Are ex vivo neutralising antibodies against IFN-beta always detrimental to therapeutic efficacy in multiple sclerosis?

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.

Using Serum Metabolomics to Predict Development of Anti-drug Antibodies in Multiple Sclerosis Patients Treated With IFNβ

Background: Neutralizing anti-drug antibodies (ADA) can greatly reduce the efficacy of biopharmaceuticals used to treat patients with multiple sclerosis (MS). However, the biological factors pre-disposing an individual to develop ADA are poorly characterized. Thus, there is an unmet clinical need for biomarkers to predict the development of immunogenicity, and subsequent treatment failure. Up to 35% of MS patients treated with beta interferons (IFNβ) develop ADA. Here we use machine learning to predict immunogenicity against IFNβ utilizing serum metabolomics data. Methods: Serum samples were collected from 89 MS patients as part of the ABIRISK consortium-a multi-center prospective study of ADA development. Metabolites and ADA were quantified prior to and after IFNβ treatment. Thirty patients became ADA positive during the first year of treatment (ADA+). We tested the efficacy of six binary classification models using 10-fold cross validation; k-nearest neighbors, decision tree, random forest, support vector machine and lasso (Least Absolute Shrinkage and Selection Operator) logistic regression with and without interactions. Results: We were able to predict future immunogenicity from baseline metabolomics data. Lasso logistic regression with/without interactions and support vector machines were the most successful at identifying ADA+ or ADA- cases, respectively. Furthermore, patients who become ADA+ had a distinct metabolic response to IFNβ in the first 3 months, with 29 differentially regulated metabolites. Machine learning algorithms could also predict ADA status based on metabolite concentrations at 3 months. Lasso logistic regressions had the greatest proportion of correct classifications [F1 score (accuracy measure) = 0.808, specificity = 0.913]. Finally, we hypothesized that serum lipids could contribute to ADA development by altering immune-cell lipid rafts. This was supported by experimental evidence demonstrating that, prior to IFNβ exposure, lipid raft-associated lipids were differentially expressed between MS patients who became ADA+ or remained ADA-. Conclusion: Serum metabolites are a promising biomarker for prediction of ADA development in MS patients treated with IFNβ, and could provide novel insight into mechanisms of immunogenicity.

Effectiveness of glatiramer acetate in neutralizing antibody-positive patients previously treated with interferon-β

BACKGROUND

Some patients with multiple sclerosis who are treated with interferon-β(IFNβ) develop neutralizing antibodies (NAbs), which reduce or abolish the therapeutic effects of the treatment. These patients are usually switched to a non-IFNβ treatment, such as glatiramer acetate (GA). It is unknown whether a patient's previous disease activity in combination with their NAb-status can provide further insights on their risk of future disease activity. Consequently, we investigated treatment outcomes in patients switching from IFNβ to GA according to NAb-status and clinical disease activity, while on IFNβ.

METHODS

We identified all patients switching from IFNβ to GA and having information on NAb-status from the Danish Multiple Sclerosis Registry and compared treatment outcomes while on GA according to previous disease activity and the presence of NAbs.

RESULTS

We included 568 patients in the study: 107 NAb-negative patients switched due to adverse events (group 1), 24 NAb-negative patients switched with disease activity (group 2), 397 NAb-positive patients switched without disease activity (group 3) and 40 NAb-positive patients switched with disease activity (group 4). Compared to the reference (group 1), group 2 had an increased risk of future relapses (HR 1.79 95% Confidence interval (CI): 1.00-3.19). Group 3 showed a trend of a lower risk of future relapses (HR 0.74, 95%CI: 0.53-1.04). Group 4 had, on average, a similar risk of future relapses (HR 1.15 95% CI: 0.69-1.92). Similarly, group 2 had a higher probability of treatment discontinuation due to disease activity compared to the other groups.

CONCLUSION

While on GA, patients switched from IFNβ in the context of disease activity and no NAbs had the highest risk of future disease activity, while NAb positive patients without previous activity had the lowest. We did not find any average difference between NAb-positive patients switching in a context of disease activity and NAb-negative patients switched due to adverse events, although carefulness in the interpretation of this result is advised.

