Disease-modifying therapies in multiple sclerosis: an update on recent and ongoing trials and future strategies

Interferon-β Decreases the Hypermetabolic State of Red Blood Cells from Patients with Multiple Sclerosis

Multiple sclerosis (MS) is an inflammatory disease characterized by damage to the myelin sheath surrounding axons in the central nervous system. While the exact mechanism of this destruction is unknown, excess nitric oxide (NO) and adenosine triphosphate (ATP) have been measured in tissues and fluids obtained from people with MS. Here, incubation of interferon-beta (IFN-β), an MS drug with an unknown mechanism of action, with red blood cells (RBCs) obtained from people with MS provide evidence of a potential hypermetabolic state in the MS RBC that is decreased with IFN-β intervention. Specifically, binding of all three components of an albumin/C-peptide/Zn²⁺ complex to MS RBCs was significantly increased in comparison to control RBCs. For example, the binding of C-peptide to MS RBCs was significantly increased (3.4 ± 0.1 nM) compared to control RBCs (1.6 ± 0.2 nM). However, C-peptide binding to MS RBCs was reduced to a value (1.6 ± 0.3 nM) statistically equal to that of control RBCs in the presence of 2 nM IFN-β. Similar trends were measured for albumin and Zn²⁺ binding to RBCs when in the presence of IFN-β. RBC function was also affected by incubation of cells with IFN-β. Specifically, RBC-derived ATP and measurable membrane GLUT1 were both significantly decreased (56 and 24%, respectively) in the presence of IFN-β. Collectively, our results suggest that IFN-β inhibits albumin binding to the RBC, thereby reducing its ability to deliver ligands such as C-peptide and Zn²⁺ to the cell and normalizing the basal hypermetabolic state.

The innovative development in interferon beta treatments of relapsing-remitting multiple sclerosis

The introduction of interferon beta therapies more than 20 years ago marked a milestone in the treatment of relapsing-remitting multiple sclerosis (RRMS) with a significant impact on the approach to modern multiple sclerosis (MS) care. Key learnings and perspectives from the early days of disease modifying therapies in MS have improved the knowledge base of MS, need for treatment, and patient care. The continuous development of interferons over the past two decades outlines a journey with increased understanding of the pharmacodynamics and pharmacokinetic mechanisms of interferons, leading to innovative formulations with an improved benefit/risk profile.

Interferon-beta: the neutralizing antibody (NAb) titre predicts reversion to NAb negativity

Background: It has been reported that in some patients with MS who develop neutralizing antibodies (NAbs) against interferon beta (IFNb), antibody levels can initially increase and then decrease thereafter even when treatment is continued. Objective: To determine whether NAb titre correlates with time to reversion to NAb negativity in patients with multiple sclerosis (MS). Methods: Twenty-eight patients with MS who were NAb-positive during treatment with one of the currently available IFNbs were included in this retrospective study. NAb titres were determined by the myxovirus resistance protein A induction assay. Patients were considered NAb-positive if they had at least two consecutive samples with titres of]/20 neutralizing units (NU). Reversion to NAb-negative status was defined as two consecutive negative samples (NAb titre of B/20 NU) after NAb positivity. Results: When measured two years after treatment initiation, a NAb titre of B/75 NU had a 91.7% sensitivity and a 87.5% specificity for reversion to NAb negativity in the following two years (after a total of four years of treatment). In addition, somewhat surprisingly, patients whose serum converted to NAb-negative generally developed peak NAb titres earlier than patients who remained NAb-positive (mean time of first detection was 21 versus 38 months, respectively). Conclusion: The NAb titre might support treatment decisions in patients with MS whose test results are positive for NAbs.

Nurses' perspective on approaches to limit flu-like symptoms during interferon therapy for multiple sclerosis

BACKGROUND

Several interferon beta (IFNβ) formulations are approved for first-line use as disease-modifying therapies to treat patients with multiple sclerosis (MS). Systemic post-injection reactions, often termed flu-like symptoms (FLS), occur in approximately half of all patients treated with IFNβs and can affect adherence to therapy. These symptoms, which include pyrexia, chills, malaise, myalgia, and headaches, usually resolve within 24 hours or persist intermittently following each injection. Because FLS, which usually occur early in the treatment course and diminish over time, are a primary cause of nonadherence to IFNβ therapy, it is important to employ strategies that can attenuate these side effects.

