Development of neutralizing antibodies in patients with relapsing-remitting multiple sclerosis treated with IFN-beta1a

[Anti-cytokine autoantibodies: Review of the literature]

Anti-cytokine antibodies (ACA) are an emerging cause of acquired immunodeficiency, especially in previously healthy adults. The most frequently reported are anti-IFN-γ responsible for disseminated non-tuberculous mycobacteria infections, and anti-GM-CSF mainly in mycobacteria, cryptococcosis and nocardiosis infections. The presence of anti-IFN-α in severe COVID-19 infections has recently been described. The search for and detection of these ACAs in an unusual infection situation makes it possible to set up specific therapies in addition to the anti-infective treatment. ACAs are also frequent in various autoimmune pathologies where, in addition to being indicators of the breakdown of immune tolerance, they can modulate the activity of the disease according to their cytokine target. In this review of the literature, we will focus on the epidemiology and the clinical impact of these ACAs in healthy subjects and in infectious or dysimmune diseases.

Drug Holiday of Interferon Beta 1b in Multiple Sclerosis: A Pilot, Randomized, Single Blind Study of Non-inferiority

Introduction: To compare a schedule with cyclic withdrawal (CW) of interferon beta (IFN-b) 1b, respect to the full regimen (FR), in relapsing-remitting MS (RR-MS).

Methods: Participants were randomly assigned to CW or FR schedule and monthly monitored with brain MRI scans for 12 months (three of run-in and 9 of treatment). CW schedule included drug withdrawal for 1 month after two of treatment for a total of three quarters over the 9-month treatment period. The assessing neurologist and the expert neuroradiologists were blind. After the blind phase of the study all participants took their indicated disease modifying therapies in a prospectively planned, open-label extension phase (up to 120 months).

Results: Of 60 randomized subjects 56 (29 in FR and 27 in CW group) completed the single-blind phase: the two groups were comparable, except for a non-significant difference in the number of contrast-enhanced lesions (CEL) at the end of run-in. The two-sided 90% CI for the ratio between median number of cumulative CEL was 0.29–1.07, allowing to significantly reject the null hypothesis of a ratio ≥1.2 and to meet the primary end-point of non-inferiority (the threshold and the ratio between median were chosen according to the non-normal distribution of the data). The differences (CW vs. FR) were also non-significant for secondary end points: mean cumulative number of T2-weighted new and enlarging lesions (3.48 ± 5.34 vs. 3.86 ± 6.76); mean number and volume (cm³) of black holes (1.24 ± 1.61 vs. 2.71 ± 4.56; 489.11 ± 1488.12 vs. 204.48 ± 396.98); number of patients with at least an active scan (21 vs. 22); mean relapse rate (0.52 ± 0.89 vs. 0.34 ± 0.66), relapse risk ratio adjusted for baseline variables (2.15 [0.64–7.18]), EDSS score (1.0 [1–1.56] vs. 1.5 [1–1.78]), proportion of patients with antibodies anti-IFN (5 [21%] vs. 8 [36%]). Fifty-four patients (27 for each study arm) completed the open-label phase. The annualized RR, EDSS, proportion of patients shifting to progressive disease and hazard ratio of shifting, adjusting for baseline covariates, were comparable between the two study groups.

Conclusions: A calendar with CW was non-inferior than FR at the beginning of IFN-b therapy, and may not affect the long-term outcome.

Clinical Trial Registration:www.ClinicalTrials.gov, identifier: NCT00270816

Measuring and evaluating interferon b-induced antibodies in patients with multiple sclerosis

Author for correspondence: Klaus Bendtzen, Institute for Inflammation Research IIR 7521, Rigshospitalet University Hospital, 9 Blegdamsvej, DK-2100 Copenhagen, Denmark. E-mail: address: kben@mail.dk Administration of interferons (IFNs) may induce antibodies that interfere with therapeutic efficacy. We have optimized and validated methods for large-scale economic screening. Sera from patients with relapsing-remitting multiple sclerosis (MS) were investigated for binding antibody (BAb) by protein-G affinity-chromatography radioimmunoassay and a commercially available enzyme immunoassay (EIA). Neutralizing antibody (NAb) was investigated by cytopathic effect assays (CEA) using both fixed amount and serially diluted sera. BAb correlated with log10-transformed titres obtained by EIA (r=0.70, p<0.0001); the latter, however, failed to demonstrate low-level BAb. Comparison of clinical significance of NAb-positivity measured by biological assays with different sensitivities demonstrated an optimal odds ratio for relapse rate using 10 laboratory units (LU)/mL. Purification of IgG prior to CEA removed toxicity from toxic sera. The neutralizing capacity data correlated linearly with log10-transformed titres obtained by a Kawade 10-to-1 LU/mL CEA (r=0.77, p<0.0001). In conclusion, neutralizing capacity CEA utilizing a fixed amount of serum predicts differences in relapse rates in IFNβ-treated MS patients and correlates with NAb titres of the 10-to- 1 LU/mL CEA. Neutralizing capacity CEA is less laborious and more economical than titre-based NAb assays and suitable for large-scale screenings of MS patients.

Longitudinal analyses of the effects of neutralizing antibodies on interferon beta-1b in relapsing-remitting multiple sclerosis

We have analysed data on exacerbation rates, Expanded Disability Status Scale (EDSS) scores, and lesion burdens using the results of two neutralizing antibody (NA B) assays (C PE and MxA) from the pivotal relapsing-remitting multiple sclerosis (MS) trial of interferon beta-1b (IFNB) with a longitudinal appro ach, where the influence of NA Bs in individual patients is assessed by comparing responses during NAB- positive and NA B-negative periods. There are apparent influences on exacerbation rate related to dose of IFNB, titer level, and duration of positivity. With the MxA assay, exacerbation rates after switching to NA B-positive status are estimated to be 28% higher [95% confidence interval (CI): (-15%, 92%)] and -2% higher [95% CI: (-21%, 21%)] on the low- and high-dose IFNB arms, respectively. When compared with all NA B-negative periods, exacerbation rates during NA B-positive periods are estimated to be 29% higher [95% C I: (0%, 67%)] and 18% higher [95% CI: (0%, 40%)] on the low- and high-dose IFNB arms, respectively. When NA B-positive patients again become NA B-negative, no evidence of increased exacerbation rates could then be demonstrated. More detailed exploratory analyses indicate that the effects are most evident in the approximately 20% of patients developing high titers. In these patients, the influence of NABs may be self-limited, as titers often diminish or NA Bs become undetectable with time.

