Effects of prophylactic and therapeutic teriflunomide in transcranial magnetic stimulation-induced motor-evoked potentials in the dark agouti rat model of experimental autoimmune encephalomyelitis

Improving reproducibility of motor evoked potentials in mice

BACKGROUND

In preclinical research involving murine models of neurological diseases, Motor Evoked Potentials (MEPs) can detect pathological alterations in nerve conduction throughout the cortico-spinal tract. In mice, MEPs elicited by electrical stimulation of the motor cortex can be performed with epicranial or subdermal electrodes such as implanted screws or removable needles, which are associated with invasive surgery and variability in placement of the stimulating electrodes, respectively.

METHODS

We compared MEPs induced by epicranial or subcutaneous stimulation with a non-invasive surface cup electrode over five recording sessions, in healthy C57BL/6 mice. Additionally, using surface stimulation, we examined the recordings obtained with intramuscular needles or surface electrodes to understand if MEP reproducibility could be improved.

RESULTS

Resting motor threshold (RMT), MEP latency and amplitude were comparable among the different stimulation methods. Epicranial, subcutaneous and surface stimulation techniques presented good repeatability over time, with surface stimulation showing a significantly reduced inter-session variability. Compared with intramuscular needles, MEPs recorded with surface electrode showed reduced peak-to-peak amplitude at all timepoints. RMT and MEP latency were comparable with both recording methods. On the other hand, amplitudes recorded with the surface electrode presented a significantly lower inter-session variance, resulting in improved repeatability.

CONCLUSION

Overall, there is evidence for highly reproducible results using different stimulating methods, with indication for reduced inter-session variability for surface stimulation. Moreover, MEP recording with surface electrode provided a decrease in amplitude variability over time, indicating improved measurement stability when considering amplitude as functional outcome in longitudinal studies.

In vivo detection of teriflunomide-derived fluorine signal during neuroinflammation using fluorine MR spectroscopy

Background: Magnetic resonance imaging (MRI) is indispensable for diagnosing neurological conditions such as multiple sclerosis (MS). MRI also supports decisions regarding the choice of disease-modifying drugs (DMDs). Determining in vivo tissue concentrations of DMDs has the potential to become an essential clinical tool for therapeutic drug monitoring (TDM). The aim here was to examine the feasibility of fluorine-19 (¹⁹F) MR methods to detect the fluorinated DMD teriflunomide (TF) during normal and pathological conditions.

Methods: We used ¹⁹F MR spectroscopy to detect TF in the experimental autoimmune encephalomyelitis (EAE) mouse model of multiple sclerosis (MS) in vivo. Prior to the in vivo investigations we characterized the MR properties of TF in vitro. We studied the impact of pH and protein binding as well as MR contrast agents.

Results: We could detect TF in vivo and could follow the ¹⁹F MR signal over different time points of disease. We quantified TF concentrations in different tissues using HPLC/MS and showed a significant correlation between ex vivo TF levels in serum and the ex vivo¹⁹F MR signal.

Conclusion: This study demonstrates the feasibility of ¹⁹F MR methods to detect TF during neuroinflammation in vivo. It also highlights the need for further technological developments in this field. The ultimate goal is to add ¹⁹F MR protocols to conventional ¹H MRI protocols in clinical practice to guide therapy decisions.

Vidofludimus calcium, a next generation DHODH inhibitor for the Treatment of relapsing-remitting multiple sclerosis

BACKGROUND

Inhibition of dihydroorotate dehydrogenase (DHODH) is an established mechanism for the treatment of relapsing-remitting multiple sclerosis (RRMS). Currently approved treatments have several shortcomings. Consequently, new and effective treatments with improved safety and convenience profiles are sought after by patients.

OBJECTIVE

To explore the overall profile of vidofludimus for the treatment of RRMS.

METHODS

Preclinical investigations were done exploring the species-dependency of DHODH inhibition of vidofludimus. In addition, the preclinical efficacy in a rat experimental autoimmune encephalomyelitis (EAE) model and the inhibition of cytokine release from activated PBMC were investigated. Pharmacokinetic data were also obtained in a Phase 1 multiple ascending dose trial of the formulation IMU-838 (vidofludimus calcium).

