Multiple sclerosis: trial of a synthetic polypeptide

Glatiramer Acetate for the Treatment of Multiple Sclerosis: From First-Generation Therapy to Elucidation of Immunomodulation and Repair

Multiple sclerosis (MS) is a chronic inflammatory demyelinating and neurodegenerative disease of the central nervous system (CNS), with a putative autoimmune origin and complex pathogenesis. Modification of the natural history of MS by reducing relapses and slowing disability accumulation was first attained in the 1990 s with the development of the first-generation disease-modifying therapies. Glatiramer acetate (GA), a copolymer of L-alanine, L-lysine, L-glutamic acid, and L-tyrosine, was discovered due to its ability to suppress the animal model of MS, experimental autoimmune encephalomyelitis. Extensive clinical trials and long-term assessments established the efficacy and the safety of GA. Furthermore, studies of the therapeutic processes induced by GA in animal models and in MS patients indicate that GA affects various levels of the innate and the adaptive immune response, generating deviation from proinflammatory to anti-inflammatory pathways. This includes competition for binding to antigen presenting cells; driving dendritic cells, monocytes, and B-cells toward anti-inflammatory responses; and stimulating T-helper 2 and T-regulatory cells. The immune cells stimulated by GA reach the CNS and secrete in situ anti-inflammatory cytokines alleviating the pathological processes. Furthermore, cumulative findings reveal that in addition to its immunomodulatory effect, GA promotes neuroprotective repair processes such as neurotrophic factors secretion, remyelination, and neurogenesis. This review aims to provide an overview of MS pathology diagnosis and treatment as well as the diverse mechanism of action of GA. SIGNIFICANCE STATEMENT: Understanding the complex MS immune pathogenesis provided multiple targets for therapeutic intervention, resulting in a plethora of agents, with various mechanisms of action, efficacy, and safety profiles. However, promoting repair beyond the body's limited spontaneous extent is still a major challenge. GA, one of the first approved disease-modifying therapies, induces diverse immunomodulatory effects. Furthermore, GA treatment results in elevated neurotrophic factors secretion, remyelination and neurogenesis, supporting the notion that immunomodulatory treatment can support in situ a growth-promoting and repair environment.

Disease modifying therapy and pregnancy outcomes in multiple sclerosis: A systematic review and meta-analysis

OBJECTIVES

To report pregnancy outcomes among multiple sclerosis (MS) patients treated with disease-modifying therapies (DMTs).

METHODS

We performed a retrospective chart review of articles published from June 1996 to May 2023. Additional information was acquired from the drug registries of individual pharmaceutical companies. A comparison was also made with pregnancy data of the general population using the World Health Organization database. Summary analysis was achieved using R statistical software (v3.6), and the overall prevalence of outcomes was estimated using a random effects model.

RESULTS

A meta-analysis of 44 studies was conducted. Dimethyl fumarate had the highest prevalence of premature births at 0.6667% (SD:0.5236-0.7845). The highest rates of stillbirths and infant deaths (perinatal and neonatal) were observed with interferons at 0.004% (SD:0.001-0.010) and 0.009% (SD:0.005-0.0015), respectively. Cladribine had the majority of ectopic pregnancies (0.0234%, SD:0.0041-1217), while natalizumab had the highest prevalence of spontaneous abortions (0.1177%, SD:0.0931-0.1477) and live birth defects (0.0755%, SD:0.0643-0.0943).None of the outcomes were significantly different from those of the general population (p > 0.05), except ectopic pregnancy and spontaneous abortion (p < 0.001), where the odds were 0.665 (0.061-0.886) and 0.537(0.003-0.786), respectively. The pooled prevalence of MS relapses was 221% for a single episode (SD:0.001-0.714), 0.075% for more than one episode (SD:0.006-0.167), and 0.141% for at least one episode requiring steroids (SD:0.073-0.206) none of these reached clinical significance.

CONCLUSION

Existing research suggests that DMT use in MS patients during pregnancy is generally considered safe. This study supports their utilization on a case-by-case basis. However, further primary research on this topic with clinical trials is warranted.

Synergistic Activity of Repurposed Peptide Drug Glatiramer Acetate with Tobramycin against Cystic Fibrosis Pseudomonas aeruginosa