Qualitative and quantitative analysis of antibody response against IFNβ in patients with multiple sclerosis

To date, inter-and intra-laboratory consistency of binding assays for measuring anti-interferon (IFN)β antibodies has not been assessed. In this investigation, two independent laboratories tested a library of 80 serum specimens obtained from multiple sclerosis (MS) patients treated with IFNβ. For binding antibodies (BAbs) evaluations, each laboratory used both a capture-ELISA (cELISA) and an enzyme-immuno-assay (EIA), which is commercially available. Samples were also tested for neutralizing antibodies (NAbs). Data demonstrated good intra-laboratory reliability (rpearson≥0.86), and a good overall agreement between the results obtained from the two centers, using both the cELISA (69/80 of observed agreements) and the EIA (67/80). Accordingly, kappa coefficients (K) showed good concurrence (K ≥ 0.651). There was also substantial agreement between cELISA and EIA measurements, as performed in both centers (Orbassano, 66/80, K = 0.631; Basel, 70/80, K = 0.717). However, by comparing NAbs and BAbs titers obtained with both assays, we found that a high degree of BAb-negative samples were positive in NAb-assay. Thus, our study does not support the usefulness of ELISA-based BAb assays as a screening tool for NAbs. Otherwise, BAb-assays can be used as a confirmation test, indicating that the decrease of the biological effects is due to antibodies. In this context, both ELISA-based assays are equally reliable techniques.

Persistence of neutralizing antibodies after discontinuation of IFNβ therapy in patients with relapsing-remitting multiple sclerosis

Objective The main objective was to follow serum levels of neutralizing antibodies (NABs) against interferon-beta (IFNβ) after discontinuation of IFNβ therapy.

Background A large proportion of patients treated with recombinant IFNβ for multiple sclerosis (MS) develop therapy-induced NABs. Knowledge of persistence of NABs after discontinuation of therapy is limited. Design/patients: A retrospective follow-up study of patients treated in Denmark for relapsing-remitting (RR) MS with IFNβ for at least 12 months. NAB-positive patients, who discontinued therapy, were followed up with measurements of NABs.

Methods We measured NAB-neutralizing capacity and NAB titres a.m. Kawade using a clinically validated cytopathic effect assay.

Results Thirty-seven patients were included. Mean follow-up time was 22 months. Of the 29 patients with a NAB titre at or above 25 prior to termination of therapy, only three patients reverted to a titre below 25. Of these, two had a titre below 200 and one patient a titre of 600 at the last examination before treatment stop. The longest post-treatment follow-up during which a patient maintained NAB positivity was 59 months.

Conclusion NABs against IFNβ, especially with high titres, tend to persist for a long time after discontinuation of IFNβ therapy. NABs should always be measured before reinstitution of IFNβ treatment in NAB-positive patients.

Treatment Optimization in Multiple Sclerosis

The treatment of multiple sclerosis has finally become possible with the advent of the current disease-modifying therapies (DMTs) that have had a significant impact on those living with this disease. Though demonstrating clear efficacy on a number of short-term outcome measures, unfortunately, these agents are not “cures” and many patients with multiple sclerosis continue to experience disease activity in spite of treatment. Clinicians are becoming more comfortable initiating therapy with DMTs, but it is now important to focus attention on monitoring the results of the chosen therapy and deciding whether or not a patient is responding well to treatment. At present, however, clinicians lack criteria for defining optimal versus suboptimal responses to DMTs as well as evidence-based guidelines on how to improve treatment outcomes. Using a recently published model as a framework, The Canadian Multiple Sclerosis Working Group developed practical recommendations on how neurologists can assess the status of patients on DMTs and decide when it may be necessary to modify treatment in order to optimize outcomes. The Canadian Multiple Sclerosis Working Group's recommendations are based on monitoring relapses, neurological progression and MRI activity. Other possible causes of suboptimal treatment responses or treatment failure are also considered.

MxA mRNA expression as a biomarker of interferon beta response in multiple sclerosis patients

Myxovirus resistance protein A (MxA) is a molecule induced after interferon-β injection. The aim of this study was to investigate whether MxA determination one year after starting interferon-β can predict treatment response in multiple sclerosis patients. MxA mRNA expression was evaluated in blood samples obtained at baseline and at month 12. Clinical variables were prospectively recorded. A threshold of 5 was defined to establish MxA induction. On survival analysis, time to the next relapse and to EDSS progression were significantly longer in patients showing MxA induction, suggesting that MxA induction after one year may be useful to identify interferon-β responders.

Short-term suboptimal response criteria for predicting long-term non-response to first-line disease modifying therapies in multiple sclerosis: A systematic review and meta-analysis

INTRODUCTION

There is no consensus about short-term suboptimal response to first-line treatments in relapsing-remitting multiple sclerosis.

METHODS

We searched studies with interferon beta or glatiramer acetate in which a long-term (≥ 2 years (y)) outcome could be predicted using short-term (≤ 1 y) suboptimal response criteria (EDSS-, imaging- and/or relapse-based). We obtained pooled diagnostic accuracy parameters for the 1-y criteria used to predict disability progression between 2-5 y.

RESULTS

We selected 45 articles. Eight studies allowed calculating pooled estimates of 16 criteria. The three criteria with best accuracy were: new or enlarging T2-weighted lesions (newT2) ≥ 1 (pooled sensitivity: 85.5%; specificity:70.2%; positive predictive value:48.0%; negative predictive value:93.8%), newT2 ≥ 2 (62.4%, 83.6%, 55.0% and 87.3%, respectively) and RIO score ≥ 2 (55.8%, 84.4%, 47.8% and 88.2%). Pooled percentages of suboptimal responders were 43.3%, 27.6% and 23.7%, respectively. Pooled diagnostic odds ratios were 14.6 (95% confidence interval: 1.4-155), 9.2 (1.4-59.0) and 8.2 (3.5-19.2).

CONCLUSIONS

All criteria had a limited predictive value. RIO score ≥ 2 at 1-y combined fair accuracy and consistency, limiting the probability of disability progression in the next years to 1 in 8 optimal responders. NewT2 ≥ 1 at 1-y had similar positive predictive value, but diminished the false negatives to 1 in 16 patients. More sensitive measures of treatment failure at short term are needed.

MxA mRNA quantification and disability progression in interferon beta-treated multiple sclerosis patients

Even though anti-interferon beta (IFNβ) antibodies are the main determinants of IFNβ bioactivity loss and Myxovirus-resistance protein A (MxA) is the most established marker of IFNβ biological activity in IFNβ-treated multiple sclerosis patients, their usefulness in the routine clinical practice is still debated. Therefore, 118 multiple sclerosis patients naïve for treatment were enrolled for a 3-year longitudinal observational study mimicking the conditions of a real-world setting. In order to evaluate the kinetics of bioactivity loss in blood samples obtained every 6 months after therapy initiation, MxA and interferon receptor isoform/subunit mRNA were quantified by real-time PCR, anti-IFNβ binding antibodies were detected by radioimmunoprecipitation, and neutralizing antibodies by cytopathic effect inhibition assay. Clinical measures of disease activity and disability progression were also obtained at all time points. We found that, at the individual-patient level, the response to IFNβ therapy was extremely heterogeneous, including patients with stable or transitory, early or late loss of IFNβ bioactivity, and patients with samples lacking MxA mRNA induction in spite of absence of antibodies. No interferon receptor isoform alterations that could explain these findings were found. At the group level, none of these biological features correlated with the measures of clinical disease activity or progression. However, when MxA mRNA was evaluated not at the single time point as a dichotomic marker (induced vs. non-induced), but as the mean of its values measured over the 6-to-24 month period, the increasing average MxA predicted a decreasing risk of short-term disability progression, independently from the presence of relapses. Therefore, a more bioactive treatment, even if unable to suppress relapses, reduces their severity by an amount that is proportional to MxA levels. Together with its feasibility in the routine laboratory setting, these data warrant the quantification of MxA mRNA as a primary tool for a routine monitoring of IFNβ therapy.

