Peter Connick

Drug Repurposing: A Systematic Approach to Evaluate Candidate Oral Neuroprotective Interventions for Secondary Progressive Multiple Sclerosis

Objective To develop and implement an evidence based framework to select, from drugs already licenced, candidate oral neuroprotective drugs to be tested in secondary progressive multiple sclerosis. Design Systematic review of clinical studies of oral putative neuroprotective therapies in MS and four other neurodegenerative diseases with shared pathological features, followed by systematic review and meta-analyses of the in vivo experimental data for those interventions. We presented summary data to an international multi-disciplinary committee, which assessed each drug in turn using pre-specified criteria including consideration of mechanism of action. Results We identified a short list of fifty-two candidate interventions. After review of all clinical and pre-clinical evidence we identified ibudilast, riluzole, amiloride, pirfenidone, fluoxetine, oxcarbazepine, and the polyunsaturated fatty-acid class (Linoleic Acid, Lipoic acid; Omega-3 fatty acid, Max EPA oil) as lead candidates for clinical evaluation. Conclusions We demonstrate a standardised and systematic approach to candidate identification for drug rescue and repurposing trials that can be applied widely to neurodegenerative disorders.

Verbal fluency as a rapid screening test for cognitive impairment in progressive multiple sclerosis

Application of multidimensional assessment batteries is a well-established approach to detect cognitive impairment in multiple sclerosis (MS), the best known example being the Brief Repeatable Neuropsychological Battery. Although relatively easy to administer, these batteries require equipment, training and take 30–60 min.1 Current bedside screening techniques based on the Symbol Digit Modality Test, Paced Auditory Serial Additions Test (PASAT) and Faces Symbol Test are quick to administer (5–10 min), but they also require training and availability of relevant equipment.2 A rapid portable screening test that could be widely applied at the bedside or in the busy clinic is therefore highly desirable. Given that deficits in both phonemic (letter) and semantic (category) fluency are common in progressive MS and have been described among the earliest detectable cognitive features, both are of interest as candidate screening tests.3 Testing requires the subject to generate words beginning with a given letter (eg, p) or semantic category (eg, animals) over a defined time period (usually 1 min). Crucially, minimal test equipment is …

Patterns of cognitive dysfunction in progressive MS

Background: Progressive MS is associated with a high frequency of cognitive impairment. However, it is not clear to what extent this reflects global dysfunction, or independent deficits in specific functions. Objective: To characterise patterns of cognitive impairment in progressive MS on a multi-dimensional cognitive assessment tool well established in neurodegenerative diseases. Methods: Patients with secondary (SPMS; n = 60) and primary progressive MS (PPMS; n = 28) were assessed using the Addenbrooke’s Cognitive Examination-Revised (ACE-R) multi-dimensional cognitive assessment scale. Independent dimensions of impairment and their relative contribution to the overall burden of cognitive dysfunction were then determined by factor analysis. Results: Two independent dimensions of impairment were seen: frontal-executive (attention, verbal fluency, recall) on one hand, and language and visuospatial functions on the other. These accounted for 55% and 45% respectively of the variance not explained by a global influence (14.2% and 11.6% respectively of total variance). Isolated language and visuospatial dysfunction was seen in both groups, whereas isolated impairment in frontal-executive functions was underrepresented in SPMS (p = 0.001) and not seen in PPMS patients (p = 0.040). Conclusions: In addition to a prominent global influence on cognitive performance, patients with progressive MS commonly exhibit language and visuospatial deficits. Evaluation of these abilities should therefore be included in clinical assessment of cognition in progressive MS.

Hypothermic Preconditioning of Human Cortical Neurons Requires Proteostatic Priming.

Hypothermia is potently neuroprotective but poor mechanistic understanding has restricted its clinical use. Rodent studies indicate that hypothermia can elicit preconditioning, wherein a subtoxic cellular stress confers resistance to an otherwise lethal injury. The molecular basis of this preconditioning remains obscure. Here we explore molecular effects of cooling using functional cortical neurons differentiated from human pluripotent stem cells (hCNs). Mild-to-moderate hypothermia (28–32 °C) induces cold-shock protein expression and mild endoplasmic reticulum (ER) stress in hCNs, with full activation of the unfolded protein response (UPR). Chemical block of a principal UPR pathway mitigates the protective effect of cooling against oxidative stress, whilst pre-cooling neurons abrogates the toxic injury produced by the ER stressor tunicamycin. Cold-stress thus preconditions neurons by upregulating adaptive chaperone-driven pathways of the UPR in a manner that precipitates ER-hormesis. Our findings establish a novel arm of neurocryobiology that could reveal multiple therapeutic targets for acute and chronic neuronal injury.