Pseudomonas aeruginosa is the most common pathogen infecting the lungs of people with cystic fibrosis (CF), causing both acute and chronic infections. Intrinsic and acquired antibiotic resistance, coupled with the physical barriers resulting from desiccated CF sputum, allow P. aeruginosa to colonize and persist in spite of antibiotic treatment. As well as the specific difficulties in eradicating P. aeruginosa from CF lungs, P. aeruginosa is also subject to the wider, global issue of antimicrobial resistance. Glatiramer acetate (GA) is a peptide drug, used in the treatment of multiple sclerosis (MS), which has been shown to have moderate antipseudomonal activity. Other antimicrobial peptides (AMPs) have been shown to be antibiotic resistance breakers, potentiating the activities of antibiotics when given in combination, restoring and/or enhancing antibiotic efficacy. Growth, viability, MIC determinations, and synergy analysis showed that GA improved the efficacy of tobramycin (TOB) against reference strains of P. aeruginosa, reducing TOB MICs and synergizing with the aminoglycoside. This was also the case for clinical strains from people with CF. GA significantly reduced the MIC50 of TOB for viable cells from 1.69 mg/L (95% confidence interval [CI], 0.26 to 8.97) to 0.62 mg/L (95% CI, 0.15 to 3.94; P = 0.002) and the MIC90 for viable cells from 7.00 mg/L (95% CI, 1.18 to 26.50) to 2.20 mg/L (95% CI, 0.99 to 15.03; P = 0.001), compared to results with TOB only. Investigation of mechanisms of GA activity showed that GA resulted in significant disruption of outer membranes, depolarization of cytoplasmic membranes, and permeabilization of P. aeruginosa and was the only agent tested (including cationic AMPs) to significantly affect all three mechanisms. IMPORTANCE The antimicrobial resistance crisis urgently requires solutions to the lost efficacy of antibiotics. The repurposing of drugs already in clinical use, with strong safety profiles, as antibiotic adjuvants to restore the efficacy of antibiotics is an important avenue to alleviating the resistance crisis. This research shows that a clinically used drug from outside infection treatment, glatiramer acetate, reduces the concentration of tobramycin required to be effective in treating Pseudomonas aeruginosa, based on analyses of both reference and clinical respiratory isolates from people with cystic fibrosis. The two agents acted synergistically against P. aeruginosa, being more effective combined in vitro than predicted for their combination. As a peptide drug, glatiramer acetate functions similarly to many antimicrobial peptides, interacting with and disrupting the P. aeruginosa cell wall and permeabilizing bacterial cells, thereby allowing tobramycin to work. Our findings demonstrate that glatiramer acetate is a strong candidate for repurposing as an antibiotic resistance breaker of pathogenic P. aeruginosa.

Treatment Challenges in Multiple Sclerosis – A Continued Role for Glatiramer Acetate?

Earlier diagnosis, access to disease-modifying therapies (DMTs), and improved supportive care have favorably altered the disease course of multiple sclerosis (MS), leading to an improvement in long-term outcomes for people with MS (PwMS). This success has changed the medical characteristics of the population seen in MS clinics. Comorbidities and the accompanying polypharmacy, immune senescence, and the growing number of approved DMTs make selecting the optimal agent for an individual patient more challenging. Glatiramer acetate (GA), a moderately effective DMT, interacts only minimally with comorbidities, other medications, or immune senescence. We describe here several populations in which GA may represent a useful treatment option to overcome challenges due to advanced age or comorbidities (e.g., hepatic or renal disease, cancer). Further, we weigh GA's potential merits in other settings where PwMS and their neurologists must base treatment decisions on factors other than selecting the most effective DMT, e.g., family planning, conception and pregnancy, or the need for vaccination.

Immunological Aspects of Approved MS Therapeutics

Multiple sclerosis (MS) is the most common neurological immune-mediated disease leading to disability in young adults. The outcome of the disease is unpredictable, and over time, neurological disabilities accumulate. Interferon beta-1b was the first drug to be approved in the 1990s for relapsing-remitting MS to modulate the course of the disease. Over the past two decades, the treatment landscape has changed tremendously. Currently, more than a dozen drugs representing 1 substances with different mechanisms of action have been approved (interferon beta preparations, glatiramer acetate, fingolimod, siponimod, mitoxantrone, teriflunomide, dimethyl fumarate, cladribine, alemtuzumab, ocrelizumab, and natalizumab). Ocrelizumab was the first medication to be approved for primary progressive MS. The objective of this review is to present the modes of action of these drugs and their effects on the immunopathogenesis of MS. Each agent's clinical development and potential side effects are discussed.

The Evolving Mechanisms of Action of Glatiramer Acetate

Glatiramer acetate (GA) is a synthetic amino acid copolymer that is approved for treatment of relapsing remitting multiple sclerosis (RRMS) and clinically isolated syndrome (CIS). GA reduces multiple sclerosis (MS) disease activity and has shown comparable efficacy with high-dose interferon-β. The mechanism of action (MOA) of GA has long been an enigma. Originally, it was recognized that GA treatment promoted expansion of GA-reactive T-helper 2 and regulatory T cells, and induced the release of neurotrophic factors. However, GA treatment influences both innate and adaptive immune compartments, and it is now recognized that antigen-presenting cells (APCs) are the initial cellular targets for GA. The anti-inflammatory (M2) APCs induced following treatment with GA are responsible for the induction of anti-inflammatory T cells that contribute to its therapeutic benefit. Here, we review studies that have shaped our current understanding of the MOA of GA.

Enduring Clinical Value of Copaxone® (Glatiramer Acetate) in Multiple Sclerosis after 20 Years of Use

Multiple sclerosis (MS) is a chronic progressive neurodegenerative demyelinating disease affecting the central nervous system. Glatiramer acetate (GA; Copaxone®) was the first disease-modifying treatment (DMT) for MS successfully tested in humans (1977) and was approved by the US Food and Drug Administration in December 1996. Since then, there have been numerous developments in the MS field: advances in neuroimaging allowing more rapid and accurate diagnosis; the availability of a range of DMTs including immunosuppressant monoclonal antibodies and oral agents; a more holistic approach to treatment by multidisciplinary teams; and an improved awareness of the need to consider a patient's preferences and patient-reported outcomes such as quality of life. The use of GA has endured throughout these advances. The purpose of this article is to provide an overview of the important developments in the MS field during the 20 years since GA was approved and to review clinical data for GA in MS, with the aim of understanding the continued and widespread use of GA. Both drug-related (efficacy versus side-effect profile and monitoring requirements) and patient factors (preferences regarding mode of administration and possible pregnancy) will be explored.