Anticytokine autoantibodies in infectious diseases: pathogenesis and mechanisms

Autoantibodies to cytokines occur in many different conditions and situations and can cause a wide range of disease, including pulmonary alveolar proteinosis, disseminated non-tuberculous mycobacterial disease, pure red-cell aplasia, and chronic mucocutaneous candidiasis. Anticytokine autoantibodies may also develop against exogenously administered cytokines, sometimes diminishing their effects or inhibiting the activity of the endogenous cytokine. Unlike primary congenital immunodeficiencies, autoantibodies may develop over time, wax and wane, and may change in titre or avidity. Naturally occurring autoantibodies to interferons α, β, and γ, interleukins 1α, 2, 6, and 10, tumour necrosis factor, and granulocyte-macrophage colony-stimulating factor have been reported in healthy individuals and have been identified in rheumatological diseases, graft-versus-host disease, and cancer. Therapeutic antibodies, growth factors, other biological agents, and cytokines used to treat acute, chronic, malignant, and immune diseases may elicit or overcome autoantibodies, hence influencing the primary intended therapy. The increasing number of biologically active anticytokine autoantibodies being reported suggests that currently "idiopathic" diseases may someday be explained by neutralising or agonising autoantibodies. Their protean roles in causing, treating, preventing, and responding to disease, as well as simply maintaining normal homoeostasis, offer fascinating insights into the biology of immunity, inflammation, and infection.

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.

The Clinical Application of Ozonetherapy

The reader may be eager to examine in which diseases ozonetherapy can be proficiently used and she/he will be amazed by the versatility of this complementary approach (Table 9 1). The fact that the medical applications are numerous exposes the ozonetherapist to medical derision because superficial observers or sarcastic sceptics consider ozonetherapy as the modern panacea. This seems so because ozone, like oxygen, is a molecule able to act simultaneously on several blood components with different functions but, as we shall discuss, ozonetherapy is not a panacea. The ozone messengers ROS and LOPs can act either locally or systemically in practically all cells of an organism. In contrast to the dogma that “ozone is always toxic”, three decades of clinical experience, although mostly acquired in private clinics in millions of patients, have shown that ozone can act as a disinfectant, an oxygen donor, an immunomodulator, a paradoxical inducer of antioxidant enzymes, a metabolic enhancer, an inducer of endothelial nitric oxide synthase and possibly an activator of stem cells with consequent neovascularization and tissue reconstruction.

Critical role of kallikrein in hereditary angioedema pathogenesis: A clinical trial of ecallantide, a novel kallikrein inhibitor

BACKGROUND

Hereditary angioedema (HAE) is a rare, autosomal-dominant disorder caused by C1 inhibitor gene mutation. Patients with HAE experience intermittent attacks of edema affecting the oropharynx, abdomen, gastrointestinal tract, and limbs. C1 inhibitor is the primary endogenous inhibitor of the kallikrein-kinin (contact) cascade. Unregulated kallikrein activation generates bradykinin, the likely mediator of the swelling and pain characterizing HAE attacks. Ecallantide, a novel, recombinant protein, potently inhibits kallikrein. This is the first placebo-controlled assessment in human beings of a therapeutic intervention to improve symptoms of HAE attacks under the hypothesis that the contact cascade is the putative pathway responsible for HAE pathology.

OBJECTIVE

To determine the safety and efficacy of ecallantide in patients with HAE.

METHODS

This double-blind, placebo-controlled, ascending-dose study assessed efficacy and tolerability of ecallantide (5, 10, 20, or 40 mg/m(2) intravenously) in individuals experiencing acute HAE attacks (N = 49). Twelve patients were assigned to each dose level: 10 to ecallantide and 2 to placebo, per cohort.

RESULTS

Ecallantide treatment ameliorated the symptoms of HAE attacks: 72.5% (29/40) of patients treated with ecallantide versus 25.0% (2/8) of placebo patients reported significant improvement in symptoms within 4 hours (P = .0169). Ecallantide was well tolerated at all doses.

CONCLUSION

Ecallantide, a potent, specific inhibitor of plasma kallikrein, significantly improved HAE symptoms over placebo. The trial provides strong support for the role of the kallikrein-kinin cascade and its end product, bradykinin, in the pathophysiology of HAE. Further clinical trials are underway.

CLINICAL IMPLICATIONS

Ecallantide is a promising new therapy for HAE attacks.

Reduced effectiveness of long-term interferon-β treatment on relapses in neutralizing antibody-positive multiple sclerosis patients: a Canadian multiple sclerosis clinic-based study

Multiple sclerosis (MS) patients treated with interferon-beta (IFN-β) often form anti-IFN-β antibodies accompanied by a reduction in IFN-β bioavailability. The clinical effect of these antibodies remains controversial. MS patients in British Columbia, Canada, must be diagnosed and evaluated annually by neurologists in an MS clinic in order to be reimbursed for their IFN-β prescriptions. We have identified at the UBC MS clinic a cohort of 262 patients, each having been treated with a single IFN-β preparation more than three years, some for nearly a decade. Of 119 patients treated with Betaseron® (IFN-β1b), 18 (15.1%) were neutralizing antibody positive (NAb+) at the time of the study, whereas of 131 treated with subcutaneous Rebif® (IFN-β1a SC), 16 (12.2%) were NAb+, but none of 12 treated with intramuscular Avonex ® (IFN-β1a) had detectable neutralizing antibodies. During the first two years of treatment, the relapse rate was significantly reduced from pre-treatment rates ( P < 0.001) and appeared to be unaffected by the subsequent NAb status. However, the relapse rates in the NAb+ patients were significantly greater than in the NAb— patients during years 3 ( P < 0.010) and 4 ( P < 0.027). Betaseron ®-treated NAb+ patients tended to have more relapses than NAb — patients during year 3 and this almost reached significance ( P = 0.056) but their relapse rate did not differ in year 4 and later. In contrast, Rebif ®-treated NAb+ patients tended to have more relapses in year 3 than Rebif ® -treated NAb — patients ( P = 0.074), but in year 4 they clearly ( P = 0.009) had more relapses than Rebif ®-treated NAb — patients. There was no convincing effect on progression of disability in any group. Multiple Sclerosis 2007; 13: 1127—1137. http://msj.sagepub.com

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.

