevance

Cytokines regulate many aspects of cell growth and differentiation and play pivotal roles in the orchestration of immune defence against invading pathogens. Though 'self' proteins, they are potentially immunogenic and can give rise to anti-cytokine autoantibodies (aCA). The main foci of the article are a critical summary of the various methodologies applied for detecting and measuring aCA and a broad review of studies of the occurrence, characterization and clinical relevance of aCA in normal healthy individuals, patients with autoimmune diseases or microbial infections and aCA in patients whose disease is treated with recombinant cytokine products. The need for technical and methodological improvement of assays, including validation and standardization, together with approaches to harmonize calculation and reporting of results is also discussed.

No Correlations Between the Development of Specific IgA and IgM Antibodies Against Anti-TNF Blocking Agents, Disease Activity and Adverse Side Reactions in Patients with Rheumatoid Arthritis

The use of tumour necrosis factor (TNF) antagonists (infliximab [IFN], etanercept [ETN], adalimumab [ADA]) has changed the course of many rheumatic diseases, including rheumatoid arthritis (RA). However, some questions concerning their safety have emerged since their approval because they can trigger immunisation, induce rare type I and III hypersensitivity, and cause acute and delayed reactions. The aim of this study was to evaluate the correlations between hypersensitivity reactions to biological agents, disease activity and the development of class-specific IgA and IgM antibodies against the three anti-TNF agents in patients with RA. This longitudinal observational study involved consecutive outpatients with active RA who started treatment with IFN (n=30), ETN (n=41) or ADA (n=28). Clinical data and systemic and local side effects were collected prospectively at baseline and after six months of anti-TNF treatment. Serum samples were taken at the same time points in order to measure antibodies against the TNF blockers, anti-nuclear (ANA) and anti-dsDNA antibodies. The IgA and IgM antibodies specific to all three anti-TNF-α agents were analysed using ImmunoCaP Phadia- Thermofisher especially developed in collaboration with the laboratory of Immunology and Allergy, San Giovanni di Dio, Florence. The mean age of the 99 patients (86% females) was 54.6±12.4 years, and the median disease duration was 11.2±.3.2 years (range 3-14.3). The three treatment groups were comparable in terms of age, gender, rheumatoid factor and anti-citrullinated peptide (CCP) antibody positivity, and baseline C-reactive protein levels, erythrocyte sedimentation rate, 28-joint disease activity scores, and concomitant medications. Twelve patients treated with INF (40%) had anti-IFN IgM, and two (6%) anti-IFN IgA; 19 patients treated with ADA (68%) had anti-ADA IgM, and four (6%) anti-ADA IgA; and 27 patients treated with ETN (66%) had anti-ETN IgM, and 24 (58%) anti-ETN IgA. There were five systemic reactions in the IFN group, and seven adverse local reactions in both the ADA and the ETN group. There was no correlation between drug-specific IgA and IgM antibodies (p=0.65). There was also no correlation between the antibodies and disease activity after six months of treatment (r=0.189;p=0.32). Our findings show that the development of antibodies against IFN, ADA or ETN of IgA and IgM class are not related to any decrease in efficacy or early discontinuation of anti-TNF treatment in RA patients, nor to systemic and local reactions. Further studies of larger series of RA patients are needed to confirm the relationships between the development of drug-specific antibodies, serum TNF blocker levels, and disease activity.

T-cell dependent immunogenicity of protein therapeutics: Preclinical assessment and mitigation

Protein therapeutics hold a prominent and rapidly expanding place among medicinal products. Purified blood products, recombinant cytokines, growth factors, enzyme replacement factors, monoclonal antibodies, fusion proteins, and chimeric fusion proteins are all examples of therapeutic proteins that have been developed in the past few decades and approved for use in the treatment of human disease. Despite early belief that the fully human nature of these proteins would represent a significant advantage, adverse effects associated with immune responses to some biologic therapies have become a topic of some concern. As a result, drug developers are devising strategies to assess immune responses to protein therapeutics during both the preclinical and the clinical phases of development. While there are many factors that contribute to protein immunogenicity, T cell- (thymus-) dependent (Td) responses appear to play a critical role in the development of antibody responses to biologic therapeutics. A range of methodologies to predict and measure Td immune responses to protein drugs has been developed. This review will focus on the Td contribution to immunogenicity, summarizing current approaches for the prediction and measurement of T cell-dependent immune responses to protein biologics, discussing the advantages and limitations of these technologies, and suggesting a practical approach for assessing and mitigating Td immunogenicity.

Overcoming soluble target interference in an anti-therapeutic antibody screening assay for an antibody-drug conjugate therapeutic

BACKGROUND

The standard safety evaluation of biotherapeutics includes assessment of immunogenicity. Anti-therapeutic antibodies (ATA) can be detected in serum using immunoassays with a bridging format. However, these assays can be subject to interference.

RESULTS

In the bridging ATA assay for 3A5 TDC, an antibody-drug conjugate that binds to the multimeric extracellular domain of MUC16 (CA125), soluble CA125 in the serum caused false-positive results by binding to the ATA assay reagents. This interaction was blocked by wheat germ agglutinin lectin as it binds to the glycans in CA125; thus, the specificity of the assay improved.

CONCLUSION

The assay development and validation results showed that the addition of wheat germ agglutinin eliminates the interference from circulating CA125 without impacting the ability to detect ATA.

