Suppression of experimental allergic encephalomyelitis by a synthetic polypeptide

Assessing cost-effectiveness in the management of multiple sclerosis

Multiple sclerosis (MS) is one of the most common causes of neurological disability in young and middle-aged adults, with current prevalence rates estimated to be 30 per 100,000 populations. Women are approximately twice as susceptible as males, but males are more likely to have progressive disease. The onset of the disease normally occurs between 20 and 40 years of age, with a peak incidence during the late twenties and early thirties, resulting in many years of disability for a large proportion of patients, many of whom require wheelchairs and some nursing home or hospital care. The aim of this study is to update a previous review which considered the cost-effectiveness of disease-modifying drugs (DMDs), such as interferons and glatiramer acetate, with more up to date therapies, such as mitaxantrone hydrochloride and natalizumab in the treatment of MS. The development and availability of new agents has been accompanied by an increased optimism that treatment regimens for MS would be more effective; that the number, severity and duration of relapses would diminish; that disease progression would be delayed; and that disability accumulation would be reduced. However, doubts have been expressed about the effectiveness of these treatments, which has only served to compound the problems associated with endeavors to estimate the relative cost-effectiveness of such interventions.

Cannabinoids and experimental models of multiple sclerosis

The inflammatory response is a hallmark in the development of autoimmune-mediated neurodegenerative diseases of the central nervous system (CNS). Research on these pathological phenomena is being extensively undertaken and experimental autoimmune encephalomyelitis (EAE) serves as a valuable animal model. Studies from this model have generated interesting insights into biological effects of cannabinoids and may, at least to a certain extent, reflect the cannabinoid-mediated protective mechanisms also in human diseases with similar characteristics, such as multiple sclerosis (MS). Cannabinoids are involved in regulation of the immune system. These effects comprise modulation of inflammatory reaction through components of the innate and adaptive immune responses. Cannabinoids also confer neuroprotection and assist neuroregeneration, thus maintaining a balance within the delicate CNS microenvironment and restoring function following pathological condition, commonly driven by neuroinflammation. Continued studies of cannabinoid actions in EAE pathogenesis should be beneficial for the better understanding of the mechanisms governing such a vast array of physiological effects and in development of new therapeutic strategies for the treatment of human neuroinflammatory and neurodegenerative diseases.

Antigen-Specific Therapies in Multiple Sclerosis

During recent years, many new therapies for human autoimmune diseases such as multiple sclerosis (MS) have been considered based on promising in vitro data or animal experiments. A number of them have proceeded to early clinical testing. However, very few finally advanced to approval by the regulatory agencies and are currently available to patients. The main reasons for failure were either lack of efficacy in humans and/or unexpected and untolerable adverse events. Although previous attempts toward antigen-specific immunomodulation have often been disappointing, these difficulties have led to renewed interest in therapies that aim at reestablishing tolerance to autoantigens at the level of either T cell-mediated or antibody-mediated immune responses or both. Such antigen-specific immunotherapies offer the prospect of correcting pathological immune reactivity against autoantigens in a highly specific and effective manner and also achievement of this goal with relatively little side effects. Here we will review the various approaches that are currently being considered for antigen-specific immunotherapies in MS.

Back to the future for multiple sclerosis therapy: focus on current and emerging disease-modifying therapeutic strategies

The last decade has seen numerous advances in the treatment of multiple sclerosis with six immunotherapeutic agents licensed for use. Although these therapeutic agents have powerful effects upon the inflammatory phase of disease, they have limitations in treating the progression of disability and in their safety profile. This review focuses on our current understanding of first- and second-line treatments for multiple sclerosis, including combination therapies, and also discusses the most promising novel therapeutic strategies on the horizon. Such agents include orally administered immunosuppressive drugs, monoclonal antibodies, antigen-specific tolerance, and neural protection and repair strategies. The challenge ahead lies in the delivery of potent drugs to inhibit inflammation and neurodegeneration while limiting side effects. Further elucidation of the pathophysiology of disease may provide new clinical targets and disease-relevant biomarkers that, in combination with proteomics, may help personalize treatment to individual patients.

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.

Disease-modifying agents for multiple sclerosis: recent advances and future prospects

Multiple sclerosis (MS) is a chronic autoimmune disease of the CNS. Currently, six medications are approved for immunmodulatory and immunosuppressive treatment of the relapsing disease course and secondary-progressive MS. In the first part of this review, the pathogenesis of MS and its current treatment options are discussed. During the last decade, our understanding of autoimmunity and the pathogenesis of MS has advanced substantially. This has led to the development of a number of compounds, several of which are currently undergoing clinical testing in phase II and III studies. While current treatment options are only available for parenteral administration, several oral compounds are now in clinical trials, including the immunosuppressive agents cladribine and laquinimod. A novel mode of action has been described for fingolimod, another orally available agent, which inhibits egress of activated lymphocytes from draining lymph nodes. Dimethylfumarate exhibits immunomodulatory as well as immunosuppressive activity when given orally. All of these compounds have successfully shown efficacy, at least in regards to the surrogate marker contrast-enhancing lesions on magnetic resonance imaging. Another class of agents that is highlighted in this review are biological agents, namely monoclonal antibodies (mAb) and recombinant fusion proteins. The humanized mAb daclizumab inhibits T-lymphocyte activation via blockade of the interleukin-2 receptor. Alemtuzumab and rituximab deplete leukocytes and B cells, respectively; the fusion protein atacicept inhibits specific B-cell growth factors resulting in reductions in B-cells and plasma cells. These compounds are currently being tested in phase II and III studies in patients with relapsing MS. The concept of neuro-protection and -regeneration has not advanced to a level where specific compounds have entered clinical testing. However, several agents approved for conditions other than MS are highlighted. Finally, with the advent of these highly potent novel therapies, rare, but potentially serious adverse effects have been noted, namely infections and malignancies. These are critically reviewed and put into perspective.

