Treatment trials in progressive MS—current challenges and future directions

Efficacy and safety of N-acetyl-L-leucine in Niemann-Pick disease type C

OBJECTIVE

To investigate the safety and efficacy of N-acetyl-L-leucine (NALL) on symptoms, functioning, and quality of life in pediatric (≥ 6 years) and adult Niemann-Pick disease type C (NPC) patients.

METHODS

In this multi-national, open-label, rater-blinded Phase II study, patients were assessed during a baseline period, a 6-week treatment period (orally administered NALL 4 g/day in patients ≥ 13 years, weight-tiered doses for patients 6-12 years), and a 6-week post-treatment washout period. The primary Clinical Impression of Change in Severity (CI-CS) endpoint (based on a 7-point Likert scale) was assessed by blinded, centralized raters who compared randomized video pairs of each patient performing a pre-defined primary anchor test (8-Meter Walk Test or 9-Hole Peg Test) during each study periods. Secondary outcomes included cerebellar functional rating scales, clinical global impression, and quality of life assessments.

RESULTS

33 subjects aged 7-64 years with a confirmed diagnosis of NPC were enrolled. 32 patients were included in the primary modified intention-to-treat analysis. NALL met the CI-CS primary endpoint (mean difference 0.86, SD = 2.52, 90% CI 0.25, 1.75, p = 0.029), as well as secondary endpoints. No treatment-related serious adverse events occurred.

CONCLUSIONS

NALL demonstrated a statistically significant and clinical meaningfully improvement in symptoms, functioning, and quality of life in 6 weeks, the clinical effect of which was lost after the 6-week washout period. NALL was safe and well-tolerated, informing a favorable benefit-risk profile for the treatment of NPC. CLINICALTRIALS.

GOV IDENTIFIER

NCT03759639.

Repurposing Domperidone in Secondary Progressive Multiple Sclerosis: A Simon 2-Stage Phase 2 Futility Trial

OBJECTIVE

To assess whether treatment with the generic drug domperidone can reduce the progression of disability in secondary progressive multiple sclerosis (SPMS), we conducted a phase 2 futility trial following the Simon 2-stage design.

METHODS

We enrolled patients in an open-label, Simon 2-stage, single-center, phase 2, single-arm futility trial at the Calgary Multiple Sclerosis Clinic if they met the following criteria: age of 18 to 60 years, SPMS, screening Expanded Disability Status Scale score of 4.0 to 6.5, and screening timed 25-ft walk (T25FW) of ≥9 seconds. Patients received domperidone 10 mg 4 times daily for 1 year. The primary outcome was worsening of disability, defined as worsening of the T25FW performance by ≥20% at 12 months compared to baseline. This trial is registered with ClinicalTrials.gov (NCT02308137).

RESULTS

Between February 13, 2015, and January 3, 2020, 110 patients were screened, 81 received treatment, and 64 completed follow-up, of whom 62 were analyzed. The study did not meet its primary endpoint: 22 of 62 (35%) patients experienced significant worsening of disability, which is close to the expected proportion of 40% and above the predefined futility threshold. Patients with higher prolactin levels during the study had a significantly lower risk of disability progression, which may warrant further investigation. Domperidone treatment was reasonably well tolerated, but adverse events occurred in 84% and serious adverse events in 15% of patients.

CONCLUSIONS

Domperidone treatment could not reject futility in reducing disability progression in SPMS. The Simon 2-stage trial model may be a useful model for phase 2 studies in progressive MS.

TRIAL REGISTRATION INFORMATION

ClinicalTrials.gov Identifier: NCT02308137.

CLASSIFICATION OF EVIDENCE

This study provides Class III evidence that in individuals with SPMS participating in a futility trial, domperidone treatment could not reject futility in reducing disability progression at 12 months.

A comparison of clinical outcomes in PPMS in the INFORMS original trial data set

Background:

The expanded disability status scale (EDSS) is the standard clinical outcome measure in primary progressive multiple sclerosis (PPMS), even though the timed 25-foot walk (T25FW), nine-hole peg test (NHPT) or combinations of these measures may be more useful. The paced auditory serial addition test (PASAT) is a widely used cognitive measure in MS, but little is known about change in PASAT scores over time in PPMS.

Objective:

The objective of this study is to compare clinical outcome measures in a large PPMS trial data set.

Methods:

We determined significant worsening events on the EDSS, T25FW and NHPT, and PASAT scores over the course of this 3-year trial. We compared unconfirmed, confirmed and sustained disability worsening and contrasted disability worsening with similarly defined improvement. We examined the association of baseline characteristics with the risk of disability worsening at 12, 24 and 36 months with logistic regression models.

Results:

The EDSS and T25FW showed most worsening events, while only few patients worsened on the NHPT. Adding the NHPT to a combined outcome added only few further worsening events. PASAT scores slightly increased over time, possibly due to a practice effect.

