Repurposing the multiple sclerosis drug Siponimod for osteoporosis treatment.

Osteoporosis is the most common bone disorder, in which an imbalance between osteoclastic bone resorption and osteoblastic bone formation disrupts bone homeostasis. Osteoporosis management using anti-osteoclastic agents is a promising strategy; however, this remains an unmet need. Sphingosine-1-phosphate (S1P) and its receptors (S1PRs) are essential for maintaining bone homeostasis. Here, we identified that Siponimod, a Food and Drug Administration-approved S1PR antagonist for the treatment of multiple sclerosis, shows promising therapeutic effects against osteoporosis by inhibiting osteoclast formation and function. We found that Siponimod inhibited osteoclast formation in a dose-dependent manner without causing cytotoxicity. Podosome belt staining and bone resorption assays indicated that Siponimod treatment impaired osteoclast function. Western blot and qPCR assays demonstrated that Siponimod suppressed the expression of osteoclast-specific markers, including C-Fos, Nftac1, and Ctsk. Mechanistically, we validated that Siponimod downregulated receptor activator of nuclear factor kappa B ligand (RANKL)-induced Mitogen-activated protein kinases (MAPKs) and nuclear factor kappa B (NF-κB) signaling pathways during osteoclastogenesis. Moreover, in a preclinical mouse model, Siponimod prevented ovariectomy-induced bone loss by suppressing osteoclast activity in vivo. Collectively, these results suggest that Siponimod could serve as an alternative therapeutic agent for the treatment of osteoporosis.

[The first russian experience of use of siponimod in real clinical practice]. / Pervyi rossiiskii opyt primeneniya siponimoda v real'noi klinicheskoi praktike.

Despite significant success in the treatment of multiple sclerosis achieved in the recent years, the issues of therapy for progressive forms of the disease are far from being resolved. The first medication with proven efficiency at SPMS is the oral selective sphingosine 1 phosphate (S1P) receptor modulator siponimod. Before the registration of siponimod in Russia, Novartis company organized a «Managed access program to enable siponimod in patients with secondary progressive multiple sclerosis without satisfactory alternative therapy¼. For the period from September 2020 to May 2021, 10 patients with SPMS with exacerbations were included in the programme by RAS. The results of the treatment of the patients under the programme were similar to the results of previously controlled studies. The medication was well tolerated and the expected side effects (mainly lymphopenia and Elevated transaminases) were not more severe than moderate and were stopped by temporary cancel of the current treatment or concomitant therapy. During 1 year of therapy, the stabilization of condition of all patients and positive dynamics was noticed, including a decrease in the EDSS score in 44% of patients. Despite the limited number of patients and time of observation, the safety and efficacy of siponimod in patients with SPMS are quite high. The use of the medication in routine clinical practice does not require extraordinary methods of observation and control, but nevertheless includes genetic examination before the prescription of therapy, regular monitoring of clinical blood and biochemical parameters.

Short- and long-term effects of siponimod on autonomic nervous system in secondary progressive multiple sclerosis.

OBJECTIVES: The aim of this study was to investigate the short- and long-term effects of siponimod on autonomic nervous system (ANS) function, in people with secondary progressive multiple sclerosis (pwSPMS) METHODS: The following ANS tests were performed in 26 pwSPMS: a 10 min supine resting position, Valsalva maneuver, deep breathing test and a 10 min tilt-up table test. Heart rate variability (HRV) was performed for the 10 min in supine resting position (M0) and for a 3 h period after siponimod treatment initiation (M0s1-6). All ANS tests were repeated after at least 6 months of treatment with siponimod (M6). RESULTS: In all 6 intervals after siponimod ingestion (M0s1-6), standard deviation of NN intervals (SDNN) was higher compared to M0. After 6 months of continuous treatment with siponimod, SDNN was significantly lower compared to M0. At M6, Valsalva ratio and respiratory sinus arrhythmia were lower compared to M0 values (1.510±0.338 vs 1.864±0.456, p=0.003 and 7.969±2.865 vs 13.091±4.687, p<0.001, respectively). Cardiovagal index was significantly higher at M6 compared to M0 (1 (range 0-2) vs 0 (range 0-1), p=0.008, respectively). Active Magnetic Resonance Imaging (MRI) one year prior to starting siponimod was a positive predictor of M6 SDNN and Adrenergic Index (AI) at M0 was a negative predictor of M6 SDNN. CONCLUSION: This study has shown an inverse relationship in short- versus long-term effects of siponimod on ANS function. A shift towards parasympathetic predominance was observed during the first three hours after ingestion, while after 6 or more months of continuous treatment with siponimod, a shift towards sympathetic predominance was observed.