RESULTS

It was shown that vidofludimus is 2.6 times more potent in inhibiting DHO oxidation by human DHODH compared to teriflunomide. Although both compounds increased cell apoptosis, vidofludimus was more efficacious in the inhibition of T-lymphocyte proliferation compared to teriflunomide. The same was also observed for the secretion of IL-17 and IFN-γ. Interestingly, the potency or vidofludimus to inhibit rat or mouse DHODH is 7.5 and 64.4 time lower than the for the human DHODH, respectively. The rat EAE study clearly exhibited a dose-dependent inhibition of cumulative disease scores by vidofludimus. In the multiple ascending dose Phase 1 clinical trial, the serum half-life of about 30 h provides a favorable profile for once daily dosing of IMU-838, with quick dosing to steady state through levels within 5 days and the ability to wash out drug quickly, if required.

CONCLUSIONS

The investigations highlighted that the desired selective immunomodulatory properties can be separated from general antiproliferative effects seen and related adverse events in first-generation DHODH inhibitors. Based on data obtained from a series of pre-clinical as well as phase 1 and phase 2 studies, IMU-838 is a promising next-generation candidate for the oral treatment of RRMS. However, this will need to be confirmed in the currently ongoing Phase 2 study in RRMS patients.

Transcranial Magnetic Stimulation as a Potential Biomarker in Multiple Sclerosis: A Systematic Review with Recommendations for Future Research

Multiple sclerosis (MS) is a demyelinating disorder of the central nervous system. Disease progression is variable and unpredictable, warranting the development of biomarkers of disease status. Transcranial magnetic stimulation (TMS) is a noninvasive method used to study the human motor system, which has shown potential in MS research. However, few reviews have summarized the use of TMS combined with clinical measures of MS and no work has comprehensively assessed study quality. This review explored the viability of TMS as a biomarker in studies of MS examining disease severity, cognitive impairment, motor impairment, or fatigue. Methodological quality and risk of bias were evaluated in studies meeting selection criteria. After screening 1603 records, 30 were included for review. All studies showed high risk of bias, attributed largely to issues surrounding sample size justification, experimenter blinding, and failure to account for key potential confounding variables. Central motor conduction time and motor-evoked potentials were the most commonly used TMS techniques and showed relationships with disease severity, motor impairment, and fatigue. Short-latency afferent inhibition was the only outcome related to cognitive impairment. Although there is insufficient evidence for TMS in clinical assessments of MS, this review serves as a template to inform future research.

Optic nerve involvement in experimental autoimmune encephalomyelitis to homologous spinal cord homogenate immunization in the dark agouti rat

Dark-Agouti rats were immunized with spinal cord homogenate to develop Experimental Autoimmune Encephalomyelitis, a model of multiple sclerosis. We assessed motor signs and recorded VEPs for five or eight weeks with epidural or epidermal electrodes, respectively, with final histopathology of optic nerves (ONs). Injected rats exhibited motor deficits a week after immunization. VEP delays arose from the 2nd to the 5th week, when a recovery occurred in epidermal-recorded rats. ON damage appeared in epidural-, but not in epidermal-recorded rats, probably due to a remyelination process. VEP could be exploited as neurophysiological marker to test novel treatments against neurodegeneration involving ONs.

Teriflunomide Modulates Vascular Permeability and Microglial Activation after Experimental Traumatic Brain Injury

Despite intensive research and clinical trials with numerous therapeutic treatments, traumatic brain injury (TBI) is a serious public health problem in the United States. There is no effective FDA-approved treatment to reduce morbidity and mortality associated with TBI. Inflammation plays a pivotal role in the pathogenesis of TBI. We looked to re-purpose existing drugs that reduce immune activation without broad immunosuppression. Teriflunomide, an FDA-approved drug, has been shown to modulate immunological responses outside of its ability to inhibit pyrimidine synthesis in rapidly proliferating cells. In this study, we tested the efficacy of teriflunomide to treat two different injury intensities in rat models of TBI. Our results show that teriflunomide restores blood-brain barrier integrity, decreases inflammation, and increases neurogenesis in the subgranular zone of the hippocampus. While we were unable to detect neurocognitive effects of treatment on memory and special learning abilities after treatment, a 2-week treatment following injury was sufficient to reduce neuroinflammation up to 120 days later.

