Identification and development of new therapeutics for multiple sclerosis

Molecular and neuroimmune pharmacology of S1P receptor modulators and other disease-modifying therapies for multiple sclerosis

Multiple sclerosis (MS) is a neurological, immune-mediated demyelinating disease that affects people in the prime of life. Environmental, infectious, and genetic factors have been implicated in its etiology, although a definitive cause has yet to be determined. Nevertheless, multiple disease-modifying therapies (DMTs: including interferons, glatiramer acetate, fumarates, cladribine, teriflunomide, fingolimod, siponimod, ozanimod, ponesimod, and monoclonal antibodies targeting ITGA4, CD20, and CD52) have been developed and approved for the treatment of MS. All the DMTs approved to date target immunomodulation as their mechanism of action (MOA); however, the direct effects of some DMTs on the central nervous system (CNS), particularly sphingosine 1-phosphate (S1P) receptor (S1PR) modulators, implicate a parallel MOA that may also reduce neurodegenerative sequelae. This review summarizes the currently approved DMTs for the treatment of MS and provides details and recent advances in the molecular pharmacology, immunopharmacology, and neuropharmacology of S1PR modulators, with a special focus on the CNS-oriented, astrocyte-centric MOA of fingolimod.

Modeling the impact of patient treatment preference on health outcomes in relapsing-remitting multiple sclerosis

Aims: Model how moving from current disease-modifying drug (DMD) prescribing patterns for relapsing-remitting multiple sclerosis (RRMS) observed in the United Kingdom (UK) to prescribing patterns based on patient preferences would impact health outcomes over time.Materials and methods: A cohort-based Markov model was used to measure the effect of DMDs on long-term health outcomes for individuals with RRMS. Data from a discrete choice experiment were used to estimate the market shares of DMDs based on patient preferences (i.e. preference shares). These preference shares and real-world UK market shares were used to calculate the effect of prescribing behavior on relapses, disability progression, and quality-adjusted life-years (QALYs). The incremental benefit of patient-centered prescribing over current practices for the UK RRMS population was then estimated; scenario and sensitivity analyses were also conducted.Results: Compared to current prescribing practices, when UK patients with RRMS were treated following patient preferences, health outcomes were improved. This population was expected to experience 501,690 relapses and gain 1,003,263 discounted QALYs over 50 years under patient-centered prescribing practices compared to 538,417 relapses and 958,792 discounted QALYs under current practices (-6.8% and +4.6%, respectively). Additionally, less disability progression was observed when prescribed treatment was based on patient preferences. In a scenario analysis where only oral treatments were considered, the results were similar, although the magnitude of benefit was smaller. Number of relapses was most sensitive to how the annualized relapse rate was modeled; disability progression was most sensitive to mortality rate assumptions.Limitations: Treatment efficacy estimates applied to various models in this study were based on data derived from clinical trials, rather than real-world data; the impact of patient-centered prescribing on treatment adherence and/or switching was not modeled.Conclusions: The population of UK RRMS patients may experience overall health gains if patient preferences are better incorporated into prescribing practices.

Genetic Association and Altered Gene Expression of CYBB in Multiple Sclerosis Patients

Multiple sclerosis (MS) is a chronic neurological disorder characterized by inflammation, demyelination, and axonal damage. Increased levels of reactive oxygen species (ROS), produced by macrophages and leading to oxidative stress, have been implicated as mediators of demyelination and axonal injury in both MS and experimental autoimmune encephalomyelitis, the murine model of the disease. On the other hand, reduced ROS levels can increase susceptibility to autoimmunity. In this work, we screened for association with MS 11 single nucleotide polymorphisms (SNPs) and two microsatellite markers in the five genes (NCF1, NCF2, NCF4, CYBA, and CYBB) of the nicotinamide adenine dinucleotide phosphate (NADPH) oxidase (NOX2) system, the enzymatic pathway producing ROS in the brain and neural tissues, in 347 Finnish patients with MS and 714 unaffected family members. This analysis showed suggestive association signals for NCF1 and CYBB (lowest p = 0.038 and p = 0.013, respectively). Functional relevance for disease predisposition was further supported for the CYBB gene, by microarray analysis in CD4^+/− mononuclear cells of 21 individuals from five Finnish multiplex MS families, as well as by real-time RT-PCRs performed on RNA extracted from peripheral blood mononuclear cells of an Italian replication cohort of 21 MS cases and 21 controls. Our results showed a sex-specific differential expression of CYBB, suggesting that this gene, and more in general the NOX2 system, deserve to be further investigated for their possible role in MS.

Efficacy of alemtuzumab and natalizumab in the treatment of different stages of multiple sclerosis patients

BACKGROUND

Multiple sclerosis (MS) is an autoimmune disease, in which the insulating covers of nerve cells in the brain and spinal cord are demyelinated. This study was conducted to compare the efficacy of alemtuzumab and natalizumab in the treatment of different stages of MS patients.