Interferon-alpha2a and Vogt-Koyanagi-Harada disease: a double-edged sword?

Successful therapy based on the use of interferon-alpha has been reported in different types of severe chronic uveitis. The immunomodulatory effects of this drug, combined with its antiviral properties seem to contribute to its efficacy in the treatment of different forms of severe and refractory uveitis such as Vogt-Koyanagi-Harada disease, Behçet-associated uveitis, or even human herpes virus 8 (HHV-8) associated uveitis. At the same time, severe ocular complications have been reported in patients treated with interferon-alpha for chronic viral hepatitis C. Among these complications, six cases of Vogt-Koyanagi-Harada-like disease have been described.We report a small case series of two patients with refractory Vogt-Koyanagi-Harada disease, treated with interferon-alpha and discuss the potential benefits or detrimental role of interferon therapy in these patients.

Interferon receptor expression in multiple sclerosis patients

To determine the gene expression of IFNAR1, IFNAR2 and MxA protein and the association with IFNbeta treatment response in MS patients. MS patients treated with IFNbeta had a significant decrease in IFNAR1 and IFNAR2 expression, and a significant increase in MxA compared to non-treated patients and healthy controls. Also, those patients who had a good response to treatment had a significant decrease in IFNAR1 and IFNAR2 expression compared to non-responders, non-treated patients and healthy controls. IFNbeta influences the expression of its receptors, and is greater in patients who respond to IFNbeta treatment. This down-regulation could be indicative of the response to IFNbeta.

The therapeutic potential of a kallikrein inhibitor for treating hereditary angioedema

Hereditary angioedema (HAE) manifests as intermittent, painful attacks of submucosal oedema affecting the larynx, gastrointestinal tract or limbs. Currently, acute treatment is available in Europe but not USA, and requires intravenous administration of a pooled blood product. HAE is most likely caused by dysinhibition of the contact cascade, resulting in overproduction of bradykinin. DX-88 (ecallantide, Dyax Corp.) is a highly specific recombinant plasma kallikrein inhibitor that halts the production of bradykinin and can be dosed subcutaneously. In a placebo-controlled Phase II trial in patients with HAE, DX-88 resulted in significant improvement in symptoms compared with placebo. A Phase III trial is ongoing. This review explains the pathophysiology of HAE and the mechanism by which DX-88, a non-intravenous, nonplasma-derived therapy, might improve the disease, and discusses the clinical course of HAE and available treatments. Finally, it explores the potential value and efficacy of DX-88 in treating HAE.

Neutralising antibodies to IFN-β in patients with multiple sclerosis

The development of neutralising antibodies (NABs), or neutralising activity in the absence of NABs, is a potential complication of therapy with interferon (IFN)-beta for patients with multiple sclerosis, limiting therapeutic efficacy. Discontinuation of IFN-beta therapy in patients found to have sustained titres of NABs > 1:100 over an interval of 3 - 6 months has been recently proposed as a Level A recommendation. The extent to which NABs are causative, rather than an epiphenomenon, in determining drug failure has been a matter of numerous investigations and is still controversial. Thus, further studies are warranted for determining the role that NABs may play in reducing the response to the drug. In particular, the effects of NABs in reducing the efficacy of IFN-beta therapy beyond clinical relapse rate and lesion load on conventional imaging are not as yet fully understood.

Biological markers of interferon-beta therapy: comparison among interferon-stimulated genes MxA, TRAIL and XAF-1

Biological activity of interferon-beta (IFNbeta) can be assessed by measuring IFN-stimulated genes (ISGs). Among them, myxovirus resistance protein A (MxA) appears to have the highest specificity, but it has no role in the pathogenesis of multiple sclerosis (MS). To investigate the reliability of MxA as a biomarker, we compared its expression to that of two other ISGs: TNF-related apoptosis-inducing ligand (TRAIL) and X-linked inhibitor of apoptosis factor-1 (XAF-1). Both were shown to be involved in immunoregulatory mechanisms and might play a role in MS. Quantitative-PCR measurements were performed in peripheral blood mononuclear cells from 73 MS patients after short-term and long-term treatment with IFNbeta. A time-dependent response for multiple ISGs was observed in all patients after short-term treatment. In contrast, long-term treatment induced concurrent inhibition of ISGs in 12.3% (9/73) of patients, in whom neutralizing antibodies (NAbs) were detectable. Besides, 22% (16/73) of chronically treated patients showed a non-NAbs-related abrogation of TRAIL expression. In summary, 1) MxA expression was significantly higher than both TRAIL and XAF-1, and 2) MxA was the most sensitive gene to detect decreased bioavailability due to NAbs. These findings identify MxA as an appropriate biomarker for IFNbeta, although there is no evidence for a functional role of it in MS.

Every-other-day interferon beta-1b versus once-weekly interferon beta-1a for multiple sclerosis (INCOMIN Trial) II: analysis of MRI responses to treatment and correlation with Nab

BACKGROUND

In RRMS, clinical exacerbations are usually associated with different types of active lesions at MRI, including: hyperintense lesions on T1-weighted post-gadolinium sequences; new hyperintense lesions or enlarging old lesions on PD/T2-weighted scans; or new hypointense lesions on T1-weighted pre-Gd sequences.

OBJECTIVE/METHODS

Primary outcome was the occurrence of patients with at least one active MRI lesion of the different types indicated above during treatment with 250 microg every other day (EOD) interferon beta (IFNbeta)-1b or 30 microg once weekly (OW) IFNbeta-1a in outpatients with RRMS (INCOMIN Trial).

RESULTS

The number of patients with at least one 'active' lesion, evaluated over the two-year follow-up, was significantly (P = 0.014) lower in the EOD IFNbeta-1 b arm (1 3/76, 17%) then in the OW IFNbeta-1a arm (25/73, 34%). NAb frequency over two-year follow-up was 22/65 (33.8%) in the EOD IFNbeta-1b arm and 4/62 (6.5%) in the OW IFNbeta-1a arm, significantly greater in the EOD IFNbeta-1b arm.

CONCLUSIONS

The development of MRI active lesions is strongly reduced by EOD-IFNbeta-1b compared with OW-IFNbeta-1a, indicating that EOD-IFNbeta-1b is more effective than OW-IFNbeta-1a in reducing ongoing inflammation and demyelination in MS. Logistic regression showed that NAb status did not affect the risk of MRI activity.