Glatiramer acetate reduces the risk for experimental cerebral malaria: a pilot study

Background

Cerebral malaria (CM) is associated with high mortality and morbidity caused by a high rate of transient or persistent neurological sequelae. Studies on immunomodulatory and neuroprotective drugs as ancillary treatment in murine CM indicate promising potential. The current study was conducted to evaluate the efficacy of glatiramer acetate (GA), an immunomodulatory drug approved for the treatment of relapsing remitting multiple sclerosis, in preventing the death of C57Bl/6J mice infected with Plasmodium berghei ANKA.

Methods and Results

GA treatment led to a statistically significant lower risk for developing CM (57.7% versus 84.6%) in treated animals. The drug had no effect on the course of parasitaemia. The mechanism of action seems to be an immunomodulatory effect since lower IFN-gamma levels were observed in treated animals in the early course of the disease (day 4 post-infection) which also led to a lower number of brain sequestered leukocytes in treated animals. No direct neuro-protective effect such as an inhibition of apoptosis or reduction of micro-bleedings in the brain was found.

Conclusion

These findings support the important role of the host immune response in the pathophysiology of murine CM and might lead to the development of new adjunctive treatment strategies.

A review of disease-modifying therapies for MS: maximizing adherence and minimizing adverse events

BACKGROUND

In a chronic disabling disorder such as multiple sclerosis (MS), adherence to treatment is of critical importance in maximizing benefits of therapy over the long term. Adverse events (AEs) are often cited by patients who discontinue therapy.

METHODS

Databases including Medline, CINAHL, and International Pharmaceutical Abstracts were searched for literature pertaining to adherence and AEs in MS published between January 1970 and August 2008. Clinical studies and case reports of AEs were included, as were papers that outlined factors that influence adherence. An advisory board with extensive experience in managing patients with MS developed guidelines to assist healthcare providers in maximizing adherence to disease-modifying therapy.

DISCUSSION

Internally based factors such as self-image, and externally based factors such as AEs, may influence patients' willingness and ability to adhere to therapy. Management of AEs associated with disease-modifying therapies and other therapies is reviewed, including intramuscular and subcutaneous interferon beta (IFNbeta)-1a, IFNbeta-1b, glatiramer acetate, natalizumab, methylprednisolone, mitoxantrone, cyclophosphamide, methotrexate, azathioprine, and intravenous immunoglobulin.

CONCLUSIONS

Effective management of MS is an ongoing, dynamic process that can enhance patients' adherence to therapy. Healthcare practitioners may address factors influencing adherence among patients with MS by managing treatment expectations, maintaining good communication with the patient, and managing AEs of treatment. Although the guidelines proposed herein originate from a single advisory board, it seems clear that by addressing patient concerns, healthcare practitioners can work with patients to enhance their ability to continue to adhere to their therapies and thereby gain the benefits of their treatment over the long term.

Exacerbation of autoimmune arthritis by copolymer-I through promoting type 1 immune response and autoantibody production

Copolymer-I (COP-I) is an unique immune regulatory polymer that has been shown to suppress experimental autoimmune encephalomyelitis (EAE) and is a treatment option for multiple sclerosis (MS). To investigate whether its immune suppressive effects can be extended to other autoimmune diseases, we treated mice with COP-I during the induction of collagen-induced arthritis (CIA). Our results show that COP-I treatment exacerbated CIA, leading to faster onset, more severe and longer-lasting disease. The mechanisms underlying the exacerbation of CIA by COP-I treatment include enhanced activation and inflammatory cytokine production by autoreactive T cells and elevated production of autoreactive antibodies. In addition, germinal center response was significantly enhanced by COP-I treatment. Thus, great caution should be taken when COP-I is to be used in MS patients with other autoimmune complications or its potential therapeutic effects are to be extended beyond autoimmune demyelinating diseases.

Glatiramer acetate: evidence for a dual mechanism of action

Glatiramer acetate is a disease-modifying drug approved for the treatment of relapsing-remitting multiple sclerosis. Since its discovery almost four decades ago, and in particular since the observation of its beneficial clinical effects in the late 1980s and early 1990s, numerous data have been generated and contribute pieces of a puzzle to help explain the mechanism of action of glatiramer acetate. Two major themes have emerged, namely (i) the induction of glatiramer acetate-reactive TH2 immunoregulatory cells, and (ii) the stimulation of neurotrophin secretion in the central nervous system that may promote neuronal repair.

Amino acid copolymer-specific IL-10-secreting regulatory T cells that ameliorate autoimmune diseases in mice

IL-10-secreting regulatory T cell lines specific to glatiramer acetate [poly(Y,E,A,K)n] or poly(Y,F,A,K)n have been established from the enlarged spleen and lymph nodes that result from copolymer treatment of SJL mice in which experimental autoimmune encephalomyelitis was induced by PLP139-151. These CD4+CD25+T cell lines secrete high levels of IL-10 and IL-13 but only small amounts of IL-4 and virtually no TGF-beta, IL-17, IL-6, IFN-gamma, or TNF-alpha. Their phenotypes are particularly characterized by the absence of Foxp3 and the presence of two TNFR family members, CD30 and GITR. The lines proliferated specifically to the immunizing copolymers but were autoantigen-nonspecific, in that the same T cell line could suppress autoimmunity induced by three different autoantigens in SJL mice, i.e., PLP139-151(EAE), MBP85-99 (EAE), and bovine peripheral nerve myelin (experimental autoimmune neuritis), indicating they function by bystander suppression.

The origin and application of experimental autoimmune encephalomyelitis

Experimental autoimmune encephalomyelitis (EAE) is a model of the neuroimmune system responding to priming with central nervous system (CNS)-restricted antigens. It is an excellent model of post-vaccinal encephalitis and a useful model of many aspects of multiple sclerosis. EAE has been established in numerous species and is induced by priming with a large number of CNS-derived antigens. As a consequence, the pathogenesis, pathology and clinical signs vary significantly between experimental protocols. As I describe in this Timeline article, the reductionist approach taken in some lines of investigation of EAE resulted in a reliance on results obtained under a narrow range of conditions. Although such studies made important contributions to our molecular understanding of inflammation, T-cell activation, and MHC restriction, they did not advance as effectively our knowledge of the polyantigenic responses that usually occur in CNS immunopathology and autoimmunity.