Siponimod vs placebo in active secondary progressive multiple sclerosis: a post hoc analysis from the phase 3 EXPAND study.

BACKGROUND: Siponimod is a sphingosine 1-phosphate receptor modulator approved for active secondary progressive multiple sclerosis (aSPMS) in most countries; however, phase 3 EXPAND study data are from an SPMS population with/without disease activity. A need exists to characterize efficacy/safety of siponimod in aSPMS. METHODS: Post hoc analysis of participants with aSPMS (≥ 1 relapse in 2 years before study and/or ≥ 1 T1 gadolinium-enhancing [Gd +] magnetic resonance imaging [MRI] lesions at baseline) receiving oral siponimod (2 mg/day) or placebo for up to 3 years in EXPAND. ENDPOINTS: 3-month/6-month confirmed disability progression (3mCDP/6mCDP); 3-month confirmed ≥ 20% worsening in Timed 25-Foot Walk (T25FW); 6-month confirmed improvement/worsening in Symbol Digit Modalities Test (SDMT) scores (≥ 4-point change); T2 lesion volume (T2LV) change from baseline; number of T1 Gd + lesions baseline-month 24; number of new/enlarging (N/E) T2 lesions over all visits. RESULTS: Data from 779 participants with aSPMS were analysed. Siponimod reduced risk of 3mCDP/6mCDP vs placebo (by 31%/37%, respectively; p < 0.01); there was no significant effect on T25FW. Siponimod increased likelihood of 6-month confirmed SDMT improvement vs placebo (by 62%; p = 0.007) and reduced risk of 6-month confirmed SDMT worsening (by 27%; p = 0.060). Siponimod was associated with less increase in T2LV (1316.3 vs 13.3 mm3; p < 0.0001), and fewer T1 Gd + and N/E T2 lesions than placebo (85% and 80% reductions, respectively; p < 0.0001). CONCLUSIONS: In aSPMS, siponimod reduced risk of disability progression and was associated with benefits on cognition and MRI outcomes vs placebo. TRIAL REGISTRATION: ClinicalTrials.gov number: NCT01665144.

Differential activation mechanisms of lipid GPCRs by lysophosphatidic acid and sphingosine 1-phosphate.

Lysophospholipids are bioactive lipids and can signal through G-protein-coupled receptors (GPCRs). The best studied lysophospholipids are lysophosphatidic acid (LPA) and sphingosine 1-phosphate (S1P). The mechanisms of lysophospholipid recognition by an active GPCR, and the activations of lysophospholipid GPCR-G-protein complexes remain unclear. Here we report single-particle cryo-EM structures of human S1P receptor 1 (S1P1) and heterotrimeric Gi complexes formed with bound S1P or the multiple sclerosis (MS) treatment drug Siponimod, as well as human LPA receptor 1 (LPA1) and Gi complexes in the presence of LPA. Our structural and functional data provide insights into how LPA and S1P adopt different conformations to interact with their cognate GPCRs, the selectivity of the homologous lipid GPCRs for S1P versus LPA, and the different activation mechanisms of these GPCRs by LPA and S1P. Our studies also reveal specific optimization strategies to improve the MS-treating S1P1-targeting drugs.

Risk for Cardiovascular Adverse Events Associated With Sphingosine-1-Phosphate Receptor Modulators in Patients With Multiple Sclerosis: Insights From a Pooled Analysis of 15 Randomised Controlled Trials.