Significance of neutralizing antibodies to interferon beta during treatment of multiple sclerosis: expert opinions based on the Proceedings of an International Consensus Conference

On August 30, 2002, an international panel of neurologists who specialize in the treatment of multiple sclerosis (MS) was convened in Paris (France) to discuss the issue of neutralizing antibodies (NAb) to interferon beta (IFN-beta) therapy in patients with MS. The goals of this meeting were to: (i) review the most recent clinical information on NAb, (ii) come to a consensus on the clinical relevance of NAb in the management of patients with MS receiving IFN-beta therapy, and (iii) establish a framework for the development of patient management guidelines based on scientific consensus. The meeting was chaired by Hans-Peter Hartung (Heinrich-Heine University, Düsseldorf, Germany) and Huub Schellekens (Utrecht University, Utrecht, the Netherlands). This article summarizes the opinions of the expert panel on a number of key issues raised at the meeting.

Mitoxantrone as rescue therapy in worsening relapsing-remitting MS patients receiving IFN-beta

We assessed the action of mitoxantrone (MX) when given as rescue therapy in patients with relapsing-remitting (RR) multiple sclerosis (MS), whose disease activity worsens despite IFN-beta treatment. Ten very active RR MS patients received MX 12 mg/m2 monthly, for 3 months, and then returned to the original treatment with IFN-beta. Following treatment with MX, 70% of patients were able to return to IFN-beta treatment, stabilising EDSS and relapse rate during a follow-up period of 15-18 additional months. In contrast, in 30% of the patients who were taken off MX and returned to IFN-beta treatment the EDSS score deteriorated and the number of exacerbations increased significantly. The latter patients were switched again to MX treatment at 3-month intervals, stabilising EDSS and relapse rate during 15-18 additional months. Clinical findings correlated with the number of Gd-enhancing lesions disclosed in MRI scans. Immunological data were consistent with the clinical and MRI benefits observed. We conclude that brief courses of MX may provide a safe treatment alternative for RR MS patients who experience rapid and severe worsening of their disease despite IFN-beta treatment.

Interferons in relapsing-remitting multiple sclerosis: are there benefits from long-term use?

Multiple sclerosis (MS) is one of the most common chronic neurological diseases in young adults in western countries. An important aspect of treatment of this disease is the use of interferons (IFNs). These are molecules with antiviral, immunomodulatory, antiproliferative and hormonal activities. IFNbeta, a class I IFN, has been used extensively in the therapy of MS, particularly in its relapsing-remitting (RRMS) phase, the most frequent clinical form of the disease. Although the available evidence from published clinical trials is difficult to evaluate because of methodological differences, an unbiased review of the data reveals sufficient evidence to conclude that treatment with IFNbeta in RRMS is both efficacious and safe, at least over the periods so far investigated (up to 4-6 years). While there is no reason to suspect that IFNbeta should not continue to be efficacious and safe over the longer term, studies investigating these questions over longer periods and including greater numbers of patients are needed.

Biological activity of interferon betas in patients with multiple sclerosis is affected by treatment regimen and neutralising antibodies

BACKGROUND

MxA gene expression is one of the most appropriate markers of biological activity of exogenous interferon (IFN) beta.

METHODS

We quantified MxA mRNA for five consecutive days in 62 patients treated with IFN beta (16, Avonex; 10, Betaferon; 24, Rebif 22; 12, Rebif 44), by quantitative-competitive polymerase chain reaction. Every three months, IFN beta induced neutralising antibodies (NAbs) were evaluated in sera using a cytopathic effect assay.

RESULTS

Two categories of patients were identified: one group (49/62) had a sharp post-injection increase in MxA expression (defined as "IFN beta biological responder"), whereas the other group (13/62) had no MxA induction after IFN beta administrations (defined as "IFN beta biological non-responder"). In 11/13 biological non-responders, the persistent presence of NAbs correlated with abolished biological activity, independently of treatment regimen. The two remaining IFN beta biological non-responders were NAb-. Among the 49 IFN beta biological responders, biological activity was comparable between the four preparations on day 2 and 3 (+12 and +36 hours post-injection), but it was greater in Betaferon and both Rebif preparations on day 1, 4, and 5. In biological responders treated three times a week, only 82% (59/72) of injections were considered effective, compared with 100% (13/13) of Avonex injections.

CONCLUSION

Our results suggest that an optimal IFN beta regimen is not yet available: Avonex, given once a week, shows lower cumulative biological activity. On the other hand, both Betaferon and Rebif, given three times a week, show 18% biologically ineffective injections and higher risk of developing NAbs, which abolish biological activity.

Elimination of an immunodominant CD4+ T cell epitope in human IFN-beta does not result in an in vivo response directed at the subdominant epitope

The BALB/cByJ mouse strain displays an immunodominant T cell response directed at the same CD4(+) T cell epitope peptide region in human IFN-beta, as detected in a human population-based assay. BALB/cByJ mice also recognize a second region of the protein with a lesser magnitude proliferative response. Critical residue testing of the immunodominant peptide showed that both BALB/cByJ mice and the human population response were dependent on an isoleucine residue at position 129. A variant IFN-beta molecule was constructed containing the single amino acid modification, I129V, in the immunodominant epitope. The variant displayed 100% of control antiproliferation activity. Mice immunized with unmodified IFN-beta responded weakly in vitro to the I129V variant. However, BALB/cByJ mice immunized with the I129V variant were unable to respond to either the I129V variant or the unmodified IFN-beta molecule by either T cell proliferation or Ag-specific IgG1 Ab production. This demonstrates that a single amino acid change in an immunodominant epitope can eliminate an immune response to an otherwise intact therapeutic protein. The elimination of the immunodominant epitope response also eliminated the response to the subdominant epitope in the protein. Modifying functionally immunodominant T cell epitopes within proteins may obviate the need for additional subdominant epitope modifications.

High-dose, frequently administered interferon beta therapy for relapsing–remitting multiple sclerosis must be maintained over the long term: the interferon beta dose-reduction study

Long-term trials have demonstrated the continued efficacy of interferon (IFN) beta treatment in patients with relapsing-remitting (RR) multiple sclerosis (MS) during prolonged administration. The objective of the work was to evaluate the effects of reducing IFN beta administration frequency and total weekly dose in patients with RR MS who have achieved clinical and MRI disease activity stabilization during long-term IFN beta-1b treatment. Prospective 1-year follow-up of 27 RR MS patients on long-term 250 microg every other day (standard dose) IFN beta-1b treatment were randomized either to gradually reduce dose to 30 microg once-a-week IFN beta-1a (13 patients), or to continue on IFN beta-1b standard dose (14 patients). We found significant differences in the two group of patients. In the group of patients continuously treated with IFN beta-1b standard dose, 79% remained relapse free compared to 23% in the group receiving once-weekly IFN beta-1a (p=0.006). The number of patients without new PD/T2 lesions was higher in the group of patients continuously treated with IFN beta-1b standard dose (77%) compared to the once-weekly IFN beta-1a group (23%) (p=0.04). IFN beta is a long-term treatment for MS. The reduction of IFN beta-1b administration frequency and dose is not advisable even in patients free from clinical and MRI disease activity for many years.