METHODS

To identify interventions effective in limiting FLS, a panel of United States-based nurses with expertise in MS patient care was convened and a literature review completed.

RESULTS

Panel consensus was reached on specific interventions that can attenuate FLS. These prevention and mitigation strategies include dose titration, analgesia, and optimal injection timing, as well as other techniques that panel members have found useful in their clinical practice experience.

CONCLUSIONS

These measures, in addition to effective patient education, will help to reduce the incidence of FLS secondary to IFNβ therapy, improve patient medication adherence, and positively affect long-term clinical outcomes.

Mitoxantrone (Novantrone®) in multiple sclerosis: new insights

The conclusions of a recent study of mitoxantrone (Novantrone) in multiple sclerosis and the approval of several health authorities support its use in patients with active relapsing-remitting or secondary progressive multiple sclerosis. This drug profile provides an outline on relevant preclinical and clinical studies, discusses relevant side effects of the compound and places mitoxantrone in the context of other therapeutic approaches available against this disabling disorder.

Evaluation of atorvastatin and simvastatin for treatment of multiple sclerosis

Atorvastatin and simvastatin (members of the 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitor family) are widely prescribed as cholesterol-lowering agents. As they have been shown to exhibit potent immunomodulatory effects, they may become a future treatment option for autoimmune disease in general and multiple sclerosis (MS) in particular. Several recent reports have demonstrated that statins prevent and reverse chronic and relapsing experimental autoimmune encephalomyelitis, an animal model of MS. An open-label clinical trial assessing simvastatin in MS revealed a significant decrease in the number and volume of new MRI lesions and a favorable safety profile. The results of a large multicenter, placebo-controlled clinical trial assessing atorvastatin in patients with clinically isolated syndrome (a disease that predisposes to development MS) are expected soon. However, prospective placebo-controlled trials of atorvastatin or simvastatin in definite MS are difficult to perform due to ethical and financial objections. In this review, we discuss the backgrounds, mechanisms of action and future perspectives of atorvastatin and simvastatin as putative future treatment options in MS.

Oral disease-modifying treatments for multiple sclerosis: the story so far

Multiple sclerosis (MS) represents the prototypic inflammatory autoimmune disorder of the CNS. It is the most common cause of neurological disability in young adults and exhibits considerable clinical, radiological and pathological heterogeneity. Increased understanding of the immunopathological processes underlying this disease, advances in biotechnology and the development of powerful magnetic resonance imaging (MRI) technologies, together with improvements in clinical trial design, have led to a variety of valuable therapeutic approaches to MS. Therapy for MS has changed dramatically over the past decade, yielding significant progress in the treatment of relapsing remitting and secondary progressive forms; however, most of the clinically relevant therapeutic approaches are not yet available as oral formulations. A substantial number of preliminary and pivotal reports have provided promising results for oral therapies, and various phase III clinical trials are currently being initiated or are already underway evaluating the efficacy of a variety of orally administered agents, including cladribine, teriflunomide, laquinimod, fingolimod and fumaric acid. It is hoped that these trials will advance the development of oral therapies for MS.

Pharmacokinetics and pharmacodynamics of the interferon-betas, glatiramer acetate, and mitoxantrone in multiple sclerosis

Five disease-modifying agents are currently approved for long-term treatment of multiple sclerosis (MS), namely three interferon-beta preparations, glatiramer acetate, and mitoxantrone(1). Pharmacokinetics describes the fate of drugs in the human body by studying their absorption, distribution, metabolism and excretion. Pharmacodynamics is dedicated to the mechanisms of action of drugs. The understanding of the pharmacokinetics and pharmacodynamics of the approved disease-modifying agents against MS is of importance as it might contribute to the development of future derivatives with a potentially higher efficacy and a more favourable safety profile. This article reviews data thus far present both on the pharmacokinetics as well as on the putative mechanisms of action of the interferon-betas, glatiramer acetate, and mitoxantrone in the immunopathogenesis of MS.

