A sensitive radioimmunoprecipitation assay for assessing the clinical relevance of antibodies to IFN beta

Antidrug Antibodies Against Biological Treatments for Multiple Sclerosis

The development of antidrug antibodies (ADAs) is a major problem in several recombinant protein therapies used in the treatment of multiple sclerosis (MS). The etiology of ADAs is multifaceted. The predisposition for a breakdown of immune tolerance is probably genetically determined, and many factors may contribute to the immunogenicity, including structural properties, formation of aggregates, and presence of contaminants and impurities from the industrial manufacturing process. ADAs may have a neutralizing capacity and can reduce or abrogate the bioactivity and therapeutic efficacy of the drug and cause safety issues. Interferon (IFN)-β was the first drug approved for the treatment of MS, and-although it is generally recognized that neutralizing antibodies (NAbs) appear and potentially have a negative effect on therapeutic efficacy-the use of routine measurements of NAbs and the interpretation of the presence of NAbs has been debated at length. NAbs appear after 9-18 months of therapy in up to 40% of patients treated with IFNβ, and the frequency and titers of NAbs depend on the IFNβ preparation. Although all pivotal clinical trials of approved IFNβ products in MS exhibited a detrimental effect of NAbs after prolonged therapy, some subsequent studies did not observe clinical effects from NAbs, which led to the claim that NAbs did not matter. However, it is now largely agreed that persistently high titers of NAbs indicate an abrogation of the biological response and, hence, an absence of therapeutic efficacy, and this observation should lead to a change of therapy. Low and medium titers are ambiguous, and treatment decisions should be guided by determination of in vivo messenger RNA myxovirus resistance protein A induction after IFNβ administration and clinical disease activity. During treatment with glatiramer acetate, ADAs occur frequently but do not appear to adversely affect treatment efficacy or result in adverse events. ADAs occur in approximately 5% of patients treated with natalizumab within 6 months of therapy, and persistent NAbs are associated with a lack of efficacy and acute infusion-related reactions and should instigate a change of therapy. When using the anti-CD20 monoclonal antibodies ocrelizumab and ofatumumab in the treatment of MS, it is not necessary to test for NAbs as these occur very infrequently. Alemtuzumab is immunogenic, but routine measurements of ADAs are not recommended as the antibodies in the pivotal 2-year trials at the population level did not influence lymphocyte depletion or repopulation, efficacy, or safety. However, in some individuals, NAbs led to poor lymphocyte depletion.

Low Fluctuation of Symptoms May Delay Diagnosis of Myasthenia Gravis: A Case Series

Introduction

Myasthenia gravis is an autoimmune disorder affecting neuromuscular transmission, and its hallmark is fluctuating muscular weakness affecting the ocular, bulbar, respiratory, or limb muscles. Our objective is to highlight the difficulties encountered in diagnosing this disorder in patients lacking this characteristic phenomenon.

Methods

Three cases of patients presenting with progressive weakness of bulbar and ocular muscles, in whom a lack of fluctuation delayed the diagnosis of myasthenia gravis, are described.

Results

Amyotrophic lateral sclerosis was considered in two of the patients, while cavernous sinus thrombosis was initially diagnosed in the third. Electrodiagnostic, pharmacologic, and serologic testing ultimately established the diagnosis of myasthenia gravis.

Conclusion

While the typical clinical pattern of myasthenia gravis is well known and easily recognizable, there are cases when the diagnosis, and thus the treatment, is delayed because of low or absent fluctuation of symptoms. The acknowledgment of this probably underestimated presentation is important for expeditious management.

Clinical testing for neutralizing antibodies to interferon-β in multiple sclerosis

Biopharmaceuticals are drugs which are based on naturally occurring proteins (antibodies, receptors, cytokines, enzymes, toxins), nucleic acids (DNA, RNA) or attenuated microorganisms. Immunogenicity of these agents has been commonly described and refers to a specific antidrug antibody response. Such immunogenicity represents a major factor impairing the efficacy of biopharmaceuticals due to biopharmaceutical neutralization. Indeed, clinical experience has shown that induction of antidrug antibodies is associated with a loss of response to biopharmaceuticals and also with hypersensitivity reactions. The first disease-specific agent licensed to treat multiple sclerosis (MS) was interferon-β (IFNβ). In its various preparations, it remains the most commonly used first-line agent. The occurrence of antidrug antibodies has been extensively researched in MS, particularly in relation to IFNβ. However, much controversy remains regarding the significance of these antibodies and incorporation of testing into clinical practice. Between 2% and 45% of people treated with IFNβ will develop neutralizing antibodies, and this is dependent on the specific drug and dosing regimen. The aim of this review is to discuss the use of IFNβ in MS, the biological and clinical relevance of anti-IFNβ antibodies (binding and neutralizing antibodies), the incorporation of testing in clinical practice and ongoing research in the field.

