Management of patients with neutralizing antibodies against interferon-beta: stop IFN-beta therapy or wait for the antibodies to go away?

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.

[The search for optimal decision in the treatment of multiple sclerosis: to improve adherence not reducing the efficacy]

Long-term disease modifying therapy (DMD) therapy is the basis of modern MS treatment, effiecacy of which is modulated by the patient's adherence to therapy. One of the possible solutions of low adherence improvement is the use of innovative drugs and the development of more convenient regimens of injectable medications. This article gives a brief review of peg-interferon β-1a clinical trials.

Cross-reactivity of antibodies against interferon beta in multiple sclerosis patients and interference of the JAK-STAT signaling pathway

Interferon beta (IFNβ) therapy has immunogenic properties and induces the development of neutralizing antibodies (NAbs). From the extensive literature focused in the development of NAbs in multiple sclerosis (MS) patients, their ability to cross-react has been deficiently evaluated, despite having important consequences in the clinical practice. Here, the relation between the cross-reactivity and the NAbs titers has been evaluated in MS patients, by inhibition of the antiviral activity of IFNβ by bioassay and through the interference with the activation of the IFNß pathway (JAK-STAT), by phosphoflow. Thus, patients with intermediate-high titers of NAbs, determined by bioassay, had a 79-fold increased risk of cross-reactivity compared to patients with low titers. The cross-reactivity is also demonstrated because NAbs positive sera were able to decrease significantly the activation of pSTAT1 achieved by other different IFNβ molecules in the cells patients. Besides, a linear relationship between the STAT1 phosphorylation and NAbs titers was found. The study demonstrates that cross-reactivity increases with the titer of antibodies, which has important implications in clinical practice when switching the treatment. The direct relationship between the NAbs titer and the activation of STAT1 suggest that its determination could be an indirect method to identify the presence of NAbs.

The impact of neutralizing antibodies on the risk of disease worsening in interferon β-treated relapsing multiple sclerosis: a 5 year post-marketing study

The impact of neutralizing antibodies (NAbs) on interferon β (IFNβ) efficacy in MS patients is still an object of controversy. To evaluate the clinical response to IFNβ during NAb-positive (NAb+) and NAb-negative (NAb-) statuses on a large population of relapsing remitting (RR) MS patients were followed up to 5 years. Sera from 567 RR MS patients treated with IFNβ for 2-5 years were collected every 6-12 months and evaluated for NAb presence by a cytopathic effect assay. The relapse rate and expanded disability status scale (EDSS) score were assessed at baseline and every 6 months for each patient. A NAb+ status was defined after two consecutive positive titers of NAbs >/= 20 neutralizing units (NU)/mL. Multivariate models were used to analyze the relapse rate, the time to first relapse, the time to confirmed EDSS score 4 during NAb+ and NAb- statuses. A propensity score (PS) matching analysis was performed to assess the robustness of the multivariate models. Fourteen percent of patients became NAb+ during the follow-up. A significant increase of the relapse rate (IRR = 1.38; p = 0.0247) and decrease of the time to 1st relapse (IRR = 1.51; p = 0.0111) were found during NAb+ periods. The PS matching analysis, in a selected cohort of patients, demonstrated a negative trend of NAbs on the time to reach the milestone EDSS 4 (IRR = 2.94; p = 0.0879). This long-term post-marketing observational study further confirms that the occurrence of NAbs significantly affects the risk of disease worsening in IFNβ- treated RRMS.