The importance of measuring IFNbeta bioactivity: monitoring in MS patients and the effect of anti-IFNbeta antibodies

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.

Interferon β for Multiple Sclerosis

Despite that the availability of new therapeutic options has expanded the multiple sclerosis (MS) disease-modifying therapy arsenal, interferon β (IFN-β) remains an important therapy option in the current decision-making process. This review will summarize the present knowledge of IFN-β mechanism of action, the overall safety, and the short- and long-term efficacy of its use in relapsing remitting MS and clinically isolated syndromes. Data on secondary progressive MS is also provided, although no clear benefit was identified.

Blood lymphocyte subsets identify optimal responders to IFN-beta in MS

Response to interferon-beta (IFN-beta) treatment is heterogeneous in multiple sclerosis (MS). We aimed to search for biomarkers predicting no evidence of disease activity (NEDA) status upon IFN-beta treatment in MS. 119 patients with relapsing-remitting MS (RRMS) initiating IFN-beta treatment were included in the study, and followed prospectively for 2 years. Neutralizing antibodies (NAb) were explored in serum samples obtained after 6 and 12 months of IFN-beta treatment. Soluble cytokines and blood lymphocytes were studied in basal samples by ELISA and flow cytometry, respectively. 9% of patients developed NAb. These antibodies were more frequent in patients receiving IFN-beta 1b than in those treated subcutaneous (p = 0.008) or intramuscular (p < 0.0001) IFN-beta 1a. No patient showing NAb remained NEDA during follow-up. Basal immunological variables are also associated with patient response. Percentages below 3% of CD19 + CD5 + cells (AUC 0.74, CI 0.63-0.84; OR 10.68, CI 3.55-32.15, p < 0.0001; Likelihood ratio 4.28) or above 2.6% of CD8 + perforin + T cells (AUC 0.79, CI 0.63-0.96; OR 6.11, CI 2.0-18.6, p = 0.0009; Likelihood ratio 5.47) increased the probability of achieving NEDA status during treatment. Basal blood immune cell subsets contribute to identify MS patients with a high probability of showing an optimal response to IFN-beta.

Real-time TaqMan assay for myxovirus resistance protein (MxA) mRNA: a robust marker of interferon beta bioactivity in patients with multiple sclerosis

For many patients suffering from MS, interferon beta (IFNβ) is an effective therapeutic option; however, some patients who receive long-term IFNβ therapy for relapsing-remitting MS (RRMS) develop neutralizing antibodies (NAbs) that affect IFNβ efficacy. It is therefore important to evaluate patients' therapeutic response to IFNβ over time. Myxovirus resistance protein A (MxA), a surrogate marker of individual immunologic response to IFNβ, may be a useful tool for assessing IFNβ immunogenicity. The real-time TaqMan assay for MxA messenger RNA (mRNA) has several distinct advantages, including the ability to amplify and complete quantitative analyses in one step, a high degree of quality control and prior experience and confidence in the field of quantitative viral diagnostics. The real-time TaqMan assay for MxA mRNA can be incorporated as a component of IFNβ therapy to evaluate patients during the course of treatment. Multiple Sclerosis 2007; 13: S49—S52. http://msj.sagepub.com

Neurotherapeutic Strategies for Multiple Sclerosis

Multiple sclerosis (MS) is the most common disabling neurologic disease of young adults. There are now 16 US Food and Drug Administration (FDA)-approved disease-modifying therapies for MS as well as a cohort of other agents commonly used in practice when conventional therapies prove inadequate. This article discusses approved FDA therapies as well as commonly used practice-based therapies for MS, as well as those therapies that can be used in patients attempting to become pregnant, or in patients with an established pregnancy, who require concomitant treatment secondary to recalcitrant disease activity.

Current status of biomarker research in neurology

Neurology is one of the typical disciplines where personalized medicine has been recently becoming an important part of clinical practice. In this article, the brief overview and a number of examples of the use of biomarkers and personalized medicine in neurology are described. The various issues in neurology are described in relation to the personalized medicine and diagnostic, prognostic as well as predictive blood and cerebrospinal fluid biomarkers. Such neurological domains discussed in this work are neuro-oncology and primary brain tumors glioblastoma and oligodendroglioma, cerebrovascular diseases focusing on stroke, neurodegenerative disorders especially Alzheimer's and Parkinson's diseases and demyelinating diseases such as multiple sclerosis. Actual state of the art and future perspectives in diagnostics and personalized treatment in diverse domains of neurology are given.

Peripheral blood biomarkers in multiple sclerosis

Multiple sclerosis is the most common autoimmune disorder affecting the central nervous system. The heterogeneity of pathophysiological processes in MS contributes to the highly variable course of the disease and unpredictable response to therapies. The major focus of the research on MS is the identification of biomarkers in biological fluids, such as cerebrospinal fluid or blood, to guide patient management reliably. Because of the difficulties in obtaining spinal fluid samples and the necessity for lumbar puncture to make a diagnosis has reduced, the research of blood-based biomarkers may provide increasingly important tools for clinical practice. However, currently there are no clearly established MS blood-based biomarkers. The availability of reliable biomarkers could radically alter the management of MS at critical phases of the disease spectrum, allowing for intervention strategies that may prevent evolution to long-term neurological disability. This article provides an overview of this research field and focuses on recent advances in blood-based biomarker research.

Therapeutic Plasma Exchange in Multiple Sclerosis Patients with Abolished Interferon-beta Bioavailability

BACKGROUND

Neutralizing antibodies (NAb) to interferon-beta (IFN-β) are associated with reduced bioactivity and efficacy of IFN-β in multiple sclerosis (MS). The myxovirus resistance protein A (MxA) gene expression is one of the most appropriate markers of biological activity of exogenous IFN-β. We hypothesized that therapeutic plasma exchange (TPE) can restore the ability of IFN-β to induce the MxA mRNA expression and that maintenance plasmapheresis can sustain the bioavailability of IFN-β.