Conclusion:

Both the EDSS and T25FW, but not NHPT or PASAT, appear to be useful outcome measures in PPMS.

An enrichment strategy for clinical trials in SPMS

BACKGROUND

We recently compared clinical outcomes in secondary progressive MS (SPMS) clinical trials and found an association of timed 25 foot walk (T25FW) worsening events and baseline disability scores. It is unclear whether disability worsening in clinical trials is comparable to that seen in clinical practice.

OBJECTIVE

The objective of this study is to compare disability worsening between the IMPACT and ASCEND data sets and data from the Calgary MS clinic and to characterize the association of baseline T25FW and expanded disability status scale (EDSS) scores with disability worsening.

METHODS

We combined the three data sets and investigated the impact of baseline characteristics on disability worsening with a logistic regression model. We calculated T25FW, EDSS, and 'EDSS or T25FW' worsening events as a function of ascending cut-off baseline disability scores.

RESULTS

Data source was not associated with T25FW worsening at 12 months. There was a strong association of baseline T25FW and EDSS cut-off scores with T25FW worsening. No such association was present for the EDSS and 'EDSS or T25FW'.

CONCLUSION

Our results suggest that it is possible to 'enrich' a trial cohort for expected T25FW worsening events using specific baseline T25FW and EDSS cut-off scores. These analyses inform the selection of inclusion criteria for clinical trials in SPMS.

Age-related adverse events of disease-modifying treatments for multiple sclerosis: A meta-regression

OBJECTIVE

To verify the hypothesis of an age-dependent increase of infections and neoplasms in patients with multiple sclerosis (MS) under disease-modifying treatments (DMTs) with different mechanisms of action.

METHODS

We extracted relevant data from 45 randomized clinical trials (RCTs) on currently licensed DMTs. We fitted inverse-variance weighted meta-regressions with random-effects models to estimate whether age and/or mechanism of action (immunomodulatory, sequestrating, and depletive) of currently licensed DMTs influenced the difference between experimental arm and control arm in the incidence of specific adverse events, namely, overall infections, opportunistic infections, and neoplasms.

RESULTS

A higher incidence of overall infections was observed in RCTs with depletive DMTs (event-rate ratio = 1.25, p < 0.001). Herpetic infections were more frequently observed in RCTs with both depletive (event-rate ratio = 3.51, p < 0.001) and, to a lesser extent, sequestrating DMTs (event-rate ratio = 1.52, p = 0.078). The interaction of age with depletive DMTs was associated with higher incidence of neoplasms (p = 0.017), especially above 45 years of age.

DISCUSSION

Our study supports a detrimental effect of age on the safety profile of depletive DMTs, with an increased incidence of neoplasms especially over 45 years of age. We failed to demonstrate an age-related increased incidence of infections, possibly due to latency in their occurrence.

Reaching an evidence-based prognosis for personalized treatment of multiple sclerosis

Personalized treatment is ideal for multiple sclerosis (MS) owing to the heterogeneity of clinical features, but current knowledge gaps, including validation of biomarkers and treatment algorithms, limit practical implementation. The contemporary approach to personalized MS therapy depends on evidence-based prognostication, an initial treatment choice and evaluation of early treatment responses to identify the need to switch therapy. Prognostication is directed by baseline clinical, environmental and demographic factors, MRI measures and biomarkers that correlate with long-term disability measures. The initial treatment choice should be a shared decision between the patient and physician. In addition to prognosis, this choice must account for patient-related factors, including comorbidities, pregnancy planning, preferences of the patients and their comfort with risk, and drug-related factors, including safety, cost and implications for treatment sequencing. Treatment response has traditionally been assessed on the basis of relapse rate, MRI lesions and disability progression. Larger longitudinal data sets have enabled development of composite outcome measures and more stringent standards for disease control. Biomarkers, including neurofilament light chain, have potential as early surrogate markers of prognosis and treatment response but require further validation. Overall, attainment of personalized treatment for MS is complex but will be refined as new data become available.

Validation of 0-10 MS symptom scores in the Australian multiple sclerosis longitudinal study

BACKGROUND

Multiple sclerosis (MS) symptom measurements often use multiple-item scales per symptom, creating a high burden when multiple symptoms are assessed. We aimed to examine the validity, stability and responsiveness of single-item 0-10 numeric rating MS Symptom Scores (MSSymS).

METHODS

The study included 1,985 participants from the Australian Multiple Sclerosis Longitudinal Study. Thirteen MS symptoms were assessed using the MSSymS, of which we were able to validate six (walking difficulties, fatigue, pain, feelings of anxiety, feelings of depression and vision problems). Comparison measures included Patient Determined Disease Steps (PDDS), Fatigue Severity Scale (FSS), Hospital Anxiety and Depression Scale (HADS), and Assessment of Quality of Life (AQoL). We used spearman rank correlation for concurrent validity, linear regression for predictive validity, intra-class correlations for stability, and percentage change for responsiveness.