Mechanism of action of glatiramer acetate in treatment of multiple sclerosis

Glatiramer acetate (GA) (Copolymer-1, Copaxone, Teva, Israel, YEAK) is a polypeptide-based therapy approved for the treatment of relapsing-remitting multiple sclerosis. Most investigations have attributed the immunomodulatory effect of GAs to its capability to alter T-cell differentiation. Specifically, GA treatment is believed to promote development of Th2-polarized GA-reactive CD4(+) T-cells, which may dampen neighboring inflammation within the central nervous system. Recent reports indicate that the deficiency in CD4(+)CD25(+)FoxP3(+) regulatory T-cells in multiple sclerosis is restored by GA treatment. GA also exerts immunomodulatory activity on antigen presenting cells, which participate in innate immune responses. These new findings represent a plausible explanation for GA-mediated T-cell immune modulation and may provide useful insight for the development of new and more effective treatment options for multiple sclerosis.

Glatiramer acetate in multiple sclerosis: a review

Multiple sclerosis (MS) is considered to be primarily an inflammatory autoimmune disease. Over the last 5 years, our view of the pathogenesis of MS has evolved considerably. The axonal damage was recognized as an early event in the disease process and as an important determinant of long-term disability. Therefore, the antiinflammatory and neuroprotective strategies are thought to represent promising approach to the therapy of MS. The therapeutic potential of glatiramer acetate (GA), a synthetic amino acid polymer composed of a mixture of L-glutamic acid, L-lysine, L-alanine, and L-tyrosine in defined proportions, in MS has been apparent for many years. GA has been shown to be effective in preventing and suppressing experimental allergic encephalomyelitis (EAE), the animal model of MS. GA has been, therefore, evaluated in several clinical studies and found to alter the natural history of relapsing-remitting (RR)MS by reducing the relapse rate and affecting disability. These findings were confirmed in open-label follow-up trials covering more than 10 years of treatment. The trials demonstrated sustained efficacy for GA in slowing the progression of disability. The clinical therapeutic effect of GA is consistent with the results of magnetic resonance imaging (MRI) findings from various clinical centers. At a daily standard dose of 20 mg, s.c., GA was generally well tolerated. The induction of GA-reactive T-helper 2-like regulatory suppressor cells is thought to be the main mechanism of the therapeutic action of this drug. In addition, it was recently shown that GA-reactive T cells produce neurotrophic factors (e.g., brain-derived neurotrophic factor [BDNF]) that protect neurons and axons in the area of injury.

Copaxone interferes with the PrP Sc-GAG interaction

The hallmark of prion disease-induced neurodegeneration is the accumulation of PrP(Sc), a misfolded form of PrP(C). In addition, several lines of evidence indicate a role for the immune system and, in particular, inflammation in prion disease pathogenesis. In this work, we tested whether Copaxone, an immunomodulatory agent currently used for the treatment of multiple sclerosis, can affect prion disease manifestation in scrapie-infected hamsters. We show here that Copaxone exerted no effect on prion disease incubation time when treatment commenced 2 weeks after i.p. prion infection. However, when Copaxone was mixed with the initial prion inoculum or administered to hamsters weekly starting on the day of infection, prion disease incubation time was prolonged by 30 days. This suggests that Copaxone may affect the initial infection process. In vitro experiments indicate that Copaxone significantly reduced PrP(Sc) binding to both Chinese hamster ovary (CHO) cells and heparin beads and also binds to heparin by itself. Interestingly, Copaxone also abolished PrP(Sc) accumulation in scrapie-infected cells. We propose that Copaxone delays prion infection by competing with the PrP(Sc)-glycosaminoglycans interaction. Whether the immunomodulating activity of Copaxone is related to its heparin binding and anti-prion properties remains to be established.

Copolymer-1 (Cop-1) improves neurological recovery after middle cerebral artery occlusion in rats

The damage in ischemic stroke is caused by two events: (i) the ischemic phenomenon by itself; (ii) the self-destructive mechanisms developed as a consequence of ischemia. The inflammatory response is one of these destructive phenomena that accompanies and exacerbates the developing injury. Since it has been suggested that immune cells participate in neuroprotective and restorative processes, modulation rather than elimination of this inflammatory response could be a strategy to improve the neurological outcome. The immune modulator copolymer-1 (Cop-1), a synthetic basic random copolymer of amino acids, is a potent inducer of Th2 regulatory cells which, aside from exerting modulatory actions, is capable of releasing neurotrophic factors. There is evidence that Cop-1-specific T cells exert neuroprotective and even restorative effects in diverse neurodegenerative diseases. In order to test the ability of Cop-1 to prevent ischemic injury in a model of transient middle cerebral artery (MCA) occlusion, two groups of rats were treated either with Cop-1 or with saline solution (SS). Seven days after occlusion, Cop-1 treated rats presented a significant improvement in neurological function compared to SS-treated animals (1.2+/-0.4 and 2.8+/-0.5 mean+/-S.D., respectively; p=0.008). Histological findings showed that the percentage of infarct volume was smaller in Cop-1 treated rats (4.8+/-1.5), in comparison with those receiving SS (32.2+/-8.6; p=0.004). Cop-1 constitutes a promising therapy for stroke; thereby, the enforcement of further experimental investigation is encouraged in order to be able to formulate the best strategy.

Glatiramer acetate: mechanisms of action in multiple sclerosis

Glatiramer acetate (GA) is a mixture of synthetic polypeptides composed of four amino acids resembling myelin basic protein (MBP). GA has been shown to be effective in preventing and suppressing experimental autoimmune encephalomyelitis (EAE), the animal model of multiple sclerosis. It was tested in several clinical studies and approved for the immunomodulatory treatment of relapsing-type MS in 1996. Glatiramer acetate demonstrates a strong promiscuous binding to major histocompatibility complex molecules and inhibits the T cell response to several myelin antigens. In addition, it was shown to act as a T cell receptor antagonist for the 82-100 MBP epitope. Glatiramer acetate treatment causes in vivo changes of the frequency, cytokine secretion pattern and effector function of GA-specific T cells. It was shown to induce GA-specific regulatory CD4(+) and CD8(+) T cells and a TH1-TH2 shift with consecutively increased secretion of antiinflammatory cytokines. GA-specific TH2 cells are able to migrate across the blood-brain barrier and cause in situ bystander suppression of autoaggressive TH1 T cells. In addition glatiramer acetate was demonstrated to influence antigen presenting cells (APC) such as monocytes and dendritic cells. Furthermore secretion of neurotrophic factors with potential neuroprotective effects was shown.