MATERIAL AND METHODS

Eligible patients underwent 4 primary separate plasma exchange sessions. After the induction TPE sessions, they were transferred to maintenance plasmapheresis. Bioactivity of IFN-β was expressed as in vivo MxA mRNA induction in whole blood using RT-qPCR.

RESULTS

Six patients with low IFN-β bioavailability detected by the MxA mRNA response were included. Four patients became biological responders after induction plasmapheresis. In 2 patients an increase of MxA mRNA expression was found, but the values persisted below the cut-off and the patients remained as "poor biological responders". The effect of maintenance plasmapheresis was transient: MxA mRNA expression values reverted to the baseline levels after 1-2 months.

CONCLUSIONS

Therapeutic plasma exchange is able to restore the bioavailability of IFN-β in the majority of studied patients, but the effect of TPE on the IFN-β bioavailability was transient.

High-dose intravenous interferon-beta in multiple sclerosis patients with high-titer neutralizing antibodies (HINABS II) - A pilot study

BACKGROUND

Neutralizing antibodies (NAb) against interferon-beta (IFNβ) affect its treatment efficacy. So far, there are no anti-NAb strategies available.

OBJECTIVES

To investigate if the repeated administration of high-dose IFNβ-1b intravenous in NAb positive multiple sclerosis (MS) patients induces tolerance and establishes IFNβ bioavailability as measured by the induction of myxovirus protein A (MxA).

METHODS

Nine MS patients with NAb titers >500 10-fold reduction units (TRU) received 1500μg IFNβ-1b intravenously once weekly over three months. Blood samples were collected at screening, monthly during the treatment period (before and four hours after IFNβ administration), and at follow-up after 6 months for determination of NAbs and MxA expression.

RESULTS

Median NAb titer at baseline was 1429TRU. NAb titers determined before each infusion did not significantly change over the treatment period and were not different at follow-up compared to baseline. However, NAb titers were significantly decreased four hours after IFNβ infusions (by roughly 50%) and MxA mRNA levels were significantly elevated reaching a median value of 206.

CONCLUSIONS

Weekly intravenous administration of IFNβ in patients with high NAb titers established its bioavailability, but failed to induce tolerance towards IFNβ.

Evaluation of the impact of neutralizing antibodies on IFNβ response

IFNβ therapeutic action depends on a sequence of biological steps: i) the interaction between interferon beta (IFNβ) and its receptor (IFNAR) located at the cell surface of peripheral blood mononuclear cells; ii) activation of second messengers; iii) transcription of several genes containing specific ISRE regions (Interferon Stimulated Response Elements); and iv) synthesis of specific proteins. Although IFNβ therapy has improved treatment options of patients with multiple sclerosis (MS), the long-term efficacy of IFNβs can be compromised due to the development of neutralizing antibodies (NAbs). High titer NAbs develop in about 15% of patients; they abolish IFNβ biological activity and consequently the therapeutic action of IFNβ. Different IFNβ preparations carry different risks of developing NAbs, ranging from 3 to 28%. The risk of inducing NAbs must be considered in the selection of treatment. Guidelines for NAbs testing and the therapeutic decision in case of NAbs positivity have been established. NAbs positivity predicts MRI and clinical activity. Precocious identification of Nabs-positive patients and switch to alternative treatments can improve the percentage of responders and allow a better allocation of relevant economical resources.

BAb and MxA as functional biomarkers in routine clinical laboratories for the determination of anti-IFN-beta antibodies and their bioactivity levels in multiple sclerosis patients

In MS patients under IFNβ treatment to seek alternative treatments timely is important that anti-IFNβ antibodies and/or in vivo biologic activity loss detection in these. The most common diagnostic markers used for this purpose are BAb, Nab, and MxA. In this article, we aimed to establish the availability and feasibility of the correlation between BAb and MxA gene expression (mRNA) levels using evaluation of responses to IFNβ treatment for MS patients with a routine laboratory follow-up strategy in a major Turkish MS center. Bab seropositivity was determined in blood samples of 218 MS patients treated with different IFNβ preparations and MxA mRNA levels were measured in 128 patients among the total population. BAb seropositivity ratios to im INF-β 1a, scINF-β 1a, and sc INF-β 1b were 21.4%, 28.6%, and 70.4%, respectively (total 40%), and total loss of bioactivity (MxA mRNA) were 9.3%, 9.5%, and 11.6%, respectively (total 10.2%). The correlation between high BAb titers and low MxA mRNA levels was highly significant (P = 0.00003). Our data indicate that there is a good correlation between especially high BAbs levels and diminished MxA mRNA levels.

Early detection of neutralizing antibodies to interferon-beta in multiple sclerosis patients: binding antibodies predict neutralizing antibody development

BACKGROUND

Neutralizing antibodies (NAb) affect efficacy of interferon-beta (IFN-b) treatment in multiple sclerosis (MS) patients. NAbs evolve in up to 44% of treated patients, usually between 6-18 months on therapy.

OBJECTIVES

To investigate whether early binding antibody (BAb) titers or different IFN-b biomarkers predict NAb evolution.

METHODS

We included patients with MS or clinically isolated syndrome (CIS) receiving de novo IFN-b treatment in this prospective European multicenter study. Blood samples were collected at baseline, before and after the first IFN-b administration, and again after 3, 12 and 24 months on that therapy; for determination of NAbs, BAbs, gene expression of MxA and protein concentrations of MMP-9, TIMP-1, sTRAIL, CXCL-10 and CCL-2.