From the bench to clinical practice: understanding the challenges and uncertainties in immunogenicity testing for biopharmaceuticals

Unlike conventional chemical drugs where immunogenicity typically does not occur, the development of anti-drug antibodies following treatment with biologics has led to concerns about their impact on clinical safety and efficacy. Hence the elucidation of the immunogenicity of biologics is required for drug approval by health regulatory authorities worldwide. Published ADA 'incidence' rates can vary greatly between same-class products and different patient populations. Such differences are due to disparate bioanalytical methods and interpretation approaches, as well as a plethora of product-specific and patient-specific factors that are not fully understood. Therefore, the incidence of ADA and their association with clinical consequences cannot be generalized across products. In this context, the intent of this review article is to discuss the complex nature of ADA and key nuances of the methodologies used for immunogenicity assessments, and to dispel some fallacies and myths.

Registers of multiple sclerosis in Denmark

There are two nationwide population-based registers for multiple sclerosis (MS) in Denmark. The oldest register is The Danish Multiple Sclerosis Registry (DMSR), which is an epidemiological register for estimation of prevalence and incidence of MS and survival, and for identifying exposures earlier in life that may affect the risk of MS. This register has no systematic follow-up data except for survival. The DMSR has over the years published nationwide incidence- and prevalence data from Denmark and has been involved in a number of 'historical prospective' studies to elucidate the association between a number of different environmental exposures in the past and the subsequent risk of MS. Some of these studies have been able to exonerate suspected risk factors. The other register, the nationwide Danish Multiple Sclerosis Treatment Register, is a follow-up register for all patients who have received disease-modifying treatments since 1996. It has, in particular, contributed to the knowledge of the role of antibodies against the biological drugs used for the treatment of MS.

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.

Treatment with the antipsychotic agent, risperidone, reduces disease severity in experimental autoimmune encephalomyelitis

Recent studies have demonstrated that atypical antipsychotic agents, which are known to antagonize dopamine D2 and serotonin 5-HT_2a receptors, have immunomodulatory properties. Given the potential of these drugs to modulate the immune system both peripherally and within the central nervous system, we investigated the ability of the atypical anti-psychotic agent, risperidone, to modify disease in the animal model of multiple sclerosis (MS)⁴, experimental autoimune encephalomyelitis (EAE). We found that chronic oral administration of risperidone dose-dependently reduced the severity of disease and decreased both the size and number of spinal cord lesions. Furthermore, risperidone treatment substantially reduced antigen-specific interleukin (IL)-17a, IL-2, and IL-4 but not interferon (IFN)-γ production by splenocytes at peak disease and using an in vitro model, we show that treatment of macrophages with risperidone alters their ability to bias naïve T cells. Another atypical antipsychotic agent, clozapine, showed a similar ability to modify macrophages in vitro and to reduce disease in the EAE model but this effect was not due to antagonism of the type 1 or type 2 dopamine receptors alone. Finally, we found that while risperidone treatment had little effect on the in vivo activation of splenic macrophages during EAE, it significantly reduced the activation of microglia and macrophages in the central nervous system. Together these studies indicate that atypical antipsychotic agents like risperidone are effective immunomodulatory agents with the potential to treat immune-mediated diseases such as MS.

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.

Systematic review of disease-modifying therapies to assess unmet needs in multiple sclerosis: tolerability and adherence

Reviews of therapeutic drugs usually focus on the highly selected and closely monitored patient populations from randomized controlled trials. The objective of this study was to review systematically the tolerability and adherence of multiple sclerosis disease-modifying therapies, using data from both randomized controlled trials and observational settings. Relevant literature was identified using predefined search terms, and adverse event and study discontinuation data were extracted and categorized according to study type (randomized controlled trial or observational) and study duration. A total of 151 papers were selected for analysis; 33% were classified as randomized controlled trials and 62% as observational studies. Most of the papers concerned interferon preparations and glatiramer acetate; the limited available information on mitoxantrone and natalizumab precluded extensive examination of these. The most common adverse events were flu-like symptoms (interferon therapies only) and injection-site reactions. Mean discontinuation rates ranged from 16% to 27%. There were no marked differences in tolerability or adherence data from randomized controlled trials and observational studies, but the incidence of adverse events remained high in lengthy studies and discontinuations accumulated with time. The present systematic review of randomized clinical trial and observational data highlights the tolerability and adherence issues associated with commonly used first-line multiple sclerosis treatments.