Glatiramer Acetate: Mechanisms of Action in Multiple Sclerosis

Glatiramer acetate (GA), formerly known as copolymer 1, is a mixture of synthetic polypeptides composed of four amino acids resembling the myelin basic protein (MSP). GA has been shown to be highly effective in preventing and suppressing experimental autoimmune encephalomyelitis (EAE), the animal model of multiple sclerosis (MS). Therefore, it was tested in several clinical studies and so approved for the immunomodulatory treatment of relapsing-type MS. In contrast to other immunomodulatory MS therapies, GA has a distinct mechanism of action: GA demonstrates an initial strong promiscuous binding to major histocompatibility complex molecules and consequent competition with various (myelin) antigens for their presentation to T cells. In addition, antigen-based therapy generating a GA-specific immune response seems to be the prerequisite for GA therapy. GA treatment induces an in vivo change of the frequency, cytokine secretion pattern and the effector function of GA-specific CD4+ and CD8+ T cells, probably by affecting the properties of antigen-presenting cells such as monocytes and dendritic cells. As demonstrated extensively in animal experiments, GA-specific, mostly, T helper 2 cells migrate to the brain and lead to in situ bystander suppression of the inflammatory process in the brain. Furthermore, GA-specific cells in the brain express neurotrophic factors like the brain-derived neurotrophic factor (BDNF) in addition to anti-inflammatory T helper 2-like cytokines. This might help tip the balance in favor of more beneficial influences because there is a complex interplay between detrimental and beneficial factors and mediators in the inflammatory milieu of MS lesions.

Glatiramer acetate therapy for multiple sclerosis: a review

The past decade has witnessed a revolution in the treatment of multiple sclerosis (MS), the most common demyelinating disorder of the human CNS. After being considered as an untreatable disease for more than a century, six disease-modifying treatments have been approved between 1993 and 2006. Glatiramer acetate (GA) is a worldwide drug approved for the treatment of relapsing-remitting MS in 1996. The drug is a synthetic copolymer of four amino acids based on the composition of myelin basic protein, one of several putative autoantigens implicated in the pathogenesis of MS. Three separate double-blind, placebo-controlled trials have established its efficacy in relapsing-remitting MS. Observations from an ongoing study, the longest prospective study in MS therapeutics so far, suggest that the effect of GA in reducing the relapse rate and neurological disability is maintained over a 10-year period. Independent investigators have identified several putative immunological mechanisms of action of GA, with the unique observation of the generation of GA-reactive T-helper 2 (anti-inflammatory) polarised lymphocytes within days to weeks of initiating therapy and sustaining an anti-inflammatory milieu for years in the peripheral immune system and, presumably, in the CNS. Emerging data from immunological and imaging studies quantifying axonal injury in the brain point towards neuroprotective abilities of GA. Combined with its remarkable safety and tolerability, long-term efficacy and neuroprotective effect, GA presents it self as a first-line choice in relapsing-remitting MS, and holds immense promise in developing its potential as a combination therapy in MS, as well as extending its indications to other neurodegenerative diseases.

Glatiramer acetate (GA) therapy induces a focused, oligoclonal CD8+ T-cell repertoire in multiple sclerosis

We have demonstrated that GA therapy induces a differential upregulation of GA-specific, cytotoxic/suppressor CD8+ T-cell responses in MS patients. We utilized a novel combination of flow sorting and anchored PCR to analyze the evolving clonal composition of GA-specific CD4+ and CD8+ T-cells. TCRbeta chain analysis revealed the development of an oligoclonal GA-specific CD8+ repertoire with persistence of dominant clones over long periods. Interestingly, some sequences resembled published oligoclonal CD8+ TCR sequences from MS lesions. In contrast, GA-specific CD4+ responses were polyclonal and showed continual evolution of their repertoire. This clonotypic and functional analysis provides mechanistic insights into GA therapy.

How to successfully apply animal studies in experimental allergic encephalomyelitis to research on multiple sclerosis

In their Point of View entitled "Experimental Allergic Encephalomyelitis: A Misleading Model of Multiple Sclerosis," Sriram and Steiner(1) wrote, "The most disappointing aspect of EAE [experimental allergic encephalomyelitis] as a potential model for MS is its almost total inability to point toward a meaningful therapy or therapeutic approach for MS." Actually, EAE has led directly to the development of three therapies approved for use in multiple sclerosis (MS): glatiramer acetate, mitoxantrone, and natalizumab. Several new approaches to MS are in clinical trials based on positive indications in preclinical work relying on EAE. New clues to the pathogenesis of MS and new potential surrogate markers for MS are shown from research involving EAE when it is critically coupled with actual findings in MS. There are pitfalls in overreliance on the EAE model, or on any animal model for any human disease. Nevertheless, over the past 73 years, the EAE model has proved itself remarkably useful for aiding research on MS.

During 3 years treatment of primary progressive multiple sclerosis with glatiramer acetate, specific antibodies switch from IgG1 to IgG4

In this study we analyzed the humoral immune response to glatiramer acetate in 16 GA-treated primary progressive MS patients and 9 placebo patients from the PROMiSe study. We have demonstrated that all multiple sclerosis patients (n=16) continuously treated with GA for 3 years developed anti-GA antibodies that peaked at month 3 and remained elevated during the whole study. We have also demonstrated that initially GA-reactive antibodies of the IgG1 subclass predominate, peaking at month 9 of therapy, but after 9 months IgG1 decreases while anti-GA antibodies of the IgG4 subclass increase and remain high for the 3 years of follow-up. These results support a shift from Th1 to Th2 in the antibody response to glatiramer acetate treatment.