RESULTS

We found that 22 of 164 (13.4%) patients developed NAbs during a median time of 23.8 months on IFN-b treatment. Of these patients, 78.9% were BAb-positive after 3 months. BAb titers ≥ 1:2400 predicted NAb evolution with a sensitivity of 74.7% and a specificity of 98.5%. Cross-sectionally, MxA levels were significantly diminished in the BAb/NAb-positive samples; similarly, CXCL-10 and sTRAIL concentrations in BAb/NAb-positive and BAb-positive/NAb-negative samples, respectively, were also diminished compared to BAb/NAb-negative samples.

CONCLUSIONS

BAb titers reliably predict NAbs. CXCL-10 is a promising sensitive biomarker for IFN-b response and its abrogation by anti-IFN-b antibodies.

Immunoglobulin G1 and immunoglobulin G4 antibodies in multiple sclerosis patients treated with IFNβ interact with the endogenous cytokine and activate complement

A subset of patients with relapsing-remitting multiple sclerosis (RRMS) on therapy with interferon beta (IFNβ) develop neutralising anti-drug antibodies (ADA) resulting in reduced, or loss of, therapeutic efficacy. The aims were to characterise the relative contributions of anti-IFNβ antibody isotypes to drug neutralising activity, ability of these antibodies to cross-react with endogenous IFNβ, to form immune complexes and activate complement. IFNβ-specific ADA were measured in plasma from RRMS patients treated with IFNβ1a (Rebif^®). Neutralisation of endogenous and therapeutic IFNβ by ADA was determined by IFNβ bioassay. IFNβ-ADA profile was predominantly comprised of IgG1 and IgG4 antibody isotypes. The contribution of IgG4-ADA towards neutralising activity was found to be minimal. Neutralising IFNβ-ADA blocks endogenous IFNβ activity. ADA interaction with therapeutic IFNβ results in immune complex formation and complement activation. In summary, IgG1 and IgG4 IFNβ-ADA have the ability to neutralise therapeutic and endogenous protein and to activate complement.

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IgG4 and IgG1 contributes to IFNβ-ADA profile

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Neutralising IFNβ-ADA cross reacts and blocks endogenous IFNβ activity.

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ADA-IFNβ results in IC formation and complement activation

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.

Neutralizing antibodies against interferon-Beta

The development of neutralizing antibodies (NAbs) is a major problem in multiple sclerosis (MS) patients treated with interferon-beta (IFN-ß). Whereas binding antibodies (BAbs) can be demonstrated in the vast majority of patients, only a smaller proportion of patients develop NAbs. The principle in NAb in vitro assays is the utilization of cultured cell lines that are responsive to IFN-ß. The cytopathic effect (CPE) assay measures the capacity of NAbs to neutralize IFN- ß's protective effect on cells challenged with virus and the MxA induction assay measures the ability of NAbs to reduce the IFN-ß-induced expression of MxA, either at the mRNA or the protein level. A titer of >20 neutralizing units/ml traditionally defines NAb posi-tivity. NAbs in high titers completely abrogate the in vivo response to IFN-ß, whereas the effect of low and intermediate titers is unpredictable. As clinically important NAbs appear only after 9-18 months IFN- ß0 therapy, short-term studies of two years or less are unsuitable for evaluation of clinical NAb effects. All long-term trials of three years or more concordantly show evidence of a detrimental effect of NAbs on relapses, disease activity on MRI, or on disease progression. Persistent high titers of NAbs indicate an abrogation of the biological response and, hence, absence of therapeutic efficacy, and this observation should lead to a change of therapy. As low and medium titers are ambiguous treatment decisions in patients with low NAb titres should be guided by determination of in vivo mRNA MxA induction and clinical disease activity.

Neutralizing antibodies to interferon beta-1b multiple sclerosis: a clinico-radiographic paradox in the BEYOND trial

BACKGROUND

The frequency and impact of neutralizing antibodies (NAbs) to interferon beta-1b (IFNβ-1b) on clinical and radiographic outcomes is controversial.

OBJECTIVE

To assess NAb impact in the BEYOND study.

METHODS

2244 patients were randomized (2:2:1) to receive IFNβ-1b, either 250 or 500 µg, or glatiramer acetate, 20 mg, and observed for 2-3.5 years. NAb titers were determined every 6 months. A titer ≥20 NU/ml was considered NAb positive. Efficacy was compared between NAb-positive and NAb-negative patients, using comprehensive statistical analyses, taking into account the delayed appearance of NAbs, the time-dependent changes in the relapse rate, spontaneous reversions to NAb-negative status, NAb-titer level, and also adjusting for baseline factors.

RESULTS

In the IFNβ-1b 250 µg group, NAb-positive titers were detected (≥ once) in 319 patients (37.0%); of these, 112 (35.1%) reverted to NAb-negative status. In the IFNβ-1b 500 µg group, 340 patients (40.7%) became NAb-positive and 119 (35.0%) reverted to NAb-negative status. In both IFNβ groups, especially the 250 µg arm, NAb-positive status was not associated with a convincing impact on any clinical outcome measure by any statistical analysis. By contrast, in both IFNβ groups, NAbs were associated with a very consistent deleterious impact on most MRI outcomes.

CONCLUSION

There was a notable dissociation between the impact of NAbs on MRI and clinical outcomes. On MRI measures, the impact was consistent and convincing, whereas on clinical measures a negative impact of NAbs was not found. The basis for this clinico-radiographic paradox is unknown but it suggests that the relationship between NAbs and the therapeutic effects of IFNβ-1b is complex.

Critical review: assessment of interferon-β immunogenicity in multiple sclerosis

This review discusses type I interferon (IFN) immunogenicity with focus on methods of detection of anti-IFN antibodies in patients treated with human recombinant IFN-&#x03B2;. Pitfalls involved in the clinical use of various types of assays for binding antibodies and neutralizing antibodies against IFN-&#x03B2; are presented, and the widely held distinction between binding antibodies and neutralizing antibodies is questioned both in terms of detection and clinical importance. The article also addresses important bioavailability and pharmacokinetic issues occurring with prolonged use of protein drugs. The rationale for individualized or personalized medicine, ie, optimizing therapies according to individual needs rather than using standardized trial-and-error regimens to all patients, is highlighted.