Fate of neutralizing and binding antibodies to IFN beta in MS patients treated with IFN beta for 6 years

An increasing number of evidence is showing that during prolonged treatment of relapsing-remitting multiple sclerosis (RRMS) with interferon (IFN) beta 1a or IFN beta 1b, the patients may develop serum anti-IFN antibody. It has been argued that some of the RRMS patients receiving IFN beta, who developed antibodies to IFN, lose them over time even though the treatment continues. To gain further insights into this issue, we performed a study to establish what happened to binding antibodies (BAB) and neutralizing antibodies (NAB) in 42 RRMS patients treated for 6 years with IFN beta 1a and/or IFN beta 1b. While the data of BAB analysis did not allow to reach definite conclusions, the results on NAB development confirm that the presence of this type of antibodies is transitory; in fact, most of the positive patients reverted to seronegative, although the IFN treatment is still ongoing; the only patients who were positive for NAB at 6 years of treatment are those whose serum contains high concentration of them. The paper also shows that patients lose antibodies to IFN independently on the type of IFN used for the treatment. In conclusion, the data indicate that the disappearance of the anti-IFN antibodies from the serum while the patients are still undergoing IFN treatment depends on the titer of antibodies but not on the type of IFN administered.

Clinical importance of neutralising antibodies against interferon beta in patients with relapsing-remitting multiple sclerosis

BACKGROUND

Interferon beta is the first-line treatment for relapsing-remitting multiple sclerosis, but the drug can induce neutralising antibodies against itself, which might reduce effectiveness. We aimed to assess the clinical effect of neutralising antibodies.

METHODS

We measured neutralising antibodies every 12 months for up to 60 months in 541 patients with multiple sclerosis, randomly selected from all patients who started treatment with interferon beta between 1996 and 1999. Patients left the study if they changed or discontinued therapy. Antibodies were measured blindly, using antiviral neutralisation bioassays with high, medium, and low sensitivity, and with different neutralising capacities as cutoff value for definition of a neutralising-antibody-positive result.

FINDINGS

Patients developed neutralising antibodies independent of age, sex, disease duration, and progression index at start of treatment. Relapse rates were significantly higher during antibody-positive periods (0.64-0.70) than they were during antibody-negative periods (0.43-0.46; p<0.03). When comparing the number of relapses in the neutralising-antibody-positive and neutralising-antibody-negative periods we found odds ratios in the range 1.51 to 1.58 (p<0.03). Time to first relapse was significantly increased by 244 days in patients who were antibody-negative at 12 months (log rank test 6.83, p=0.009). During this short-term study, presence of neutralising antibodies did not affect disease progression measured with the expanded disability status scale.

INTERPRETATION

Our findings suggest that the presence of neutralising antibodies against interferon beta reduces the clinical effect of the drug. In patients who are not doing well on interferon beta, the presence of such antibodies should prompt consideration about change of treatment.

Pharmacological methods to overcome IFN-beta antibody formation in the treatment of multiple sclerosis

Diminished efficacy in terms of clinical relapses and lesion load on magnetic resonance images for patients developing neutralising antibodies (NAbs) to recombinant IFN-beta may be found in multiple sclerosis. NAbs become detectable over the first few years of therapy, disappearing during the treatment course in some patients and persisting longer in some others. Therefore, the administration of concomitant therapies to recombinant IFNbeta to prevent the formation of NAbs could be indicated mainly in the latter group of patients at the early stage of the treatment. Among those therapies, steroids meet the best criteria in terms of either safety or impact on the development of NAbs, at the present time.

Persistent neutralizing antibodies abolish the interferon beta bioavailability in MS patients

BACKGROUND

MxA is an antiviral protein exclusively induced by type I interferons (IFN) and some viruses, and MxA gene expression is one of the most appropriate markers for measuring the biologic activity of exogenous IFNbeta.

METHODS

A new quantitative-competitive PCR method was used to quantify MxA mRNA in peripheral blood mononuclear cells of 99 treatment-naïve and 92 IFNbeta-treated patients with MS (22 Avonex, 17 Betaferon, and 53 Rebif-22). Every 3 months, IFNbeta-induced neutralizing antibodies (NAb) were evaluated in sera using a cytopathic effect assay. Three categories of patients were identified: NAb negative (NAb-), persistent NAb positive (NAb+, >or=2 consecutive positive samples), and isolated NAb+ (one positive sample).

RESULTS

Treatment-naïve patients expressed detectable MxA mRNA levels (mean = 36 +/- 32 fg MxA/pg glyceraldehyde-3-phosphate dehydrogenase (GAPDH); range 1 to 160) and an upper normal threshold was established (mean + 3 SD = 132 fg MxA/pg GAPDH). IFNbeta-treated patients exhibited more than 11-fold higher levels (mean = 412 +/- 282 fg MxA/pg GAPDH; range 16 to 1,172). However, 17 patients did not exhibit an increase in MxA mRNA level; 15 of these 17 patients showed a concurrent Nab+ titer. Moreover, 13 were persistent NAb+. Isolated NAb+ patients did not show a decrease in bioavailability of IFNbeta (n = 9; mean = 567 +/- 366 fg MxA/pg GAPDH; range 83 to 1,120). In NAb- patients, bioavailability was comparable among the three different IFNbeta preparations 12 hours after injection.

CONCLUSION

During IFNbeta therapy, the presence of NAb reduced or abolished bioavailability in a relevant percentage of patients. These data could be important for the early detection of patients with MS who are not responsive to IFNbeta therapy.

Serum interferon (IFN)-neutralizing antibodies and bioactivities of IFNs in patients with severe type II essential mixed cryoglobulinemia

The efficacy of alpha interferon (IFN-alpha) in the treatment of severe type II essential mixed cryoglobulinemia (EMC) has been reported previously. In some patients, the development of neutralizing antibodies to recombinant IFN-alpha (rIFN-alpha) can affect the clinical response achieved with rIFN-alpha; a second treatment with natural IFN-alpha preparations may reinduce the clinical response. In the present study the ability of leukocyte IFN (LeIFN) to restore the response was investigated from a pharmacodynamic viewpoint. Specifically, the pharmacodynamic profiles of different IFN-alpha preparations were studied by measuring the serum neopterin levels and the levels of expression of protein MxA mRNA in in vivo peripheral blood mononuclear cells in two patients with EMC whose resistance to rIFN-alpha2a treatment increased concomitantly with the development of neutralizing antibodies. These markers were measured before injection and at 24 and 48 h after a single injection of rIFN-alpha2a, consensus IFN [(C)IFN], or LeIFN. No increase or only a slight increase in MxA mRNA levels was detectable after administration of rIFN-alpha2a or (C)IFN, whereas a significant increase (>/=10-fold) in MxA mRNA expression was recorded following administration of LeIFN. The neutralizing antibodies to rIFN-alpha2a cross-react with (C)IFN. Sera from these patients neutralized most but not all of the subtypes present in the natural IFN-alpha (LeIFN) mixture, and no significant increase in neopterin levels was observed after these patients were switched to LeIFN treatment. In summary, the data demonstrate that the problem of neutralizing antibodies still exists and that LeIFN may induce an increase in the level of MxA mRNA expression but not an increase in neopterin levels in patients who are resistant to treatment with rIFN-alpha2a or (C)IFN.