Management of worsening multiple sclerosis with mitoxantrone: a review

BACKGROUND

Mitoxantrone, an intravenously administered immunosuppressant that inhibits T-cell, B-cell, and macrophage proliferation, is indicated for reducing neurologic disability and relapse frequency in patients with secondary progressive multiple sclerosis (SPMS), progressive relapsing MS, or worsening relapsing-remitting MS (RRMS).

OBJECTIVE

This article reviews the pathogenesis and natural history of MS and examines the available treatment options for patients with RRMS, worsening RRMS, or SPMS, with a focus on mitoxantrone.

METHODS

MEDLINE (1966-present) and the Cochrane Central Register of Controlled Trials (1994-present) were searched for relevant randomized, blinded, controlled clinical trials using the terms mitoxantrone, Novantrone, and multiple sclerosis.

RESULTS

Five randomized, blinded, controlled trials and an ongoing open-label Phase IV safety study were identified and included in this review. In one randomized, double-blind trial (N=25), patients with RRMS who received mitoxantrone 8 mg/m2 monthly had significantly reduced relapse rates at 1 year compared with those who received placebo (P=0.014). In a 2-year, randomized, partially blinded trial (N=51), patients with active RRMS who received mitoxantrone 8 mg/m2 monthly had significantly fewer relapses compared with those who received placebo (P<0.001), and significantly fewer patients had confirmed progression of disability (1-point increase in Expanded Disability Status Scale [EDSS] score) (P=0.02). In a randomized, double-blind trial (N=49), patients with relapsing SPMS who received mitoxantrone 12 mg/m2 monthly for 3 months followed by 12 mg/m2 g3mo for up to 32 months had significant improvements in EDSS scores compared with those who received methylprednisolone 1 g IV monthly for 3 months followed by 1 g IV g3mo (P=0.002 at 1 year, P=0.045 at 2 years) and significant reductions in the number of gadolinium-enhancing lesions on magnetic resonance imaging (MRI) (P=0.002 at 1 and 2 years, P=0.03 at 3 years). In a randomized, partially blinded Phase II trial in 42 patients with active RRMS or SPMS, patients who received mitoxantrone 20 mg IV monthly and methylprednisolone 1 g IV monthly had significantly fewer new gadolinium-enhancing lesions on MRI (P<0.001) and significantly fewer relapses (P<0.01) at 6 months compared with those who received methylprednisolone alone. In a pivotal Phase III trial (N=194), patients with worsening RRMS or SPMS who received mitoxantrone 12 mg/m2 g3mo for 2 years had significantly fewer relapses (P<0.001) and significantly less deterioration in disability, as measured by change in EDSS score (P=0.019), compared with those who received placebo. In a nonrandomized subgroup of patients from this study (n=110), those who received mitoxantrone 12 mg/m2 g3mo had a significant reduction in the number of T2-weighted MRI lesions at 24 months (P=0.027). The most common adverse events in these studies included nausea and/or vomiting (18%-85%), alopecia (33%-61%), amenorrhea (8%-53%), urinary tract infections (6%-32%), and upper respiratory tract infections (4%-53%). Leukopenia was reported in 10% to 19% of patients. Use of mitoxantrone can lead to serious adverse effects, particularly cardiotoxicity, myelosuppression, and, rarely, leukemia. Long-term use of mitoxantrone may compromise left ventricular function. Limited cardiotoxicity was reported in the clinical studies; in the pivotal clinical trial, 2 patients who received mitoxantrone 12 mg/m2 had decreases in left ventricular ejection fraction to <50% of baseline.

CONCLUSIONS

In the available clinical trials, mitoxantrone provided effective treatment for worsening RRMS or SPMS. When mitoxantrone is used as recommended, the risks of substantial myelosuppressive and cardiotoxic effects can be reduced by careful patient selection, drug administration, and monitoring. The lifetime cumulative dose should be strictly limited to 140 mg/m2, or 2 to 3 years of therapy.

Therapeutic induction of regulatory, cytotoxic CD8+ T cells in multiple sclerosis

In the setting of autoimmunity, one of the goals of successful therapeutic immune modulation is the induction of peripheral tolerance, a large part of which is mediated by regulatory/suppressor T cells. In this report, we demonstrate a novel immunomodulatory mechanism by an FDA-approved, exogenous peptide-based therapy that incites an HLA class I-restricted, cytotoxic suppressor CD8+ T cell response. We have shown previously that treatment of multiple sclerosis (MS) with glatiramer acetate (GA; Copaxone) induces differential up-regulation of GA-reactive CD8+ T cell responses. We now show that these GA-induced CD8+ T cells are regulatory/suppressor in nature. Untreated patients show overall deficit in CD8+ T cell-mediated suppression, compared with healthy subjects. GA therapy significantly enhances this suppressive ability, which is mediated by cell contact-dependent mechanisms. CD8+ T cells from GA-treated patients and healthy subjects, but not those from untreated patients with MS, exhibit potent, HLA class I-restricted, GA-specific cytotoxicity. We further show that these GA-induced cytotoxic CD8+ T cells can directly kill CD4+ T cells in a GA-specific manner. Killing is enhanced by preactivation of target CD4+ T cells and may depend on presentation of GA through HLA-E. Thus, we demonstrate that GA therapy induces a suppressor/cytotoxic CD8+ T cell response, which is capable of modulating in vivo immune responses during ongoing therapy. These studies not only explain several prior observations relating to the mechanism of this drug but also provide important insights into the natural immune interplay underlying this human immune-mediated disease.