Overcoming immunogenicity associated with the use of biopharmaceuticals

The safety and efficacy of biopharmaceuticals can be severely impaired by their immunogenicity. A risk-based strategy should be used to assess immunogenicity on a case-by-case basis using standardized methods to correlate anti-drug antibody levels with clinical outcome. In silico and in vitro techniques allow putative T-cell epitopes to be identified and eliminated in candidate molecules while maintaining structure and function. Putative T-cell epitopes can be studied in the context of the HLA allotypes representative of the target population in vitro and in transgenic mice that express human HLA genes. Mice immune tolerant to human proteins allow the study of the effect of factors such as aggregation on the loss of immune tolerance. However, significant challenges remain in order to be able predict the immunogenicity of a therapeutic protein in a particular individual.

Improved analytical methods for the detection and quantification of neutralizing antibodies to biopharmaceuticals

Biopharmaceuticals are used extensively for the treatment of a number of chronic debilitating and fatal diseases such as cancer and inflammatory or autoimmune diseases. Although biopharmaceuticals are in general well tolerated, the development of anti-drug antibodies can impair their safety and efficacy. Assessment of immunogenicity is essential for a more effective and rational use of biopharmaceuticals, and is dependent upon the establishment of efficient standardized assays that allow direct comparison of immunogenicity data with clinical outcome. Although regulatory authorities recommend the use of cell-based assays that reflect the mechanism of action of the drug for the detection of neutralizing anti-drug antibodies, conventional cell-based assays are difficult to standardize and often give variable results. A number of strategies have been adopted to improve the performance of cell-based assays, including quantification of drug-induced proteins using either real-time RT-PCR or branched DNA to detect mRNA, or ELISAs to detect protein, bridging assays using immobilized cells and the use of reporter gene assays. The relative merits and limitations of each of these methods is reviewed herein.

Immunogenicity of biological therapeutics: from assay to patient

PURPOSE OF REVIEW

To give an overview of the current knowledge on assay techniques and clinical implications of immunogenicity of biological therapeutics.

RECENT FINDINGS

Assay techniques for the measurement of immunogenicity have improved, expanding the understanding of the immune response against biological therapeutics. Knowledge on the clinical effect of immunogenicity enables the treatment of patients in a targeted fashion, as a step towards personalized medicine.

SUMMARY

Biological medications are able to induce an antidrug immune response. Immunogenicity impairs clinical response and is associated with adverse events. Several confounding factors influence the measurement of immunogenicity, including drug interference and background problems. Concomitant administration of methotrexate lowers the frequency and amount of antibodies formed, whereby the efficacy of biologicals is improved. Algorithms for therapeutic drug monitoring could aid in adapting treatment strategies in a controlled setting.

Reporter gene assay for the quantification of the activity and neutralizing antibody response to TNFα antagonists

A cell-based assay has been developed for the quantification of the activity of TNFα antagonists based on human erythroleukemic K562 cells transfected with a NFκB regulated firefly luciferase reporter-gene construct. Both drug activity and anti-drug neutralizing antibodies can be quantified with a high degree of precision within 2h, and without interference from cytokines and other factors known to activate NFκB. The assay cells also contain the Renilla luciferase reporter gene under the control of a constitutive promoter that allows TNFα-induced firefly luciferase activity to be normalized relative to Renilla luciferase expression. Thus, results are independent of cell number or differences in cell viability, resulting in intra and inter assay coefficients of variation of 10% or less. Normalization of results relative to the expression of an internal standard also provides a means for correcting for serum matrix effects and allows residual drug levels or anti-drug neutralizing antibodies to be quantified even in serum samples with a relatively high degree of cytotoxicity.

Challenges in developing bioanalytical assays for characterization of antibody–drug conjugates

With more than 34 targets being investigated and nearly 20 clinical trials at various phases of development, antibody–drug conjugates (ADCs) hold a lot of promise for improving oncological malignancy therapy. This therapeutic strategy designed to specifically or preferentially deliver a cytotoxic agent to tumor cells through conjugation to a monoclonal antibody is not new. Although this approach is relatively simple conceptually, the history of ADCs clearly attests to the high degree of complexity in their development. Each component of an ADC is important to achieve efficacy with minimal toxicity, and the ability to monitor this multicomponent therapeutic entity is deemed to be critical for their successful optimization. In this article we review the different bioanalytical strategies that have been implemented to characterize various ADCs and discuss the challenges and issues associated with these approaches.

Quality requirements for critical assay reagents used in bioanalysis of therapeutic proteins: what bioanalysts should know about their reagents

Ligand-binding assays are the standard technology used for bioanalysis of therapeutic proteins, for example, for drug quantification (pharmacokinetics assays) and immunogenicity testing (antidrug antibody assays). Besides the selection of the most suitable technology platform (e.g., ELISA, electrochemiluminescence assays and surface plasmon resonance assays) and assay procedure, a pivotal prerequisite for good assay performance on any technology platform is the design, production and characterization of high quality reagents. To enable bioanalytical project support over the complete product life cycle, an appropriate long-term reagent supply is needed. This perspective describes our opinion on the requirements for generation and QC of critical reagents used in ligand-binding assays for drug quantification and antidrug antibody detection to enable high-quality assays and long-term supply, including reagent batch switches. The critical parameters during reagent design, production and long-term supply, along with the appropriate analytical methods for QC testing and appropriate certification, are discussed.