Fingolimod inhibits brain atrophy and promotes brain-derived neurotrophic factor in an animal model of multiple sclerosis

Longitudinal brain atrophy quantification is a critical efficacy measurement in multiple sclerosis (MS) clinical trials and the determination of No Evidence of Disease Activity (NEDA). Utilising fingolimod as a clinically validated therapy we evaluated the use of repeated brain tissue volume measures during chronic experimental autoimmune encephalomyelitis (EAE) as a new preclinical efficacy measure. Brain volume changes were quantified using magnetic resonance imaging (MRI) at 7 Tesla and correlated to treatment-induced brain derived neurotrophic factor (BDNF) measured in blood, cerebrospinal fluid, spinal cord and brain. Serial brain MRI measurements revealed slow progressive brain volume loss in vehicle treated EAE mice despite a stable clinical score. Fingolimod (1 mg/kg) significantly ameliorated brain tissue atrophy in the cerebellum and striatum when administered from established EAE disease onwards. Fingolimod-dependent tissue preservation was associated with induction of BDNF specifically within the brain and co-localized with neuronal soma. In contrast, therapeutic teriflunomide (3 mg/kg) treatment failed to inhibit CNS autoimmune mediated brain degeneration. Finally, weekly anti-IL-17A antibody (15 mg/kg) treatment was highly efficacious and preserved whole brain, cerebellum and striatum volume. Fingolimod-mediated BDNF increases within the CNS may contribute to limiting progressive tissue loss during chronic neuroinflammation.

Teriflunomide slows BVL in relapsing MS: A reanalysis of the TEMSO MRI data set using SIENA

Objective:

To assess, using structural image evaluation using normalization of atrophy (SIENA), the effect of teriflunomide, a once-daily oral immunomodulator, on brain volume loss (BVL) in patients with relapsing forms of MS enrolled in the phase 3 TEMSO study.

Methods:

TEMSO MR scans were analyzed (study personnel masked to treatment allocation) using SIENA to assess brain volume changes between baseline and years 1 and 2 in patients treated with placebo or teriflunomide. Treatment group comparisons were made via rank analysis of covariance.

Results:

Data from 969 patient MRI visits were included in this analysis: 808 patients had baseline and year 1 MRI; 709 patients had baseline and year 2 MRI. Median percentage BVL from baseline to year 1 and year 2 for placebo was 0.61% and 1.29%, respectively, and for teriflunomide 14 mg, 0.39% and 0.90%, respectively. BVL was lower for teriflunomide 14 mg vs placebo at year 1 (36.9% relative reduction, p = 0.0001) and year 2 (30.6% relative reduction, p = 0.0001). Teriflunomide 7 mg was also associated with significant reduction in BVL vs placebo over the 2-year study. The significant effects of teriflunomide 14 mg on BVL were observed in both patients with and without on-study disability worsening.

Conclusions:

The significant reduction of BVL vs placebo over 2 years achieved with teriflunomide is consistent with its effects on delaying disability worsening and suggests a neuroprotective potential.

Classification of evidence:

Class II evidence shows that teriflunomide treatment significantly reduces BVL over 2 years vs placebo.

ClinicalTrials.gov identifier:

NCT00134563.

From Leflunomide to Teriflunomide: Drug Development and Immunosuppressive Oral Drugs in the Treatment of Multiple Sclerosis

BACKGROUND

Immunosuppressive drugs have been used in the treatment of multiple sclerosis (MS) for a long time. Today, orally available second generation immunosuppressive agents have been approved or are filed for licensing as MS therapeutics. Due to semi-selective targeting of cellular processes, these second-generation immunosuppressive compounds might rather be immunomodulatory. For example, Teriflunomide inhibits the de novo pyrimidine synthesis and thus only targets rapidly proliferating cells, including lymphocytes. It is used as first line disease modifying therapy (DMT) in relapsing-remitting MS (RRMS).