METHODS

A total of 585 patients diagnosed with MS and hospitalized were included and analyzed after which they were divided into the primary progressive MS A and B groups, the relapsing-remitting MS (RRMS) C and D groups, and the secondary progressive MS E and F groups. Patients in A, C, and E groups were administered alemtuzumab while those in B, D, and F groups were administered natalizumab for the treatment. The expanded disability status scale (EDSS) scores and the EDSS difference were calculated before and after treatment. The number of head magnetic resonance imaging enhanced lesions in the patients, recurrence time and recurrence rate were measured before and after treatment.

RESULTS

The EDSS score of the RRMS group was significantly lower than that of the primary progressive MS group and the secondary progressive MS group. After 12 months of treatment, the EDSS score of RRMS patients treated with natalizumab was significantly lower compared with the patients with alemtuzumab, and the difference before and after treatment was significantly higher than alemtuzumab. The recurrence rate of the RRMS-D group was significantly lower than the RRMS-C group. After 12 months of treatment, compared with the RRMS-C group, a significant reduction was observed in the number of head magnetic resonance imaging enhanced lesions and longer recurrence time in the RRMS-D group.

CONCLUSION

The efficacy of natalizumab was better than alemtuzumab in the treatment of patients in the RRMS group, while there was no significant difference among other stages of MS patients, which provided the theoretical basis and clinical guidance for the treatment of different stages of MS.

Immunologic profiles of multiple sclerosis treatments reveal shared early B cell alterations

Objective:

We undertook a systems immunology approach of the adaptive immune system in multiple sclerosis (MS), overcoming tradeoffs between scale and level of detail, in order to identify the immunologic signature of MS and the changes wrought by current immunomodulatory treatments.

Methods:

We developed a comprehensive flow cytometry platform measuring 38 immunologic cell types in the peripheral blood of 245 individuals in a routine clinical setting. These include patients with MS, untreated or receiving any of 4 current immunomodulatory treatments (interferon-β, glatiramer acetate, natalizumab, or fingolimod), patients with autoimmune thyroid disease, and healthy controls.

Results:

An increase in memory CD8⁺ T cells and B cells was observed in untreated patients with MS. Interferon-β and fingolimod induce significant changes upon multiple aspects of the peripheral immune system, with an unexpectedly prominent alteration of B cells. Overall, both treatments push the immune system in different directions, with only 2 significant effects shared across these treatments—an increase in transitional B cells and a decrease in class-switched B cells. We further identified heightened B cell-activating factor (BAFF) levels as regulating this shared B cell pathway.

Conclusions:

A systems immunology approach established different immunologic profiles induced by current immunomodulatory MS treatments, offering perspectives for personalized medicine. Pathways shared between the immunologic architecture of existing efficacious treatments identify targets for future treatment design.

Accumulation of reactivity to MBP sensitizes TRAIL mediated oligodendrocyte apoptosis in adult sub cortical white matter in a model for human multiple sclerosis

Reactivity to myelin associated proteins is the hallmark of human multiple sclerosis (M.S) and its experimental counterparts. However, the nature of such reactivity has not been described fully. Herein, we report that myelin basic protein (MBP) reactivity accumulates in a rat model for M.S. over a period of time and sensitizes TRAIL mediated progressive oligodendrocyte apoptosis. We used active immunization by Myelin Oligodendrocyte Glycoprotein (MOG, 50 μg) to study chronic remitting relapsing encephalomyelitis in rats. A time point analysis of the progressive disease revealed cumulative accumulation of anti myelin basic protein antibodies during the disease progression with minimal change in the anti-MOG antibodies. Increased reactivity to MBP was studied to sensitize TNF related apoptosis-inducing ligand (TRAIL) and other proinflammatory cytokines in a cumulative fashion leading to the Caspase dependent apoptosis of oligodendrocytes and myelin loss. In a rescue experiment, we could limit the demyelination and prevent disease progression by neutralizing the effector, TRAIL in an early stage of the disease. This is the first study to identify the accumulation of MBP antibodies in MOG induced EAE which possibly leads to TRAIL sensitized oligodendrocyte apoptosis in the white mater of EAE rats. This finding stresses on the need to study MBP antibody titers in M.S. patients and therefore might serve as an alternate marker for progressive demyelination.

From genetic associations to functional studies in multiple sclerosis

Genetic screens steadily reveal more loci that show robust associations to complex human diseases, including multiple sclerosis (MS). Although some of the identified genetic variants are easily interpreted into a biological function, most of the genetic associations are frequently challenging to interpret. Underlying these difficulties is the fact that chip-based assays typically detect single nucleotide polymorphisms (SNPs) representative of a stretch of DNA containing many genomic variants in linkage disequilibrium. Furthermore, a large proportion of the SNPs with strongest association to MS are located in regions of the DNA that do not directly code for proteins. Here we discuss challenges faced by MS researchers to follow up the large-scale genetic screens that have been published over the past years in search of functional consequences of the identified MS-associated SNPs. We discuss experimental design, tools and methods that may provide the much-needed biological insights in both disease etiology and disease manifestations.