RESULTS

We found high correlations between walking difficulties and PDDS (r = 0.82), pain and AQoL-pain (r = 0.77), fatigue and FSS (r = 0.72); moderate correlations between feelings of anxiety and HADS-Anxiety (r = 0.68), feelings of depression and HADS-Depression (r = 0.63); and low correlation between vision and AQoL-vision (r = 0.43) For predictive validity, the graphs with quality of life were largely overlapping and the R² of the regression lines were generally similar. The stability and responsiveness of the MSSymS were adequate.

CONCLUSION

The six assessed symptoms of the MSSymS performed equally well compared to validated comparison measures in terms of concurrent and predictive validity, temporal stability and responsiveness.

Clinical outcome measures in SPMS trials: An analysis of the IMPACT and ASCEND original trial data sets

Background:

Still too little is known about the natural history of clinical outcome measures beyond the Expanded Disability Status Scale (EDSS), such as the timed 25-foot walk (T25FW) and nine-hole peg test (9HPT) in secondary progressive multiple sclerosis (SPMS).

Objective:

To describe progression on the EDSS, T25FW, 9HPT, and their combinations. To investigate the association of the baseline characteristics age, sex, EDSS, T25FW, gadolinium-enhancing lesions, and relapse activity with EDSS and T25FW progression.

Methods:

Using original trial data from the placebo arms of the IMPACT and ASCEND randomized controlled trials, we describe disability progression (with and without 3- or 6-month confirmation). We investigated the association of selected baseline characteristics with EDSS and T25FW progression over 2 years using binary logistic regression.

Results:

T25FW was the single outcome measure with the largest proportion of patients progressing, followed by EDSS and 9HPT. EDSS and T25FW at baseline were associated with EDSS and T25FW progression in both data sets. Age and relapse activity were only mild and inconsistent predictors, while sex and gadolinium enhancement at baseline did not predict disability progression in either data set.

Conclusion:

Our analyses inform the selection of primary outcome measures as well as inclusion criteria for clinical trials in SPMS.

Siponimod pharmacokinetics, safety, and tolerability in combination with the potent CYP3A4 inhibitor itraconazole in healthy subjects with different CYP2C9 genotypes

PURPOSE

To evaluate the PK and safety of siponimod, a substrate of CYP2C9/3A4, in the presence or absence of a CYP3A4 inhibitor, itraconazole.

METHODS

This was an open-label study in healthy subjects (aged 18-50 years; genotype: CYP2C9 *1*2 [cohort 1; n = 17] or *1*3 [cohort 2; n = 13]). Subjects received siponimod 0.25-mg single dose in treatment period 1 (days 1-14), itraconazole 100 mg twice daily in treatment period 2 (days 15-18), and siponimod 0.25-mg single dose (day 19) with itraconazole until day 31 (cohort 1) or day 35 (cohort 2) in treatment period 3. PK of siponimod alone and with itraconazole and safety were assessed.

RESULTS

Overall, 29/30 subjects completed the study. In treatment period 1, geometric mean AUC_inf, T_1/2, and median T_max were higher while systemic clearance was lower in cohort 2 than cohort 1. In treatment period 3, siponimod AUC decreased by 10% (geo-mean ratio [90% confidence intervals]: 0.90 [0.84; 0.96]) and 24% (0.76 [0.69; 0.82]) in cohorts 1 and 2, respectively. Siponimod C_max was similar between treatment periods 1 and 3. In both cohorts, the C_max and AUC of the metabolites (M17, M3, and M5) decreased in the presence of itraconazole. All adverse events were mild.

CONCLUSIONS

The minor albeit significant reduction in plasma exposure of siponimod and its metabolites by itraconazole was unexpected. While the reason is unclear, the results suggest that coadministration of the two drugs would not cause a considerable increase of siponimod exposure independent of CYP2C9 genotype.

Anti-inflammatory disease-modifying treatment and disability progression in primary progressive multiple sclerosis: a cohort study

BACKGROUND AND PURPOSE

Treatment options in primary progressive multiple sclerosis (PPMS) are scarce and, with the exception of ocrelizumab, anti-inflammatory agents have failed to show efficacy in ameliorating disability progression. The aim of this study was to investigate a potential effect of anti-inflammatory disease-modifying treatment on disability outcomes in PPMS.

METHODS

Using MSBase, a large, international, observational database, we identified patients with PPMS who were either never treated or treated with a disease-modifying agent. Propensity score matching was used to select subpopulations with similar baseline characteristics. Expanded Disability Status Scale (EDSS) outcomes were compared with an intention-to-treat and an as-treated approach in paired, pairwise-censored analyses.