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.

Managing relapsing–remitting multiple sclerosis following first drug failure

SUMMARY IFN-β and glatiramer acetate are the usual first-line treatments for cases of relapsing–remitting multiple sclerosis. As both of these agents are only partially effective in controlling disease activity, ‘breakthrough’ disease is common. Deciding how much breakthrough constitutes a treatment failure necessitating a switch in therapy is now a common problem that most clinicians will encounter in practice. In this article we will discuss the approach to deciding when treatment failure occurs and the strategies that can be used to tackle this problem.

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.

Simvastatin treatment in patients with relapsing-remitting multiple sclerosis receiving interferon beta 1a: a double-blind randomized controlled trial

OBJECTIVES

This study was conducted to evaluate the effect of simvastatin (40 mg/day) as an adjuvant therapy to interferon beta (IFNb 1a, 30 microg once weekly) in relapsing-remitting multiple sclerosis patients, compared with placebo.

METHODS

We enrolled 85 patients with relapsing-remitting multiple sclerosis (71% female) who were already receiving IFNb 1a (Avonex), with Expanded Disability Status Scale score of less than 5.0. The patients were assigned (in random and double-blinded fashion) into the two groups of simvastatin and placebo. All patients continued to receive their current IFNb treatment. The outcome measures were total relapse rate, Expanded Disability Status Scale score, and the number of gadolinium-enhanced (Gd+) and new T2 lesions in magnetic resonance imaging after a 1-year follow-up. We used Mann-Whitney and one-way multivariate analysis of variances to analyze the data.

RESULTS

Four patients in the placebo and two in the simvastatin group prematurely withdrew from the study due to experiencing two attacks. The total attack number in the simvastatin group was significantly lower than placebo group (moderate effect size r = 0.29) (p = 0.01). The final Expanded Disability Status Scale scores were lower in the simvastatin group (1.01 +/- 1.40, mean +/- SD) than in the placebo group (1.73 +/- 1.49, mean +/- SD), but this difference was not significant after controlling the baseline Expanded Disability Status Scale score (p = 0.07). In the simvastatin group, the mean +/- SD of gadolinium-enhanced and new T2 lesions were 0.66 +/- 1.18 and 3.39 +/- 3.55, respectively, (compared with 0.74 +/- 1.21 and 3.39 +/- 3.55 in the placebo group). Although there was a decreasing trend in lesions on magnetic resonance imaging, this difference was not statistically significant (p = 0.62). The combination therapy was safe and well tolerated, and no serious adverse effect was noted.

CONCLUSION

Our study supports the safety and efficacy of simvastatin as an add-on therapy to INFb 1a in patients with relapsing-remitting multiple sclerosis.

TRIAL REGISTRATION

ClinicalTrials.gov NCT00668343. This interventional study provides Class I evidence stating that adding simvastatin 40 mg/day to IFNb 1a 30 microg a week in patients with relapsing-remitting multiple sclerosis may reduce the relapse rate (moderate effect size r = 0.29) (p = 0.01) compared with treatment with IFNb 1a alone.

