Recent developments in multiple sclerosis therapeutics

Treatment against human endogenous retrovirus: a possible personalized medicine approach for multiple sclerosis

Human endogenous retroviruses (HERV) represent about 8 % of the human genome. Some of these genetic elements are expressed in pathological circumstances. A HERV protein, the multiple sclerosis-associated retrovirus (MSRV) envelope protein (MSRV-Env), is expressed in the blood and active brain lesions of multiple sclerosis (MS) patients. It possesses pro-inflammatory and myelinotoxic properties. The patterns of expression and pathogenic properties of MSRV-Env make it a relevant drug target for MS therapeutics-in particular for preventing neurodegeneration, a key component of progressive forms of MS. An immunoglobulin G4 monoclonal antibody (mAb), called GNbAC1, has been developed to neutralize this pathogenic target. After showing neutralizing effects in vitro and in mouse models of MS, GNbAC1 is now in phase II clinical development. MSRV-related biomarkers such as MSRV-Env and MSRV polymerase (MSRV-Pol) gene transcripts are overexpressed in the blood and cerebrospinal fluid of patients with MS. These biomarkers may have prognostic value for long-term MS evolution, and their transcription levels in blood decline during treatments with GNbAC1, which has also been reported in patients administered reference MS drugs such as natalizumab or interferon-β. GNbAC1 as a new MSRV-Env-antagonist mAb could be a specific and causal treatment for MS, with a particular application for progressive forms of the disease. For possible use in companion diagnostic tests, MSRV-associated biomarkers could open the door to a personalized therapeutic approach for MS.

Multifunctional compounds: smart molecules for multifactorial diseases

Multifunctional compounds (MFCs) are designed broadly as hybrid or conjugated drugs or as chimeric drugs from two or more pharmacophores/drugs having specific pharmacological activities. These are capable of eliciting multiple pharmacological actions and have emerged as magic bullets in treatment of multifactorial diseases. Many research articles disclosing the development of such compounds for treatment of multifactorial diseases are published during last 7 years. Some successful MFC candidates for multifactorial CNS disorders include ziprasidone, duloxetine, ladostigil and M-30 whereas sunitinib, lapatinib and synthetic oleandane triterpinoids are the successful MFC candidates for various cancers. Many more compounds derived from berberine, tacrine, artemisnin, quinine, NSAIDs, pralidoxine, donepezil, rivastigmine, curcumin and various antioxidants are under investigations for exploration of their multifunctional potential. In general, MFCs possess the advantages of reduced molecularity, no drug-drug interactions and improved pharmacokinetics and pharmacodynamics. A MFC derived from two or more different pharmacophores exerts its activities by interacting with respective receptors of its constituent pharmacophores. It may also exhibit additional binding interactions with the receptor sites that may be responsible for significantly improved or additional activities. The present review discusses various MFCs developed for specific class of disorders with an aim to provide an insight into the strategies in medicinal chemistry for development of such compounds.

Novel therapeutic options for multiple sclerosis

Multiple sclerosis (MS) is considered as an autoimmune disorder of the CNS with neuro-inflammatory and neurodegenerative components. We review here the innovative drugs recently registered and those in clinical development for MS. Immunomodulation has been the preferred therapeutic approach for MS since the first IFN-β was registered in the 1990s. Several immunomodulators are now available, which show a high efficacy in reducing the number of relapses in patients with the relapsing-remitting form of MS (RRMS). The high efficacy of most immunomodulators is, however, associated with substantial safety risks, notably concerning infections or cancers. Recently oral drugs have been approved for RRMS; however, biologics, and notably, monoclonal antibodies are still well represented in the development pipelines. An unmet medical need remains the treatment of the primary and secondary forms of MS or chronic progressive MS (CPMS). Half a dozen immunomodulators with proven efficacy in RRMS are now undergoing evaluation in Phase III trials in the CPMS indication. Neuroprotective drugs that prevent demyelination and/or improve remyelination would be interesting for CPMS, but these drugs are currently in the early development phase and their efficacy has not been demonstrated yet.