Background: All agents engaging sphongosine-1-phospate receptors (S1PRs) will have some cardiovascular effect. This study aimed to elucidate the risk of cardiovascular adverse events (AEs) in patients with multiple sclerosis (MS) treated with S1PR modulators (S1PRMs). Methods: We systematically searched the PubMed, EMBASE, and Cochrane Library databases for randomised controlled trials (RCTs) published through January 5, 2021. Relative risks (RRs) and 95% confidence intervals (CIs) were calculated using the random-effects model. Sensitivity analyses and meta-regression were performed. Results: Seventeen RCTs (12 for fingolimod; 3 for ozanimod; 2 for siponimod) involving 13,295 patients were included. Compared with the control treatment, S1PRMs significantly increased the risk of cardiovascular AEs (RR, 2.21; 95% CI, 1.58-3.10; I2, 75.6%). Notably, the high-risk cardiovascular AEs associated with S1PRMs were primarily bradyarrhythmia (RR, 2.92; 95% CI, 1.91-4.46; I2, 30.8%) and hypertension (RR, 2.00; 95% CI, 1.49-2.67; I2, 56.5%). Subgroup analysis results were consistent with the primary outcomes except that ozanimod was associated with a higher risk of hypertension only (RR, 1.76; 95% CI, 1.10-2.82; I2, 0.0%), while siponimod was associated with a higher risk of bradyarrhythmia only (RR, 2.75; 95% CI, 1.75-4.31; I2, 0.0%). No significant inter-subgroup differences were observed (Pinteraction > 0.05). Conclusions: S1PRM use increased the risk of cardiovascular AEs by 1.21 times in patients with MS, and increased risks for bradyarrhythmia and hypertension were at 2.92- and 2.00-fold, respectively. These findings can help clinicians assess the risk of cardiovascular AEs in patients treated with S1PRMs. Systematic Review Registration: The PROSPERO ID is CRD42020183215.

Antinociceptive activities of a novel diarylpentanoid analogue, 2-benzoyl-6-(3-bromo-4-hydroxybenzylidene)cyclohexen-1-ol, and its possible mechanisms of action in mice.

A novel synthetic compound from the 2-benzoyl-6-benzylidenecyclohexanone analogue, namely 2-benzoyl-6-(3-bromo-4-hydroxybenzylidene)cyclohexen-1-ol (BBHC), showed pronounced nitric oxide inhibition in IFN-γ/LPS-induced RAW 264.7 cells. Based on this previous finding, our present study aimed to investigate the antinociceptive effects of BBHC via chemical and thermal stimuli in vivo. The investigation of the antinociceptive activity of BBHC (0.1, 0.3, 1.0 and 3.0 mg/kg, i.p.) was initiated with 3 preliminary screening tests, then BBHC was subjected to investigate its possible involvement with excitatory neurotransmitters and opioid receptors. The potential acute toxicity of BBHC administration was also studied. Administration of BBHC significantly inhibited acetic acid-induced abdominal constrictions, formalin-induced paw licking activity and developed notable increment in the latency time. BBHC's ability to suppress capsaicin- and glutamate-induced paw licking activities, as well as to antagonise the effect of naloxone, had indicated the possible involvement of its antinociception with TRPV1, glutamate and opioid receptors, respectively. The antinociceptive activities of BBHC was not related to any sedative action and no evidence of acute toxic effect was detected. The present study showed that BBHC possessed significant peripheral and central antinociceptive activities via chemical- and thermal-induced nociceptive murine models without any locomotor alteration and acute toxicity.

Sphingosine 1-phosphate receptor modulators in multiple sclerosis and other conditions.

The sphingosine 1-phosphate (S1P) signalling pathways have important and diverse functions. S1P receptors (S1PRs) have been proposed as a therapeutic target for various diseases due to their involvement in regulation of lymphocyte trafficking, brain and cardiac function, vascular permeability, and vascular and bronchial tone. S1PR modulators were first developed to prevent rejection by the immune system following renal transplantation, but the only currently approved indication is multiple sclerosis. The primary mechanism of action of S1PR modulators in multiple sclerosis is through binding S1PR subtype 1 on lymphocytes resulting in internalisation of the receptor and loss of responsiveness to the S1P gradient that drives lymphocyte egress from lymph nodes. The reduction in circulating lymphocytes presumably limits inflammatory cell migration into the CNS. Four S1PR modulators (fingolimod, siponimod, ozanimod, and ponesimod) have regulatory approval for multiple sclerosis. Preclinical evidence and ongoing and completed clinical trials support development of S1PR modulators for other therapeutic indications.

Autonomic nervous system abnormalities predict cardiovascular changes after initiation of siponimod in secondary progressive multiple sclerosis.