Influence of interferon-beta therapy switching on neutralizing antibody titres: results from the Austrian Switch Study

Neutralizing antibodies against interferon-beta are associated with a reduction of the efficacy of this drug. Continuing treatment leads to a decline or even loss of neutralizing antibodies over years. No strategies are currently available to shorten the period of neutralizing antibody positivity. The objective of this study was to investigate the effect of switching between high and low immunogenic interferon-beta products on neutralising antibody titres. Twenty-four patients treated with the subcutaneously administered interferon-beta 1b or 1a and high titres of neutralizing antibodies were included. At baseline interferon-beta therapy was interrupted for 3 months and two pulses of high dose methylprednisolone were applied. Patients were then randomized to receive either the previous interferon-beta preparation or the low immunogenic intramuscular interferon-beta 1a. The primary end-point was the change of neutralizing antibody titres 12 months after randomization. Twelve patients were switched to interferon-beta 1a intramuscularly and 12 patients remained on previous treatment. Median neutralizing antibody titres were 846 NU at baseline and 196 NU at the end of the study. The median change of neutralizing antibody titres did not differ significantly between therapy switchers and non-switchers. Baseline and final neutralizing antibody titres correlated significantly. In conclusion, neither switching nor continuous therapy with any subcutaneous interferon-beta preparation significantly changed neutralizing antibody titres.

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.

High-dose intravenous interferon beta in patients with neutralizing antibodies (HINABS): a pilot study

Background

Neutralizing antibodies (NABs) against interferon beta (IFNβ) are associated with a loss of IFNβ bioactivity and clinical effectiveness. To date, there are no anti-NAB strategies available. The primary objective of this trial was to investigate whether intravenous IFNβ-1b can restore bioactivity in NAB-positive patients with MS.

Methods

NAB-positive patients with MS were treated with 8 MIU IFNβ-1b s.c., 8 MIU i.v., and 16 MIU i.v. Each application was preceded by a wash-out period of 1 week. Blood samples were collected before, 3, 12, and 24 h after each administration. Myxovirus protein A (MxA) RNA and protein levels were determined. The study has been approved by the local ethics committee.

Results

Five patients completed the study. NAB titers ranged from 42 to 4482 neutralizing units. Median MxA protein (1821, range 12–3234) and RNA (2186, range 114–7525) area under the curve levels for the four measurements at each IFNβ injection were significantly higher after i.v. application of 16 MIU as compared with both 8-MIU dosages, which were 743 (0–2709) for MxA protein after 8 MIU i.v. and 254 (0–1200) after s.c., and 1763 (25–7188) for MxA RNA after 8 MIU i.v., and 557 (5–2265) after s.c. applications. NAB titers decreased significantly and transiently after infusion of 16 MIU IFNβ-1b but not after both forms of 8 MIU applications. Typical side effects could be controlled by paracetamol. No allergic reaction was observed.

Discussion

The results indicate that i.v. administration of IFNβ can restore bioavailability of IFNβ in patients with NABs.

Safety and immunogenicity of a new formulation of interferon beta-1a (Rebif New Formulation) in a Phase IIIb study in patients with relapsing multiple sclerosis: 96-week results

BACKGROUND

A new formulation of subcutaneous (s.c.) interferon-beta-1a has been developed (Rebif New Formulation, RNF), produced without fetal bovine serum and without human serum albumin as an excipient, with the aim of improving injection tolerability, and reducing immunogenicity.

OBJECTIVES

This article reports 96-week analyses of a Phase IIIb, open-label study of the safety and immunogenicity of RNF compared with historical (EVIDENCE study) and recent (REGARD study) data on the original formulation.

METHODS

Patients with relapsing multiple sclerosis (McDonald criteria) and an Expanded Disability Status Scale score < 6.0 received RNF, 44 microg s.c. three times weekly.

RESULTS

The proportion of neutralizing antibody-positive (NAb+) patients (serum NAb status >or=20 neutralizing units/mL) at week 96 (last observation carried forward; primary endpoint) was 17.4% (exact 95% confidence interval [CI]: 13.0-22.5), compared with 21.4% (95% CI: 17.2-26.2) in the EVIDENCE study, and 27.3% (95% CI: 22.8-32.1) in the REGARD study. The proportion of patients NAb+ at any time during the 96 weeks was 18.9% (95% CI: 14.4-24.2), compared with 27.1% (95% CI: 22.4-32.2) and 33.7% (95% CI: 28.9-38.7), respectively. Most pre-specified categories of adverse events were reported by patients in the RNF study at a similar or lower proportion than in the EVIDENCE and REGARD studies. Injection-site reactions were experienced by fewer patients than in the EVIDENCE and REGARD studies.