Patient preferences for disease-modifying drugs in multiple sclerosis therapy: a choice-based conjoint analysis

OBJECTIVES

With an increasing number of disease-modifying treatments (DMTs) for multiple sclerosis (MS), patient preferences will gain importance in the decision-making process. We assessed patients' implicit preferences for oral versus parenteral DMTs and identified factors influencing patients' treatment preference.

METHODS

Patients with relapsing-remitting MS (n = 156) completed a questionnaire assessing treatment preferences, whereby they had to decide between pairs of hypothetical treatment scenarios. Based on this questionnaire a choice-based conjoint analysis was conducted.

RESULTS

Treatment frequency and route of administration showed a stronger influence on patient preference compared with frequency of mild side effects. The latter attribute was more important for treatment-naïve patients compared with DMT-experienced patients. The higher the Extended Disability Status Scale score, the more likely pills, and the less likely fewer side effects were preferred. Pills were preferred over injections by 93% of patients, when treatment frequency and frequency of side effects were held constant. However, preference switched to injections when pills had to be taken three times daily and injections only once per week. Injections were also preferred when pills were associated with frequent side effects.

CONCLUSIONS

Our results suggest that route of administration and treatment frequency play an important role in the patients' preference for a given DMT.

Can we switch microglia's phenotype to foster neuroprotection? Focus on multiple sclerosis

Microglia cells, the resident innate immune cells in the brain, are highly active, extending and retracting highly motile processes through which they continuously survey their microenvironment for 'danger signals' and interact dynamically with surrounding cells. Upon sensing changes in their central nervous system microenvironment, microglia become activated, undergoing morphological and functional changes. Microglia activation is not an 'all-or-none' process, but rather a continuum depending on encountered stimuli, which is expressed through a spectrum of molecular and functional phenotypes ranging from so-called 'classically activated', with a highly pro-inflammatory profile, to 'alternatively activated' associated with a beneficial, less inflammatory, neuroprotective profile. Microglia activation has been demonstrated in most neurological diseases of diverse aetiology and has been implicated as a contributor to neurodegeneration. The possibility to promote microglia's neuroprotective phenotype has therefore become a therapeutic goal. We have focused our discussion on the role of microglia in multiple sclerosis, a prototype of inflammatory, demyelinating, neurodegenerative disease, and on the effect of currently approved or on-trial anti-inflammatory therapeutic strategies that might mediate neuroprotection at least in part through their effect on microglia by modifying their behaviour via a switch of their functional phenotype from a detrimental to a protective one. In addition to pharmaceutical approaches, such as treatment with glatiramer acetate, interferon-β, fingolimod or dimethyl fumarate, we address the alternative therapeutic approach of treatment with mesenchymal stem cells and their potential role in neuroprotection through their 'calming' effect on microglia.

Disease-modifying therapy in multiple sclerosis and chronic inflammatory demyelinating polyradiculoneuropathy: common and divergent current and future strategies

Multiple sclerosis (MS) and chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) represent chronic, autoimmune demyelinating disorders of the central and peripheral nervous system. Although both disorders share some fundamental pathogenic elements, treatments do not provide uniform effects across both disorders. We aim at providing an overview of current and future disease-modifying strategies in these disorders to demonstrate communalities and distinctions. Intravenous immunoglobulins (IVIG) have demonstrated short- and long-term beneficial effects in CIDP but are not effective in MS. Dimethyl fumarate (BG-12), teriflunomide and laquinimod are orally administered immunomodulatory drugs that are already approved or likely to be approved in the near future for the basic therapy of patients with relapsing-remitting MS (RRMS) due to positive results in Phase III clinical trials. However, clinical trials with these drugs in CIDP have not (yet) been initiated. Natalizumab and fingolimod are approved for the treatment of RRMS, and trials to evaluate their safety and efficacy in CIDP are now planned. Alemtuzumab, ocrelizumab and daclizumab respresent monoclonal antibodies in advanced stages of clinical development for their use in RRMS patients. Attempts to study the safety and efficacy of alemtuzumab and B cell-depleting anti-CD20 antibodies, i.e. rituximab, ocrelizumab or ofatumumab, in CIDP patients are currently under way. We provide an overview of the mechanism of action and clinical data available on disease-modifying immunotherapy options for MS and CIDP. Enhanced understanding of the relative effects of therapies in these two disorders may aid rational treatment selection and the development of innovative treatment approaches in the future.