Stem cells as a resource for regenerative neurology.

Public and media interest in the potential applications of stem cells in regenerative neurology has led to growing hope and expectation. This interest is heightened by the current paucity of treatments available for neurodegenerative diseases and their generally poor prognosis. Patient discussions about stem cells are therefore a common occurrence in clinical practice, requiring neurologists to offer clear and accurate information. In the context of a complex and rapidly evolving field, this can be extremely challenging. Here we address issues around stem cell populations relevant to regenerative neurology, including the opportunities they offer for research and their potential application as direct therapies, concluding with a pragmatic assessment of the likely clinical benefits of stem cell research.

Genetic epidemiology of motor neuron disease-associated variants in the Scottish population

Genetic understanding of motor neuron disease (MND) has evolved greatly in the past 10 years, including the recent identification of association between MND and variants in TBK1 and NEK1. Our aim was to determine the frequency of pathogenic variants in known MND genes and to assess whether variants in TBK1 and NEK1 contribute to the burden of MND in the Scottish population. SOD1, TARDBP, OPTN, TBK1, and NEK1 were sequenced in 441 cases and 400 controls. In addition to 44 cases known to carry a C9orf72 hexanucleotide repeat expansion, we identified 31 cases and 2 controls that carried a loss-of-function or pathogenic variant. Loss-of-function variants were found in TBK1 in 3 cases and no controls and, separately, in NEK1 in 3 cases and no controls. This study provides an accurate description of the genetic epidemiology of MND in Scotland and provides support for the contribution of both TBK1 and NEK1 to MND susceptibility in the Scottish population.

The clinico-radiological paradox of cognitive function and MRI burden of white matter lesions in people with multiple sclerosis: a systematic review and meta-analysis.

Background Moderate correlation exists between the imaging quantification of brain white matter lesions and cognitive performance in people with multiple sclerosis (MS). This may reflect the greater importance of other features, including subvisible pathology, or methodological limitations of the primary literature. Objectives To summarise the cognitive clinico-radiological paradox and explore the potential methodological factors that could influence the assessment of this relationship. Methods Systematic review and meta-analysis of primary research relating cognitive function to white matter lesion burden. Results Fifty papers met eligibility criteria for review, and meta-analysis of overall results was possible in thirty-two (2050 participants). Aggregate correlation between cognition and T2 lesion burden was r = -0.30 (95% confidence interval: -0.34, -0.26). Wide methodological variability was seen, particularly related to key factors in the cognitive data capture and image analysis techniques. Conclusions Resolving the persistent clinico-radiological paradox will likely require simultaneous evaluation of multiple components of the complex pathology using optimum measurement techniques for both cognitive and MRI feature quantification. We recommend a consensus initiative to support common standards for image analysis in MS, enabling benchmarking while also supporting ongoing innovation.

Hypothermic Preconditioning Reverses Tau Ontogenesis in Human Cortical Neurons and is Mimicked by Protein Phosphatase 2A Inhibition

Hypothermia is potently neuroprotective, but the molecular basis of this effect remains obscure. Changes in neuronal tau protein are of interest, since tau becomes hyperphosphorylated in injury-resistant, hypothermic brains. Noting inter-species differences in tau isoforms, we have used functional cortical neurons differentiated from human pluripotent stem cells (hCNs) to interrogate tau modulation during hypothermic preconditioning at clinically-relevant temperatures. Key tau developmental transitions (phosphorylation status and splicing shift) are recapitulated during hCN differentiation and subsequently reversed by mild (32 °C) to moderate (28 °C) cooling — conditions which reduce oxidative and excitotoxic stress-mediated injury in hCNs. Blocking a major tau kinase decreases hCN tau phosphorylation and abrogates hypothermic neuroprotection, whilst inhibition of protein phosphatase 2A mimics cooling-induced tau hyperphosphorylation and protects normothermic hCNs from oxidative stress. These findings indicate a possible role for phospho-tau in hypothermic preconditioning, and suggest that cooling drives human tau towards an earlier ontogenic phenotype whilst increasing neuronal resilience to common neurotoxic insults. This work provides a critical step forward in understanding how we might exploit the neuroprotective benefits of cooling without cooling patients.