CONCLUSIONS

RNF has improved overall immunogenicity and safety profiles compared with the original formulation.

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.

Immunogenicity and tolerability of an investigational formulation of interferon-beta1a: 24- and 48-week interim analyses of a 2-year, single-arm, historically controlled, phase IIIb study in adults with multiple sclerosis

BACKGROUND

RNF (Rebif New Formulation, Merck Serono International S.A., Geneva, Switzerland), a formulation of interferon-beta1a (IFN-beta1a) without human- or animal-derived components, is currently under investigation. It was developed with the aim of maximizing the treatment benefit for patients with multiple sclerosis (MS) by improving injection tolerability and reducing the development of neutralizing antibodies (NAbs).

OBJECTIVE

This paper reports the results of planned 24- and 48-week interim analyses comparing immunogenicity and tolerability data from an ongoing study of RNF with historical-control data for the currently approved formulation of IFN-beta1a from the EVIDENCE (EVidence of Interferon Dose-response: European North American Comparative Efficacy) study.

METHODS

Patients in the 96-week, multicenter, singlearm, Phase IIIb RNF study received 44 microg/0.5 mL SC tiw; patients in the EVIDENCE study received an identical regimen of the currently approved formulation of IFN-beta1a. Criteria for inclusion in the RNF study were age between 18 and 60 years, an Expanded Disability Status Scale (EDSS) score <6.0, and a diagnosis of relapsing MS (McDonald criteria). Criteria for inclusion in the EVIDENCE study were age between 18 and 55 years, an EDSS score of 0 to 5.5, and a diagnosis of clinically definite relapsing-remitting MS (Poser criteria). Patients in both studies were treatment naive. Both studies used the same cytopathic-effect assay for NAbs to assess immunogenicity; patients who had NAb titers >or=20 neutralizing units (NU)/mL were considered NAb+. The primary end point was to compare the proportions of NAb+ patients in the RNF study and the historical data. Comparisons were descriptive and used exact 95% CIs. Safety analyses included 8 prespecified adverse events (AEs) of interest.

RESULTS

Baseline demographic characteristics were well balanced between the RNF (N = 260) and EVIDENCE (N = 339) studies, except that patients in the RNF study were slightly younger (median age, 34.0 vs 39.0 years, respectively), and a few had secondary progressive MS (n = 6) or progressive relapsing MS (n = 1). At week 48, 87.3% of patients in the RNF study remained on treatment. The incidence of the prespecified AEs of interest in the RNF and EVIDENCE studies was as follows: flu-like symptoms (70.8% and 48.1%, respectively), injection-site reactions (29.6% and 83.8%), hepatic disorders (13.1% and 16.8%), cytopenia (9.6% and 11.8%), depression and suicidal ideation (5.8% and 19.8%), skin rashes (5.4% and 12.1%), hypersensitivity reactions (5.4% and 3.2%), and thyroid disorders (2.3% and 5.0%). Overall, the majority (96.9%) of AEs in the RNF study were mild (69.5%) or moderate (27.5%) in severity. The proportions of patients in the RNF and EVIDENCE studies with NAbs at both 24 and 48 weeks were 2.5% (95% CI, 0.9-5.5) and 14.3% (95% CI, 10.7-18.6), respectively; the proportions with NAbs at week 48 only were 13.9% (95% CI, 9.9-18.7) and 24.4% (95% CI, 19.9-29.4). The proportions of NAb+ patients with high NAb titers (>1000 NU/mL) at week 48 were 11.1% in the RNF study and 19.5% in the EVIDENCE study.

CONCLUSIONS

The results of these interim analyses suggest that RNF had an improved overall tolerability and safety profile and a lower immunogenic potential compared with the approved IFN-beta1a formulation assessed in the EVIDENCE study. Two-year results from the RNF study are anticipated before the end of 2007.

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.