Comparative study of four different assays for the detection of binding antibodies against interferon-beta

BACKGROUND

Binding antibodies (BAB) against interferon-beta (IFNbeta) are often determined as screening assays before performing an expensive and elaborate neutralizing antibody (NAB) test.

METHODS

In this study, we compared four BAB tests, a western blot (WB), a direct binding enzyme-linked immunosorbent assay (ELISA) (dELISA), a capture ELISA (cELISA), and a commercial enzyme immuno-assay (EIA) in 325 multiple sclerosis patients with and without neutralizing antibodies to evaluate the sensitivity and specificity to detect NAB by receiver operating characteristics analysis.

RESULTS

The area under the curve (AUC) values were 0.907 for the dELISA, 0.925 for the cELISA, and 0.776 for the EIA (P < 0.0001 for all). At a sensitivity of 95%, the specificity was approximately 30% in the dELISA, 55% in the cELISA, and 13% in the EIA. The WB as a qualitative BAB detection method had a given sensitivity of 97% and a specificity of 55%. There was a strong and significant correlation between high NAB titers (>500 neutralizing units [NU]) and titers obtained by all quantitative BAB assays. However, low to medium NAB titers (20-500 NU) did not significantly correlate with BAB titers.

CONCLUSION

We conclude that the cELISA seems to be most suitable for NAB screening, but BAB titers cannot reliably predict NAB titers.

Neutralising antibodies to interferon β in multiple sclerosis

Interferon beta (IFNbeta) therapy for multiple sclerosis (MS) is associated with a potential for the development of neutralising antibodies (NAbs) that negatively affect therapy. Several factors influence the development of NAbs, such as lack of complete sequence homology with the endogenous IFNbeta sequence, frequency of administration, level of dose and formulation of IFNbeta. Taken together, the evidence that NAb status reduces clinical efficacy in MS patients is strong. Standardised assays for NAbs are lacking, and titres vary over time. NAb testing is a critical component of care for MS patients because it provides information on one of the most important factors determining clinical responsiveness to IFNbeta therapy. This expert panel report attempts to move the field towards resolution of the remaining issues and considers several aspects of NAbs, including their clinical relevance, factors influencing immunogenicity, assays to quantify NAbs and the definition of clinically relevant titres.

Neutralizing antibodies to interferon beta in multiple sclerosis: Analytical evaluation for validation of a cytopathic effect assay

BACKGROUND

Recent guidelines have recommended the use of validated assays for the measurement of neutralizing antibodies (NABs) to interferon beta (IFNbeta) in patients with multiple sclerosis (MS). In an attempt of validation, we studied the analytical performance of a bioassay based on antiviral cytopathic effect (CPE) using WISH cells and the vesicular stomatitis virus (WISH/VSV CPE).

METHODS

NAB titres measured with the WISH/VSV CPE assay in 63 sera from IFNbeta-treated MS patients were compared to those obtained with the reference CPE method using A549 cells and the encephalomyocarditis virus. Binding antibodies (BABs) were measured using a capture ELISA as a screening test for NABs.

RESULTS

No false-negative BAB was obtained in our patients. The between-run coefficients of variation (CVs) determined with log10 titres of the NIH anti-IFNbeta (G038-501-572) yielded good results (<or=10.4%) and within-run variability was excellent (CV<or=2%). The log10 titres obtained with both CPE assays were highly correlated (r=0.969 and r=0.884 for anti-IFNbeta-1a and anti-IFNbeta-1b, respectively). The same patients were found NAB-positive with both CPE assays.

CONCLUSION

Because of its good precision, sensitivity and excellent correlation with the reference CPE method, the WISH/VSV CPE bioassay can be used in the follow-up of IFNbeta-treated MS patients.