METHODS

Review of online content related to oral immunosuppressants in MS with an emphasis on Teriflunomide.

RESULTS

Teriflunomide and Cladribine are second-generation immunosuppressants that are efficient in the treatment of MS patients. For Teriflunomide, a daily dose of 14 mg reduces the annualized relapse rate (ARR) by more than 30% and disability progression by 30% compared to placebo. Cladribine reduces the ARR by about 50% compared to placebo but has not yet been licensed due to unresolved safety concerns. We also discuss the significance of older immunosuppressive compounds including Azathioprine, Mycophenolate mofetile, and Cyclophosphamide in current MS therapy.

CONCLUSION

Teriflunomide has shown a favorable safety and efficacy profile in RRMS and is a therapeutic option for a distinct group of adult patients with RRMS.

Induction of gut regulatory CD39+ T cells by teriflunomide protects against EAE

Objective:

To determine whether as an orally delivered treatment, teriflunomide, an inhibitor of the mitochondrial enzyme dihydroorotate dehydrogenase approved to treat relapsing forms of multiple sclerosis, could affect gut-associated lymphoid tissue (GALT) immune responses functionally.

Methods:

C57BL/6 mice were treated orally with teriflunomide and flow cytometric analysis of immune GALT cells performed ex vivo, and adoptive transfer experiments were used to test the protective effects of GALT regulatory T (Treg) cells.

Results:

Teriflunomide reduced the percentages of antigen-presenting cells of Peyer patches when compared to controls. Conversely, a significant increase of the relative frequency of CD39⁺ Treg cells was observed. In vivo, the protective effect of GALT-derived teriflunomide-induced CD39⁺ Treg cells was established by adoptive transfer into recipient experimental autoimmune encephalomyelitis mice.

Conclusions:

Our results identify specific GALT-derived CD39⁺ Treg cells as a mechanism of action that may contribute to the efficacy of teriflunomide during CNS inflammatory demyelination and as an oral therapeutic in relapsing multiple sclerosis.

Therapeutic strategies in multiple sclerosis: a focus on neuroprotection and repair and relevance to schizophrenia

Multiple sclerosis is the leading nontraumatic cause of neurologic disability in young adults. The need to prevent neurodegeneration and promote repair in multiple sclerosis (MS) has gained increasing interest in the last decade leading to the search and development of pharmacological agents and non-pharmacologic strategies able to target not only the inflammatory but also the neurodegenerative component of the disease. This paper will provide an overview of the therapeutics currently employed in MS, with a focus on their potential neuroprotective effects and on the MRI methods employed to detect and monitor in-vivo neuroprotection and repair and the relevance of this information to schizophrenia investigation and treatment.

Teriflunomide: a novel oral treatment for relapsing multiple sclerosis

INTRODUCTION

Multiple sclerosis is a disabling chronic inflammatory disease of the CNS. New emerging oral treatments can offer efficacy with higher levels of therapeutic adherence. Teriflunomide is one such oral agent that has recently been approved for the treatment of relapsing multiple sclerosis (RMS).

AREAS COVERED

The aim of this review is to describe the pharmacological profile of teriflunomide and review the vast clinical development program that paved the way for its approval, with emphasis on its safety and tolerability.

EXPERT OPINION

Teriflunomide is a safe new oral medication for treating RMS. It is effective at reducing relapses, MRI activity and slowing disability progression. It is well tolerated, with mild and transitory side effects. Although teriflunomide is given a pregnancy category 'X' by the FDA and an effective contraception is needed, to date, there has been no evidence of teratogenicity in humans and a rapid washout procedure can lead to a virtually complete elimination. Its effectiveness appeared to be at least comparable to that of high-dose IFN-β-1a, and although direct comparisons with other orals are still lacking, its tolerability and encouraging safety data suggest that teriflunomide could be considered an ideal first-line medication for RMS.