Divergent Immunomodulation Capacity of Individual Myelin Peptides-Components of Liposomal Therapeutic against Multiple Sclerosis

Multiple sclerosis (MS) is an autoimmune disease characterized by demyelination and consequent neuron injury. Although the pathogenesis of MS is largely unknown, a breach in immune self-tolerance to myelin followed by development of autoreactive encephalitogenic T cells is suggested to play the central role. The myelin basic protein (MBP) is believed to be one of the main targets for autoreactive lymphocytes. Recently, immunodominant MBP peptides encapsulated into the mannosylated liposomes, referred as Xemys, were shown to suppress development of experimental autoimmune encephalomyelitis, a rodent model of MS, and furthermore passed the initial stage of clinical trials. Here, we investigated the role of individual polypeptide components [MBP peptides 46-62 (GH17), 124-139 (GK16), and 147-170 (QR24)] of this liposomal peptide therapeutic in cytokine release and activation of immune cells from MS patients and healthy donors. The overall effects were assessed using peripheral blood mononuclear cells (PBMCs), whereas alterations in antigen-presenting capacities were studied utilizing plasmacytoid dendritic cells (pDCs). Among three MBP-immunodominant peptides, QR24 and GK16 activated leukocytes, while GH17 was characterized by an immunosuppressive effect. Peptides QR24 and GK16 upregulated CD4 over CD8 T cells and induced proliferation of CD25⁺ cells, whereas GH17 decreased the CD4/CD8 T cell ratio and had limited effects on CD25⁺ T cells. Accordingly, components of liposomal peptide therapeutic differed in upregulation of cytokines upon addition to PBMCs and pDCs. Peptide QR24 was evidently more effective in upregulation of pro-inflammatory cytokines, whereas GH17 significantly increased production of IL-10 through treated cells. Altogether, these data suggest a complexity of action of the liposomal peptide therapeutic that does not seem to involve simple helper T cells (Th)-shift but rather the rebalancing of the immune system.

CD206-Targeted Liposomal Myelin Basic Protein Peptides in Patients with Multiple Sclerosis Resistant to First-Line Disease-Modifying Therapies: A First-in-Human, Proof-of-Concept Dose-Escalation Study

Previously, we showed that CD206-targeted liposomal delivery of co-encapsulated immunodominant myelin basic protein (MBP) sequences MBP46-62, MBP124-139 and MBP147-170 (Xemys) suppressed experimental autoimmune encephalomyelitis in dark Agouti rats. The objective of this study was to assess the safety of Xemys in the treatment of patients with relapsing-remitting multiple sclerosis (MS) and secondary progressive MS, who failed to achieve a sustained response to first-line disease-modifying therapies. In this phase I, open-label, dose-escalating, proof-of-concept study, 20 patients with relapsing-remitting or secondary progressive MS received weekly subcutaneously injections with ascending doses of Xemys up to a total dose of 2.675 mg. Clinical examinations, including Expanded Disability Status Scale score, magnetic resonance imaging results, and serum cytokine concentrations, were assessed before the first injection and for up to 17 weeks after the final injection. Xemys was safe and well tolerated when administered for 6 weeks to a maximum single dose of 900 μg. Expanded Disability Status Scale scores and numbers of T2-weighted and new gadolinium-enhancing lesions on magnetic resonance imaging were statistically unchanged at study exit compared with baseline; nonetheless, the increase of number of active gadolinium-enhancing lesions on weeks 7 and 10 in comparison with baseline was statistically significant. During treatment, the serum concentrations of the cytokines monocyte chemoattractant protein-1, macrophage inflammatory protein-1β, and interleukin-7 decreased, whereas the level of tumor necrosis factor-α increased. These results provide evidence for the further development of Xemys as an antigen-specific, disease-modifying therapy for patients with MS.

Immune regulation of multiple sclerosis by CD8+ T cells

The role of CD8+ T cells in the process of autoimmune pathology has been both understudied and controversial. Multiple sclerosis (MS) is an inflammatory, demyelinating disorder of the central nervous system (CNS) with underlying T cell-mediated immunopathology. CD8+ T cells are the predominant T cells in human MS lesions, showing oligoclonal expansion at the site of pathology. It is still unclear whether these cells represent pathogenic immune responses or disease-regulating elements. Through studies in human MS and its animal model, experimental autoimmune encephalomyelitis (EAE), we have discovered two novel CD8+ T cell populations that play an essential immunoregulatory role in disease: (1) MHC class Ia-restricted neuroantigen-specific "autoregulatory" CD8+ T cells and (2) glatiramer acetate (GA/Copaxone(®)) therapy-induced Qa-1/HLA-E-restricted GA-specific CD8+ T cells. These CD8+ Tregs suppress proliferation of pathogenic CD4+ CD25- T cells when stimulated by their cognate antigens. Similarly, CD8+ Tregs significantly suppress EAE when transferred either pre-disease induction or during peak disease. The mechanism of disease inhibition depends, at least in part, on an antigen-specific, contact-dependent process and works through modulation of CD4+ T cell responses as well as antigen-presenting cells through a combination of cytotoxicity and cytokine-mediated modulation. This review provides an overview of our understanding of CD8+ T cells in immune-mediated disease, focusing particularly on our findings regarding regulatory CD8+ T cells both in MS and in EAE. Clinical relevance of these novel CD8-regulatory populations is discussed, providing insights into a potentially intriguing, novel therapeutic strategy for these diseases.