One-year evaluation of factors affecting the biological activity of interferon beta in multiple sclerosis patients

MxA is an antiviral protein induced by type I interferons (IFN) and some viruses; MxA gene expression is an appropriate marker for measuring biologic activity of exogenous IFNβ, as its induction indicates IFNAR receptor stimulation. A recent study has shown that measurement of MxA mRNA, after 1 year of treatment, predicts clinical responsiveness to IFNβ therapy. Loss of IFNβ bioactivity is mostly due to anti-IFNβ antibodies (both neutralizing and binding), non-compliance and receptor saturation. The aim of this study was to evaluate all possible causes of loss of IFNβ bioactivity after 1 year in treated patients. One hundred sixty-seven multiple sclerosis (MS) patients were included. One year after beginning IFNβ therapy, each patient underwent a blood test; MxA gene expression was measured by real time PCR, antiviral CPE assay to detect neutralizing antibodies (NAbs), and capture-ELISA (cELISA) to measure binding antibodies (BAbs). For MxA an upper normal threshold of 87 (RE) was considered, 20 TRU/mL was the threshold for NAbs, and 1 U for BAbs positivity. Thirty-seven out of 167 patients (22%) were MxA-negative; of these, 22 were both BAbs and NAbs+, whereas 12 were BAbs+ but Nabs-, and three were both BAbs and NAbs-. The following conclusions were drawn from the study: (1) MxA mRNA should be measured after 1 year of IFNβ therapy; (2) after 1 year of IFNβ treatment, absence of IFNβ bioactivity was detected in 22% of the patients; (3) different biological phenomena and reduced compliance explain this absence; (4) identification of the reason for absence of IFN bioactivity improves patients' management.

Recommendations for clinical use of data on neutralising antibodies to interferon-beta therapy in multiple sclerosis

The identification of factors that can affect the efficacy of immunomodulatory drugs in relapsing-remitting multiple sclerosis (MS) is important. For the available interferon-beta products, neutralising antibodies (NAb) have been shown to affect treatment efficacy. In June, 2009, a panel of experts in MS and NAbs to interferon-beta therapy convened in Amsterdam, Netherlands, under the auspices of the Neutralizing Antibodies on Interferon beta in Multiple Sclerosis consortium, a European-based project of the 6th Framework Programme of the European Commission, to review and discuss data on NAbs and their practical consequences for the treatment of patients with MS on interferon beta. The panel believed that information about NAbs and other markers of biological activity of interferons (ie, myxovirus resistance protein A [MxA]) can be integrated with clinical and imaging indicators to guide individual treatment decisions. In cases of sustained high-titre NAb positivity and/or lack of MxA bioactivity, a switch to a non-interferon-beta therapy should be considered. In patients who are doing poorly clinically, therapy should be switched irrespective of NAb or MxA bioactivity.

Disease biomarkers in multiple sclerosis: potential for use in therapeutic decision making

Multiple sclerosis (MS) is an autoimmune disorder of the brain and spinal cord that predominantly affects white matter. MS has a variable clinical presentation and has no 'diagnostic' laboratory test; this often results in delays to definite diagnosis. In confronting the disease, early diagnosis and appropriate, timely therapeutic intervention are critical factors in ensuring favorable long-term outcomes. The availability of reliable biomarkers could radically alter our management of MS at critical phases of the disease spectrum. Identification of markers that could predict the development of MS in high-risk populations would allow for intervention strategies that may prevent evolution to definite disease. Work with anti-myelin antibodies and the ongoing analysis of microarray gene expression have thus far not yielded biomarkers that predict future disease development. Similarly, extensive studies with serum and cerebrospinal fluid (CSF) have not yielded a disease-specific and sensitive diagnostic biomarker for MS. Establishment of disease diagnosis always leads to questions about long-term prognosis because in an individual patient the natural history of the disease is clinically unpredictable. Biomarkers that correlate with myelin loss, spinal cord disease, grey matter and subcortical demyelination need to be developed in order to accurately predict the disease course. The bulk of effort in biomarker development in MS has been concentrated in the area of monitoring disease activity. At present, a disease 'activation' panel of CSF biomarkers would include the following: interleukin-6 or its soluble receptor, nitric oxide and nitric oxide synthase, osteopontin, and fetuin-A. Although disease activity in MS is predominantly inflammatory, disease progression is likely to be the result of neurodegeneration. Therefore, the roles of proteins indicative of neuronal, axonal, and glial loss such as neurofilaments, tau, 14-3-3 proteins, and N-acetylaspartate are all under investigation, as are proteins affecting remyelination and regeneration, such as Nogo-A. With the increasing awareness of cognition dysfunction in MS, molecules such as apolipoprotein and proteins in the amyloid precursor protein pathway implicated in dementia are also being examined. Serum biomarkers that help monitor therapeutic efficacy such as the titer of antibody to beta-interferon, a first-line medication in MS, are established in clinical practice. Ongoing work with biomarkers that reflect drug bioavailability and factors that distinguish between medication responders and nonresponders are also under investigation. The discovery of new biomarkers relies on applying advances in proteomics along with microarray gene and antigen analysis and will hopefully result in the establishment of specific biomarkers for MS.

