Laquinimod (ABR-215062) suppresses the development of experimental autoimmune encephalomyelitis, modulates the Th1/Th2 balance and induces the Th3 cytokine TGF-beta in Lewis rats

Emerging oral therapies in multiple sclerosis

Multiple sclerosis (MS) is a chronic inflammatory disease of the central nervous system. The seven therapies currently approved by regulatory agencies are administered by subcutaneous or intramuscular injection or intravenous infusion. Many phase 2 trials involving oral MS therapeutics were recently completed, as were two phase 3 trials of fingolimod and one phase 3 trial of cladribine. Numerous other oral treatments are being investigated in ongoing phase 3 trials. Although an oral route of administration is attractive, these medications also present new challenges in balancing convenience, efficacy, and safety. In this review, we examine the safety and efficacy data from emerging oral therapies in an attempt to clarify their potential future role in the treatment of MS patients.

Emerging disease-modifying oral therapies for multiple sclerosis

Although therapy for multiple sclerosis (MS) has changed substantially over the past few decades, introducing immunomodulatory drugs into everyday clinical practice, it is still not satisfactory enough in halting the disease progression and increasing disability. Moreover, its injection-based administration leads to suboptimal adherence, even further reducing the potential treatment benefits. Emerging disease-modifying oral agents for MS are therefore warranted. In this paper advances in the novel oral therapeutic approaches to MS treatment are reviewed.

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

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

Update on the treatment options for multiple sclerosis

Recent progress in the treatment of multiple sclerosis (MS) is remarkable, and the introduction of new therapies is yielding improvements in the management of MS. Furthermore, clinical trials with many different types of agents, especially selected monoclonal antibodies, have been undertaken or are ongoing, and some of the agents involved will probably be available as treatments for MS in the near future. Although these new and promising agents include targeted immunotherapies, some of them have limitations such as associated severe adverse events and the development of neutralizing antibodies. With regard to risk-benefit ratios, pharmacogenetics could shed light on inherited differences in drug metabolism and response, which would make individualized therapy possible in MS. Here, we review the recent progress in current therapeutic strategies for MS, and the potential options for future MS treatment.

Laquinimod suppress antigen presentation in relapsing-remitting multiple sclerosis: in-vitro high-throughput gene expression study

Laquinimod (LAQ) is a new immunomodulatory drug shown to be effective in the treatment of relapsing-remitting multiple sclerosis (RRMS); however, its molecular target pathways are not well recognized. In this study we characterized in-vitro the molecular effects of LAQ in peripheral blood mononuclear cells (PBMC) of healthy subjects and RRMS patients by gene expression microarrays. We demonstrated that LAQ induced suppression of genes related to antigen presentation and corresponding inflammatory pathways. These findings were demonstrated mainly via the NFkB pathway. Analysis of PBMC subpopulations identified activation of Th2 response in CD14+ and CD4+ cells and suppression of proliferation in CD8+ cells.

Optimizing the benefit of multiple sclerosis therapy: the importance of treatment adherence

Poor treatment adherence is problematic in many therapy areas, including multiple sclerosis (MS). Several immunomodulatory drugs are available for the treatment of MS, all of which require frequent parenteral administration. Current first-line therapies are two formulations of interferon (IFN) beta-1a, one of IFN beta-1b, and one of glatiramer acetate. Discontinuation of treatment is common, particularly in the first few months after initiation. Although the true effect of poor adherence to MS therapy is not known, it is likely to lead to a fall in treatment efficacy. Many factors influence a patient's adherence to treatment, including the patient's MS subtype and disability level, cognitive impairment resulting from MS, perceived lack of efficacy of the prescribed medication, and adverse events associated with MS therapy. This article summarizes the barriers to adherence to MS therapies, and discusses patient management strategies that can be employed to encourage adherence. Future advances in the field of MS treatment will be explored, including the development of orally administered drugs, which may enhance adherence.