Fingolimod in the treatment algorithm of relapsing remitting multiple sclerosis: a statement of the Central and East European (CEE) MS Expert Group

Fingolimod is the first oral treatment of multiple sclerosis. It is the first-in-class sphingosine 1-phosphate receptor modulator that binds to sphingosine 1-phophate receptors on lymphocytes and via downregulation of the receptor prevents lymphocyte egress from lymphoid tissues into the circulation. This mechanism reduces the infiltration of potentially auto-aggressive lymphocytes into the central nervous system. Two large phase III studies with fingolimod have shown superior efficacy of the drug in two dosages compared to placebo and to weekly intramuscular injections of Interferon beta-1a. Among possible side effects of the drug is a transient bradycardia after the first dose of fingolimod including possible AV blockade and therefore monitoring of pulse rate and blood pressure for 6 h following the first application is needed. During treatment, attention has to be given to specific infections, elevated liver enzymes, and ophthalmologic changes. Recommendations on the use of fingolimod including safety aspects are given in this article.

Vitamin D and multiple sclerosis: review of a possible association

There has been growing interest in determining environmental risk factors that may play a role in the development or progression of multiple sclerosis (MS). Epidemiological evidence and data from human and animal studies have shown an association between low serum vitamin D levels and an increased incidence of MS and that supplementation with vitamin D may protect against MS development and/or disease relapses. The most appropriate vitamin D dosage for patients with MS is unclear, but investigator shave proposed that serum vitamin D concentrations between 75 and 100 nmol/L (30-40 ng/mL) are optimal to achieve favor able clinical outcomes. Vitamin D supplemented in doses up to 3000 International Units (IU) daily may be necessary to achieve these levels in many patients, and doses of 500 to 800 IU daily appear to be necessary to maintain desired serum vitamin D levels.Short-term supplementation with doses up to 40 000 IU daily has been found to be safe. However, larger and longer clinical studies are needed to assess whether a true relationship exists between serum vitamin D concentrations and MS and to determine a safe and effective amount of vitamin D supplementation.

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

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

Modulation of autoimmune demyelination by laquinimod via induction of brain-derived neurotrophic factor

Laquinimod is a promising, orally available compound that has been successfully evaluated in placebo-controlled phase II/III studies of relapsing-remitting multiple sclerosis (MS). Studies are ongoing to further define laquinimod's modulatory mechanisms. Analyses in the animal model of experimental autoimmune encephalomyelitis (EAE) demonstrate that laquinimod reduces infiltration of leukocytes into the central nervous system, induces a Th1 to Th2/3 shift, and suppresses Th17 responses. To evaluate the potential neuroprotective capacity of laquinimod via modulation of brain-derived neurotrophic factor (BDNF), we analyzed the expression of BDNF in blood samples from 203 MS patients treated with laquinimod. Furthermore, we investigated the effect of laquinimod in EAE using a conditional BDNF knockout strain lacking BDNF expression in myeloid cells and T cells (LLF mice). Treatment with laquinimod resulted in a significant and persistent increase in BDNF serum levels of MS patients when compared to baseline and placebo-treated patients. LLF mice treated with laquinimod display a more severe EAE disease course in comparison to wild-type mice. Furthermore, laquinimod-treated wild-type monocytes secreted an anti-inflammatory cytokine pattern in comparison to untreated wild-type monocytes and treated LLF monocytes. Adoptive transfer of laquinimod stimulated monocytes into mice with EAE ameliorated the disease course. Consistent with immunomodulatory properties, laquinimod skewed monocytes toward a regulatory phenotype and also acted via modulation of BDNF, which may contribute to neuroprotection in MS patients.

Long-term daclizumab therapy in relapsing-remitting multiple sclerosis

We performed a retrospective review of side effects and clinical outcomes in relapsing-remitting (RR) multiple sclerosis (MS) patients receiving long-term treatment with daclizumab. Twelve patients with RR MS were initially treated with daclizumab at 1 mg/kg IV, again 14 days later and then monthly treatments (average duration 42.1 months). Daclizumab dose (0.85 mg/kg to 1.5 mg/kg) was adjusted based on clinical response. Daclizumab was generally well tolerated. There was a significant reduction in relapse rate and improvement in Expanded Disability Status Scores (EDSSs) (p < 0.0001). Long-term treatment with daclizumab in RR MS patients has apparent benefit that will require formal confirmation.