The pharmacokinetics of glatiramer acetate for multiple sclerosis treatment

INTRODUCTION

Multiple sclerosis (MS) is a T-cell-mediated disease affecting the central nervous system (CNS), characterized by demyelination and axonal degeneration. INF-β1b was the first drug approved for MS patients in 1993. In 1996, glatiramer acetate (GA), a synthetic copolymer, was approved in the USA for the treatment of relapsing-remitting MS (RRMS) and clinically isolated syndrome (CIS). Although the immunological action of GA has been fully investigated, the exact mechanisms of action of GA are still not completely elucidated. Several in vitro studies on mice and human antigen-presenting cells (APCs) have shown that GA is able to bind to the major histocompatibility complex (MHC), on the surface of APCs, recognizing myelin basic protein (MBP).

AREAS COVERED

This review explores the pharmacological characteristics of GA, its mechanism of action and its pharmacokinetics properties. The article also provides information on the efficacy, tolerability and an overview of the most important clinical data on GA.

EXPERT OPINION

Despite the development of novel compounds, it is not surprising that GA is, to date, one of the most prescribed drugs for RRMS patients and CIS patients. The proven efficacy and the mild adverse events, makes GA a good therapeutic option in the early stage of the disease. This is particularly useful for patients who suffer flu-like symptoms from other RRMS therapies as an alternative.

Interferon beta and glatiramer acetate therapy

Interferon beta and glatiramer acetate have been mainstays of treatment in relapsingremitting multiple sclerosis for two decades. Remarkable advances in our understanding of immune function and dysfunction as well as increasingly sophisticated clinical trial design have stemmed from efforts to better understand these drugs. In this chapter, we review the history of their development and elaborate on known and theorized mechanisms of action. We describe the pivotal clinical trials that have led to their widespread use. We evaluate the clinical use of the drugs including tolerability, side effects, and efficacy measures. Finally, we look to the future of interferon beta and glatiramer acetate in the context of an ever growing armamentarium of treatments for relapsing remitting multiple sclerosis.

Clinical utility of glatiramer acetate in the management of relapse frequency in multiple sclerosis

Glatiramer acetate (GA) represents one of the most common disease-modifying therapies for multiple sclerosis. GA is currently approved for patients at high risk of developing clinically definite multiple sclerosis (CDMS) after having experienced a well-defined first clinical episode (clinically isolated syndrome or CIS) and for patients with relapsing-remitting multiple sclerosis (RRMS). GA’s efficacy and effectiveness to reduce relapse frequency have been proved in placebo-controlled and observational studies. Comparative trials have also confirmed the lack of significant differences over other choices of treatment in the management of relapse frequency, and long-term studies have supported its effect at extended periods of time. Additionally, RRMS patients with suboptimal response to interferon β may benefit from reduced relapse rate after switching to GA, and those with clinically isolated syndrome may benefit from delayed conversion to CDMS. All these results, together with its proven long-term safety and positive effect on patients’ daily living, support the favorable risk-benefit of GA for multiple sclerosis treatment.

Efficacy, safety, and cost-effectiveness of glatiramer acetate in the treatment of relapsing-remitting multiple sclerosis

The current Multiple Sclerosis (MS) therapeutic landscape is rapidly growing. Glatiramer acetate (GA) remains unique given its non-immunosuppressive mechanism of action as well as its superior long-term safety and sustained efficacy data. In this review, we discuss proposed mechanisms of action of GA. Then we review efficacy data for reduction of relapses and slowing disability as well as long term safety data. Finally we discuss possible future directions of this unique polymer in the treatment of MS.

Glatiramer acetate for multiple sclerosis: a comprehensive review of mechanisms and clinical efficacy

The 'Decade of the Brain' (1990-2000) saw unprecedented advances in neurosciences including multiple sclerosis. It could have not been more aptly named, as it produced a shift in the paradigm of multiple sclerosis management, making multiple sclerosis a treatable disorder with the availability of several therapeutic options. For a chronic progressive neurological disorder like multiple sclerosis, this change in the understanding and treatment touched the lives of hundreds of thousands of patients worldwide and many more who provided care and counsel as family and friends. Of the four agents available for the treatment of the most common type of multiple sclerosis - relapsing-remitting - three are beta-interferons and one is a noninterferon polypeptide of four amino acids (glatiramer acetate) with a distinct immunomodulating profile. Glatiramer acetate is now approved and available in North America, Europe and many other countries. It has been tested in pivotal trials as well as long term extension trials for almost 10 years (8 years published) providing remarkable evidence of efficacy and safety. This review will highlight the immune mechanisms and clinical data reported with glatiramer acetate in multiple sclerosis over the past three decades.

Glatiramer acetate for multiple sclerosis

BACKGROUND

This is an updated Cochrane review of the previous version published (Cochrane Database of Systematic Reviews 2004 , Issue 1 . Art. No.: CD004678. DOI: 10.1002/14651858.CD004678)Previous studies have shown that glatiramer acetate (Copaxone (R)), a synthetic amino acid polymer is effective in experimental allergic encephalomyelitis (EAE), and improve the outcome of patients with multiple sclerosis (MS).

OBJECTIVES

To verify the clinical efficacy of glatiramer acetate in the treatment of MS patients with relapsing remitting (RR) and progressive (P) course.

SEARCH STRATEGY

We searched the Cochrane MS Group Trials Register (26 March 2009), the Cochrane Central Register of Controlled Trials (The Cochrane Library, Issue 1, 2009), MEDLINE (PubMed) (January 1966 to 26 March 2009), EMBASE (January 1988 to 26 March 2009) and hand searching of symposia reports (1990-2009).