RESULTS

Of the 1284 included patients, 533 were matched (treated, n = 195; untreated n = 338). Median on-study pairwise-censored follow-up was 3.4 years (quartiles 1.2-5.5). No difference in the hazard of experiencing 3-month confirmed EDSS progression events was observed between the groups [hazard ratio (HR), 1.0; 95% confidence interval (CI), 0.6-1.7, P = 0.87]. We did not find significant differences in the hazards of confirmed EDSS improvement (HR, 1.0; 95% CI, 0.6-1.6, P = 0.91) or reaching a confirmed EDSS step ≥7 (HR, 1.1; 95% CI, 0.7-1.6, P = 0.69).

CONCLUSION

Our pooled analysis of disease-modifying agents suggests that these therapies have no substantial effect on short- to medium-term disability outcomes in PPMS.

Patient-reported outcomes are worse for progressive-onset multiple sclerosis than relapse-onset multiple sclerosis, particularly early in the disease process

BACKGROUND AND PURPOSE

Treatments for progressive-onset multiple sclerosis (MS) are lacking. To improve the disease management for progressive-onset MS, the differences between relapse-onset MS and progressive-onset MS in patient-reported disability, progression and symptoms were examined.

METHODS

A total of 1985 participants of the Australian Multiple Sclerosis Longitudinal Study were included. Associations between onset type and outcomes were assessed with negative binomial regression.

RESULTS

The severity of 17 of the 19 outcomes was significantly higher for progressive-onset MS patients than relapse-onset MS patients, including perspectives from disability, progression over the last year, fatigue, sensory, walking difficulties, pain, balance, spasticity, sexual dysfunction, bladder, bowel, anxiety, depression and the European quality of life (EQ-5D) (P < 0.05; adjusted mean ratio ranged from 1.11 to 1.52). The differences between the two onset types were most pronounced early in the disease process and reduced with increasing MS duration, and the interaction was significant for disability, progression over the last year, walking difficulties, bladder problems, bowel problems and spasticity.

CONCLUSION

Participants with progressive-onset MS were significantly worse off on nearly all patient-reported outcomes than relapse-onset MS participants, and the differences were most pronounced early in the disease course, highlighting the importance of early intervention for those with progressive-onset MS.

Over three decades study populations in progressive multiple sclerosis have become older and more disabled, but have lower on-trial progression rates: A systematic review and meta-analysis of 43 randomised placebo-controlled trials

BACKGROUND

Progression is the major driver of disability and cost in multiple sclerosis (MS). However, the search for treatments in progressive multiple sclerosis (PMS) has not mirrored the success in relapsing MS.

OBJECTIVES

To assess changes in PMS trials over time.

METHODS

PubMed, MEDLINE and Embase were searched to identify randomised, double-blind, placebo-controlled trials in PMS. Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines were used, study quality was assessed and trends were examined by regression.

RESULTS

Placebo groups of 43 studies published between 1988 and 2018 were included. The mean age at trial entry increased by 9.8 years per decade (95% confidence interval (CI): [2.7; 4.9]; p < 0.001). Mean baseline Expanded Disability Status Scale (EDSS) scores increased by 0.36 points (95% CI: [0.09; 0.62]; p = 0.009) and disease durations at baseline were prolonged by 1.8 years (95% CI: [0.7; 2.9]; p = 0.003) per decade. The trials became larger, specifically placebo groups increased by about 222 patients (95% CI: [36; 409]; p = 0.021) and 88 patients (95% CI: [12; 165]; p = 0.025) per decade for primary progressive multiple sclerosis (PPMS) and secondary progressive multiple sclerosis (SPMS), respectively. The proportion of patients on placebo experiencing disability progression within 24 months decreased by 7.6 percentage points (95% CI: [1.2; 14.1]; p = 0.022) per year.

CONCLUSION

Over three decades, PMS trial populations changed and are now older, with a longer disease duration and more disability, with lower on-trial progression rates.

Teriflunomide attenuates neuroinflammation-related neural damage in mice carrying human PLP1 mutations

BACKGROUND

Genetically caused neurological disorders of the central nervous system (CNS) are mostly characterized by poor or even fatal clinical outcome and few or no causative treatments are available. Often, these disorders are associated with low-grade, disease-promoting inflammation, another feature shared by progressive forms of multiple sclerosis (PMS). We previously generated two mouse lines carrying distinct mutations in the oligodendrocytic PLP1 gene that have initially been identified in patients diagnosed with MS. These mutations cause a loss of PLP function leading to a histopathological and clinical phenotype common to both PMS and genetic CNS disorders, like hereditary spastic paraplegias. Importantly, neuroinflammation promotes disease progression in these models, suggesting that pharmacological modulation of inflammation might ameliorate disease outcome.

