Siponimod (BAF312) for the treatment of secondary progressive multiple sclerosis: Design of the phase 3 EXPAND trial

Revisiting CYP2C9-Mediated drug-drug Interactions: A Review

Drug-drug interactions (DDI) are the most common cases that occur in our healthcare in which are very alarming as it may lead to severe complications. Consumption of natural products concomitantly with conventional drugs or treatment using polypharmacy have become the norm that promoting the potential of pharmacokinetic or pharmacodynamic drug interactions as the combination may mimic, increase or reduce the effects of the drug or the herb which could result in clinically significant interactions. CYP2C9 is the second major isoform from CYP450 family of enzyme, which responsible in phase 1 metabolism of 15-20% clinical drugs. Up to date, many substrates of CYP2C9 have been discovered and these discoveries may open more doors for potential drug-drug interactions in patients. Many studies have been done to evaluate the effect of drugs on the activity of CYP2C9 and how it influenced the effectiveness of therapy in patients. Various data regarding CYP2C9 related DDI from in vitro, in vivo and clinical studies were critically discussed in this review to provide insights on how these drugs and natural products may exhibit drug interactions clinically. This review could be beneficial reference material for health practitioners and researchers.

Ponesimod suppresses hepatitis B virus infection by inhibiting endosome maturation

The discovery of novel antivirals to treat hepatitis B virus (HBV) infection is urgently needed, as the currently available drugs mainly target viral proteins at replication step, whereas host factors also play significant roles in HBV infection. Although numerous studies have reported candidate drugs for HBV treatment, there remains a need to find a new drug that may target other steps of the HBV life cycle. In this study, by drug screening of a 533 G-protein-coupled receptors (GPCRs)-associated compound library, we identified ponesimod, a selective agonist of sphingosine-1-phosphate receptor 1 (S1P₁), as a drug candidate for the suppression of HBV infection. However, the anti-HBV effect of ponesimod is independent of S1P₁ and other sphingosine-1-phosphate receptors (S1PRs). Treatment with ponesimod at an early step of infection but not at a post-entry step significantly reduced the HBV relaxed circular DNA (rcDNA) level in a dose-dependent manner. Ponesimod treatment did not inhibit attachment, binding, or internalization of HBV particles via endocytosis through an interaction with sodium taurocholate cotransporting polypeptide (NTCP) or epidermal growth factor receptor (EGFR). Importantly, during the transportation of HBV particles to the nucleus, co-localization of HBV with early endosomes but not with late endosomes and lysosomes was induced by the treatment with ponesimod, suggesting that ponesimod interferes with the conversion of early endosomes to late endosomes without significant damage to cellular growth. Conclusion: Ponesimod is a promising anti-HBV drug targeting the endosome maturation of HBV. This finding can be applied to the development of novel antivirals that target the trafficking pathway of HBV particles.

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.

Pharmacological Approaches to the Management of Secondary Progressive Multiple Sclerosis

It is well recognised that the majority of the impact of multiple sclerosis (MS), both personal and societal, arises in the progressive phase where disability accumulates inexorably. As such, progressive MS (PMS) has been the target of pharmacological therapies for many years. However, there are no current licensed treatments for PMS. This stands in marked contrast to relapsing remitting MS (RRMS) where trials have resulted in numerous licensed therapies. PMS has proven to be a more difficult challenge compared to RRMS and this review focuses on secondary progressive MS (SPMS), where relapses occur before the onset of gradual, irreversible disability, and not primary progressive MS where disability accumulation occurs without prior relapses. Although there are similarities between the two forms, in both cases pinpointing when PMS starts is difficult in a condition in which disability can vary from day to day. There is also an overlap between the pathology of relapsing and progressive MS and this has contributed to the lack of well-defined outcomes, both surrogates and clinically relevant outcomes in PMS. In this review, we used the search term 'randomised controlled clinical drug trials in secondary progressive MS' in publications since 1988 together with recently completed trials where results were available. We found 34 trials involving 21 different molecules, of which 38% were successful in reaching their primary outcome. In general, the trials were well designed (e.g. double blind) with sample sizes ranging from 35 to 1949 subjects. The majority were parallel group, but there were also multi-arm and multidose trials as well as the more recent use of adaptive designs. The disability outcome most commonly used was the Expanded Disability Status Scale (EDSS) in all phases, but also magnetic resonance imaging (MRI)-measured brain atrophy has been utilised as a surrogate endpoint in phase II studies. The majority of the treatments tested in SPMS over the years were initially successful in RRMS. This has a number of implications in terms of targeting SPMS, but principally implies that the optimal strategy to target SPMS is to utilise the prodrome of relapses to initiate a therapy that will aim to both prevent progression and slow its accumulation. This approach is in agreement with the early targeting of MS but requires treatments that are both effective and safe if it is to be used before disability is a major problem. Recent successes will hopefully result in the first licensed therapy for PMS and enable us to test this approach.