Immunomodulatory vaccines against autoimmune diseases

Vaccines are for healthy people, to prevent them from becoming ill. Such prophylactic vaccines have been a great success. Therapeutic vaccines become more and more important, especially as life expectancy increases. Efforts to develop vaccines against such diseases as cancer, AIDS, hepatitis, tuberculosis, Alzheimer disease, and mad cow disease have not yet reached the stage where they can be successfully used on a daily basis. However, significant progress has been made in the realm of autoimmune diseases, resulting (at least in one case) in an immunomodulatory vaccine against multiple sclerosis that was developed in the author's laboratory, and that is in daily use by about 100,000 patients. The drug or therapeutic vaccine against the exacerbating-remitting type of multiple sclerosis is a copolymer of four amino acid residues, denoted Copaxone, which are related to myelin basic protein. This paper discusses Copaxone as well as a candidate immunomodulatory vaccine against myasthenia gravis, a peptide derived from the nicotinic acetylcholine receptor. Copolymer 1 (Cop 1, glatiramer acetate, Copaxone) is a synthetic amino acid random copolymer that is immunologically cross-reactive with myelin basic protein and suppresses experimental allergic encephalomyelitis in several animal species. Cop 1 slows the progression of disability and reduces the relapse rate in exacerbating-remitting multiple sclerosis patients. Cop 1 is a potent inducer of T helper 2 (Th2) regulatory cells in mice and humans; and Th2 cells are found in both the brains and spinal cords of Cop 1-treated mice and humans. MG and experimental autoimmune MG are T cell-regulated, antibody-mediated autoimmune diseases. Two peptides, representing sequences of the human AChR-alpha-subunit, p195-212 and p259-271, are immunodominant T-cell epitopes in MG patients and two strains of mice. Altered peptide ligand, composed of the randomly arranged two single amino acid analogs inhibits in vitro and in vivo MG-associated autoimmune responses. The active suppression is mediated by the CD4+ CD25+ immunoregulatory cells and is associated with the downregulation of Th1-type cytokines and upregulation of the secretion of IL-10 and the immunosuppressive cytokine transforming growth factor beta.

Interferon as a treatment for uveitis associated with multiple sclerosis

AIM

In addition to optic neuritis (ON), multiple sclerosis (MS) may also involve the eye with a typically bilateral intermediate uveitis. The aim of this pilot study was to evaluate the efficacy of type I interferons (IFN) for the treatment of MS associated uveitis.

METHODS

In this non-randomised, retrospective observational case series 13 patients (eight female, five male) with proved MS and associated uveitis from five uveitis centres who were treated with interferon beta1a were included. Visual acuity (VA), cell count in the aqueous humour and vitreous, as well as the presence of cystoid macula oedema (CMO) were observed.

RESULTS

All except one patient had a bilateral form of intermediate uveitis (total of 24 eyes). Seven patients had documented CMO before IFN treatment (n = 13 eyes). Median duration of treatment was 24.6 months (range 7.9-78.7). VA improved in 17 eyes (comparing VA before therapy and at last follow up); while 10 eyes (36%) improved >or=3 Snellen lines. Aqueous cell count improved by 1.2 (SD 1.1) grades in all eyes. Vitreous cell count improved by 1.7 (1.4) in all eyes. Only two patients still had minimal CMO on last follow up angiographically. CMO resolved after or during IFN treatment in nine eyes.

CONCLUSIONS

IFN has been shown to have beneficial effects in patients with MS and/or ON. As shown in the models of experimental allergic encephalomyelitis (EAE) and uveitis, the neurological and ophthalmological manifestations seem to share similar pathogenic mechanisms. Treatment of MS associated uveitis with IFN appears to have beneficial effects on VA, intraocular inflammation activity, and the presence of CMO.

Virtues and pitfalls of EAE for the development of therapies for multiple sclerosis

Experimental autoimmune encephalomyelitis (EAE) is a useful model for aiding the development of new treatments for MS. All therapies approved for MS ameliorate EAE. Two approved medications, glatiramer acetate and Natalizumab, were developed directly from studies in EAE. Several trials are ongoing in MS after success in EAE, including altered peptide ligands of myelin, DNA vaccines and statins. However, EAE has failed to predict the outcome of certain approaches. The reasons underlying such failures are discussed here.

Glatiramer acetate in multiple sclerosis: update on potential mechanisms of action

Glatiramer acetate is a synthetic random copolymer approved for the immunomodulatory therapy of relapsing-type multiple sclerosis (MS). Previous work has focused on the effects of this drug on T cells, especially the glatiramer-acetate-induced shift of the cytokine profile towards those characteristic of T-helper-2 (Th2) cells. Glatiramer acetate was thought to bring about this Th2 shift by acting like an altered peptide ligand but more recent work has shown that the drug notably affects the properties of antigen-presenting cells, such as monocytes and dendritic cells. These new observations might offer an explanation for the previously observed Th2 shift. In this review, we focus on these new findings. We address several controversial issues, including the possible neurotrophic effects of glatiramer acetate, the potential role of neutralising antibodies to the drug, and attempts to develop biomarkers of the treatment response. Finally, we will think about how a better understanding of glatiramer acetate might help the development of new immunomodulatory agents for MS.

Amelioration of established experimental autoimmune encephalomyelitis by an MHC anchor-substituted variant of proteolipid protein 139-151

Murine experimental autoimmune encephalomyelitis (EAE) is a CD4+ T cell-mediated autoimmune disorder directed against myelin proteins within the CNS. We propose that variant peptides containing amino acid substitutions at MHC anchor residues will provide a unique means to controlling the polyclonal autoimmune T cell response. In this study, we have identified an MHC variant of proteolipid protein (PLP) 139-151 (145D) that renders PLP(139-151)-specific T cell lines anergic in vitro, as defined by a significant reduction in proliferation and IL-2 production following challenge with wild-type peptide. In vivo administration of 145D before challenge with PLP(139-151) results in a significant reduction in disease severity and incidence. Importantly, we demonstrate the ability of an MHC variant peptide to ameliorate established EAE. An advantage to this treatment is that the MHC variant peptide does not induce an acute hypersensitivity reaction. This is in contrast to previous work in the PLP(139-151) model demonstrating that anaphylactic shock resulting in death occurs upon rechallenge with the encephalitogenic peptide. Taken together, these data demonstrate the effectiveness of MHC anchor-substituted peptides in the treatment of EAE and suggest their utility in the treatment of other autoimmune disorders.

Glatiramer acetate for the treatment of multiple sclerosis

Glatiramer acetate (Copaxone, Teva Pharmaceuticals Ltd) is a collection of immunomodulatory, synthetic polypeptides indicated for the treatment of relapsing-remitting multiple sclerosis (RR MS). Preclinical and clinical studies provide an evolving understanding of the mechanisms by which glatiramer acetate exerts both immunological and potential neuroprotective effects that account for its clinical efficacy. The results of pivotal controlled clinical trials and long-term data, derived from organised extension studies, are evaluated in detail and supportive data from open-label comparison, combination treatment and therapeutic switch studies are considered in order to determine the place of glatiramer acetate among other approved therapies for RR MS. The efficacy of glatiramer acetate is stable or may increase over time and the drug has a favourable side effect profile. Glatiramer acetate is an appropriate first-line immunomodulatory therapy for RR MS.