Teriflunomide and its mechanism of action in multiple sclerosis

Treatment of multiple sclerosis (MS) is challenging: disease-modifying treatments (DMTs) must both limit unwanted immune responses associated with disease initiation and propagation (as T and B lymphocytes are critical cellular mediators in the pathophysiology of relapsing MS), and also have minimal adverse impact on normal protective immune responses. In this review, we summarize key preclinical and clinical data relating to the proposed mechanism of action of the recently approved DMT teriflunomide in MS. Teriflunomide selectively and reversibly inhibits dihydro-orotate dehydrogenase, a key mitochondrial enzyme in the de novo pyrimidine synthesis pathway, leading to a reduction in proliferation of activated T and B lymphocytes without causing cell death. Results from animal experiments modelling the immune activation implicated in MS demonstrate reductions in disease symptoms with teriflunomide treatment, accompanied by reduced central nervous system lymphocyte infiltration, reduced axonal loss, and preserved neurological functioning. In agreement with the results obtained in these model systems, phase 3 clinical trials of teriflunomide in patients with MS have consistently shown that teriflunomide provides a therapeutic benefit, and importantly, does not cause clinical immune suppression. Taken together, these data demonstrate how teriflunomide acts as a selective immune therapy for patients with MS.

Teriflunomide: a review of its use in relapsing multiple sclerosis

Teriflunomide (Aubagio™) is the main active metabolite of leflunomide, an established disease-modifying anti-rheumatic drug. Teriflunomide is an inhibitor of de novo pyrimidine synthesis, reducing lymphocyte proliferation, amongst other immunomodulatory effects; autoimmunity is believed to be one of the potential mechanisms of disease for multiple sclerosis. Teriflunomide is considered cytostatic but not cytotoxic: it does not affect resting or slowly dividing lymphocytes. This article reviews the available pharmacological properties of oral teriflunomide and its clinical efficacy and tolerability in patients with relapsing multiple sclerosis. While both the 7 and the 14 mg/day dosages are discussed, the 7 mg/day dosage is not approved in the EU. Both dosages are approved in the USA. In phase III trials, teriflunomide 7 or 14 mg/day was consistently demonstrated to be more effective than placebo and as effective as interferon beta-1a in the prevention of relapses in patients with relapsing forms of multiple sclerosis; moreover, teriflunomide 14 mg/day was also consistently shown to be more effective than placebo in prevention of disability progression. Teriflunomide was generally well tolerated in these patients. Long-term, extension data were generally similar to those observed in the shorter-term trials. Teriflunomide is associated with increased liver enzyme levels, and is contraindicated in pregnant patients because of a potential risk of teratogenicity. As an oral treatment, it offers an alternative to the traditional, parenteral, disease-modifying therapies; however, further investigation into the efficacy and/or tolerability differences between teriflunomide and other available oral drugs would be of great use in the placement of this drug. At present, given the relatively limited long-term data, it is difficult to draw definite conclusions with regard to safety; however, as teriflunomide is the main active metabolite of leflunomide, long-term safety data can be extrapolated from the large amount of post-approval data available regarding its parent drug. Oral teriflunomide is a valuable addition to available treatment options for patients with relapsing multiple sclerosis, in particular those patients who prefer an oral drug.

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.

Teriflunomide attenuates immunopathological changes in the dark agouti rat model of experimental autoimmune encephalomyelitis

Teriflunomide is an oral disease-modifying therapy recently approved in several locations for relapsing-remitting multiple sclerosis. To gain insight into the effects of teriflunomide, immunocyte population changes were measured during progression of experimental autoimmune encephalomyelitis in Dark Agouti rats. Treatment with teriflunomide attenuated levels of spinal cord-infiltrating T cells, natural killer cells, macrophages, and neutrophils. Teriflunomide also mitigated the disease-induced changes in immune cell populations in the blood and spleen suggesting an inhibitory effect on pathogenic immune responses.