Guidelines on use of anti-IFN-beta antibody measurements in multiple sclerosis: report of an EFNS Task Force on IFN-beta antibodies in multiple sclerosis

Therapy-induced binding and neutralizing antibodies is a major problem in interferon (IFN)-beta treatment of multiple sclerosis. The objective of this study was to provide guidelines outlining the methods and clinical use of the measurements of binding and neutralizing antibodies. Systematic search of the Medline database for available publications on binding and neutralizing antibodies was undertaken. Appropriate publications were reviewed by one or more of the task force members. Grading of evidence and recommendations was based on consensus by all task force members. Measurements of binding antibodies are recommended for IFN-beta antibody screening before performing a neutralizing antibody (NAB) assay (Level A recommendation). Measurement of NABs should be performed in specialized laboratories with a validated cytopathic effect assay or MxA production assay using serial dilution of the test sera. The NAB titre should be calculated using the Kawade formula (Level A recommendation). Tests for the presence of NABs should be performed in all patients at 12 and 24 months of therapy (Level A recommendation). In patients who remain NAB-negative during this period measurements of NABs can be discontinued (Level B recommendation). In patient with NABs, measurements should be repeated, and therapy with IFN-beta should be discontinued in patients with high titres of NABs sustained at repeated measurements with 3- to 6-month intervals (Level A recommendation).

Analysis of neutralizing antibodies to therapeutic interferon-beta in multiple sclerosis patients: a comparison of three methods in a large Australasian cohort

Persistent high-titre neutralizing antibodies (NAB) to therapeutic interferon-beta(IFNbeta)in multiple sclerosis patients reduce therapeutic efficacy. Difficulties in standardization of cell-based bioactivity assays have hindered interlaboratory comparison of NAB titres and the determination of a clinically relevant definition of seropositivity. We determined NAB status in Australasian multiple sclerosis patients receiving IFNbetausing both the antiviral cytopathic effect (CPE) assay (n = 227) and the more specific ELISA for the type I interferon-inducible MxA protein (n = 350). While the log(10) titres determined in the two assays were highly correlated (p < 0.0001; r = 0.967) with similar distributions, the MxA assay was more sensitive, detecting lower concentrations of NAB than the CPE assay. The range of titres determined in the CPE assay was 10 to >7290; and 9 to 53,700 in the MxA assay, with ranked titre distribution highlighting the arbitrary nature of currently accepted definitions of NAB seropositivity. Bioactivity of injected IFNbetawas significantly reduced in NAB-positive patients (p = 0.006; NAB MxA titres = 184 to 5340) compared to NAB-negative patients as assessed ex vivo using real-time RT-PCR analysis of MxA gene induction. The range of MxA mRNA levels in healthy controls was remarkably consistent with previously published results, regardless of the assay standardization method [Gilli, F., Sala, A., Marnetto, F., Lindberg, R.L., Leppert, D. and Bertolotto, A. (2003) Comparison of IFNbeta bioavailability evaluations by MxA mRNA using two independent quantification methods. Abstract, ECTRIMS Meeting, Milan, Italy; Pachner, A., Narayan, K., Price, N., Hurd, M. and Dail, D. (2003a) MxA Gene Expression Analysis as an Interferon-beta Bioactivity Measurement in Patients with Multiple Sclerosis and the Identification of Antibody-Mediated Decreased Bioactivity. Mol. Diagn. 7, 17-25]. Assessment of IFNbetaresponse ex vivo accounts for both circulating factors and the cellular response to IFNbeta, and the data support the development of the MxA gene induction assay for the routine screening of patients receiving IFNbeta.

Neutralizing antibodies to interferon beta: implications for the management of multiple sclerosis

PURPOSE OF REVIEW

Antibodies against interferon-beta (IFN-beta) can appear in a relevant number of patients. The subset of antibodies that can neutralize IFN-beta activity are called neutralizing antibodies. This review focuses on their impact both on therapeutic efficacy and on bioactivity of IFN-beta, and on the management of antibody-positive patients.

RECENT FINDINGS

When IFN-betas were first used, neutralizing antibodies were not considered important. However, recent clinical, biologic, and immunologic data have demonstrated that they reduce or abolish the therapeutic efficacy of IFN-beta in 10-20% of patients. Quantification of antibodies using various biologic methods make it difficult to compare among different laboratories, and hence, standardization of assay procedures is necessary. Despite these technical difficulties, data consistently show differences in immunogenicity among the different IFN-beta products and the negative effects of neutralizing antibodies on the clinical efficacy of IFN-betas. Because the therapeutic action of IFN-beta depends on activation of IFN-inducible genes, new methods for the quantification of the biologic activity of IFN-beta have been developed, and a good correlation has been found between the presence of neutralizing antibodies and abrogation of IFN-beta bioactivity.

SUMMARY

Quantification of neutralizing antibodies and the in-vivo bioactivity of IFN-beta through IFN-beta-inducible gene products such as Myxovirus protein A, offer valuable information on IFN-beta therapy. Important questions such as the optimal therapeutic strategy for managing neutralizing antibodies positive patients require further study in clinical trials.