METHODS

We applied teriflunomide, an approved medication for relapsing-remitting MS targeting activated T-lymphocytes, in the drinking water (10 mg/kg body weight/day). Experimental long-term treatment of PLP mutant mice was non-invasively monitored by longitudinal optical coherence tomography and by rotarod analysis. Immunomodulatory effects were subsequently analyzed by flow cytometry and immunohistochemistry and treatment effects regarding neural damage, and neurodegeneration were assessed by histology and immunohistochemistry.

RESULTS

Preventive treatment with teriflunomide attenuated the increase in number of CD8+ cytotoxic effector T cells and fostered the proliferation of CD8+ CD122+ PD-1+ regulatory T cells in the CNS. This led to an amelioration of axonopathic features and neuron loss in the retinotectal system, also reflected by reduced thinning of the innermost retinal composite layer in longitudinal studies and ameliorated clinical outcome upon preventive long-term treatment. Treatment of immune-incompetent PLP mutants did not provide evidence for a direct, neuroprotective effect of the medication. When treatment was terminated, no rebound of neuroinflammation occurred and histopathological improvement was preserved for at least 75 days without treatment. After disease onset, teriflunomide halted ongoing axonal perturbation and enabled a recovery of dendritic arborization by surviving ganglion cells. However, neither neuron loss nor clinical features were ameliorated, likely due to already advanced neurodegeneration before treatment onset.

CONCLUSIONS

We identify teriflunomide as a possible medication not only for PMS but also for inflammation-related genetic diseases of the nervous system for which causal treatment options are presently lacking.

Progressive multiple sclerosis, cognitive function, and quality of life

Background

Patients with progressive multiple sclerosis (MS) often have cognitive impairment in addition to physical impairment. The burden of cognitive and physical impairment progresses over time, and may be major determinants of quality of life. The aim of this study was to assess to which degree quality of life correlates with physical and cognitive function in progressive MS.

Methods

This is a retrospective study of 52 patients with primary progressive (N = 18) and secondary progressive MS (N = 34). Physical disability was assessed using the Expanded Disability Status Scale, Timed 25 Foot Walk (T25FW) test and 9-Hole Peg Test (9HPT). Cognitive function was assessed using Symbol Digit Modalities Test (SDMT), Paced Auditory Serial Addition Test, and Trail Making Test B (TRAIL-B). In addition, quality of life was assessed by the Short Form 36 (SF-36) questionnaire.

Results

Only measures of cognitive function correlated with the overall SF-36 quality of life score and the Mental Component Summary score from the SF-36. The only physical measure that correlated with a measure of quality of life was T25FW test, which correlated with the Physical Component Summary from the SF-36. We found no other significant correlations between the measures of cognitive function and the overall physical measures but interestingly, we found a possible relationship between the 9HPT score for the nondominant hand and the SDMT and TRAIL-B.

Conclusion

Our findings support inclusion of measures of cognitive function in the assessment of patients with progressive MS as these correlated closer with quality of life than measures of physical impairment.

Pathogenic inflammation in the CNS of mice carrying human PLP1 mutations

Progressive forms of multiple sclerosis lead to chronic disability, substantial decline in quality of life and reduced longevity. It is often suggested that they occur independently of inflammation. Here we investigated the disease progression in mouse models carrying PLP1 point mutations previously found in patients displaying clinical features of multiple sclerosis. These mouse models show loss-of-function of PLP1 associated with neuroinflammation; the latter leading to clinically relevant axonal degeneration, neuronal loss and brain atrophy as demonstrated by inactivation of the recombination activating gene 1. Moreover, these pathological hallmarks were substantially amplified when we attenuated immune regulation by inactivation of the programmed cell death-1 gene. Our observations support the view that primary oligodendroglial abnormalities can evoke pathogenically relevant neuroinflammation that drives neurodegeneration, as observed in some forms of multiple sclerosis but also in other, genetically-mediated neurodegenerative disorders of the human nervous system. As many potent immunomodulatory drugs have emerged during the last years, it is tempting to consider immunomodulation as a treatment option not only for multiple sclerosis, but also for so far non-treatable, genetically-mediated disorders of the nervous system accompanied by pathogenic neuroinflammation.

Anti-inflammatory disease-modifying treatment and short-term disability progression in SPMS

OBJECTIVE

To investigate the effect of disease-modifying treatment on short-term disability outcomes in secondary progressive multiple sclerosis (SPMS).

METHODS

Using MSBase, an international cohort study, we previously validated a highly accurate definition of SPMS. Here, we identified patients in MSBase who were either untreated or treated with a disease-modifying drug when meeting this definition. Propensity score matching was used to select subpopulations with comparable baseline characteristics. Disability outcomes were compared in paired, pairwise-censored analyses adjusted for treatment persistence, visit density, and relapse rates.