SELECTION CRITERIA

All randomised controlled trials (RCTs) comparing glatiramer acetate and placebo in patients with definite MS, whatever the administration schedule and disease course, were eligible for this review.

DATA COLLECTION AND ANALYSIS

Both patients with RR and P MS were analysed. Study protocols were comparable across trials. No major flaws were found in methodological quality. However, efficacy of blinding should be balanced against side effects, including injection-site reactions.

MAIN RESULTS

Among 409 retrieved references, we identified 16 RCTs; six of them, published between 1987 and 2007, met the selection criteria and were included in this review. Five hundred and forty RR patients and 1049 PMS contributed to the analysis. In RR MS, a decrease in the mean EDSS score (-0.33 and -0.45), was found respectively at 2 years and 35 months without any significant effect on sustained disease progression. The reduction of mean number of relapse was evident at 1 year (-0.35 ) 2 years (-0.51 ) and 35 months (-0.64), but significant studies ' heterogeneity was found. The number of hospitalisations and steroid courses were significantly reduced. No benefit was shown in P MS patients. No major toxicity was found. The most common systemic adverse event was a transient and self-limiting patterned reaction of flushing, chest tightness, sweating, palpitations, anxiety. Local injection-site reactions were observed in up to a half of patients treated with glatiramer acetate, thus making a blind assessment of outcomes questionable.

AUTHORS' CONCLUSIONS

Glatiramer acetate did show a partial efficacy in RR MS in term of relapse -related clinical outcomes, without any significant effect on clinical progression of disease measured as sustained disability. The drug is not effective in progressive MS patients.

Long-term (up to 22 years), open-label, compassionate-use study of glatiramer acetate in relapsing—remitting multiple sclerosis

To evaluate the safety and efficacy of long-term glatiramer acetate (GA) therapy, 46 patients with relapsing—remitting multiple sclerosis (RRMS) were treated for up to 22 years in an ongoing, open-label study. Kurtzke expanded disability status scale (EDSS) was measured every six months, relapses were reported at occurrence and patients self-reported adverse events (AEs). At GA initiation, disease durations ranged from 0—20 years (median 6.0 years) and at data cut-off (October 2004), GA therapy duration ranged from 1—22 years (median 12.0 years). Mean EDSS score increased 0.9 ± 1.9 from the pretreatment score (3.0 ± 1.8; P = 0.076). Only 10/28 (36%) patients with baseline EDSS <4.0 had a last observed value ≥ 4.0 and 8/34 (24%) with entry EDSS < 6.0 reached EDSS ≥ 6.0. A majority (57%) maintained improved or unchanged EDSS scores. Annualized relapse rate decreased to 0.1 ± 0.2 from 2.9 ± 1.4 prestudy ( P < 0.0001). Of the 18 remaining patients in October 2004 (average disease duration 23 years), 17% with baseline EDSS scores < 4.0 reached EDSS ≥ 4.0 and 28% with baseline scores < 6.0 reached EDSS ≥ 6.0. Adverse events were similar to those reported in short-term clinical trials. This study shows a low rate of relapses and EDSS progression in RRMS patients on GA for up to 22 years. Multiple Sclerosis 2008; 14: 494—499. http://msj.sagepub.com

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 the treatment of multiple sclerosis

Glatiramer acetate is an immunomodulating drug used in the treatment of multiple sclerosis. It consists of a copolymer of amino acid residues in the same stoichiometric proportions as in myelin basic protein. Its mechanism of action is not entirely known and is probably multifaceted, with deletion of some immune cell populations and stimulation of others in these patients. Some mechanisms involve neuroprotectant effects. There is ample evidence of its efficacy in relapsing-remitting disease, using both clinical and imaging measures of disease activity, and in this paper we review the clinical and basic studies of this drug. Finally we discuss how some of its neuroprotectant effects may be useful in neurodegeneration such as is seen in more advanced cases of multiple sclerosis and other diseases such as amyotrophic lateral sclerosis and Parkinson's disease.

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.

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.

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.

Therapy with glatiramer acetate for multiple sclerosis

BACKGROUND

Some clinical data have shown that glatiramer acetate (Copaxone), a synthetic amino acid polymer empirically found to suppress experimental allergic encephalomyelitis (EAE), an animal model of MS, might help improve the outcome of patients with multiple sclerosis (MS).

OBJECTIVES

We performed a Cochrane review of all randomised, placebo-controlled trials of glatiramer acetate in MS, whatever the disease course.

SEARCH STRATEGY

We searched the Cochrane MS Group trials register (June 2003), the Cochrane Central Register of Controlled Trials (CENTRAL) (Issue 2, 2003), MEDLINE (PubMed) (January 1966 to June 2003), EMBASE (January 1988 to June 2003) and hand searching of symposia reports (1990-2002) from the neurological Associations and MS Societies in both Europe and America.

SELECTION CRITERIA

All randomised controlled trials (RCTs) comparing glatiramer acetate and placebo in patients with definite MS, whatever the administration schedule and disease course, were eligible for this review.

DATA COLLECTION AND ANALYSIS

Both patients with relapsing-remitting (RR) and chronic progressive (CP) MS were analysed. Study protocols were comparable across trials as to patient entry criteria and outcome definition. No major flaws were found in methodological quality. However, efficacy of blinding should be balanced against well-known side effects, including injection-site reactions in glatiramer acetate-treated patients.