Practical considerations on the use of rituximab in autoimmune neurological disorders

Rituximab (Mabthera, Rituxan) is a chimeric human/murine monoclonal antibody against CD-20 surface antigen expressed on B-cells. Rituximab, by causing B-cell depletion, appears to be effective in several autoimmune disorders; it has been approved for rheumatoid arthritis and is a promising new agent in the treatment of several autoimmune neurological disorders. A controlled study in patients with relapsing remitting multiple sclerosis has shown that rituximab significantly reduces the number of new MRI lesions and improves clinical outcome; it also showed some promise in a subset of patients with primary progressive MS. The drug is also effective in a number of patients with Devic's disease, myasthenia gravis, autoimmune neuropathies, and inflammatory myopathies. The apparent effectiveness of rituximab has moved B-cells into the center stage of clinical and laboratory investigation of autoimmune neurological disorders. We review the evidence-based effectiveness of rituximab in neurological disorders based on controlled trials and anecdotal reports, including our own experience, and address the immunobiology of B-cells in autoimmune central nervous system (CNS) and peripheral nervous system (PNS) disorders. In addition, we provide practical guidelines on how best to use this drug in clinical practice and highlight its potential toxicity.

Fumaric acid esters exert neuroprotective effects in neuroinflammation via activation of the Nrf2 antioxidant pathway

Inflammation and oxidative stress are thought to promote tissue damage in multiple sclerosis. Thus, novel therapeutics enhancing cellular resistance to free radicals could prove useful for multiple sclerosis treatment. BG00012 is an oral formulation of dimethylfumarate. In a phase II multiple sclerosis trial, BG00012 demonstrated beneficial effects on relapse rate and magnetic resonance imaging markers indicative of inflammation as well as axonal destruction. First we have studied effects of dimethylfumarate on the disease course, central nervous system, tissue integrity and the molecular mechanism of action in an animal model of chronic multiple sclerosis: myelin oligodendrocyte glycoprotein induced experimental autoimmune encephalomyelitis in C57BL/6 mice. In the chronic phase of experimental autoimmune encephalomyelitis, preventive or therapeutic application of dimethylfumarate ameliorated the disease course and improved preservation of myelin, axons and neurons. In vitro, the application of fumarates increased murine neuronal survival and protected human or rodent astrocytes against oxidative stress. Application of dimethylfumarate led to stabilization of the transcription factor nuclear factor (erythroid-derived 2)-related factor 2, activation of nuclear factor (erythroid-derived 2)-related factor 2-dependent transcriptional activity and accumulation of NADP(H) quinoline oxidoreductase-1 as a prototypical target gene. Furthermore, the immediate metabolite of dimethylfumarate, monomethylfumarate, leads to direct modification of the inhibitor of nuclear factor (erythroid-derived 2)-related factor 2, Kelch-like ECH-associated protein 1, at cysteine residue 151. In turn, increased levels of nuclear factor (erythroid-derived 2)-related factor 2 and reduced protein nitrosylation were detected in the central nervous sytem of dimethylfumarate-treated mice. Nuclear factor (erythroid-derived 2)-related factor 2 was also upregulated in the spinal cord of autopsy specimens from untreated patients with multiple sclerosis. In dimethylfumarate-treated mice suffering from experimental autoimmune encephalomyelitis, increased immunoreactivity for nuclear factor (erythroid-derived 2)-related factor 2 was detected by confocal microscopy in neurons of the motor cortex and the brainstem as well as in oligodendrocytes and astrocytes. In mice deficient for nuclear factor (erythroid-derived 2)-related factor 2 on the same genetic background, the dimethylfumarate mediated beneficial effects on clinical course, axon preservation and astrocyte activation were almost completely abolished thus proving the functional relevance of this transcription factor for the neuroprotective mechanism of action. We conclude that the ability of dimethylfumarate to activate nuclear factor (erythroid-derived 2)-related factor 2 may offer a novel cytoprotective modality that further augments the natural antioxidant responses in multiple sclerosis tissue and is not yet targeted by other multiple sclerosis therapies.

[Monoclonal antibodies in [corrected] development in [corrected] multiple sclerosis]

INTRODUCTION

The last fifteen years have see the gradual appearance of a number of different drugs that have been shown to be effective as disease modifying therapies in multiple sclerosis. The opening and subsequent widening of the therapeutic armamentarium in multiple sclerosis will continue on a expanding course in the next few years due to the already known positive results of phase III clinical trials with orally administered molecules. Along with these, we have also seen the appearance of a group of drugs which, instead of being defined by their route of administration, are considered together as a consequence of their similar design: the monoclonal antibodies.

CONTENTS AND METHODS

The principal safety and efficacy results of three of the monoclonal antibodies that have already obtained positive results in phase II studies will be reviewed in this paper: alemtuzumab, rituximab / ocrelizumab, and daclizumab. For the preparation of this paper, information was obtained from already published articles and from the following web pages: www.clinicaltrials.gov of the National Institute of Health of the U.S.A., the EMA (European Medicines Agency) web page and the Spanish Medicines Agency (Agencia Española del Medicamento) web page.