OBJECTIVE: The aim of this study was to identify whether autonomic nervous system (ANS) dysfunction identified prior to treatment initiation can predict siponimod related decrease in heart rate (HR) after treatment initiation. METHODS: In 26 people with secondary progressive multiple sclerosis (SPMS) the following ANS testing protocol was applied: 10-min supine resting position, Valsalva maneuver, deep breathing test, 10 min tilt-up table test, 5-min supine resting period, ingestion of siponimod, followed by 180-min supine resting period recordings. Heart rate variability (HRV) parameters were investigated as possible predictors of decrease in HR (ΔHR) after treatment initiation. RESULTS: After treatment initiation, there was a statistically significant drop in HR (71.1 ± 9.2 to 66.3 ± 8.1, p < 0.001) and elevation of systolic blood pressure (sBP) (113.2 ± 12.4 to 117.1 ± 10.8, p = 0.04). Values of the diastolic BP (dBP) followed similar trend as did sBP, however not reaching statistical significance (72.8 ± 9.6 to 74.9 ± 8.3, p = 0.13). In a multivariable regression model, disease duration and standard deviation of NN intervals (SDNN) were identified as independent predictors for ΔHR, where increase in SDNN and longer disease duration predict smaller ΔHR. CONCLUSION: ANS abnormalities may predict cardiovascular abnormalities associated with treatment initiation with siponimod. SIGNIFICANCE: Results of this study may help mitigate risks associated with siponimod treatment.

Siponimod: Disentangling disability and relapses in secondary progressive multiple sclerosis.

BACKGROUND: In multiple sclerosis, impact of treatment on disability progression can be confounded if treatment also reduces relapses. OBJECTIVE: To distinguish siponimod's direct effects on disability progression from those on relapses in the EXPAND phase 3 trial. METHODS: Three estimands, one based on principal stratum and two on hypothetical scenarios (no relapses, or equal relapses in both treatment arms), were defined to determine the extent to which siponimod's effects on 3- and 6-month confirmed disability progression were independent of on-study relapses. RESULTS: Principal stratum analysis estimated that siponimod reduced the risk of 3- and 6-month confirmed disability progression by 14%-20% and 29%-33%, respectively, compared with placebo in non-relapsing patients. In the hypothetical scenarios, risk reductions independent of relapses were 14%-18% and 23% for 3- and 6-month confirmed disability progression, respectively. CONCLUSION: By controlling the confounding impact of on-study relapses on confirmed disability progression, these statistical approaches provide a methodological framework to assess treatment effects on disability progression in relapsing and non-relapsing patients. The analyses support that siponimod may be useful for treating secondary progressive multiple sclerosis in patients with or without relapses.

Siponimod and Cognition in Secondary Progressive Multiple Sclerosis: EXPAND Secondary Analyses.

OBJECTIVE: To investigate the effects of siponimod on cognitive processing speed in patients with secondary progressive (SP) multiple sclerosis (MS), by means of a predefined exploratory and post hoc analysis of the Exploring the Efficacy and Safety of Siponimod in Patients With Secondary Progressive Multiple Sclerosis (EXPAND) study, a randomized controlled trial comparing siponimod and placebo. METHODS: EXPAND was a double-blind, placebo-controlled phase 3 trial involving 1,651 patients with SPMS randomized (2:1) to either siponimod 2 mg/d or placebo. Cognitive function was assessed with the Symbol Digit Modalities Test (SDMT), Paced Auditory Serial Addition Test (PASAT), and Brief Visuospatial Memory Test-Revised (BVMT-R) administered at baseline, 6-month intervals, and end of treatment. RESULTS: Between-group differences in mean change from baseline in SDMT scores were significantly better in siponimod- vs placebo-treated patients at month 12 (difference 1.08 [95% confidence interval 0.23-1.94]; p = 0.0132), month 18 (1.23 [0.25-2.21); p = 0.0135), and month 24 (2.30 [1.11-3.50]; p = 0.0002). Siponimod-treated patients were at significantly lower risk for having a 4-point sustained decrease in SDMT score (hazard ratio [HR] 0.79 [0.65-0.96]; p = 0.0157), while their chance for having a 4-point sustained increase in SDMT score was higher (HR 1.28 [1.05-1.55]; p = 0.0131). PASAT and BVMT-R scores did not differ significantly between the 2 treatment groups (all p > 0.28). CONCLUSION: Siponimod had a significant benefit on SDMT in patients with SPMS. Siponimod-treated patients were at significantly lower risk for having a ≥4-point decrease in SDMT score and had a significantly higher chance for having a ≥4-point increase in SDMT score, a magnitude of change accepted as clinically meaningful. CLINICALTRIALSGOV IDENTIFIER: NCT01665144. CLASSIFICATION OF EVIDENCE: This study provides Class II evidence that, for patients with SPMS, siponimod had a significant benefit on cognitive processing speed.