MAIN RESULTS

A total of 646 patients contributed to this review, as it is summarised in Table 01. Glatiramer acetate did not show any significant effect on disease progression, measured as a sustained worsening in the Expanded Disability Status Scale (EDSS). On the other hand, a slight decrease in the mean EDSS score, driven by a major study, should be considered in the light of the limited validity of this outcome measure. No benefit was shown in CP MS patients (progression at two years: RR=0.69, 95% CI [0.33 to 1.46]). The frequency of reported adverse events does not support any major toxicity associated with glatiramer acetate administration. The most common systemic adverse event was a transient and self-limiting patterned reaction of flushing, chest tightness, sweating, palpitations, anxiety (relative risk = 3.40 (95% CI [2.22 to 5.21], p <0.00001]). Local injection-site reactions were observed in up to a half of patients treated with glatiramer acetate, thus making a blind assessment of outcomes questionable.

REVIEWER'S CONCLUSIONS

Glatiramer acetate did not show any beneficial effect on the main outcome measures in MS, i.e. disease progression, and it does not substantially affect the risk of clinical relapses. Therefore its routine use in clinical practice is not currently supported. More investigations are needed. Further research should also develop more reliable measures of patient disability over time and include quality of life among primary outcomes.

Functional roles and therapeutic targeting of gelatinase B and chemokines in multiple sclerosis

Multiple sclerosis (MS) is a demyelinating disease of the CNS of unknown cause. Pathogenetic mechanisms, such as chemotaxis, subsequent activation of autoreactive lymphocytes, and skewing of the extracellular proteinase balance, are targets for new therapies. Matrix metalloproteinase gelatinase B (MMP-9) is upregulated in MS and was recently shown to degrade interferon beta, one of the drugs used to treat MS. Consequently, the effect of endogenously produced interferon beta or parenterally given interferon beta may be increased by gelatinase B inhibitors. Blockage of chemotaxis or cell adhesion molecule engagement, and inhibition of hydroxymethyl-glutaryl-coenzyme-A reductase to lower expression of gelatinase B, may become effective treatments of MS, alone or in combination with interferon beta. This may allow interferon beta to be used at lower doses and prevent side-effects.

Glatiramer acetate (Copaxone) therapy for multiple sclerosis

Glatiramer acetate (GA) (Copaxone(R)) is a worldwide-approved drug for the treatment of relapsing multiple sclerosis (MS), an autoimmune disease of the CNS. The drug is a synthetic copolymer with an amino acid composition based on the structure of myelin basic protein, one of the autoantigens implicated in the pathogenesis of MS and experimental autoimmune encephalomyelitis (EAE). Developed initially as a "tool" to study EAE, the drug unexpectedly inhibited disease and was subsequently developed for the treatment of MS. The drug has been shown in controlled clinical trials to significantly reduce relapse rate and progression of disability in MS with long-term efficacy, remarkable safety, and tolerability. Efficacy as measured by magnetic resonance imaging parallels its clinical benefits as manifested by a reduction in gadolinium-enhancing lesions and brain atrophy. The mechanism of action of the drug in humans is believed to involve the induction of glatiramer-reactive regulatory cells, including CD4+ and CD8+ T-cells. Glatiramer-reactive Th2 cells are believed to enter the brain and, through cross-reactivity with myelin antigens, produce bystander suppression, antiinflammatory effects, and neuroprotection.

Comparative assessment of immunomodulating therapies for relapsing-remitting multiple sclerosis

The past decade has seen unprecedented advances in the development of disease-modifying therapies for relapsing-remitting multiple sclerosis (RRMS), a disease that has a worldwide prevalence of two million patients. Four agents with the ability to modulate the immune system are now being widely used for RRMS. Of these, three are forms of interferon (IFN)-beta [IFNbeta-1b and two preparations of IFNbeta-1a (Avonex and Rebif], and one is a polypeptide of four amino acids (glatiramer acetate) with a unique mechanism of action. The administration regimens for the IFNbeta-1a products differ, with Avonex being given as 30 microg intramuscularly once a week and Rebif being given as 22 or 44 microg subcutaneously three times a week. It appears safe to predict that both forms of IFNbeta and glatiramer acetate will remain standard treatments for MS for years to come. However, with four therapeutic options available for RRMS, selecting a single therapy is often difficult and necessitates comparisons of the agents, which can be contentious. All four agents have shown superiority over placebo in pivotal phase III trials. Three recent prospective comparative studies have indicated that IFNbeta-1b, Rebif and glatiramer acetate may be more optimal choices than Avonex for patients with RRMS. In a pharmaceutical environment with an estimated worldwide market of $US2.5 billion annually for RRMS, comparative studies are understandably provocative, but at the same time provide meaningful information to clinicians and patients.

Glatiramer acetate (Copaxone) therapy induces CD8(+) T cell responses in patients with multiple sclerosis

Glatiramer acetate (GA; Copaxone) is a random copolymer of glutamic acid, lysine, alanine, and tyrosine that is used therapeutically in patients with multiple sclerosis (MS). To investigate the mechanism of the drug's immunomodulatory effect, we used immunophenotypic approaches to characterize the precise nature of GA-induced T cell responses. We demonstrate here that healthy individuals and untreated MS patients exhibit prominent T cell proliferative responses to GA. However, these responses are different in distinct subsets of T cells. Whereas GA-induced CD4(+) T cell responses are comparable in healthy individuals and MS patients, CD8(+) T cell responses are significantly lower in untreated MS patients. Treatment with GA results in upregulation of these CD8(+) responses with restoration to levels observed in healthy individuals. Both CD4(+) and CD8(+) GA-specific responses are HLA-restricted. GA therapy also induces a change in the cytokine profile of GA-specific CD4(+) and CD8(+) T cells. This study provides the first direct immunophenotypic evidence, to our knowledge, of GA-specific CD8(+) T cell responses and their upregulation during the course of therapy, which may suggest a role for these responses in the immunomodulatory effects of the drug.