Multiple sclerosis therapies: molecular mechanisms and future

The current treatments for multiple sclerosis (MS) are, by many measures, not satisfactory. The original interferon-β therapies were not necessarily based on an extensive knowledge of the pathophysiological mechanisms of the disease. As more and more insight has been acquired about the autoimmune mechanisms of MS and, in particular, the molecular targets involved, several treatment approaches have emerged. In this chapter, we highlight both promising preclinical approaches and therapies in late stage clinical trials that have been developed as a result of the improved understanding of the molecular pathophysiology of MS. These clinical stage therapies include oral agents, monoclonal antibodies, and antigen-specific therapies. Particular emphasis is given to the molecular targets when known and any safety concerns that have arisen because, despite the need for improved efficacy, MS remains a disease in which the safety of any agent remains of paramount importance.

Immunotherapy of multiple sclerosis

Multiple sclerosis (MS) is regarded as a prototypic inflammatory autoimmune central nervous system disorder causing neurological disability in young adults. Recommended basic immunomodulatory therapies of MS are currently interferon beta and glatiramer acetate. Both have proven to be clinically and paraclinically effective and clinical evidence suggests that treatment should be initiated as early as possible. However, despite the fact that therapeutic options for MS have significantly been widened over the past decade there is still tremendous activity in the search for new treatment options for MS. One important development in the field is reflected by the substantial number of promising results for oral therapies. Various phase III clinical trials are currently being initiated or are already underway evaluating the efficacy of a variety of orally administered agents, including cladribine, teriflunomide, laquinimod, fingolimod and fumaric acid. It is hoped that these oral therapies for MS further broaden our armament for MS therapy.

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.

Multiple sclerosis: clinical features, pathophysiology, neuroimaging and future therapies

Multiple sclerosis (MS) is a common immune-mediated progressive neurodegenerative disease of the CNS that typically manifests with periods of disease activity followed by intervals of remission. The etiology of MS remains unknown; however, existing evidence indicates that MS is a ‘whole-brain disease’ that is driven by a potent immune response against CNS antigen(s), particularly myelin peptide antigens. The immunopathogenesis of MS includes both the cell- and humorally-mediated arms of the immune system. Genetic and environmental factors play important roles in the development of MS. Application of various neuroimaging techniques to the world of MS have expanded our knowledge concerning its pathogenesis and assist us in the more accurate diagnosis of MS versus its imitators. Current treatments target acute attacks and aim to reduce future clinical relapses. A summary of the potential future therapies for MS is presented.

Kynurenine pathway metabolites in humans: disease and healthy States

Tryptophan is an essential amino acid that can be metabolised through different pathways, a major route being the kynurenine pathway. The first enzyme of the pathway, indoleamine-2,3-dioxygenase, is strongly stimulated by inflammatory molecules, particularly interferon gamma. Thus, the kynurenine pathway is often systematically up-regulated when the immune response is activated. The biological significance is that 1) the depletion of tryptophan and generation of kynurenines play a key modulatory role in the immune response; and 2) some of the kynurenines, such as quinolinic acid, 3-hydroxykynurenine and kynurenic acid, are neuroactive. The kynurenine pathway has been demonstrated to be involved in many diseases and disorders, including Alzheimer's disease, amyotrophic lateral sclerosis, Huntington's disease, AIDS dementia complex, malaria, cancer, depression and schizophrenia, where imbalances in tryptophan and kynurenines have been found. This review compiles most of these studies and provides an overview of how the kynurenine pathway might be contributing to disease development, and the concentrations of tryptophan and kynurenines in the serum, cerebrospinal fluid and brain tissues in control and patient subjects.