RESULTS

Of the 2,381 included patients, 1,378 patients were matchable (treated n = 689, untreated n = 689). Median pairwise-censored follow-up was 2.1 years (quartiles 1.2-3.8 years). No difference in the risk of 6-month sustained disability progression was observed between the groups (hazard ratio [HR] 0.9, 95% confidence interval [CI] 0.7-1.1, p = 0.27). We also did not find differences in any of the secondary endpoints: risk of reaching Expanded Disability Status Scale (EDSS) score ≥7 (HR 0.6, 95% CI 0.4-1.1, p = 0.10), sustained disability reduction (HR 1.0, 95% CI 0.8-1.3, p = 0.79), or change in disability burden (area under the EDSS-time curve, β = -0.05, p = 0.09). Secondary and sensitivity analyses confirmed the results.

CONCLUSIONS

Our pooled analysis of the currently available disease-modifying agents used after conversion to SPMS suggests that, on average, these therapies have no substantial effect on relapse-unrelated disability outcomes measured by the EDSS up to 4 years.

CLASSIFICATION OF EVIDENCE

This study provides Class IV evidence that for patients with SPMS, disease-modifying treatment has no beneficial effect on short-term disability progression.

Drug discovery for remyelination and treatment of MS

Glia constitute the majority of the cells in our nervous system, yet there are currently no drugs that target glia for the treatment of disease. Given ongoing discoveries of the many roles of glia in numerous diseases of the nervous system, this is likely to change in years to come. Here we focus on the possibility that targeting the oligodendrocyte lineage to promote regeneration of myelin (remyelination) represents a therapeutic strategy for the treatment of the demyelinating disease multiple sclerosis, MS. We discuss how hypothesis driven studies have identified multiple targets and pathways that can be manipulated to promote remyelination in vivo, and how this work has led to the first ever remyelination clinical trials. We also highlight how recent chemical discovery screens have identified a host of small molecule compounds that promote oligodendrocyte differentiation in vitro. Some of these compounds have also been shown to promote myelin regeneration in vivo, with one already being trialled in humans. Promoting oligodendrocyte differentiation and remyelination represents just one potential strategy for the treatment of MS. The pathology of MS is complex, and its complete amelioration may require targeting multiple biological processes in parallel. Therefore, we present an overview of new technologies and models for phenotypic analyses and screening that can be exploited to study complex cell-cell interactions in in vitro and in vivo systems. Such technological platforms will provide insight into fundamental mechanisms and increase capacities for drug-discovery of relevance to glia and currently intractable disorders of the CNS.

Comparative utility of disability progression measures in PPMS: Analysis of the PROMiSe data set

OBJECTIVE

To assess the comparative utility of disability progression measures in primary progressive MS (PPMS) using the PROMiSe trial data set.

METHODS

Data for patients randomized to placebo (n = 316) in the PROMiSe trial were included in this analysis. Disability was assessed using change in single (Expanded Disability Status Scale [EDSS], timed 25-foot walk [T25FW], and 9-hole peg test [9HPT]) and composite disability measures (EDSS/T25FW, EDSS/9HPT, and EDSS/T25FW/9HPT). Cumulative and cross-sectional unconfirmed disability progression (UDP) and confirmed disability progression (CDP; sustained for 3 months) rates were assessed at 12 and 24 months.

RESULTS

CDP rates defined by a ≥20% increase in T25FW were higher than those defined by EDSS score at 12 and 24 months. CDP rates defined by T25FW or EDSS score were higher than those defined by 9HPT score. The 3-part composite measure was associated with more CDP events (41.4% and 63.9% of patients at 12 and 24 months, respectively) than the 2-part measure (EDSS/T25FW [38.5% and 59.5%, respectively]) and any single measure. Cumulative UDP and CDP rates were higher than cross-sectional rates.

CONCLUSIONS

The T25FW or composite measures of disability may be more sensitive to disability progression in patients with PPMS and should be considered as the primary endpoint for future studies of new therapies. CDP may be the preferred measure in classic randomized controlled trials in which cumulative disability progression rates are evaluated; UDP may be feasible for cross-sectional studies.

Cortical excitability changes over time in progressive multiple sclerosis

In 25 patients with progressive forms of multiple sclerosis (MS), motor cortex excitability was longitudinally studied over one year by means of transcranial magnetic stimulation (TMS). The following TMS parameters were considered: resting and active motor thresholds (MTs), input-output curve, short-interval intracortical inhibition (SICI), and intracortical facilitation. Clinical evaluation was based on the Expanded Disability Status Scale (EDSS). In the 16 patients not receiving disease-modifying drugs, the EDSS score worsened, resting MT increased, and SICI decreased. By contrast, no clinical for neurophysiological changes were found over time in the nine patients receiving immunomodulatory therapy. The natural course of progressive MS appears to be associated with a decline in cortical excitability of both pyramidal neurons and inhibitory circuits. This pilot study based on a small sample suggests that disease-modifying drugs may allow cortical excitability to remain stable, even in patients with progressive MS.