CONCLUSIONS

Final results from the phase III clinical trials in progress are required to produce definitive statements on the efficacy and safety of the reviewed drugs. However, and subject to confirmation of the presently available data from phase II trials, it is likely that this group of drugs is to be placed one step beyond the currently available disease-modifying therapies in terms of efficacy, but with a safety pattern which will make careful monitoring of treated patients a mandatory requirement so as to obtain adequate risk/benefit profiles.

A critical appraisal of treatment decisions in multiple sclerosis--old versus new

Interferon β and glatiramer acetate have been available for the treatment of multiple sclerosis (MS) for over a decade and their efficacy and safety are well established. These agents have detectable effects on the immune system, but have not been associated with a breakdown of immune surveillance. Novel MS therapies have been approved, or are awaiting approval, that differ from established immunotherapies with regard to their mechanisms of action, modes of administration, adverse-effect profiles and, possibly, the clinical and paraclinical benefits that they may provide for patients. Neurologists will soon be required to make complex treatment decisions with their patients on the basis of very limited clinical data and evidence. Under these circumstances, optimal assessment of risks and benefits will be challenging. In this Review, the anticipated benefits of novel therapies, including reduction in disease activity, possible prevention of disability, and improvement in quality of life, are outlined. In addition, the current acceptance of potential risks--including serious or even life-threatening adverse effects, the likelihood of which may rise with increased cumulative exposure to a particular agent--by patients with MS will be reviewed.

Monoclonal antibody therapy in multiple sclerosis: Paradigm shifts and emerging challenges

Therapeutic approaches to multiple sclerosis (MS) are based on altering the functions of the immune system, either by using broad immunosuppressive drugs used for transplantation rejection and rheumatology, or by modulating them more discreetly with beta interferon and synthetic amino-acid copolymers. These strategies are only partially successful, have important safety and tolerability limitations, and have shown to be mostly effective in earlier stages of the disease, in which acute relapses dominate the clinical picture. For progressive phenotypes of MS there are currently no effective therapeutic options. As very specific and potent immunosuppressive agents, monoclonal antibodies (mAbs) may offer considerable advantages over other therapies for MS. During the last decade, anti-a4 integrin natalizumab became the first approved mAb for treatment of relapsing MS, after convincingly demonstrating clinically significant effects on two large Phase 3 trials. Moreover, the concept of disease remission was introduced for the first time, to describe patients that show no signs of clinical or imaging markers of disease activity during therapy with natalizumab. Of the mAbs under development for MS, alemtuzumab and rituximab have also shown promising evidence of effectiveness, and potentially expanded the therapeutic horizon to reversal of disease progression in early relapsing patients, and progressive patients who previously had not been studied. However, the appearance of progressive multifocal leukoencephalopathy (PML) in natalizumab-treated MS patients, as well as in patients with lymphoma, lupus and rheumatoid arthritis treated with rituximab, and autoimmune-type complications in alemtuzumab-treated MS patients underlines the fact that extended efficacy comes with significant clinical risks. The challenge is then how best to utilize therapies that have evidently superior efficacy in a chronic disease of young adults, to obtain the best benefit-risk ratio, and how to monitor and prevent emergent safety concerns.

Complementary roles of retinoic acid and TGF-β1 in coordinated expression of mucosal integrins by T cells

α(4) and β(7) integrins, such as α(4)β(1), α(4)β(7), and α(E)β(7), are major integrins required for migration of leukocytes into mucosal tissues. The mechanisms responsible for coordinated expression of these three integrins have been poorly elucidated to date. We report that expression of the Itg-α(4) subunit by both CD4(+) and CD8(+) T cells requires the retinoic acid signal. In contrast, transcription of Itg-α(E) genes is induced by the transforming growth factor-β1 (TGFβ1) signal. Expression of Itg-β(7) is constitutive but can be further increased by TGFβ1. Consistently, expression of α(4)-containing integrins is severely suppressed in vitamin A deficiency with a compensatory increase of α(E)β(7), whereas expression of Itg-α(E) and Itg-β(7) is decreased in TGFβ-signal deficiency with a compensatory increase in α(4)β(1). The retinoic acid-mediated regulation of α(4) integrins is required for specific migration of T cells in vitro and in vivo. These results provide central regulatory mechanisms for coordinated expression of the major mucosal integrins.

Oral therapies for multiple sclerosis: a review of agents in phase III development or recently approved

Several disease-modifying therapies are approved for the management of multiple sclerosis (MS). While reasonably effective, these therapies require long-term parenteral self-injection, which is inconvenient for some patients and can be associated with injection-related adverse effects. Consequently, there is a need in MS for an oral therapy option. Currently, five oral therapies are in phase III development or have recently been approved for the treatment of relapsing-remitting MS: cladribine (approved in Russia and Australia), fingolimod (approved in the US and Russia), BG-12 (phase III), laquinimod (phase III) and teriflunomide (phase III). While the availability of oral therapies has been much anticipated by physicians and patients, neurologists will need to be cautious in selecting such therapy, which may appear to have efficacy and convenience advantages versus current therapies, but may also carry novel safety and tolerability concerns. The decision to use these new therapies will most likely be based on an overall assessment of efficacy, safety, tolerability and adherence, the potential need for monitoring and cost effectiveness. The objective of this article is to review the currently available data for each of these new oral therapies, which addresses the mechanism of action, efficacy and safety, and to provide a perspective on the potential future role of these therapies within clinical practice. Although better patient compliance is expected with the oral agents compared with the injectables, the safety profiles of these new oral drugs will have to be watched carefully.