Peptide 15-mers of defined sequence that substitute for random amino acid copolymers in amelioration of experimental autoimmune encephalomyelitis

Myelin basic protein (MBP) is a major candidate autoantigen in multiple sclerosis (MS). Its immunodominant epitope, MBP 85-99, forms a complex with human leukocyte antigen (HLA)-DR2 with which multiple sclerosis is genetically associated. Copolymer 1 (Copaxone), a random amino acid copolymer [poly (Y,E,A,K)n] as well as two modified synthetic copolymers [poly (F,Y,A,K)n and poly (V,W,A,K)n] also form complexes with HLA-DR2 (DRA/DRB1*1501) and compete with MBP 85-99 for binding. Moreover, two high-affinity synthetic peptide 15-mers that could inhibit binding even more effectively were previously designed. Here, we show that further-modified peptide 15-mers inhibited even more strongly (in order J5 > J3 > J2) both the binding of MBP 85-99 to HLA-DR2 and IL-2 production by two MBP 85-99-specific HLA-DR2-restricted T cells. J5, J3, and J2 also suppressed both MBP 85-99-induced experimental autoimmune encephalomyelitis (EAE) in humanized mice and proteolipid protein 139-151-induced EAE in SJL/J mice. Moreover, none of these previously uncharacterized peptide inhibitors crossreacted with MBP 85-99- or proteolipid protein 139-151-specific T cells. In both cases, spleen and lymph node cultures stimulated with these peptides produced large amounts of Th2 cytokines (IL-4 and IL-10), and adoptive transfer of established T cell lines suppressed disease induction. These peptide 15-mers provide specific, nonrandom sequences that appear to be at least as effective as random copolymers in suppressing EAE in several models.

Therapeutic vaccines in autoimmunity

Similarly to prophylactic vaccines whose purpose is to prevent infectious diseases, therapeutic vaccines against autoimmune diseases are based on their similarity to the putative causes of the disease. We shall describe here two such examples: a copolymer of amino acids related to myelin basic protein, in the case of multiple sclerosis, and a peptide derived from the nicotinic acetylcholine receptor (AChR), in the case of myasthenia gravis (MG). Copolymer 1 (Cop 1, glatiramer acetate, Copaxone) is a synthetic amino acid random copolymer, immunologically cross-reactive with myelin basic protein and suppresses experimental allergic encephalomyelitis in several animal species. Cop 1 slows the progression of disability and reduces relapse rate in exacerbating-remitting multiple sclerosis patients. It was approved by the Food and Drug Administration in 1996, and today is used by tens of thousands of patients. Cop 1 is a potent inducer of T helper 2 (Th2) regulatory cells in mice and humans, and Th2 cells are found both in the brains and spinal cords of Cop 1-treated mice. MG and experimental autoimmune MG are T cell-regulated, antibody-mediated autoimmune diseases. Two peptides, representing sequences of the human AChR alpha-subunit, p195-212 and p259-271, are immunodominant T cell epitopes in MG patients and in two strains of mice. Altered peptide ligand, composed of the tandemly arranged two single amino acid analogs, inhibits in vitro and in vivo MG-associated autoimmune responses. The active suppression is mediated by the CD4(+)CD25(+) immunoregulatory cells and is associated with the down-regulation of Th1-type cytokines and the up-regulation of the secretion of IL-10 and the immunosuppressive cytokine, transforming growth factor beta.

Mechanism of action of glatiramer acetate in multiple sclerosis and its potential for the development of new applications

Glatiramer acetate (GA, Copaxone, Copolymer 1) is an approved drug for the treatment of multiple sclerosis and is highly effective in the suppression of experimental autoimmune encephalomyelitis in various species. The mode of action of GA is by initial strong promiscuous binding to MHC molecules and consequent competition with various myelin antigens for their presentation to T cells. A further aspect of its action is potent induction of specific suppressor cells of the T helper 2 (Th2) type that migrate to the brain and lead to in situ bystander suppression. Furthermore, the GA-specific cells in the brain express the antiinflammatory cytokines IL-10 and transforming growth factor beta, in addition to brain-derived neurotrophic factor, whereas they do not express IFN-gamma. Based on this immunomodulatory mode of action, we explored the potential of GA for two other applications: prevention of graft rejection and amelioration of inflammatory bowel diseases. GA was effective in amelioration of graft rejection in two systems by prolongation of skin graft survival and inhibition of functional deterioration of thyroid grafts, across minor and major histocompatibility barriers. In all transplantation systems GA treatment inhibited the detrimental secretion of Th1 inflammatory cytokines and induced beneficial Th2/3 antiinflammatory response. GA was effective also in combination with low-dose immunosuppressive drugs. Inflammatory bowel diseases are characterized by detrimental imbalanced proinflammatory immune reactivity in the gut. GA significantly suppressed the various manifestations of trinitrobenzene sulfonic acid-induced colitis, including mortality, weight loss, and macroscopic and microscopic colonic damage. GA suppressed local lymphocyte proliferations and tumor necrosis factor alpha detrimental secretion but induced transforming growth factor beta, thus confirming the involvement of Th1 to Th2 shift in GA mode of action.