Cytokine storms caused by novel coronavirus 2019 and treatment for cardiac injury.

Since December 2019, an outbreak of a new coronavirus, COVID-19, infection has been taking place. At present, COVID-19 has spread to most countries worldwide. The latest evidence suggests that cytokine storm syndrome (CSS) is an important cause of the transition from mild to critical pneumonia and critically ill patients' death. The sudden exacerbation of COVID-19 may be related to a cytokine storm. Therefore, early identification and active treatment of CSS may play very important roles in improving the patients' prognosis, and these tasks are given attention in the current treatment of new Coronavirus pneumonia. However, there is still no specific medicine for this purpose. This article reviews cytokine storms and conducts an exploratory review of pharmacotherapy for cytokine storms to provide a reference for clinical treatment.

A Sphingosine-1-Phosphate Receptor Modulator Attenuated Secondary Brain Injury and Improved Neurological Functions of Mice after ICH.

BACKGROUND: Stroke activates the immune system and induces brain infiltration by immune cells, aggravating brain injury. Poststroke immunomodulation via (S1P-)receptor modulation is beneficial; however, the S1P-modulator in clinical use (FTY-720) is unspecific, and undesirable side effects have been reported. Previously, we tested effects of a novel selective S1P-receptor modulator, Siponimod, on ICH-induced brain injury in acute stage of the disease. In the current study, we investigated whether protective effects of Siponimod, evaluated in a short-term study, will protect the brain of ICH animals at long term as well. METHODS: 134 C57BL/6N mice were divided into sham and ICH-operated groups. Collagenase model of ICH was employed. ICH animals were divided into Siponimod treated and nontreated. Dose- and time-dependent effects of Siponimod were investigated. Contraplay between development of brain injury and the number of lymphocytes infiltrating the brain was investigated by forelimb placing, T-Maze test, brain water content calculation, MRI scanning, and immunostaining. RESULTS: Depending on the therapeutic strategy, Siponimod attenuated the development of brain edema, decreased ICH-induced ventriculomegaly and improved neurological functions of animals after ICH. It was associated with less lymphocytes in the brain of ICH animals. CONCLUSION: Siponimod is able to decrease the brain injury and improves neurological functions of animals after ICH.

The multiple sclerosis (MS) drugs as a potential treatment of ARDS in COVID-19 patients.

We encourage studies on the effectiveness of multiple sclerosis drugs for the treatment of ARDS in COVID-19 infection. These drugs, through the inhibition of the RhoA/actin-dependent expression of virus receptors in the macrophages and macrophage recruitment to the lungs, have the potential to inhibit cytokine storm of lung macrophages, reduce or eliminate ARDS and improve the outcome of COVID-19 infection.

Risk of domperidone induced severe ventricular arrhythmia.

There has been controversy over the cardiovascular safety of domperidone, attributable to the lack of a well-designed study as well as inconsistent results. This study aimed to examine the risk of severe domperidone-induced ventricular arrhythmia (VA), compared to mosapride, itopride, or non-use of all three prokinetics, in the general population. We conducted a population-based, self-controlled case series analysis. Enrolled subjects were individuals who were diagnosed with severe VA and were prescribed domperidone, mosapride, or itopride from 2003 to 2013 in the National Health Insurance Service-National Sample Cohort. The incidence rate ratio for severe VA was measured during exposure to prokinetics and compared with unexposed periods and itopride (no-proarrhythmic effect)-exposure periods, as control. A total of 2,817 subjects were included. Domperidone, mosapride, or itopride use was associated with increased risk of severe VA, compared with non-use (adjusted incidence rate ratios (IRR) of 1.342 (95% CI 1.096-1.642), 1.350 (95% CI 1.105-1.650), and 1.486 (95% CI 1.196-1.845), respectively). The risk of severe domperidone-induced VA was lower, compared to that of itopride [adjusted IRR of 0.548 (95% CI 0.345-0.870)]. Of the subjects who had been prescribed all three prokinetics, domperidone-exposure was associated with a lower risk of severe VA, compared to itopride-exposure (crude IRR, 0.571; 0.358-0.912). Mosapride-exposure did not show IRR difference for severe VA, compared to itopride-exposure. Domperidone, mosapride, or itopride use is associated with an increased risk of severe VA. However, the magnitude of association was modest and domperidone use does not increase further the risk, compared with other prokinetics.