Defining secondary progressive multiple sclerosis

A number of studies have been conducted with the onset of secondary progressive multiple sclerosis as an inclusion criterion or an outcome of interest. However, a standardized objective definition of secondary progressive multiple sclerosis has been lacking. The aim of this work was to evaluate the accuracy and feasibility of an objective definition for secondary progressive multiple sclerosis, to enable comparability of future research studies. Using MSBase, a large, prospectively acquired, global cohort study, we analysed the accuracy of 576 data-derived onset definitions for secondary progressive multiple sclerosis and first compared these to a consensus opinion of three neurologists. All definitions were then evaluated against 5-year disease outcomes post-assignment of secondary progressive multiple sclerosis: sustained disability, subsequent sustained progression, positive disability trajectory, and accumulation of severe disability. The five best performing definitions were further investigated for their timeliness and overall disability burden. A total of 17 356 patients were analysed. The best definition included a 3-strata progression magnitude in the absence of a relapse, confirmed after 3 months within the leading Functional System and required an Expanded Disability Status Scale step ≥4 and pyramidal score ≥2. It reached an accuracy of 87% compared to the consensus diagnosis. Seventy-eight per cent of the identified patients showed a positive disability trajectory and 70% reached significant disability after 5 years. The time until half of all patients were diagnosed was 32.6 years (95% confidence interval 32-33.6) after disease onset compared with the physicians' diagnosis at 36 (35-39) years. The identified patients experienced a greater disease burden [median annualized area under the disability-time curve 4.7 (quartiles 3.6, 6.0)] versus non-progressive patients [1.8 (1.2, 1.9)]. This objective definition of secondary progressive multiple sclerosis based on the Expanded Disability Status Scale and information about preceding relapses provides a tool for a reproducible, accurate and timely diagnosis that requires a very short confirmation period. If applied broadly, the definition has the potential to strengthen the design and improve comparability of clinical trials and observational studies in secondary progressive multiple sclerosis.

Secondary Progressive Multiple Sclerosis: Definition and Measurement

Secondary progressive multiple sclerosis (SPMS) is diagnosed retrospectively and involves a clinical course characterized by a progressive accumulation of neurological disability, independent of relapses, following an initial relapsing-remitting (RR) phase. Our incomplete understanding of the pathological mechanisms underlying neurodegeneration in multiple sclerosis (MS) may explain why, to date, there is no definitive imaging or laboratory test that is able to inform us when the disease is clearly entering into a progressive phase and why the vast majority of clinical trials testing immunosuppressant and immunomodulating drugs in SPMS patients has so far yielded disappointing or mixed results. Here we discuss the definition(s) of SPMS and how it may vary, outcome measurements (current and emerging) and modern trial design.

Bone marrow-derived macrophages and the CNS: An update on the use of experimental chimeric mouse models and bone marrow transplantation in neurological disorders

The central nervous system (CNS) is a very unique system with multiple features that differentiate it from systemic tissues. One of the most captivating aspects of its distinctive nature is the presence of the blood brain barrier (BBB), which seals it from the periphery. Therefore, to preserve tissue homeostasis, the CNS has to rely heavily on resident cells such as microglia. These pivotal cells of the mononuclear lineage have important and dichotomous roles according to various neurological disorders. However, certain insults can overwhelm microglia as well as compromising the integrity of the BBB, thus allowing the infiltration of bone marrow-derived macrophages (BMDMs). The use of myeloablation and bone marrow transplantation allowed the generation of chimeric mice to study resident microglia and infiltrated BMDM separately. This breakthrough completely revolutionized the way we captured these 2 types of mononuclear phagocytic cells. We now realize that microglia and BMDM exhibit distinct features and appear to perform different tasks. Since these cells are central in several pathologies, it is crucial to use chimeric mice to analyze their functions and mechanisms to possibly harness them for therapeutic purpose. This review will shed light on the advent of this methodology and how it allowed deciphering the ontology of microglia and its maintenance during adulthood. We will also compare the different strategies used to perform myeloablation. Finally, we will discuss the landmark studies that used chimeric mice to characterize the roles of microglia and BMDM in several neurological disorders. This article is part of a Special Issue entitled: Neuro Inflammation edited by Helga E. de Vries and Markus Schwaninger.