Risk-benefit assessment of glatiramer acetate in multiple sclerosis

Glatiramer acetate, formerly known as copolymer 1, is a mixture of synthetic polypeptides composed of four amino acids. Glatiramer acetate has been shown to be effective in preventing and suppressing experimental autoimmune encephalitis (EAE), the animal model of multiple sclerosis (MS). Therefore it was tested in several clinical studies, where it was found to slow the progression of disability and to reduce the relapse rate and the magnetic resonance imaging (MRI)-defined disease activity and burden in relapsing-remitting MS. As a daily standard dose, 20mg of glatiramer acetate is injected subcutaneously. After injection, glatiramer acetate undergoes rapid degradation to amino acids and shorter peptides; so it is not possible to measure any systemic plasma concentrations or excretion rates. Two major mechanisms have been proposed to explain the effects of glatiramer acetate in EAE and MS: the induction of glatiramer acetate-reactive T helper 2 (Th2)-like regulatory suppressive cells and the interference with T cell activation as an altered peptide ligand. The most common adverse effects were mild injection site reactions (erythema, inflammation and induration). The most remarkable adverse event is the acute and transient immediate postinjection reaction manifested by flushing, chest tightness, palpitations and dyspnoea. Other reported adverse effects are transient chest pain and lymphadenopathy. Antibodies to glatiramer acetate induced during treatment do not interfere with its clinical effects. In several controlled clinical studies, glatiramer acetate has been shown to provide consistent, reproducible clinical benefits in the target population of patients with relapsing-remitting MS. The safety profile and risk-benefit ratio are excellent. Overall, glatiramer acetate is very well tolerated and has an excellent risk-benefit profile in patients with relapsing-remitting MS.

Copolymer 1 (glatiramer acetate) in relapsing forms of multiple sclerosis: open multicenter study of alternate-day administration

Daily 20-mg doses of Copolymer 1 have been shown to significantly decrease the relapse rate in patients with multiple sclerosis (MS). In the present open-label study, patients with relapsing MS were treated with the same dose of Copolymer 1 administered on alternate days. Sixty-eight patients were recruited: fifty-one and forty-one patients completed 1 and 2 years of treatment respectively. The relapse rate during the 2 years of treatment decreased by 80.8% compared with the 2 years before treatment (means, 0.56 +/- 1.02 versus 2.91 +/- 1.10, respectively; p < 0.0001). This lower rate is comparable with that obtained with daily open-label administration previously reported by the authors. The score on the Expanded Disability Status Scale did not differ from that at baseline after the first year of treatment, although it increased somewhat at the end of the second year (baseline = 2.72 +/- 1.55, 1 year = 2.71 +/- 1.59, 2 years = 2.97 +/- 1.80; p < 0.008). The drug was very well tolerated. This preliminary open-label study suggests that alternate-day therapy has beneficial effects and is well tolerated, comparing favorably with the effects of daily injections of Copolymer 1 in patients with relapsing MS. These results should be confirmed by randomized double-blind examinations.

Glatiramer acetate in the treatment of multiple sclerosis

This review article summarises the initial preclinical studies as well as the different stages of clinical trials in multiple sclerosis (MS) with Copolymer 1 (Cop 1), recently denoted glatiramer acetate. Experimental studies on autoimmune encephalomyelitis (EAE), the animal model of MS, as well as studies on the mechanism of action in both animals and humans are discussed. The review describes the early clinical trials which were followed by Phase II and III trials, culminating in FDA approval in 1996 for the treatment of relapsing-remitting MS. The accumulated experience with glatiramer acetate indicates that its efficacy is apparently increased as a function of usage time while the favourable side effect profile is sustained. MRI studies revealed that treatment with glatiramer acetate resulted in a significant reduction of gadolinium (Gd)-enhancing lesions. Ongoing clinical trials which might extend its usage or change its mode of delivery are also described. Glatiramer acetate appears to be a treatment of choice for the relapsing-remitting type of MS.

The concept of specific immune treatment against autoimmune diseases

Copolymer 1 (Cop 1, Copaxone) is a synthetic amino acid copolymer effective in suppression of experimental allergic encephalomyelitis (EAE). The suppressive effect of Cop 1 in EAE is not restricted to a certain species, disease type or encephalitogen used for EAE induction. In phases II and III clinical trials Cop 1 was found to slow progression of disability and reduce the relapse rate in exacerbating-remitting multiple sclerosis (MS) patients. To extend this concept we have more recently shown that a similar approach is possible in the case of myasthenia gravis. We used two myasthenogenic T cell epitopes of the human acetylcholine receptor alpha-subunit and demonstrated that they are capable of triggering peripheral blood lymphocytes of the majority (>80%) of myasthenic patients tested. Both single amino acid analogs, and a dual analog composed of the tandemly arranged two single amino acid analogs were able to inhibit in vitro proliferative responses of T cell lines, and in vivo priming of lymph node cells. The dual analog inhibited experimental autoimmune myasthenia gravis even when the mice were treated fourteen days after the injection of the pathogenic T cell line.