[New Arrival of Disease Modifying Drugs Initiates New Era in Multiple Sclerosis Treatment in Japan].

Multiple sclerosis disease modifying drugs (MS-DMD) currently used in Japan are interferon ß-1a, interferon ß-1b and gratiramer acetate, fingolimod, dimethyl furmarate, and natalizumab. Ofatumumab and siponimod will be approved probably in 2021. Ofatumumab is an ant-CD20 human monoclonal antibody. A clinical trial revealed that the efficacy of ofatumumab is clearly superior to teriflunomide that has comparable efficacy to dimethyl fumarate. Siponimod, a selective sphingosine-1-phosphate receptor modulator, exhibited mild, but significant efficacy for secondary progressive form of MS. OCH, a synthetic glycolipid agent, is being tested in phase II clinical trials in Japan. What DMD is to select is challenging since MS prognosis varies and is unexpected. Only very few have truly benign course without treatment. Silent progression should be considered especially in cases with those with interferon ß-1a, interferon ß-1b and gratiramer acetate. Escalation therapy is more widely accepted than initiation of high efficacy therapy in Japan because emphasizing safety. In such strategy three injectables and dimethyl fumarate are regarded as first line therapies. On the other hand, initiation of high efficacy drugs may be reasonable to prevent from disease progression. Even if either is acceptable, early induction of DMD with sufficient efficacy is mandatory for MS treatment.

New Drugs 2020, part 2.

This article reviews seven drugs recently approved by the FDA, including indications, precautions, adverse reactions, and nursing considerations.

Moscatilin, a bibenzyl derivative from the orchid Dendrobium loddigesii, induces apoptosis in melanoma cells.

The use of orchids in herbal medicine has a very long history. Dendrobium species are known to produce a variety of secondary metabolites such as phenanthrens, bibenzyls, fluorenones and sesquiterpenes, and alkaloids and are responsible for their wide variety of medicinal properties. For decades, bibenzyls, which are the main bioactive components derived from Dendrobium species, have been subjected to extensive investigation as likely candidates for cancer treatment. The present study was undertaken to investigate the effect of moscatilin, a bibenzyl derivative from the orchid Dendrobium loddigesii on human melanoma cells. In A375 cells compound moscatilin showed a clear dose-response relationship in the range of 6.25-50 µM concentrations. In addition, we demonstrated an apoptotic response after treatment of cancer cells with this bibenzyl compound at 6.25 and 12.5 µM concentrations that probably involves PTEN activity, inhibition of Hsp70 expression and reactive oxygen species production. Alternatively, the inhibition of the caspase cascade at higher concentrations, 25 and 50 µM, correlated with additional reactive oxygen species increase, probably switched the mode of moscatilin-induced cell death from apoptosis to necrosis.

The window of opportunity for treatment of progressive multiple sclerosis.

PURPOSE OF REVIEW: Based on the knowledge of disease mechanisms in the progressive course of multiple sclerosis and the experience from randomized clinical trials, we assessed the timing of disease-modifying therapy in patients with progressive multiple sclerosis to define the optimal window of opportunity for treatment of progressive multiple sclerosis. RECENT FINDINGS: In progressive multiple sclerosis both small molecules that cross the blood--brain barrier (siponimod) and monoclonal antibodies (ocrelizumab) have shown therapeutic efficacy and have been approved for treatment of progressive multiple sclerosis. However, the majority of phase II and phase III trials in progressive forms of multiple sclerosis have been negative, probably owing to either late start of treatment or use of drugs that are ineffective for treatment of progressive multiple sclerosis. SUMMARY: Results from phase II and III trials suggest that the window of opportunity for treatment of progressive multiple sclerosis with anti-inflammatory drugs is predominantly in the early phase of the progressive disease course when patients have lower age, shorter duration of progressive multiple sclerosis, and more pronounced clinical and MRI inflammatory activity. Ongoing trials of neuroprotective drugs may widen the window of opportunity by expanding targeted pathophysiologies.