Immunomodulation by the copolymer glatiramer acetate

Glatiramer acetate (GA; Copaxone, also known as Copolymer 1 or Cop-1), a copolymer of amino acids, is very effective in the suppression of experimental autoimmune encephalitis (EAE), the animal model for multiple sclerosis (MS), in various species including primates. The immunological cross-reaction between the myelin basic protein and GA serves as the basis for the suppressive activity of GA in EAE, by the induction of antigen-specific suppressor cells. The mode of action of GA is by initial strong promiscuous binding to major histocompatibility complex class II molecules and competition with MBP and other myelin proteins for such binding and presentation to T cells. Suppressor T cells induced by GA are of the Th2 type, migrate to the brain and lead to in situ bystander suppression. Clinical trials with GA, both phase II and phase III, were performed in relapsing-remitting MS (RRMS) patients, and demonstrated efficacy in reducing the relapse rate, decreasing MRI-assessed disease activity and burden and slowing progression of disability. GA is generally well tolerated and is not associated with influenza-like symptoms and formation of neutralizing antibodies seen with beta-interferons. It exerts its suppressive effect primarily by immunomodulation, and has recently shown ameliorating effect in a few additional autoimmune disorders as well as in graft rejection. At present GA is considered a valuable first-line treatment option for patients with RRMS.

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..

The cost of multiple sclerosis and the cost effectiveness of disease-modifying agents in its treatment

Multiple sclerosis (MS) is one of the most common causes of neurological disability in young and middle-aged adults. The full economic cost of MS is substantial given that MS patients experience a major perturbation in their daily activities and the disease affects mainly young people who are obliged to restrict their levels of economic activity, either temporarily or permanently. A positive relationship exists between the direct and indirect costs of MS and its severity. Cost variations between countries exist because of differences in the costs of inpatient care, the number of ambulatory visits, drug usage and the extent and type of informal care. The development and availability of new agents has been accompanied by an increased optimism that treatment regimens for MS would be more effective. However, doubts have been expressed about the effectiveness of these treatments, which have compounded the problems associated with estimating the relative cost effectiveness of such interventions. In addition, variations in the utility scores associated with disease categories, the impact of relapses and the resulting utility losses, plus the speed of disease progression have all contributed to the difficulty of estimating the quality-adjusted life year (QALY) losses for a patient experiencing MS. Differences between studies with respect to the costs associated with each disability level, the timescale of the disease and the period over which costs and QALYs are to be measured, and the perspective employed in relation to costing have also resulted in a wide range of estimates being produced for the cost effectiveness of interferons and glatiramer acetate in the management of MS. These range from situations of cost savings, to over $US1.6 million (euro1.85 million) per QALY gained. Recent cost-effectiveness studies have benefited from more relevant and up-to-date data relating to disease progression and have generally produced more favourable cost-effectiveness ratios. However, the lack of homogeneity in the design of the studies partly accounts for the extent of variation in the estimates of cost effectiveness, and the difficulty of arriving at a consensus. The UK Department of Health has introduced a scheme that provides disease-modifying agents in the National Health Service for those patients with clinically active relapsing disease. Patients are monitored annually and payments to manufacturers are dependent on outcomes achieved. This initiative, although not without its detractors, will hopefully enhance the quantity and quality of evidence on the impact of drugs on disease progression and address some of the current difficulties with estimating the relative cost effectiveness of disease-modifying drugs in the treatment of patients with MS.

Amelioration of proteolipid protein 139-151-induced encephalomyelitis in SJL mice by modified amino acid copolymers and their mechanisms

Copolymer 1 [Cop1, glatiramer acetate, Copaxone, poly(Y,E,A,K)n] is widely used in the treatment of relapsing/remitting multiple sclerosis in which it reduces the frequency of relapses by approximately 30%. In the present study, copolymers with modified amino acid compositions (based on the binding motif of myelin basic protein 85-99 to HLA-DR2) have been developed with the aim of suppressing multiple sclerosis more effectively. The enhanced efficacy of these copolymers in experimental autoimmune encephalomyelitis (EAE) induced in SJL/J mice with proteolipid protein 139-151 was demonstrated by using three protocols: (i) simultaneous administration of autoantigen and copolymer (termed prevention), (ii) pretreatment with copolymers (vaccination), or (iii) administration of copolymers after disease onset (treatment). Strikingly, in the treatment protocol administration of soluble VWAK and FYAK after onset of disease led to stasis of its progression and suppression of histopathological evidence of EAE. The mechanisms by which these effects are achieved have been examined in several types of assays: binding of copolymers to I-A(s) in competition with proteolipid protein 139-151 (blocking), cytokine production by T cells (T helper 2 polarization), and transfer of protection by CD3(+) splenocytes or, notably, by copolymer-specific T cell lines (induction of regulatory T cells). The generation of these copolymer-specific regulatory T cells that secrete IL-4 and IL-10 and are independent of the immunizing autoantigen is very prominent among the multiple mechanisms that account for the observed suppressive effect of copolymers in EAE.

Induction of IL-10 in rat peritoneal macrophages and dendritic cells by glatiramer acetate

Glatiramer acetate (GLAT) is a mixture of basic polypeptides that have been shown to suppress experimental autoimmune encephalomyelitis (EAE). As Copaxone, GLAT is approved for the treatment of relapsing-remitting multiple sclerosis (MS). Different immunomechanisms have been suggested to contribute to the beneficial effects of GLAT which rely on blockade of MHC class II molecules or cross-recognition with myelin basic protein (MBP). Because GLAT could also inhibit experimental autoimmunity not related to myelin proteins, we searched for additional, less-restricted immunomodulatory actions of GLAT. Using freshly isolated resident peritoneal macrophages from naive Lewis rats, it is shown that GLAT profoundly modulates cytokine secretion of the cells. In unseparated macrophages (MPhi) and MPhi of low density, GLAT enhanced constitutive and LPS-induced production of interleukin 10 (IL-10) while LPS-induced synthesis of tumor necrosis factor-alpha (TNF-alpha) was dose-dependently suppressed by GLAT. Although both basic proteins GLAT and MBP facilitated adherence of MPhi, MBP had opposite effects on cytokine production suggesting unique properties of GLAT. In contrast to MPhi, peritoneal mast cells produced only little amounts of cytokines. The inductive effect of GLAT on IL-10 production by antigen-presenting cells was also observed in bone marrow-derived rat dendritic cells (DCs) which, unlike MPhi, were not suppressed in their production of TNF-alpha. Induction of IL-10 in different antigen-presenting cells is a new immunomodulatory mechanism of GLAT. In part, it goes along with the inhibition of TNF-alpha and may be a common basis for the known beneficial effects of GLAT on various cellular autoimmune responses including MS.