The natural history of early versus late disability accumulation in primary progressive MS

BACKGROUND

Primary progressive multiple sclerosis (PPMS) is the least common MS disease course and carries the worst prognosis. In relapsing-remitting multiple sclerosis (RRMS) disability accumulation occurs in two distinct phases, but it is unclear whether this is also true for PPMS. Here we investigate factors associated with early and late disability accumulation in PPMS.

METHODS

We used Kaplan-Meier survival analyses and Cox regression to investigate the influence of sex, age at disease onset and onset symptoms on time to, and age at, Expanded Disability Status Scale (EDSS) 4 and 6, as well as the time from EDSS 4 to 6 in patients with PPMS.

RESULTS

We identified 500 patients with PPMS. The analyses on time to EDSS 4 included 358 patients, and those on time to EDSS 6 included 392 patients. The median times to EDSS 4 and EDSS 6 were 5 and 9 years. The analyses on age at EDSS 4 included 360 patients, and those on age at EDSS 6 included 402 patients. The median ages at EDSS 4 and EDSS 6 were 51 and 55 years. Older age at onset and bilateral motor onset symptoms were independently associated with a shorter time to both EDSS 4 and EDSS 6. Sex and other onset symptoms were not associated with time to, or age at, landmark disability. Only age at onset was significantly associated with the time from EDSS 4 to EDSS 6.

CONCLUSIONS

Age at disease onset is the most important predictor of disability accumulation in PPMS. Bilateral motor onset symptoms were associated with quicker disease progression. In contrast to RRMS, we found no evidence for distinct phases of disability accumulation in PPMS. Disability accumulation in PPMS appears to be affected by the same factors throughout its course.

Cerebrospinal fluid markers reveal intrathecal inflammation in progressive multiple sclerosis

OBJECTIVE

The management of complex patients with neuroimmunological diseases is hindered by an inability to reliably measure intrathecal inflammation. Currently implemented laboratory tests developed >40 years ago either are not dynamic or fail to capture low levels of central nervous system (CNS) inflammation. Therefore, we aimed to identify and validate biomarkers of CNS inflammation in 2 blinded, prospectively acquired cohorts of untreated patients with neuroimmunological diseases and embedded controls, with the ultimate goal of developing clinically useful tools.

METHODS

Because biomarkers with maximum utility reflect immune phenotypes, we included an assessment of cell specificity in purified primary immune cells. Biomarkers were quantified by optimized electrochemiluminescent immunoassays.

RESULTS

Among markers with cell-specific secretion, soluble CD27 is a validated biomarker of intrathecal T-cell activation, with an area under the receiver operating characteristic curve of 0.97. Comparing the quantities of cerebrospinal fluid (CSF) immune cells and their respective cell-specific soluble biomarkers (released by CSF cells as well as their counterparts in CNS tissue) provided invaluable information about stationary CNS immune responses, previously attainable via brain biopsy only. Unexpectedly, progressive and relapsing-remitting multiple sclerosis (MS) patients have comparable numbers of activated intrathecal T and B cells, which are preferentially embedded in CNS tissue in the former group.

INTERPRETATION

The cell-specific biomarkers of intrathecal inflammation may improve diagnosis and management of neuroimmunological diseases and provide pharmacodynamic markers for future therapeutic developments in patients with intrathecal inflammation that is not captured by imaging, such as in progressive MS.

Progression rates and sample size estimates for PPMS based on the CLIMB study population

Background:

The clinical trial design for primary progressive multiple sclerosis (PPMS) requires understanding of disability progression in modern patient cohorts.

Objective:

The objective of this paper is to characterize demographic and clinical characteristics of PPMS and assess rate of disability progression.

Methods:

We studied PPMS ( n = 73) and relapsing-onset MS (ROMS) patients ( n = 1541) enrolled in CLIMB, a longitudinal study of MS patients at the Brigham and Women’s Hospital (Boston, MA). Disability progression for each group was compared using interval-censored survival analysis and time to six-month sustained progression.

Results:

The PP group had a 1.09:1 male:female ratio compared to 1:2.89 for the RO group and greater mean age of onset (PP: 44.4±9.6; RO: 32.7±9.9; p < 0.0001). Motor symptoms at onset and first symptoms localized to spinal cord were each strongly associated with PPMS ( p < 0.001). Median time from onset to EDSS 6.0 was faster in PPMS ( p < 0.001). PPMS patients progressed faster to EDSS 3 ( p < 0.001) and from EDSS 3 to 6 ( p < 0.001). Median time to sustained progression in the PP group was 4.85 years (95% CI 2.83–8.35), significantly faster than the RO group ( p < 0.001).

Conclusions:

Our modern PPMS cohort is demographically similar to previously studied cohorts. PPMS is associated with faster disability accrual than ROMS. Current real-world observations of time to sustained progression will inform design of new clinical trials for PPMS.