New approaches in the management of multiple sclerosis

Multiple sclerosis (MS) is a central nervous system chronic inflammatory disease that is characterized by an extensive and complex immune response. Scientific advances have occurred in immunology, pathophysiology, and diagnostic and clinical assessment tools, and recent discovery of unique therapeutic targets has spurred numerous Phase II and Phase III clinical trials. Reductions in MS relapse rates and improvements in T₂ or gadolinium-enhancing lesion burdens have been reported from Phase III trials that include fingolimod, alemtuzumab, cladribine, and rituximab. Promising Phase II trial data exist for teriflunomide, daclizumab, laquinimod, and fumarate. The optimism created by these favorable findings must be tempered with evaluation of the adverse effect profile produced by these new agents. Given the discovery of progressive multifocal leukoencephalopathy with the use of natalizumab, ongoing vigilance for rare and life-threatening reactions due to new agents should be paramount. Patients with MS often experience difficulty with ambulation, spasticity, and cognition. Recent clinical trial data from two Phase III dalfampridine-SR trials indicate certain patients receive benefits in ambulation. This article provides an overview of data from clinical trials of newer agents of potential benefit in MS.

Animal models of multiple sclerosis--potentials and limitations

Experimental autoimmune encephalomyelitis (EAE) is still the most widely accepted animal model of multiple sclerosis (MS). Different types of EAE have been developed in order to investigate pathogenetic, clinical and therapeutic aspects of the heterogenic human disease. Generally, investigations in EAE are more suitable for the analysis of immunogenetic elements (major histocompatibility complex restriction and candidate risk genes) and for the study of histopathological features (inflammation, demyelination and degeneration) of the disease than for screening of new treatments. Recent studies in new EAE models, especially in transgenic ones, have in connection with new analytical techniques such as microarray assays provided a deeper insight into the pathogenic cellular and molecular mechanisms of EAE and potentially of MS. For example, it was possible to better delineate the role of soluble pro-inflammatory (tumor necrosis factor-α, interferon-γ and interleukins 1, 12 and 23), anti-inflammatory (transforming growth factor-β and interleukins 4, 10, 27 and 35) and neurotrophic factors (ciliary neurotrophic factor and brain-derived neurotrophic factor). Also, the regulatory and effector functions of distinct immune cell subpopulations such as CD4+ Th1, Th2, Th3 and Th17 cells, CD4+FoxP3+ Treg cells, CD8+ Tc1 and Tc2, B cells and γδ+ T cells have been disclosed in more detail. The new insights may help to identify novel targets for the treatment of MS. However, translation of the experimental results into the clinical practice requires prudence and great caution.

Emerging oral treatments in multiple sclerosis - clinical utility of cladribine tablets

Multiple sclerosis (MS) is a chronic inflammatory disorder of the central nervous system (CNS) that represents one of the first causes of neurological disability in young adults. Although the pathogenesis of MS is still unclear, an autoimmune mechanism has been demonstrated. According to this evidence in the last 15 years different treatments acting on the immune system have been developed. Current disease-modifying drugs (DMDs) for MS require regular and frequent parenteral administration and are associated with limited long-term treatment adherence. Moreover the clinical efficacy of these disease-modifying drugs is suboptimal. Thus, there is an important need for the development of new therapeutic strategies. Several oral therapies (fingolimod, fumaric acid, teriflunomide, laquinimod) are in development; Among these cladribine is the only therapy with the potential for short-course dosing. Cladribine is an immunosuppressant that offers sustained regulation of the immune system through a preferential lymphocyte depleting action. Cladribine has a well-characterized and well-known safety profile, derived from more than 15 years of use of the parenteral formulation both in the oncology field and in MS. This paper reviews the new oral emerging treatments and presents the available data about the use of cladribine in MS and the future perspective of its clinical use.