A comparison of the mechanisms of action of interferon beta and glatiramer acetate in the treatment of multiple sclerosis

BACKGROUND

The development of immunomodulatory agents has represented a major advance in the treatment of multiple sclerosis (MS). To date, immunomodulatory agents approved for the treatment of relapsing MS in the United States include 3 forms of recombinant interferon (IFN) beta (2 formulations of IFN beta-1a and 1 of IFN beta-1b) and synthetic glatiramer acetate (GA). Recognition of how these agents work to regulate the immune system may lead to a better understanding of disease mechanisms, as well as to development of more effective therapies or combinations of therapy.

OBJECTIVE

This article reviews the potential mechanisms of action of IFN beta products and GA in the context of their regulatory effects on autoimmune components that may be of importance in MS.

METHODS

MEDLINE and Current Contents/Clinical Medicine were searched for articles published in English from 1993 to the present using the search terms interferon beta, glatiramer acetate, and multiple sclerosis.

RESULTS

IFN beta products affect the disease process in MS through multiple potential mechanisms of action, including antiviral, antiproliferative, and anti-inflammatory effects. The mechanisms of action of GA are less clear, but may involve immune regulation induced by a gradual shift of T-cell phenotype from proinflammatory (type 1 T-helper cells) to anti-inflammatory (type 2 T-helper cells) and interference with antigen presentation.

CONCLUSION

Understanding the mechanisms of action of IFN beta products and GA provides important insights into the disease processes involved in MS.

Differential effects of three interferon betas on neutralising antibodies in patients with multiple sclerosis: a follow up study in an independent laboratory

OBJECTIVE

To evaluate the incidence and the prevalence of neutralising antibodies (NABs) to three interferon beta (IFNbeta) products in patients with multiple sclerosis (MS).

METHODS

Sera were tested from 125 patients with relapsing-remitting MS. Patients were treated with IFNbeta-1b (Betaferon, n = 29) 8 MIU subcutaneously every other day, IFNbeta-1a (Avonex, n = 44) 30 microg intramuscularly once weekly, or IFNbeta-1a (Rebif, n = 36) 22 microg subcutaneously three times weekly for 6 to 18 months. An additional 16 patients were treated with Rebif 22 microg intramuscularly once or twice weekly. NABs were assessed using the cytopathic effect assay before treatment and every three months during treatment. Patients with two or more consecutive positive samples were considered to be persistent NAB positive (NAB+).

RESULTS

At baseline, no patients were NAB+. NABs developed during the first three months of treatment and continued to develop until month 18. Over 18 months of treatment, the risk of being persistent NAB+ was 31% for Betaferon, 15% for Rebif, and 2% for Avonex (Betaferon versus Avonex, p = 0.001; Betaferon versus Rebif, p = 0.19; Rebif versus Avonex, p = 0.04). In all patients with one or more NAB+ samples, the risk of becoming NAB+ was 38% for Betaferon, 18% for Rebif, and 7% for Avonex (Betaferon versus Avonex, p = 0.0007; Betaferon versus Rebif, p = 0.10; Rebif versus Avonex, p = 0.07). At month 18, the prevalence of persistent NAB+ patients was 31.6% for Betaferon, 18.7% for Rebif, and 4% for Avonex. Numbers of NAB+ patients observed were similar with intramuscular Rebif and with subcutaneous Rebif.

CONCLUSION

The three IFNbeta preparations have different degrees of immunogenicity, with Betaferon producing the highest incidence of NABs and Avonex the lowest. These differences should be considered by neurologists when selecting treatment for their patients with MS because NABs can reduce both bioavailability and clinical efficacy of IFNbeta.

Discordant effect of IFN-beta1a therapy on anti-IFN antibodies and thyroid disease development in patients with multiple sclerosis

Interferon-beta1b (IFN-beta1b) therapy is associated with a relatively high risk of developing thyroid disease. IFN-beta1a is regarded as less immunogenic than IFN-beta1b because of its structural homology to natural IFN-beta. We assessed the effect of 1 year of IFN-beta1a treatment on thyroid function and autoimmunity in 14 multiple sclerosis (MS) patients. The results were compared with those obtained in a series of 31 MS patients treated with IFN-beta1b. The prevalence of positive binding antibody (BAb) titer and neutralizing (NAb) anti-IFN antibody titer in the two groups was also assessed. The BAb and NAb positivity rate in IFN-beta1a-treated patients was significantly lower than in the group submitted to IFN-beta1b therapy (7% vs. 84% and 0% vs. 30%, respectively). Although the incidence of thyroid dysfunction was slightly higher in IFN-beta1b-treated patients than in those undergoing IFN-beta1a treatment (33% vs. 23%, respectively), it did not reach statistical significance. Thyroid disease was unrelated to the presence of positive serum BAb or NAb titer in both the group undergoing IFN-beta1a therapy and in that treated with IFN-beta1b. In both groups, thyroid disease developed mostly in women (71%) against a background of preexisting thyroiditis and a diffuse hypoechoic ultrasound thyroid pattern (80%). IFN-beta1a treatment was associated with a significantly lower prevalence of both BAb and NAb-positive titers than was IFN-beta1b. Conversely, thyroid disease was similar and unrelated to the presence of positive anti-IFN-beta antibody titer. Therefore, routine thyroid assessment may be advised during IFN-beta1a treatment, especially in patients with preexisting thyroiditis.

Neutralizing and binding antibodies to IFN-beta: relative frequency in relapsing-remitting multiple sclerosis patients treated with different IFN-beta preparations

The frequencies of anti-interferon-beta (IFN-beta) antibody development reported to date in patients treated with different IFN-beta preparations are not readily comparable mainly because of differences in underlying diseases and assay methods. Thus, the frequency of neutralizing antibody (NAb) and binding antibody (BAb) development was analyzed in a sample of sera derived from a homogeneous group of relapsing-remitting multiple sclerosis (RRMS) patients treated with different IFN-beta preparations. The frequency of developing NAb and BAb to IFN-beta varied according to the IFN-beta given. Specifically, the NAb seroconversion frequency was significantly higher in patients treated with Betaferon, Schering AG, Berlin, Germany (31.3%) than in patients treated with both preparations of recombinant IFN-beta 1a (Rebif, Serono, Geneva, Switzerland [7.4%] or Avonex, Biogen, Cambridge, MA [6.3%]). Analysis of BAb seroconversion frequency in the same patients revealed that different IFN-beta preparations may also have different capability to induce BAb development and that BAb are produced during IFN-beta therapy at a significantly higher rate than NAb. Our main conclusion is that different human IFN-beta preparations may possess different immunogenicities, leading to varying frequency of development of antibody to IFN-beta in RRMS.