Hybrid transgenic immune tolerant mouse model for assessing the breaking of B cell tolerance by human interferon beta

To date, the therapeutic efficacy of recombinant human proteins is limited by their potential to break B cell tolerance in patients. The formation of neutralising antibodies (NABs) directed against recombinant human interferon beta (rhIFNbeta) is associated with a decrease in the therapeutic effect of the protein. For this reason, there is a need to study factors that can cause the immunogenicity of rhIFNbeta. Transgenic C57Bl/6 mice that are immune tolerant for human interferon beta (hIFNbeta) have been employed in a mouse model for assessing the breaking of immune tolerance by rhIFNbeta. In this study, we used the original C57Bl/6 mouse model as well as the hybrid offspring from crossings of transgenic C57Bl/6 mice with wildtype FVB/N mice to study the immunogenicity of three commercial rhIFNbeta products, Rebif, Avonex and Betaferon. As determined by ELISA, wildtype C57Bl/6 mice failed to form binding antibodies (BABs) against Rebif and Avonex formulated with human serum albumin. Because not all interferon beta products induce antibodies in wildtype C57Bl/6 mice, the transgenic C57Bl/6 mice cannot be used to study the breaking of tolerance by these products. However, the crossing of transgenic C57Bl/6 mice with FVB/N mice resulted in wildtype hybrid offspring in which all products were immunogenic and transgenic hybrid offspring that showed immune tolerance for hIFNbeta. Thus, these C57Bl/6 x FVB/N hybrid transgenic mice can be used to study the breaking of immune tolerance for all rhIFNbeta products. Of the three products, only Betaferon was able to break immune tolerance in the transgenic hybrids. With an MxA gene expression inhibition assay, NABs were detected in Betaferon treated wildtype hybrid mice, but not in transgenic hybrid mice, indicating a distinct immune mechanism in wildtype and transgenic mice. A pegylated rhIFNbeta-1a variant, PEG-rhIFNbeta-1a, induced antibodies in wildtype hybrid mice, but did not break the immune tolerance of transgenic hybrid mice. This suggests that pegylation did not affect the potential of rhIFNbeta-1a to break B cell tolerance.

Neutralizing antibodies explain the poor clinical response to interferon beta in a small proportion of patients with multiple sclerosis: a retrospective study

Background

Neutralizing antibodies (NAbs) against Interferon beta (IFNβ) are reported to be associated with poor clinical response to therapy in multiple sclerosis (MS) patients. We aimed to quantify the contribution of NAbs to the sub-optimal response of IFNβ treatment.

Methods

We studied the prevalence of NAbs in MS patients grouped according to their clinical response to IFNβ during the treatment period. Patients were classified as: group A, developing ≥ 1 relapse after the first 6 months of therapy; group B, exhibiting confirmed disability progression after the first 6 months of therapy, with or without superimposed relapses; group C, presenting a stable disease course during therapy. A cytopathic effect assay tested the presence of NAbs in a cohort of ambulatory MS patients treated with one of the available IFNβ formulations for at least one year. NAbs positivity was defined as NAbs titre ≥ 20 TRU.

Results

Seventeen patients (12.1%) were NAbs positive. NAbs positivity correlated with poorer clinical response (p < 0.04). As expected, the prevalence of NAbs was significantly lower in Group C (2.1%) than in Group A (17.0%) and Group B (17.0%). However, in the groups of patients with a poor clinical response (A, B), NAbs positivity was found only in a small proportion of patients.

Conclusion

The majority of patients with poor clinical response are NAbs negative suggesting that NAbs explains only partially the sub-optimal response to IFNβ.

Neutralizing antibodies against IFN beta in patients with multiple sclerosis: a comparative study of two cytopathic effect tests (CPE) for their detection

Neutralizing antibodies (NABs) against IFN beta should be measured in specialized laboratories, using a test of inhibition of the cytopathic effect (bioassay or CPE test), based on the capacity of IFNss to block the infection of live monolayer-cultured cells by a virus, depending on the presence or absence of NABs. The European Federation of Neurological Societies (EFNS) considers this assay to be the gold standard. However, the various different ways to perform this assay complicate comparison of the results between laboratories. The World Health Organization (WHO) has published several recommendations to perform this assay using the A549 cell line and the murine encephalomyocarditis virus (EMCV). In order to validate the results previously obtained in our laboratory with HEP2/VSV, we undertook a comparative analysis of the two bioassays, HEP2/VSV and A549/EMCV, to assess whether the use of different cell lines and viruses influences sensitivity. We also calibrated the A549/EMCV assay with a reference IFNss. Our results confirm that the bioassay with HEP2/VSV is as sensitive as the assay with A549/EMCV and that a significant association and correlation exist in the results between both assays. Thus, past results with HEP2/VSV in our laboratory could be comparable with those obtained with A549/EMCV in both our laboratory and others.

Influence of antidrug antibodies on plectasin efficacy and pharmacokinetics

Plectasin is a 4.4-kDa antimicrobial peptide with the potential to be a treatment of infections caused by gram-positive bacteria. Since plectasin is a large molecule compared to conventional antibiotics, the development of antidrug antibodies (ADAs) could be anticipated. The immunogenic properties of plectasin were assessed through immunization studies. In mice treated for 5 days with one to two daily subcutaneous doses of plectasin, no antibody response was observed. If the animals were immunized again, after a rest period, low levels of antibodies developed in approximately half the animals. Additionally, mice were immunized with plectasin in Freund's incomplete adjuvant (FIA). Ninety-two percent of these mice developed ADAs after repeated immunizations, with two-thirds having high levels of antibodies. An agar diffusion bioassay showed that sera from animals immunized with plectasin did not inhibit the efficacy of the drug, while hyperimmune sera from animals in which an immune response was provoked by immunization with plectasin in FIA reduced the efficacy of plectasin at the lowest concentration tested. Studies in the murine peritonitis model showed an excellent efficacy of plectasin for the treatment of Streptococcus pneumoniae infections both in naïve animals and in animals with ADAs. No difference in bacterial counts was seen when the animals were treated with plectasin at 2.5 mg/kg of body weight, a dose below the expected therapeutic level. When animals were treated with plectasin at 0.625 mg/kg, the effect was reduced but not neutralized in animals with high levels of ADAs. No animals showed signs of hypersensitivity or injection site reactions toward plectasin, and the half-life of the compound did not vary between animals with and without antibodies.