Novel therapeutic strategies for multiple sclerosis--a multifaceted adversary

Therapeutic strategies for multiple sclerosis have radically changed in the past 15 years. Five regulatory-approved immunomodulatory agents are reasonably effective in the treatment of relapsing-remitting multiple sclerosis, and appear to delay the time to progression to disabling stages. Inhibiting disease progression remains the central challenge for the development of improved therapies. As understanding of the immunopathogenesis of multiple sclerosis has advanced, a number of novel potential therapeutics have been identified, and are discussed here. It has also become apparent that traditional views of multiple sclerosis simply as a CD4+ T-cell-mediated disease of the central nervous system are incomplete. The pathogenic role of other immune components such as the innate immune system, regulatory T cells, T helper 17 cells and B cells is reaching centre stage, opening up exciting avenues and novel potential targets to affect the natural course of multiple sclerosis.

Development of laquinimod for relapsing–remitting multiple sclerosis

Laquinimod, a quinoline-3-carboxamide derivative, is a new, once-daily oral immunomodulatory therapy in development for the treatment of relapsing–remitting multiple sclerosis (MS). It has demonstrated efficacy in both acute and chronic experimental allergic encephalitis and in animal models of other inflammatory autoimmune diseases. It appears to act, in part, by shifting the immune response from a Th1 to a Th2 response and does not act through nonspecific immunosuppression. In Phase II studies in relapsing forms of MS, laquinimod brought about a 60% decrease in the cumulative number of gadolinium-enhancing lesions and a 33% decrease in relapse rates. In Phase II studies it was safe and well-tolerated. The most common laboratory abnormalities were a transient rise in alanine aminotransferase and C-reactive protein that returned to normal values despite continued therapy. There was no evidence of a proinflammatory effect. Phase III clinical trials for registration are in progress. Laquinimod may find use as a first-line agent in the treatment of relapsing forms of MS.

In vitrometabolism andin vivopharmacokinetics of quinoline 3-carboxamide derivatives in various species

The metabolism of a group of quinoline 3-carboxamide derivatives was evaluated in liver microsomes from various species. In addition, metabolism data were compared with in vivo pharmacokinetics in the mouse. The studied compounds were metabolized by cytochrome P450 enzymes. Microsomal clearance was low and seemed independent of a substituent in the quinoline moiety, whereas clearance was enhanced when an ethyl group replaced the methyl group at the carboxamide position. A similar metabolism with hydroxylated and dealkylated metabolites was found in the various species, with quantitative differences due to substituent. As predicted from the in vitro studies, in vivo pharmacokinetics showed low clearance and thus high exposure of the parent compounds in the mouse. The therapeutic effect seen in the acute EAE mouse model for these related compounds seems dependent on the high exposure of parent compound rather than formation of any potentially active metabolites.

Identification and development of new therapeutics for multiple sclerosis

In recent years, large efforts have been undertaken to establish new therapeutic options for the treatment of multiple sclerosis (MS). So far, all of these strategies more or less specifically target subsets of the immune response in MS, including not only activation and expansion of T cells, their circulation and transmigration over the blood-brain barrier but also other cell types such as B cells and probably also natural killer cells. Here, we review available data on the most promising (at present) new therapeutic approaches. These involve the orally available compounds cladribine, FTY720, fumaric-acid esters, laquinimod and teriflunomide in addition to the monoclonal antibodies alemtuzumab, daclizumab, natalizumab and rituximab. After successful completion of Phase III studies, these compounds might have the potential to add to the current therapeutic armentarium especially for relapsing remitting disease courses in the near future, possibly opening the way to a more individualized treatment.

Emerging oral therapies for multiple sclerosis

BACKGROUND

Current disease-modifying drugs (DMDs) have positively affected the treatment of relapsing-remitting multiple sclerosis (RRMS); however, the requirement for long-term injections imposes a burden on patients and may lead to reduced adherence in some cases. Furthermore, not all patients respond adequately to current DMDs, suggesting that certain patients require different therapeutic approaches. Therefore, alternative MS treatments with less invasive routes of administration and new modes of action are needed to expand the current treatment repertoire, increase patient satisfaction and adherence, and thereby improve efficacy.

DISCUSSION

This review discusses the current unmet need for an orally administered treatment for RRMS, including potential benefits of this route of administration, and implications for improved treatment outcomes. Oral drugs that are currently in Phase II/III clinical development are discussed.