The Use of Oral Disease-Modifying Therapies in Multiple Sclerosis

Three oral disease-modifying drugs-fingolimod, teriflunomide, and dimethyl fumarate (DMF)-are available for treatment of relapsing forms of multiple sclerosis (MS). All three agents were approved in the last decade, primarily on the basis of a moderate to substantial reduction in the occurrence of MS relapses and central nervous system lesion formation detected by MRI. In the trials leading to approval, the first oral disease-modifying drug, fingolimod, reduced the annualized relapse rate (ARR) from 0.40 in placebo-treated patients to 0.18 (FREEDOMS) and from 0.33 in patients treated with interferon β1a intramuscularly to 0.16 (TRANSFORMS). Teriflunomide, approved on the basis of the two placebo-controlled trials TEMSO and TOWER, demonstrated a reduction in the ARR from 0.54 to 0.37 and from 0.50 to 0.32 respectively. The latest oral MS medication, approved in 2014, is DMF, which had been used in a different formulation for treatment of psoriasis for decades. In the 2-year DEFINE study, the proportion of patients with a relapse was reduced to 27 %, compared with 46 % in placebo arm, whereas in the CONFIRM trial, the ARR was reduced from 0.40 (placebo) to 0.22 in the DMF-treated group of patients. In this review, we will elucidate the mechanisms of action of these three medications and compare their efficacy, safety, and tolerability as a practical guideline for their use. We will further discuss effects other than relapse reduction these small molecules may exert, including potential activities within the central nervous system, and briefly summarize emerging data on new oral MS drugs in clinical development.

The dual S1PR1/S1PR5 drug BAF312 (Siponimod) attenuates demyelination in organotypic slice cultures

Background

BAF312 (Siponimod) is a dual agonist at the sphingosine-1 phosphate receptors, S1PR1 and S1PR5. This drug is currently undergoing clinical trials for the treatment of secondary progressive multiple sclerosis (MS). Here, we investigated the effects of BAF312 on isolated astrocyte and microglia cultures as well as in slice culture models of demyelination.

Methods

Mouse and human astrocytes were treated with S1PR modulators and changes in the levels of pERK, pAkt, and calcium signalling as well as S1PR1 internalization and cytokine levels was investigated using Western blotting, immunochemistry, ELISA and confocal microscopy. Organotypic slice cultures were prepared from the cerebellum of 10-day-old mice and treated with lysophosphatidylcholine (LPC), psychosine and/or S1PR modulators, and changes in myelination states were measured by fluorescence of myelin basic protein and neurofilament H.

Results

BAF312 treatment of human and mouse astrocytes activated pERK, pAKT and Ca²⁺ signalling as well as inducing S1PR1 internalization. Notably, activation of S1PR1 increased pERK and pAKT in mouse astrocytes while both S1PR1 and S1PR3 equally increased pERK and pAKT in human astrocytes, suggesting that the coupling of S1PR1 and S1PR3 to pERK and pAKT differ in mouse and human astrocytes. We also observed that BAF312 moderately attenuated lipopolysaccharide (LPS)- or TNFα/IL17-induced levels of IL6 in both astrocyte and microglia cell cultures. In organotypic slice cultures, BAF312 reduced LPC-induced levels of IL6 and attenuated LPC-mediated demyelination. We have shown previously that the toxic lipid metabolite psychosine induces demyelination in organotypic slice cultures, without altering the levels of cytokines, such as IL6. Importantly, psychosine-induced demyelination was also attenuated by BAF312.

Conclusions

Overall, this study suggests that BAF312 can modulate glial cell function and attenuate demyelination, highlighting this drug as a further potential therapy in demyelinating disorders, beyond MS.

Therapeutic Advances and Future Prospects in Progressive Forms of Multiple Sclerosis

Identifying effective therapies for the treatment of progressive forms of multiple sclerosis (MS) is a highly relevant priority and one of the greatest challenges for the global MS community. Better understanding of the mechanisms involved in progression of the disease, novel trial designs, drug repurposing strategies, and new models of collaboration may assist in identifying effective therapies. In this review, we discuss various therapies under study in phase II or III trials, including antioxidants (idebenone); tyrosine kinase inhibitors (masitinib); sphingosine receptor modulators (siponimod); monoclonal antibodies (anti-leucine-rich repeat and immunoglobulin-like domain containing neurite outgrowth inhibitor receptor-interacting protein-1, natalizumab, ocrelizumab, intrathecal rituximab); hematopoetic stem cell therapy; statins and other possible neuroprotective agents (amiloride, riluzole, fluoxetine, oxcarbazepine); lithium; phosphodiesterase inhibitors (ibudilast); hormone-based therapies (adrenocorticotrophic hormone and erythropoietin); T-cell receptor peptide vaccine (NeuroVax); autologous T-cell immunotherapy (Tcelna); MIS416 (a microparticulate immune response modifier); dopamine antagonists (domperidone); and nutritional supplements, including lipoic acid, biotin, and sunphenon epigallocatechin-3-gallate (green tea extract). Given ongoing and planned clinical trial initiatives, and the largest ever focus of the global research community on progressive MS, future prospects for developing targeted therapeutics aimed at reducing disability in progressive forms of MS appear promising.

Sphingosine 1-phosphate signaling in astrocytes: Implications for progressive multiple sclerosis

Multiple sclerosis is an autoimmune disorder characterized by recurrent attacks against the central nervous system. After many years, certain patients enter a progressive disease phase, characterized by steady clinical deterioration. However, in 10-15% of patients, the disease is progressive from the beginning, and thus diagnosed as Primary Progressive Multiple Sclerosis. Unlike relapsing-remitting forms, progressive MS lacks effective therapy. Astrocytes are a major component of glial cells and are now thought to play a role in disease progression. Sphingosine 1-phophate is a molecule with extensive receptor expression on both immune and glial cells and is also a target of fingolimod, a drug used in relapsing remitting patients that sequesters lymphocytes within lymph nodes. However, because sphingosine 1-phosphate receptors are also expressed in astrocytes, and also because modification of this pathway has shown interesting benefits in animal models of Multiple Sclerosis, this astrocyte pathway has become an interesting target for developing potential new therapeutic approaches for Multiple Sclerosis.