Differential outcome of tolerance induction in naive versus activated Theiler's virus epitope-specific CD8+ cytotoxic T cells

Tolerance induced by the intravenous injection of peptide-pulsed, ethylene carbodiimide (ECDI)-fixed splenic antigen-presenting cells (Ag-SP) is a safe and effective method of inducing specific unresponsiveness in CD4+ T cells for the prevention and treatment of a variety of autoimmune diseases. We determined whether Ag-SP tolerance could also be used to tolerize CD8+ T cells. We show in the Theiler's murine encephalomyelitis virus (TMEV)-induced demyelinating disease model of multiple sclerosis that CD8+ T cells specific for both dominant and subdominant epitopes can be rendered tolerant. Interestingly, although virus clearance was delayed, lack of the virus-specific cytotoxic T-lymphocyte response did not result in the conversion of normally TMEV-resistant C57BL/6 mice to a susceptible phenotype. Importantly, we found that Ag-SP tolerance may not be a practical treatment for human diseases in which CD8+ T cells play a major role in pathogenesis, as tolerance induction in mice previously infected with TMEV led to a severe, often fatal reaction.

Analysis of the C/T(-1) single nucleotide polymorphism in the CD40 gene in multiple sclerosis

The costimulatory CD40-CD40L pathway plays a critical role in the generation and maintenance of adaptive immune responses. Genetic interference of CD40-CD40L interactions strongly influences the onset and course in many autoimmune disease models including experimental autoimmune encephalomyelitis. We analysed the association of a single nucleotide polymorphism of the CD40 gene (C/T(-1)) in 287 patients with multiple sclerosis (MS) and 184 matched controls. No significant differences were found in the frequency of the C/T(-1) polymorphism between the patients with MS and the controls (53% vs 49%) or among different MS subtypes. Cell surface expression of CD40 did not differ within the different genotypes, but carriers of the T allele showed a trend for a lower stimulatory index compared with individuals with the CC genotype. Although these subtle differences indicate functional consequences in the immune stimulatory capabilities related to the CD40 C/T(-1) polymorphism, our population-based study found no association with disease susceptibility or disease course in MS.

Multiple sclerosis: Mitoxantrone promotes differential effects on immunocompetent cells in vitro

Mitoxantrone is an anti-neoplastic anthracenedione derivative that, based on its immunosuppressive properties, is approved for the treatment of severe forms of relapsing-remitting or secondary progressive multiple sclerosis (MS). Whether the beneficial clinical effects of mitoxantrone in MS are due to a broad immunosuppression, or whether there is a specific mechanism of action remains unknown. Peripheral blood mononuclear cells (PBMCs) from untreated or interferon-beta-treated patients with MS or from healthy donors were stimulated in the presence or absence of mitoxantrone. Irrespective of the source of the cells and the cellular phenotype, mitoxantrone inhibited proliferation of activated PBMCs, B lymphocytes, or antigen-specific T-cell lines (TCLs) stimulated on antigen-presenting cells (APCs) in a dose-dependent manner. For functional analysis, TCLs or APCs were incubated separately with mitoxantrone. Pre-incubation of APC more effectively impaired TCL proliferation than pre-incubation of TCLs. Production of cytokines, expression of activation markers, matrix metalloproteinases, and chemokine receptors were not influenced substantially by mitoxantrone. In contrast, in dendritic cells (DCs), mitoxantrone interfered with the antigen-presenting capabilities. For evaluation of apoptotic cell death of target cells, annexin-V-conjugates and a DNA fragmentation assay were applied. Mitoxantrone induced apoptosis of PBMCs, monocytes and DCs at low concentrations, whereas higher doses caused cell lysis. Our observations suggest that the beneficial effects of mitoxantrone in MS result (i) from its immunosuppressive action based on nonspecific cytotoxic effects on lymphocytes, (ii) by inducing programmed cell death of professional APCs, such as DCs.

[Possible target specific molecular imaging with ultrasound contrast agents]

Non-invasive molecular imaging technologies provide researchers with the opportunity to study cellular and molecular processes. Among different imaging technologies, ultrasound based molecular imaging methods are also of interest, since the use of ultrasound contrast agents allows specific and sensitive depiction of molecular targets. Recent studies are encouraging and have demonstrated the feasibility of ultrasound based molecular imaging. This review summarizes current experiences and recent preclinical studies with target-specific ultrasound contrast agents.