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

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

Novel oral agents for multiple sclerosis

In 1993, interferon beta-1b, the first clinically proven disease-modifying agent for multiple sclerosis, was approved, with several comparable agents following close behind. These agents have been beneficial in reducing relapse events and MRI lesions, but all require parenteral administration, leading some otherwise eligible patients to decline such therapies. Oral agents have been studied for decades with mixed results, but a small number of medications currently being tested in phase II/III clinical trials have shown promise in efficacy and tolerability. This review assesses the results of the more thoroughly studied of these agents, some of which may soon be approved for use in multiple sclerosis.

Inhibition of the development of chronic experimental autoimmune encephalomyelitis by laquinimod (ABR-215062) in IFN-beta k.o. and wild type mice

Laquinimod is a novel oral immunomodulatory substance, which is currently developed for the treatment of multiple sclerosis (MS). The ability of laquinimod to inhibit disease development was investigated in chronic experimental autoimmune encephalomyelitis (chEAE) in IFN-beta k.o. mice and wild type mice. Laquinimod was shown to inhibit both disease development and histopathological changes in the CNS. Furthermore, laquinimod was found to be independent of endogenous IFN-beta for its effect in chEAE. When laquinimod was combined with exogenous IFN-beta, a synergistic disease inhibitory effect was seen. These findings using laquinimod in preclinical disease models for MS emphasize the potential of laquinimod in the future treatment of MS also in patients that do not respond to IFN-beta monotherapy. Furthermore, the results indicate that laquinimod may favourably be combined with IFN-beta.

Determination of the immunomodulator laquinimod in human plasma by liquid chromatography/tandem mass spectrometry; development, validation and application of two methods in clinical pharmacokinetic profiling

Laquinimod (ABR-215062) is a synthetic compound currently undergoing clinical development for oral treatment of multiple sclerosis. The present paper describes the development, validation and clinical application of two rapid and sensitive methods for the determination of ABR-215062 in human plasma. Both methods use liquid chromatography/tandem mass spectrometry (LC/MS/MS) with electrospray ionization in positive mode and a stable isotope (13C6)-labeled ABR-215062 as internal standard for calibration. The selected reaction monitoring was based on the transitions m/z 357.1 --> 236.1 for ABR-215062, and either m/z 363.2 --> 236.1 or 365.2 --> 238.1 for 13C6-ABR-215062. Method 1, aimed and validated for low level determinations (0.4-100 nmol/L) of ABR-215062, utilizes solid-phase extraction followed by isocratic elution. Method 2, aimed and validated for wide range determinations (0.75-15000 nmol/L) of ABR-215062, utilizes protein precipitation followed by fast gradient elution. The methods were validated with respect to selectivity, lower limit of quantification (LLOQ), dynamic range, precision, accuracy, extraction recovery and ruggedness. Furthermore, the stability of low level ABR-215062 in plasma was investigated. The methods were also applied in clinical trials. The LLOQs were 0.4 and 0.75 nmol/L for methods 1 and 2, respectively. The intra- and inter-day precision for the methods were 1.6-3.5% and 2.1-5.7%. The extraction recoveries were 90-97% for both methods. ABR-215062 was stable in plasma for at least 3 months when stored at -20 degrees C. In conclusion, our developed methods were found to be selective, sensitive, robust and suitable for applications in clinical pharmacokinetic profiling.

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.

Design, synthesis, and biological evaluation of novel 4-hydro-quinoline-3-carboxamide derivatives as an immunomodulator

A series of novel quinoline-3-carboxamide derivatives were synthesized and evaluated for their immunomodulatory activity. The compounds were tested in vitro for effects on spleen lymphocyte proliferation and TNF-alpha production by macrophage. Three compounds showed immunomodulatory profiles similar to and more potent than those of linomide and FR137316 and were selected for further pharmacological studies in vivo.