Impairment of Visual Cognition in Progressive Multiple Sclerosis

Background: Impairment of visual cognition occurs in up to 25% of patients with MS, however data on progressive disease is limited and the neural basis remains unknown. Objective: To evaluate the influence of multifocal inflammatory CNS white matter demyelination burden on visual cognition in equivalent SPMS and PPMS cohorts. Methods: 59 SPMS and 27 PPMS patients matched for demographic and disease characteristics were evaluated using visuospatial and visuoperceptual components of the Addenbrooke’s cognitive examination-revised (ACE-R) battery. Factors influencing performance were then identified by logistic regression. Exploratory logistic models were also used to determine the predictive value of deficits in attention, working memory, and arithmetic abilities. Finally, comparison of deficits between equivalent primary (PPMS) and secondary (SPMS) progressive disease groups was used to evaluate a potential dose-response for cumulative multifocal inflammatory CNS white matter demyelination. Results: The overall prevalence of impairment in visual cognition was 14.0% (95%CI=6.4 to 21.4%) with no difference between disease groups. Qualitatively, the observed deficits in visual cognition were subtle, and patients were not able to predict them. Impairment was more common in women (OR 3.2; 95% CI=0.8 to 13.2), and subjects with a Beck depression inventory II score ≥ 25 (OR 5.2; 95% CI=1.1 to 24.2). No effect was seen for: age, years in full-time education, disease duration, clinical evidence of anterior visual pathway dysfunction, or motor disability. Exploratory analyses showed no predictive association with deficits in attention or working memory, however impairment of basic arithmetic skills was a highly significant predictor of impaired visual cognition (OR 29.4, 95% CI 3.0 to 291.9). Allowing for all significant predictors, secondary and primary progressive disease groups had equivalent rates of impairment (OR 1.6, 95% CI 0.4 to 7.1; p=0.538). Conclusions: Impairment of visual cognition in progressive MS is more common in women and patients with high levels of depressive symptomatology, but occurs independently from anterior visual pathway dysfunction and the cumulative burden of inflammatory CNS white matter demyelination. These findings suggest that the site rather than the absolute quantity of brain pathology is crucial, with the strong association observed to impairment of basic arithmetic skills implicating possible localization to the intraparietal sulcus.

Multiple Sclerosis-Secondary Progressive Multi-Arm Randomisation Trial (MS-SMART): a multiarm phase IIb randomised, double-blind, placebo-controlled clinical trial comparing the efficacy of three neuroprotective drugs in secondary progressive multiple sclerosis

Introduction The major unmet need in multiple sclerosis (MS) is for neuroprotective therapies that can slow (or ideally stop) the rate of disease progression. The UK MS Society Clinical Trials Network (CTN) was initiated in 2007 with the purpose of developing a national, efficient, multiarm trial of repurposed drugs. Key underpinning work was commissioned by the CTN to inform the design, outcome selection and drug choice including animal models and a systematic review. This identified seven leading oral agents for repurposing as neuroprotective therapies in secondary progressive MS (SPMS). The purpose of the Multiple Sclerosis-Secondary Progressive Multi-Arm Randomisation Trial (MS-SMART) will be to evaluate the neuroprotective efficacy of three of these drugs, selected with distinct mechanistic actions and previous evidence of likely efficacy, against a common placebo arm. The interventions chosen were: amiloride (acid-sensing ion channel antagonist); fluoxetine (selective serotonin reuptake inhibitor) and riluzole (glutamate antagonist). Methods and analysis Patients with progressing SPMS will be randomised 1:1:1:1 to amiloride, fluoxetine, riluzole or matched placebo and followed for 96 weeks. The primary outcome will be the percentage brain volume change (PBVC) between baseline and 96 weeks, derived from structural MR brain imaging data using the Structural Image Evaluation, using Normalisation, of Atrophy method. With a sample size of 90 per arm, this will give 90% power to detect a 40% reduction in PBVC in any active arm compared with placebo and 80% power to detect a 35% reduction (analysing by analysis of covariance and with adjustment for multiple comparisons of three 1.67% two-sided tests), giving a 5% overall two-sided significance level. MS-SMART is not powered to detect differences between the three active treatment arms. Allowing for a 20% dropout rate, 110 patients per arm will be randomised. The study will take place at Neuroscience centres in England and Scotland. Ethics and dissemination MS-SMART was approved by the Scotland A Research Ethics Committee on 13 January 2013 (REC reference: 13/SS/0007). Results of the study will be submitted for publication in a peer-reviewed journal. Trial registration numbers NCT01910259; 2012-005394-31; ISRCTN28440672.