Specific vaccines against autoimmune diseases

Copolymer 1 (Cop 1, Copaxone) is a synthetic amino acid copolymer effective in suppression of experimental allergic encephalomyelitis (EAE). The suppressive effect of Cop 1 in EAE is not restricted to a certain species, disease type or encephalitogen used for EAE induction. In phase II and III clinical trials, Cop 1 was found to slow the progression of disability and reduce the relapse rate in exacerbating-remitting multiple sclerosis (MS) patients. In vivo and in vitro studies suggest that the mechanism for Cop 1 activity in EAE and MS involves, as an initial step, the binding of Cop 1 to MHC class II molecules. This binding results in competition with myelin antigens for T-cell activation, both at the MHC and T-cell receptor levels and in induction of specific suppressor cells of the Th2 type. As an antigen-specific intervention, Cop 1 has the advantage of reduced probability for long-term damage to the immune system, and is thus a safe and effective novel therapeutic approach to MS. It also serves to illustrate the new concept of a drug/vaccine specific for a single autoimmune disease. Indeed, we have used a similar approach for myasthenia gravis. Myasthenia gravis (MG) and its experimental animal model, experimental autoimmune MG (EAMG), are immune disorders characterized by circulating antibodies and lymphocyte autoreactivity to nicotinic acetylcholine receptor (AChR). We utilized peptides representing different sequences of the human acetylcholine receptor alpha-subunit to study the role of T cells in the initiation, development and immunomodulation of myasthenia gravis. Here we summarize our studies over the last decade on T cells specific to 'myasthenogenic' epitopes of the alpha-subunit of the human acetylcholine receptor and their relevance for myasthenia gravis.

Cop 1 as a candidate drug for multiple sclerosis

Copolymer 1 (Cop 1), a synthetic copolymer of amino acids, is very effective in suppression of experimental autoimmune encephalomyelitis (EAE), the animal model for multiple sclerosis (MS). Cop 1 was found incapable of inducing EAE, yet it suppressed EAE in a variety of animal species, including primates. The immunological cross-reaction between the myelin basic protein (MBP) and Cop 1 serves as the basis for the suppressive activity of Cop 1 in EAE, by the induction of antigen-specific suppressor cells and competition with MBP for binding to major histocompatibility complex (MHC) molecules. Clinical trials with Cop 1, both Phase II and Phase III, were performed in relapsing-remitting (E-R) patients. The latter, a two-year multicenter double blind trial with 251 participating patients was conducted at 11 leading medical centers in the USA. It demonstrated a significant beneficial effect of Cop 1 in both diminishing the rate of exacerbations and improving the clinical status. The side effects of Cop 1 were only minimal. The cumulative results indicate that Cop 1 is a promising candidate drug for multiple sclerosis.

A review of the clinical efficacy profile of copolymer 1: new U.S. phase III trial data

Copolymer 1 (Copaxone) is a mixture of synthetic peptides composed of four amino acids. It has been shown to alter positively the natural history of multiple sclerosis by both reducing the relapse rate and affecting disability. A recently completed, large-scale, phase III, multicenter, double-blind study confirmed the therapeutic benefit shown in previous pilot studies. Side effects were mild and the daily subcutaneous treatment was well tolerated. Laboratory studies have shown that copolymer 1 prevents or modifies experimental allergic encephalomyelitis in several mammalian species. It induces immunologic suppressor cells, which are deficient in multiple sclerosis, and competitively inhibits the effect of central nervous system myelin antigens, thought to be important in the pathogenesis of multiple sclerosis. Copolymer 1 joins interferon beta in ushering in a new era of well-tolerated treatments for multiple sclerosis.

Synthetic approaches to vaccines for infectious and autoimmune diseases

The development is outlined of some synthetic vaccines against infectious diseases, in particular cholera, shigella and influenza. In the last case, use of the synthetic adjuvant MDP in combination with a haemagglutinin peptide has led to a synthetic vaccine with built-in adjuvanticity. The production of vaccines both by chemical synthesis and genetic engineering is described. The successful use of the synthetic amino acid copolymer COP-1 as an immunomodulatory vaccine to suppress the onset of allergic encephalomyelitis in experimental animals has led to clinical trials with patients suffering from exacerbating remitting multiple sclerosis. T-cell vaccination is an alternative approach to immunization against autoimmune diseases.

Delta 9-tetrahydrocannabinol: a novel treatment for experimental autoimmune encephalomyelitis

Since multiple sclerosis (MS) is believed to be an immune-mediated disease, it follows that its therapies should be directed towards modulating the immune system. Current MS treatments, which include the use of exogenous steroids that are immunosuppressive, do not meet therapeutic objectives. delta 9-Tetrahydrocannabinol (THC), an active component of marijuana, has been shown to be immunosuppressive. To test THC's ability to suppress an immune-mediated disease, experimental autoimmune encephalomyelitis (EAE), the laboratory model of MS, was used. Lewis rats and strain 13 guinea pigs were administered THC either before inoculation for EAE or treated with THC after injection. Control animals received placebo. The effect of dose, in addition to the timing of treatment, was also investigated. All animals treated with placebo developed severe clinical EAE 10-12 days post-injection (d.p.i.) and more than 98% died by 15 d.p.i. THC-treated animals had either no clinical signs or mild signs with delayed onset (13-15 d.p.i.) with survival greater than 95%. Examination of central nervous system tissue revealed a marked reduction of inflammation in the THC-treated animals. Therefore, as THC has been shown to inhibit both clinical and histologic EAE, it may prove to be a new and relatively innocuous agent for the treatment of immune-mediated diseases.