In vivo molecular imaging of adhesion molecules in experimental autoimmune encephalomyelitis (EAE)

The infiltration of autoreactive T cells into the central nervous system (CNS) requires a complex molecular interplay between immune cells and the blood-brain barrier (BBB), especially involving adhesion molecules like intercellular adhesion molecule (ICAM)-1. Here we study the molecular expression at the BBB during adoptively transferred (AT) myelin basic protein (MBP)-experimental autoimmune encephalomyelitis (EAE) in vivo by sensitive particle acoustic quantification (SPAQ)-enhanced ultrasound after intravenous application of specific gas-filled MP (MP) targeted against ICAM-1 (ICAM-MP) as contrast agent. Our results reveal a clear periventricular and cerebellar upregulation of ICAM-1 expression at the disease maximum of AT-EAE. Moreover, SPAQ-enhanced ultrasound enables the sensitive quantification of ICAM-1 expression in vivo. This allows to monitor therapeutic changes as shown by suppression of ICAM-1 expression after pretreatment of rats with corticosteroids (P < 0.008). All imaging results were confirmed by parallel immunohistochemistry. In vivo magnetic resonance imaging and albumin staining of rat brains after sonification did not reveal a disturbance of the BBB, thereby proving the safety of the method. Subsequent application of specific MP did not influence follow-up measurements, a prerequisite for sequential measurements in longitudinal studies. Based on these data, quantitative molecular imaging of adhesion molecules by SPAQ-enhanced ultrasound proves to be a safe and reliable technology to monitor changes at the BBB in vivo.

Ultrasound derived imaging and quantification of cell adhesion molecules in experimental autoimmune encephalomyelitis (EAE) by Sensitive Particle Acoustic Quantification (SPAQ)

Molecular imaging requires, not only the identification of an appropriate marker, but also its quantitative analysis. We used the Sensitive Particle Acoustic Quantification (SPAQ) technology - a novel ultrasound technique - for detection and quantification of cell adhesion molecules in isolated tissue and in live animals. By conjugating gas-filled microparticles (MPs) with antibodies to intercellular adhesion molecule 1 (ICAM-1) and vascular cell adhesion molecule 1 (VCAM-1), we were able to depict and quantify ICAM-1 and VCAM-1 in isolated brain and spinal cord from rats with autoimmune encephalomyelitis (EAE), an established inflammatory disease model of human multiple sclerosis (MS). Depiction and quantification of specific MPs were also feasible in living animals with AT-EAE with similar results. After treatment with methylprednisolone, the measured number of targeted anti-ICAM-1 and VCAM-1-MPs was significantly lower (P<0.01) compared to untreated animals demonstrating the high sensitivity of this imaging technique. Depending on the antibody linked to the surface of the MPs, the technique can be used to quantify the expression of any accessible antigen expressed on the luminal surface of endothelial cells and is therefore a promising tool for the non-invasive and dynamic assessment of disease-related molecules.

Multiple sclerosis – novel insights and new therapeutic strategies

PURPOSE OF REVIEW

This review focuses on novel aspects of the pathogenesis and advances in the therapy of multiple sclerosis (MS).

RECENT FINDINGS

Recent observations suggest that early lesion development in MS may start in some forms with oligodendrocyte death and that inflammation appears as a secondary phenomenon only. The lack of sufficient remyelination in MS may be the result of a disturbed function of basic helix-loop-helix transcription factors. Clinically the identification of patients with a clinically isolated syndrome at high risk to develop clinically definite MS remains difficult; the predictive value of serum antibodies against myelin proteins remains controversial. The role of neutralizing antibodies in interferon therapy is discussed. New therapeutic approaches in MS are emerging.

SUMMARY

The existing view on the pathogenesis of MS is still changing. The original assumption that cell-mediated demyelination is the key event in lesion development dictating clinical disability is critically reviewed and alternative pathways have been suggested. Oligodendrocyte death, axonal loss, the role of CD8 T lymphocytes, T regulatory cells, and B lymphocytes have come into the focus of newly evolving concepts in MS pathogenesis. A deepened understanding of the immunopathogenesis of this disease translates into innovative therapeutic approaches, such as blockade of alpha4 integrins by a humanized monoclonal antibody. In various animal models cell-replacement strategies yield promising results; however, turning these findings into an effective therapy in MS patients has a long way to go.