Treatment with azathioprine and cyclic methylprednisolone has little or no effect on bioactivity in anti-interferon beta antibody-positive patients with multiple sclerosis

Background

It is unknown whether immunosuppression of patients who have developed interferon-β (IFN-β) neutralizing antibodies (NAbs) hastens disappearance of NAbs in the blood.

Objective

We wanted to test whether immunosuppression with cyclic methylprednisolone (MP) in combination with azathioprine (AZA) for 6 months accelerates recovery of IFN-β bioactivity in patients with multiple sclerosis (MS) with abolished in-vivo myxovirus resistance protein A (MxA) mRNA response to IFN-β.

Methods

We included 13 patients with MS with NAbs and a low IFN-β bioavailability detected by the MxA-mRNA response in a descriptive, non-randomized trial. Another 14 NAb-positive patients with a low MxA-mRNA response served as controls. The primary outcome was the fraction of patients who regained an MxA-mRNA response to IFN-β. NAbs were measured by means of a clinically validated cytopathic effect assay and a new reporter gene assay. The in-vivo MxA-mRNA response was measured by real-time polymerase chain reaction.

Results

A total of 11 patients in the treatment group completed the trial. In all, two of these 11 patients regained an in-vivo MxA-mRNA response as compared to one of 14 patients in the control group.

Conclusion

Treatment with AZA and cyclic MP for 6 months has little or no effect on IFN-β bioactivity in NAb-positive patients with MS.

Decreased type I interferon receptor-soluble isoform in antiretroviral-treated HIV-positive children

We developed a real-time PCR assay to simultaneously measure the mRNA level of type I interferon (IFN) receptor (IFNAR) components in peripheral blood cells of children with chronic immune stimulation due to HIV infection. All patients were undergoing antiretroviral therapy and were divided into two groups on the basis of the induction of MxA mRNA, a marker of type I IFN bioactivity. We found that IFNAR-2 subunit mRNA was higher than that of the IFNAR-1 subunit, that the mRNA for the IFNAR-2.2 functional isoform was more expressed than that for the truncated IFNAR-2.1 isoform, and both were much more represented than that of the IFNAR-2.3 soluble isoform. We also demonstrated that soluble isoform mRNA was significantly diminished in the subgroup of patients with MxA mRNA below the cutoff value (determined as the 99th percentile of MxA measured in healthy controls). These results suggest that downregulation of the soluble receptor isoform, which would not compete with the functional isoform for binding to the target cytokine, would give type I IFN, eventually induced in these patients in the case of viral reactivation, the opportunity to promptly exert its antiviral activity.

MxA protein assay for optimal monitoring of IFN-beta bioactivity in the treatment of MS patients

OBJECTIVES

Myxovirus resistance protein A (MxA) can be used as a marker of the bioactivity of interferon-beta (IFN-beta) therapy. Two to forty per cent of IFN-beta-treated multiple sclerosis (MS) patients develop IFN-beta-neutralizing antibodies (NAb) with subsequent attenuation of MxA protein induction. The aim of this study was to set up a simple MxA enzyme immunoassay (EIA) for the measurement of MxA protein and to evaluate the EIA test by comparing the results with flow cytometric analysis and the measurement of NAb.

METHODS

total of 51 IFN-beta-treated relapsing-remitting MS (RRMS) patients were tested for MxA protein expression by using both MxA EIA assay and flow cytometric analysis. Thirteen patients were confirmed to be NAb-positive.

RESULTS

The correlation between EIA and flow cytometric analysis was significant with a wider range of measured levels in the EIA. Patients with NAb had low MxA levels, but in some patients, remaining MxA induction could be detected despite NAb.

CONCLUSIONS

The MxA EIA assay seems to be a practical method for large-scale analysis of the bioactivity of IFN-beta treatment.

Is the treatment effect of IFN-β restored after the disappearance of neutralizing antibodies?

Objective

To establish whether multiple sclerosis (MS) patients, who have lost the therapeutic effect of interferon-beta (IFN-β) owing to neutralizing antibodies (NAbs) and subsequently revert from a NAb-positive to a NAb-negative state under continued IFN-β-1b therapy, regain clinical effect after reversion.

Background

Several studies have shown that a significant proportion of patients treated with IFN-β develop NAbs that hamper or abolish the therapeutic effect of IFN-β. However, some patients, who become NAb-positive under treatment with IFN-β-1b, may revert to a NAb-negative state under continuous treatment.

Methods

We identified 40 patients from the Danish IFN protocol, who fulfilled the criteria: NAb-positive status for at least 12 months followed by reversion to NAb-negative state for at least 12 months. For comparison, we included 64 matching cases that had remained NAb-negative during an observation time of at least 36 months. The two groups were clinically and demographically alike. We measured NAb-neutralizing capacity using a clinically validated cytopathic effect assay. A blood sample with a neutralizing capacity of 20% or more was considered as NAb-positive. A patient was defined as NAb-positive after two consecutive blood tests separated by at least 6 months. Reversion to a NAb-negative state required at least two consecutive negative tests. To allow for the confounding effect of time we employed a mixed Poisson model.

Results

Patients who had been NAb-positive and reverted to a NAb-negative state regained treatment effect with the relapse rate as before the NAb-positive period adjusting for the effect of time, and the relapse rate was the same as in the permanently NAb-negative patients in corresponding time periods. The relapse rate ratio comparing the NAb-positive with the NAb-negative periods was 1.98 (95% confidence interval: 1.32–2.97).

Conclusion

Under NAb-positive periods, the clinical effect of IFN-β was abolished. When NAbs disappeared spontaneously under continued treatment, patients regained the full effect of INF-β-1b therapy with no negative carry-over effect from the previous NAb-positive period.