Optimizing therapeutics in the management of patients with multiple sclerosis: a review of drug efficacy, dosing, and mechanisms of action

Multiple sclerosis (MS) is a debilitating neurological disorder that affects nearly 2 million adults, mostly in the prime of their youth. An environmental trigger, such as a viral infection, is hypothesized to initiate the abnormal behavior of host immune cells: to attack and damage the myelin sheath surrounding the neurons of the central nervous system. While several other pathways and disease triggers are still being investigated, it is nonetheless clear that MS is a heterogeneous disease with multifactorial etiologies that works independently or synergistically to initiate the aberrant immune responses to myelin. Although there are still no definitive markers to diagnose the disease or to cure the disease per se, research on management of MS has improved many fold over the past decade. New disease-modifying therapeutics are poised to decrease immune inflammatory responses and consequently decelerate the progression of MS disease activity, reduce the exacerbations of MS symptoms, and stabilize the physical and mental status of individuals. In this review, we describe the mechanism of action, optimal dosing, drug administration, safety, and efficacy of the disease-modifying therapeutics that are currently approved for MS therapy. We also briefly touch upon the new drugs currently under investigation, and discuss the future of MS therapeutics.

Adaptive immune responses in CNS autoimmune disease: mechanisms and therapeutic opportunities

The processes underlying autoimmune CNS inflammation are complex, but key roles for autoimmune lymphocytes seem inevitable, based on clinical investigations in multiple sclerosis (MS) and related diseases such as neuromyelitis optica, together with the known pathogenic activity of T cells in experimental autoimmune encephalomyelitis (EAE) models. Despite intense investigation, the details of etiopathology in these diseases have been elusive. Here we describe recent advances in the rodent models that begin to allow a map of pathogenic and protective immunity to be drawn. This map might illuminate previous successful and unsuccessful therapeutic strategies targeting particular pathways, whilst also providing better opportunities for the future, leading to tailored intervention based on understanding the quality of each individual's autoimmune response.

The use of focus groups to characterize symptoms in persons with multiple sclerosis

Multiple sclerosis is a chronic neurological disease with a myriad of symptoms. Because most work has been quantitative, it is important to capture symptoms as described by patients who experience them, using a qualitative approach. The purpose of our study was to describe and identify symptoms, with emphasis on co-occurrence, using focus groups. Three focus groups were conducted (N = 16) with relapsing-remitting multiple sclerosis patients. Common symptoms, described as both singular and co-occurring, were problems with balance, cognition, vision, and heat intolerance. These findings augment past characterizations of symptoms experienced in persons with relapsing-remitting multiple sclerosis and provide evidence for future studies.

GNbAC1, a humanized monoclonal antibody against the envelope protein of multiple sclerosis-associated endogenous retrovirus: a first-in-humans randomized clinical study

BACKGROUND

Human endogenous retrovirus (HERV) genes represent about 8% of the human genome. A member of the HERV family W, the Multiple Sclerosis-Associated Retrovirus (MSRV) gene, encodes an envelope protein (Env), which can activate a proinflammatory and autoimmune cascade through its interaction with Toll-like receptor 4. Due to its proinflammatory property and an inhibitory effect on oligodendrocyte precursor cell differentiation, the MSRV-Env protein could play a crucial role in the pathogeny of multiple sclerosis. GNbAC1 is a humanized monoclonal antibody of the immunoglobulin G4 type, which is directed against MSRV-Env. After validation of the MSRV-Env as a therapeutic target in preclinical experimental models, a clinical development program was initiated.

OBJECTIVE

This study evaluated the safety profile, pharmacokinetic parameters, and immunogenicity of GNbAC1 in healthy male volunteers.

METHODS

In this first-in-humans, Phase I, randomized, double-blind, placebo-controlled, dose-escalation study, each subject received a single dose of IV GNbAC1 0.0025, 0.025, 0.15, 0.6, 2, or 6 mg/kg or inactive vehicle (placebo), infused over 1 hour. Tolerability and other laboratory parameters were observed, and regular blood sampling was performed, to study the pharmacokinetic properties and immunogenicity of this monoclonal antibody.