Role of Magnetic Resonance Imaging and Immunotherapy in Treating Multiple Sclerosis

Significant advances in magnetic resonance imaging (MRI) technology and treatment of multiple sclerosis (MS) have been made during the past decade. These advances have revealed evidence of profound heterogeneity in MS. There is a clear need to revisit the key issues in MS pathogenesis and treatment strategies, taking new data into consideration. This paper provides an overview of recent progress in MS research, including (a) a review of clinical, pathologic, and immunologic aspects of MS, (b) a discussion of the mechanism of action of currently available disease-modifying drugs for MS, (c) an account of the role of MRI in clinical management and clinical trials in MS, and (d) an overview of some emerging treatments for MS.

T cell vaccination in multiple sclerosis relapsing-remitting nonresponders patients

Myelin autoreactive T cells are involved in the pathogenesis of multiple sclerosis (MS) and lead to propagation of the disease. We evaluated the efficacy of T cell vaccination (TCV) therapy for patients with aggressive relapsing-remitting MS who failed to respond to immunomodulatory treatments. Twenty nonresponders relapsing-remitting MS patients were immunized with autologous attenuated T cell lines after activation with synthetic myelin basic protein (MBP) and myelin oligodendrocyte glycoprotein (MOG) encephalitogenic peptides. Each patient received three vaccinations in 6- to 8-week intervals. Annual relapse rate decreased from 2.6 to 1.1, P = 0.026. Neurological disability stabilized as compared with the 2- and 1-year pretreatment progression rates. Significant reduction in the number and volume of active lesions, as well as reduction in T2 lesion burden, was demonstrated by quantitative MRI analysis. No serious adverse events were observed. Our findings suggest that TCV has beneficial clinical effects in MS patients who, in spite of immunomodulatory treatments, continue to deteriorate. TCV could serve as a potential alternative therapy for this subgroup of nonresponders patients.

What do we know about the mechanism of action of disease-modifying treatments in MS?

Multiple sclerosis (MS), a chronic inflammatory disorder of the central nervous system (CNS), 2 results in damage to axons and their surrounding myelin sheath. The exact cause of inflammation remains unclear, but an autoimmune response directed against CNS antigens is suspected. MS can affect the brain, optic nerve and spinal cord, thus causing many neurological symptoms. These can include limb numbness or weakness, sensory or motor changes, ataxia, blurry vision, painful eye movements, bladder and bowel dysfunction, decreased memory, fatigue and effective disorders. This article will include a concise overview of the pathogenesis of MS in order to set the stage for subsequent discussion of the mechanisms of action of disease-modifying treatments, and whether these should influence our treatment choices. Although the exact pathogenesis of MS is not fully understood, current knowledge has already led to the development of effective treatments, namely interferon (IFN) 3 and glatiramer acetate, both of which have been shown to reduce relapse rates, while IFN 3- 1 a also reduces confirmed disability progression. Further increases in our understanding of the pathogenesis of MS are likely to assist in the identification of new targets for disease-modifying therapies and in the optimisation of current treatments..

Type 2 monocyte and microglia differentiation mediated by glatiramer acetate therapy in patients with multiple sclerosis

Glatiramer acetate (GA) therapy of patients with multiple sclerosis (MS) represents a unique setting in which in vivo Th2 deviation of T cells is consistently observed and associated with clinical benefit in a human autoimmune disease. We postulated that APCs are important targets of GA therapy and demonstrate that treatment of MS patients with GA reciprocally regulates the IL-10/IL-12 cytokine network of monocytes in vivo. We further show that Th1- or Th2-polarized GA-reactive T cells isolated from untreated or treated MS patients mediate type 1 and 2 APC differentiation of human monocytes, based on their ability to efficiently induce subsequent Th1 and Th2 deviation of naive T cells, respectively. These observations are extended to human microglia, providing the first demonstration of type 2 differentiation of CNS-derived APCs. Finally, we confirm that the fundamental capacity of polarized T cells to reciprocally modulate APC function is not restricted to GA-reactive T cells, thereby defining a novel and dynamic positive feedback loop between human T cell and APC responses. In the context of MS, we propose that GA therapy results in the generation of type 2 APCs, contributing to Th2 deviation both in the periphery and in the CNS of MS patients. In addition to extending insights into the therapeutic mode of action of GA, our findings revisit the concept of bystander suppression and underscore the potential of APCs as attractive targets for therapeutic immune modulation.