Modulation of IFNAR1 mRNA expression in multiple sclerosis patients

Interferon-beta receptor (IFNAR) is composed of 2 subunits, IFNAR1 and IFNAR2, the latter of which is expressed as functional (IFNAR2.2), non-functional (IFNAR2.1) and soluble (IFNAR2.3) isoform. Real-Time PCR analysis of mRNA for all IFNAR components in multiple sclerosis patients naïve for therapy and undergoing long-term treatment with interferon-beta shows that IFNAR1 mRNA level is lower than in healthy controls. If long-term treated patients are divided according to the production of mRNA for Myxovirus protein-A, a marker of interferon-beta bioactivity, IFNAR1 mRNA reaches the values observed in controls only in Myxovirus protein-A-induced patients. Since chronic cell stimulation by interferon-beta induces IFNAR protein down-regulation, we suggest that the increase of IFNAR1 mRNA might serve as a mechanism for counterbalancing the loss of protein receptor, enhancing, at least in this sub-group of patients, cell responsiveness to interferon-beta.

Development of a bioassay for quantification of neutralising antibodies against human interferon-beta in mouse sera

Therapeutic proteins like recombinant human interferon-beta (rhIFNbeta) may induce neutralising antibodies (NABs), which inhibit their efficacy. Hence, there is a great need for strategies to predict whether a formulation will induce an immune response. Immune tolerant transgenic animals are important tools to study this phenomenon. This article describes a bioassay for NABs detection in mouse sera. The bioassay corresponds to the MxA Gene expression Assay (MGA) for human sera and measures the inhibition by mouse serum of the IFNbeta induced MxA mRNA. Samples from 6 non-immunised and 14 IFNbeta-immunised mice were tested for both binding antibodies (BABs) and NABs using the bioassay. All 16 mouse sera tested positive for NABs were also positive for BABs; BAB and NAB levels were correlated with a coefficient of 0.62 (p=0.0186). The intra-assay variations ranged from 1.38% to 5.26% (mean 3.03%). Effects of cytotoxicity against A549 cells were slightly evident at low serum dilutions (i.e. 1/10, 1/20), but levels of damaged cells were easily evaluated based on the threshold cycle (Ct) values of the housekeeping gene 18SrRNA. The possibility of measuring NABs, in addition to BABs, in mouse sera increases the usefulness of the animal model, in studying the many factors influencing the immunogenicity of rhIFNbeta.

Anti-interferon-beta neutralising activity is not entirely mediated by antibodies

Many multiple sclerosis (MS) patients treated with interferon-beta (IFNbeta) develop anti-IFNbeta antibodies (BAbs), which can interfere with both in vitro and in vivo bioactivity of the injected cytokine. Objective of this study was to correlate these measures. Among the 256 enrolled patients, 11 (4.3%) showed a significant inhibition of the IFNbeta activity in vitro, but no measurable BAbs. As a whole, in vivo bioactivity was inhibited in 9/11 (82%) of these patients. A minority of IFNbeta treated patients have a non-antibody mediated neutralising activity, which competitively inhibits the bioactivity both in vitro and in vivo.

Identification of interferon-beta antibodies in a reference laboratory setting: Findings for 1144 consecutive sera

Clinical studies demonstrate differences in interferon-beta (IFNbeta) antibody detection frequencies among multiple sclerosis patients receiving different IFNbeta products. We sought to determine if these differences are also found when IFNbeta antibodies are measured in a reference laboratory, where factors normally controlled in clinical studies are unknown. Serum IFNbeta binding antibodies (BAbs) were quantitated by ELISA; BAbs-positive samples were then tested in a bioassay for neutralizing antibodies (NAbs). Consistent with clinical studies, frequencies of BAbs-positive sera and NAbs-positive sera were lower in the Avonex (IFNbeta-1a) treatment group than Rebif (IFNbeta-1a) and Betaseron (IFNbeta-1b) groups. We further identified a predictive relationship between positive BAbs levels and NAbs activity in patients treated with IFNbeta-1a products, but not those treated with IFNbeta-1b.

Using measurements of neutralizing antibodies: the challenge of IFN-? therapy

Although the occurrence of neutralizing antibodies (NAbs) to interferon (IFN)-beta has been acknowledged since the pivotal trials of IFN-beta in multiple sclerosis (MS), the effect of these antibodies has for several reasons been debated. The main reason for the controversies has been insufficient knowledge of the fact that clinically relevant NAbs do not appear until 12-18 months after initiation of IFN-beta therapy which make studies of 2 years or less unsuited to assess the clinical relevance of NAbs. Further, changes in NAb affinity occur and contribute to increase NAb effects by time. The present paper reviews our current knowledge of NAbs and stresses the importance of using measurements of NAbs routinely. It is concluded that NAb titres are important for the biological response to IFN-beta. Patients with low or intermediate titres may have preserved a full or partial biological response and might still benefit from IFN-beta therapy. However, persistent high titres of NAbs indicate an abrogation of the biological response and, hence, absence of therapeutic efficacy, and this observation should lead to a change of therapy. The application of the existing information about NAbs in clinical practice would lead to improved efficacy of IFN-beta treatment for the benefit of patients with MS.

Binding antibodies: Vancouver's perspective

Binding antibodies (BAbs) and neutralizing antibodies (NAbs) develop following the use of interferon beta (IFNβ) in patients with relapsing-remitting multiple sclerosis (RRMS). The appearance of anti-IFNβ antibodies has been associated with reduction of the therapeutic efficacy of IFNβ therapy; however, while BAbs and NAbs arise from exposure to IFNβ, they have different characteristics and different impacts on clinical outcomes. Not all patients develop BAbs and NAbs, and patients who do may revert to seronegative status for each of these antibodies, even with continued IFNβ treatment. This review examines the potential clinical and biological effect of BAbs and NAbs on therapeutic efficacy in the treatment of RRMS. Multiple Sclerosis 2007; 13: S36—S43. http://msj.sagepub.com

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.