Regulation by IFN-beta of inducible nitric oxide synthase and interleukin-12/p40 in murine macrophages cultured in the presence of Chlamydia pneumoniae antigens

Chlamydia pneumoniae has been demonstrated in the cerebrospinal fluid (CSF) of patients with multiple sclerosis (MS). Interferon-beta (IFN-beta) has favorable effects on the clinical course of MS. We investigated whether the beneficial effects of IFN-beta in MS may involve its role in regulating nitric oxide (NO) and interleukin-12 (IL-12) in macrophages, as these immune modulators form part of the innate immune response to intracellular pathogens, such as C. pneumoniae. Murine macrophages in cultures exposed to elementary body antigens or recombinant major outer membrane protein (rMOMP) of C. pneumoniae demonstrate a significant increase in NO as well as production of IL-12/p40 in culture supernatants compared with basal levels. Addition of murine IFN-beta increased NO activity in murine macrophages cultured with chlamydial antigens. Addition of neutralizing anti-IFN-beta antibody prevented the NO increase. In contrast to its effect on inducible NO synthase (iNOS), IFN-beta reduced induction of IL-12/p40 following culture with either elementary body antigens or rMOMP. Inhibition was reversed with anti-IFN-beta antibody. If C. pneumoniae infection is responsible for the inflammatory response in the pathogenesis of MS, the beneficial effects of IFN-beta in MS may be due to its enhancing intracellular NO activity while inhibiting secretion of the proinflammatory cytokine, IL-12.

Immunoglobulin subclasses in patients with neutralizing and nonneutralizing antibodies against IFN-beta1b

Treatment of multiple sclerosis (MS) with interferon-beta1b (IFN-beta1b) induces the production of antibodies in some patients. A proportion of these antibodies can reduce the biologic activity of IFN-beta, and they are, therefore, referred to as neutralizing antibodies (NAB). The remaining antibodies do not interfere with the biologic activity of IFN-beta and are referred to as nonneutralizing antibodies (NNAB) in this paper. Immunoglobulin (Ig) subtyping of these antibodies was carried out, and Ig subclass patterns in 20 patients with NAB were compared with those of NNAB in 39 patients. In patients with NAB, IgG2 and IgG4 were found to occur more frequently than in patients with NNAB (30% vs. 3%, p = 0.05, and 55% vs. 18%, p = 0.003, respectively) The NAB titer correlated strongly with the IgG4 titer (r = 0.53, p = 0.02). Median total IgG, IgG1, and IgG4 titers were significantly higher in NAB than in NNAB patients (respectively, 8000 vs. 3200, p = 0.01; 1600 vs. 400, p = 0.0004; 200 vs. 0, p = 0.004). It is concluded that the development of NAB is related to both the quantity and the quality of the antibodies against IFN-beta1b.

Does high-dose interferon beta-1b improve clinical response in more severely disabled multiple sclerosis patients?

Prospective clinical open label follow-up of 52 multiple sclerosis patients treated with interferon beta-1b. After 18 months of treatment at standard 8 million international units (MIU) dose, subcutaneously on alternate days, IFNB dose was increased to 12 MIU in ten clinically non-responder patients. Eighteen months after, mean exacerbation rate, number and severity of exacerbations and number of patients with exacerbations or requiring corticosteroid treatment significantly improved, becoming similar to those of IFNB responders, always treated with 8 MIU. Baseline EDSS score of non-responders was higher than that of responders. Frequency and severity of adverse events were trending higher and dropout frequency higher in 12 MIU IFNB-treated patients.

Interferon beta neutralizing antibodies in multiple sclerosis: neutralizing activity and cross-reactivity with three different preparations

The presence and titer of neutralizing antibodies (NABs) was evaluated by an antiviral biological assay in 387 samples of 111 multiple sclerosis (MS) patients treated with one of the three commercial preparations of interferon beta (IFNbeta). Fifty NAB positive samples were found in 19 patients: 11 treated with IFNbeta-1b (Betaferon(R)) and eight with IFNbeta-1a (five with Avonex(R) and three with Rebif(R)). All the 38 NABs+ samples of patients treated with IFNbeta-1b cross-reacted with IFNbeta-1a of both commercial types. The median level of neutralizing units (NUs) of the sera was higher when tested against IFNbeta-1a than against IFNbeta-1b (p=0.000 vs. Avonexr(R) and p=0.003 vs. Rebif(R)). In line with these data, the NABs+ sera of patients treated with IFNbeta-1a cross-reacted with IFNbeta-1b and the level of NUs were lower when tested against IFNbeta-1b than against IFNbeta-1a (p=0.003). The different amount of NUs against IFNbeta types 1a and 1b could be due to the presence of aggregates in the IFNbeta-1b preparation. The different levels of cross-reactivity of NABs could reduce the bioavailability and therapeutic efficacy of IFNbeta in NABs+ patients switching from IFNbeta-1b to IFNbeta-1a.

Further study on the specificity and incidence of neutralizing antibodies to interferon (IFN) in relapsing remitting multiple sclerosis patients treated with IFN beta-1a or IFN beta-1b

The development of neutralizing antibodies (NAbs) to interferon (IFN) is a common phenomenon of IFN beta therapy for relapsing-remitting multiple sclerosis (RRMS) patients. Here we examine the specificity of NAbs developed during therapy for RRMS with recombinant interferon (rIFN) beta-1a or rIFN beta-1b, and study the effect of switching from rIFN beta-1a to rIFN beta-1b on the incidence and specificity of NAbs. The relative ability to neutralize rIFN beta-1a and beta-1b was assayed in sera positive for NAbs derived from RRMS patients treated with either rIFN beta-1a (N=9) or rIFN beta-1b (N=16), while the incidence and specificity of NAbs to IFN beta developed during therapy were studied in 50 RRMS patients who were treated for two years with rIFN beta-1a followed by a further year either switching to rIFN beta-1b (N=34) or continuing treatment with rIFN beta-1a (N=16). The results show that all positive sera, independent of the source, may recognize both forms of rIFN beta and that a further year of treatment does not significantly affect the incidence and specificity of the NAbs developed during the first two years of treatment even if treatment is switched to a different type of IFN beta. The data then suggests that it is unlikely that the administration of rIFN beta-1b to anti-rIFN beta-1a NAbs-positive patients can overcome the inhibitory effect exerted by the serum antibodies (and vice versa), and that a further period of treatment with IFN beta-1b in patients previously treated with rIFN beta-1a does not significantly change the pattern of antibody response to IFN beta.