Molecular regulation of JC virus tropism: insights into potential therapeutic targets for progressive multifocal leukoencephalopathy

Progressive multifocal leukoencephalopathy (PML) is a growing concern for patients undergoing immune modulatory therapies for treatment of autoimmune diseases such as multiple sclerosis. Currently, there are no drugs approved for the treatment of PML that have been demonstrated in the patient to effectively and reproducibly alter the course of disease progression. The human polyoma virus JC is the causative agent of PML. JC virus (JCV) dissemination is tightly controlled by regulation of viral gene expression from the promoter by cellular transcription factors expressed in cells permissive for infection. JCV infection likely occurs during childhood, and latent virus containing PML-associated promoter sequences is maintained in lymphoid cells within the bone marrow. Because development of PML is tightly linked to suppression and or modulation of the immune system as in development of hematological malignancies, AIDS, and monoclonal antibody treatments, further scrutiny of the course of JCV infection in immune cells will be essential to our understanding of development of PML and identification of new therapeutic targets.

A GMCSF-neuroantigen fusion protein is a potent tolerogen in experimental autoimmune encephalomyelitis (EAE) that is associated with efficient targeting of neuroantigen to APC

Cytokine-NAg fusion proteins represent an emerging platform for specific targeting of self-antigen to particular APC subsets as a means to achieve antigen-specific immunological tolerance. This study focused on cytokine-NAg fusion proteins that targeted NAg to myeloid APC. Fusion proteins contained GM-CSF or the soluble extracellular domain of M-CSF as the N-terminal domain and the encephalitogenic 69-87 peptide of MBP as the C-terminal domain. GMCSF-NAg and MCSF-NAg fusion proteins were approximately 1000-fold and 32-fold more potent than NAg in stimulating antigenic proliferation of MBP-specific T cells, respectively. The potentiated antigenic responses required cytokine-NAg covalent linkage and receptor-mediated uptake. That is, the respective cytokines did not potentiate antigenic responses when cytokine and NAg were added as separate molecules, and the potentiated responses were inhibited specifically by the respective free cytokine. Cytokine-dependent targeting of NAg was specific for particular subsets of APC. GMCSF-NAg and MCSF-NAg targeted NAg to DC and macrophages; conversely, IL4-NAg and IL2-NAg fusion proteins, respectively, induced an 1000-fold enhancement in NAg reactivity in the presence of B cell and T cell APC. GMCSF-NAg significantly attenuated severity of EAE when treatment was completed before encephalitogenic challenge or alternatively, when treatment was initiated after onset of EAE. MCSF-NAg also had significant tolerogenic activity, but GMCSF-NAg was substantially more efficacious as a tolerogen. Covalent GMCSF-NAg linkage was required for prevention and treatment of EAE. In conclusion, GMCSF-NAg was highly effective for targeting NAg to myeloid APC and was a potent, antigen-specific tolerogen in EAE.

Kv1.3 potassium channels as a therapeutic target in multiple sclerosis

We discuss the potential use of inhibitors of Kv1.3 potassium channels in T lymphocytes as therapeutics for multiple sclerosis. Current treatment strategies target the immune system in a non-selective manner. The resulting general immunosuppression, toxic side-effects and increased risk of opportunistic infections create the need for more selective therapeutics. Autoreactive effector-memory T (T(EM)) cells, considered to be major mediators of autoimmunity, express large numbers of Kv1.3 channels. Selective blockers of Kv1.3 inhibit calcium signaling, cytokine production and proliferation of T(EM) cells in vitro, and T(EM) cell-motility in vivo. Kv1.3 blockers ameliorate disease in animal models of multiple sclerosis, rheumatoid arthritis, type 1 diabetes mellitus and contact dermatitis without compromising the protective immune response to acute infections. Kv1.3 blockers have a good safety profile in rodents and primates.

Immunotherapy of multiple sclerosis

Multiple sclerosis (MS) is regarded as a prototypic inflammatory autoimmune central nervous system disorder causing neurological disability in young adults. Recommended basic immunomodulatory therapies of MS are currently interferon beta and glatiramer acetate. Both have proven to be clinically and paraclinically effective and clinical evidence suggests that treatment should be initiated as early as possible. However, despite the fact that therapeutic options for MS have significantly been widened over the past decade there is still tremendous activity in the search for new treatment options for MS. One important development in the field is reflected by the substantial number of promising results for oral therapies. 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 oral therapies for MS further broaden our armament for MS therapy.

Animal models of multiple sclerosis for the development and validation of novel therapies - potential and limitations

Various types of experimental autoimmune encephalomyelitis (EAE) reflect some of the pathogenetic, clinical, and therapeutic features of the different forms of multiple sclerosis (MS), thereby, providing some, albeit limited, insight into the molecular and cellular basis of the human disease. Specific questions of MS therapy including the search for new therapeutic targets and strategies and their validation require investigations in different available EAE models. A survey is given of experimental therapeutic approaches that are currently under study with the most promising examples of monoclonal antibodies, gene therapy, stem cell transplantation and orally applied small molecular weight disease-modifying drugs. Reasons for therapy failure and adverse side-effects of some experimental trials are discussed. Precaution is advised, if results of new experimental approaches are translated into clinical practice.