Pharmacodynamics of interferon beta in multiple sclerosis patients with or without serum neutralizing antibodies

To analyze the in vivo biological effect of anti-interferon beta (IFN-beta) neutralizing antibodies (NABs), blood concentrations of neopterin, beta2microglobulin (Beta2-MG), mRNA-dependent myxovirusresistant protein A (MxA) and dsRNA-dependent protein kinase (PKR) were measured before (predose) and 24 hours after (postdose) IFN-beta administration in 49 patients with multiple sclerosis (MS) with (n = 25) and without (n = 24) NABs. The results indicated that predose levels of MxA-mRNA and PKR-mRNA were highly variable [coefficient of variation (CV) > 100%] among patients. A lower inter-individual variability was observed for pre-dose levels of Beta2-MG and neopterin (CVs of 29% and 44%, respectively). Significantly lower pre- and post-dose blood levels of IFN induced markers, except for postdose PKR-mRNA (p = 0.09), were seen in NAB+ compared with NAB-patients and between patients with high (> 200 t(1/10)) and low ( pound 200 t(1/10)) NAB titers. A significant inverse correlation between NAB titer and pre-dose levels of the above IFN-induced markers was found. In summary, our findings confirm that NABs affect absolute concentrations of IFN-beta induced markers and suggest that such an effect occurs in a titer-dependent manner.

Development and validation of a real time PCR-based bioassay for quantification of neutralizing antibodies against human interferon-beta

There are two commonly employed types of bioassays for the detection of neutralizing antibodies (NAbs) against interferon-beta (IFNbeta): the cytopatic effect assay (CPE), and the MxA (myxovirus resistance protein A) protein assay (MPA). This article describes a bioassay based on the real time PCR measurement of mRNA that results from the induction, in cultured human cells, of the MxA gene by IFNbeta. Serum samples from 104 patients with multiple sclerosis (MS) treated with IFNbeta were tested for NAbs using our real time PCR bioassay. NAbs also were measured in the same specimens by the MPA assay and CPE assay. The calibration range of the real time PCR bioassay is 0.125-30 LU/mL. The range of the intra- and inter-assay variations (coefficients of variation in log(10)) were 4.05% (range 0.88%-7.90%) and 4.42% (range 0.31%-9.15%), respectively. Samples of the three commercial preparations of IFNbeta-1a and -1b were measured showing dose-response curves parallel to that of the NIH reference IFNbeta (mean SD at the midpoint of the dose-response curve=5%). In addition, the assay was robust with respect to number of cells plated (i.e., increasing cell densities from 12x10(3)/well to 384x10(3)/well resulted in 3.03% variability in MxA expression normalized with glyceraldehyde-3 phosphate dehydrogenase). NAbs titers measured were closely comparable to those obtained by the MPA [r(spearman)=0.899; 89% of observed agreements; K=0.779] and the CPE [r(spearman)=0.7899); 86%; K=0.729] assays. Despite the obvious disadvantage of cost, when carried out according to quality assurance guidelines for molecular diagnostics the new MxA gene-expression assay (MGA) has significant advantages over the other methods for testing NAbs: it has excellent reliability and reproducibility, and utilizes equipment and methodologies already accessible in many clinical laboratories.

Measuring and management of anti-interferon beta antibodies in subjects with multiple sclerosis

Interferon Beta is well established as a first line agent to treat relapsing remitting Multiple Sclerosis. It frequently induces the formation of neutralising anti-Interferon Beta Antibodies (Nabs) which may abrogate the clinical efficacy of the drug. Numerous studies have shown a loss of bioactivity of the drug in the presence of Nabs. The focus has shifted to reliable quantification of Nabs and their appropriate incorporation into clinical practice. Here we review the development and persistence of Nabs, the effect on Interferon beta bioactivity, clinical and para-clinical autocome measures in trials, Nab assays and discuss management strategies to optimise the use of Interferon beta in relapsing remitting MS.

Cell-surface and cytokine biomarkers in autoimmune and inflammatory diseases

Increasing emphasis is being placed on biomarkers as indicators of disease states in patients with autoimmune and inflammatory disorders, such as rheumatoid arthritis, multiple sclerosis and systemic lupus erythematosus. Careful description of the expression of cell-surface markers and cytokines produced by T and B lymphocytes can lead to a more complete characterization of disease activity in patient populations, and serve as an indicator of the patient's response to therapy.

Dynamics of interferon-beta modulated mRNA biomarkers in multiple sclerosis patients with anti-interferon-beta neutralizing antibodies

The objective of this study was to evaluate multiple interferon (IFN) specific mRNA biomarkers in multiple sclerosis (MS) patients with anti-IFN-beta neutralizing antibodies (NAB) using a pharmacodynamic study design. Thirty patients were enrolled. Blood samples were drawn at pre-treatment, 4-, 8-h time points following the intramuscular dose of IFN-beta-1a. Total RNA was obtained from peripheral blood cells, processed to cDNA and analyzed using quantitative real-time polymerase chain reaction. Pre-treatment serum samples were analyzed for anti-IFN-beta binding and neutralizing antibodies: 22 patients were NAB negative; equal numbers of the eight remaining patients were either NAB positive or had borderline NAB status. The results showed that early assessment (at 4 h after IFN-beta injection) of mRNAs for Stat-1, MxA, MxB and TRAIL was more sensitive than the later measurements. Furthermore, the NAB positive patients had strongly attenuated gene expression responses on all the mRNAs. Patients with borderline NAB had average responses that appear to be lower than NAB negative patients on several genes, notably Stat-1, TRAIL and beta2 microglobulin.