RESULTS

A total of 33 male subjects (mean age, 44 years) completed the study. GNbAC1 was well tolerated after dosing in all subjects and in each dose cohort. Only minor and nonspecific adverse events (AEs) were recorded; no serious AEs were reported. Pharmacokinetic data show a dose-linear pharmacokinetic profile. The mean elimination half-life ranged between 19 and 26 days, with therapeutically efficient concentrations maintained over a 4-week periods at doses of 2 and 6 mg/kg. No emergence of anti-GNbAC1 antibodies were detected after dosing in any subject over the entire observation period of 64 days.

CONCLUSIONS

In these healthy male subjects, the safety and pharmacokinetic profiles of GNbAC1 appeared favorable. These findings are expected to allow for the launch of a Phase II development program for this innovative therapeutic approach in patients with multiple sclerosis. ClinicalTrials.gov identifier: NCT01699555.

Sphingosine kinase 1 deficiency exacerbates LPS-induced neuroinflammation

The pathogenesis of inflammation in the central nervous system (CNS), which contributes to numerous neurodegenerative diseases and results in encephalopathy and neuroinflammation, is poorly understood. Sphingolipid metabolism plays a crucial role in maintaining cellular processes in the CNS, and thus mediates the various pathological consequences of inflammation. For a better understanding of the role of sphingosine kinase activation during neuroinflammation, we developed a bacterial lipopolysaccharide (LPS)-induced brain injury model. The onset of the inflammatory response was observed beginning 4 hours after intracerebral injection of LPS into the lateral ventricles of the brain. A comparison of established neuroinflammatory parameters such as white matter rarefactions, development of cytotoxic edema, astrogliosis, loss of oligodendrocytes, and major cytokines levels in wild type and knockout mice suggested that the neuroinflammatory response in SphK1-/- mice was significantly upregulated. At 6 hours after intracerebroventricular injection of LPS in SphK1-/- mice, the immunoreactivity of the microglia markers and astrocyte marker glial fibrillary acidic protein (GFAP) were significantly increased, while the oligodendrocyte marker O4 was decreased compared to WT mice. Furthermore, western blotting data showed increased levels of GFAP. These results suggest that SphK1 activation is involved in the regulation of LPS induced brain injury. RESEARCH HIGHLIGHTS: • Lipopolysaccharide (LPS) intracerebral injection induces severe neuroinflammation. • Sphingosine kinase 1 deletion worsens the effect of the LPS. • Overexpression of SphK1 might be a potential new treatment approach to neuroinflammation.

Enhancing adherence through education

The treatment of multiple sclerosis (MS) has advanced greatly since the introduction of disease-modifying therapies (DMTs) in the early 1990s. Although the DMTs have exhibited significant efficacy in relapsing-remitting MS and other forms of the disease, the degree of benefit depends heavily on patient adherence to recommended regimens. This article addresses some of the most pressing areas of unmet need in educating advanced-practice nurses, neurologists, patients, and support care partners regarding strategies that can overcome obstacles to adherence. The observations presented here are based on clinical experience with real-life cognitive, psychosocial, and cultural impediments to adherence. The article also explores the ways in which adherence may be affected by emerging therapies for MS (such as oral agents) as well as the educational needs that will arise with the further evolution of MS care.

Voltage-gated sodium channels as therapeutic targets in epilepsy and other neurological disorders

Voltage-gated sodium channels (VGSCs) are key mediators of intrinsic neuronal and muscle excitability. Abnormal VGSC activity is central to the pathophysiology of epileptic seizures, and many of the most widely used antiepileptic drugs, including phenytoin, carbamazepine, and lamotrigine, are inhibitors of VGSC function. These antiepileptic drugs might also be efficacious in the treatment of other nervous system disorders, such as migraine, multiple sclerosis, neurodegenerative diseases, and neuropathic pain. In this Review, we summarise the structure and function of VGSCs and their involvement in the pathophysiology of several neurological disorders. We also describe the biophysical and molecular bases for the mechanisms of action of antiepileptic VGSC blockers and discuss the efficacy of these drugs in the treatment of epileptic and non-epileptic disorders. Overall, clinical and experimental data indicate that these drugs are efficacious for a range of diseases, and that the development of drugs with enhanced selectivity for specific VGSC isoforms might be an effective and novel approach for the treatment of several neurological diseases.