Extracellular vesicle-derived miRNAs improve stem cell-based therapeutic approaches in muscle wasting conditions

Skeletal muscle holds an intrinsic capability of growth and regeneration both in physiological conditions and in case of injury. Chronic muscle illnesses, generally caused by genetic and acquired factors, lead to deconditioning of the skeletal muscle structure and function, and are associated with a significant loss in muscle mass. At the same time, progressive muscle wasting is a hallmark of aging. Given the paracrine properties of myogenic stem cells, extracellular vesicle-derived signals have been studied for their potential implication in both the pathogenesis of degenerative neuromuscular diseases and as a possible therapeutic target. In this study, we screened the content of extracellular vesicles from animal models of muscle hypertrophy and muscle wasting associated with chronic disease and aging. Analysis of the transcriptome, protein cargo, and microRNAs (miRNAs) allowed us to identify a hypertrophic miRNA signature amenable for targeting muscle wasting, consisting of miR-1 and miR-208a. We tested this signature among others in vitro on mesoangioblasts (MABs), vessel-associated adult stem cells, and we observed an increase in the efficiency of myogenic differentiation. Furthermore, injections of miRNA-treated MABs in aged mice resulted in an improvement in skeletal muscle features, such as muscle weight, strength, cross-sectional area, and fibrosis compared to controls. Overall, we provide evidence that the extracellular vesicle-derived miRNA signature we identified enhances the myogenic potential of myogenic stem cells.

074 Long-term effect of idebenone in reducing respiratory function decline in patients with Duchenne muscular dystrophy

Two placebo-controlled trials of 52-week duration showed that idebenone consistently reduced respira- tory function decline rate in patients with DMD. Long-term data from the DELPHI-Extension (DELPHI-E) study and SYROS (DELOS patients who transitioned to idebenone under an Expanded Access Program) are now presented. The aim was to assess the consistency of the long-term effect of idebenone.

11 DELPHI-E and 18 SYROS patients with abnormal (<80%) forced vital capacity (as percent predicted, FVC%p) were treated with idebenone for an average of 2.0 and 4.2 years respectively. Annualized FVC%p decline rates were compared to untreated patients from SYROS or matched external controls.

Mean (SD) baseline age was 13.6 (2.3) and 13.3 (2.7) years in DELPHI (N=11) and DELOS (N=18), respec- tively, and FVC%p was 47.2% (19.7%) and 58.7% (17.6%). For the first 2-year period, the average annual decline rate was comparable in treated patients (4.5% and 5.4% in DELPHI-E and SYROS) and lower than in untreated SYROS patients and external controls (7.9% untreated and 8.1% in CINRG-DNHS). During years 3–6, the annual decline rate was consistently lower than for matched controls.

Treatment with idebenone resulted in a sustained reduction in the rate of decline in respiratory function. laurent.servais@paediatrics.ox.ac.uk

Human iPSC model reveals a central role for NOX4 and oxidative stress in Duchenne cardiomyopathy

Duchenne muscular dystrophy (DMD) is a progressive muscle disorder caused by mutations in the Dystrophin gene. Cardiomyopathy is a major cause of early death. We used DMD-patient-specific human induced pluripotent stem cells (hiPSCs) to model cardiomyopathic features and unravel novel pathologic insights. Cardiomyocytes (CMs) differentiated from DMD hiPSCs showed enhanced premature cell death due to significantly elevated intracellular reactive oxygen species (ROS) resulting from depolarized mitochondria and increased NADPH oxidase 4 (NOX4). CRISPR-Cas9 correction of Dystrophin restored normal ROS levels. ROS reduction by N-acetyl-L-cysteine (NAC), ataluren (PTC124), and idebenone improved hiPSC-CM survival. We show that oxidative stress in DMD hiPSC-CMs was counteracted by stimulating adenosine triphosphate (ATP) production. ATP can bind to NOX4 and partially inhibit the ROS production. Considering the complexity and the early cellular stress responses in DMD cardiomyopathy, we propose targeting ROS production and preventing detrimental effects of NOX4 on DMD CMs as promising therapeutic strategy.

Defining the phenotype of FHF1 developmental and epileptic encephalopathy

Fibroblast growth-factor homologous factor (FHF1) gene variants have recently been associated with developmental and epileptic encephalopathy (DEE). FHF1 encodes a cytosolic protein that modulates neuronal sodium channel gating. We aim to refine the electroclinical phenotypic spectrum of patients with pathogenic FHF1 variants. We retrospectively collected clinical, genetic, neurophysiologic, and neuroimaging data of 17 patients with FHF1-DEE. Sixteen patients had recurrent heterozygous FHF1 missense variants: 14 had the recurrent p.Arg114His variant and two had a novel likely pathogenic variant p.Gly112Ser. The p.Arg114His variant is associated with an earlier onset and more severe phenotype. One patient carried a chromosomal microduplication involving FHF1. Twelve patients carried a de novo variant, five (29.5%) inherited from parents with gonadic or somatic mosaicism. Seizure onset was between 1 day and 41 months; in 76.5% it was within 30 days. Tonic seizures were the most frequent seizure type. Twelve patients (70.6%) had drug-resistant epilepsy, 14 (82.3%) intellectual disability, and 11 (64.7%) behavioral disturbances. Brain magnetic resonance imaging (MRI) showed mild cerebral and/or cerebellar atrophy in nine patients (52.9%). Overall, our findings expand and refine the clinical, EEG, and imaging phenotype of patients with FHF1-DEE, which is characterized by early onset epilepsy with tonic seizures, associated with moderate to severe ID and psychiatric features.

Long-term data with idebenone on respiratory function outcomes in patients with Duchenne muscular dystrophy

Decline in respiratory function in patients with DMD starts during early teenage years and leads to early morbidity and mortality. Published evidence of efficacy for idebenone on respiratory function outcomes is currently limited to 12 months of follow-up time. Here we report data collected as retrospective cohort study (SYROS) from 18 DMD patients not using glucocorticoids who were treated with idebenone (900 mg/day) under Expanded Access Programs (EAPs). The objective was to assess the long-term respiratory function evolution for periods On-Idebenone compared to periods Off-Idebenone in the same patients. The mean idebenone exposure in the EAPs was 4.2 (range 2.4-6.1) years. The primary endpoint was the annual change in forced vital capacity percent of predicted (FVC%p) compared between Off-Idebenone and On-Idebenone periods. The annual rate of decline in FVC%p was reduced by approximately 50% from -7.4% (95% CI: -9.1, -5.8) for the Off-Idebenone periods to -3.8% (95% CI: -4.8, -2.8) for the On-Idebenone periods (N = 11). Similarly, annual change in peak expiratory flow percent of predicted (PEF%p) was -5.9% (95% CI: -8.0, -3.9) for the Off-Idebenone periods (N = 9) and reduced to -1.9% (95% CI: -3.2, -0.7) for the On-Idebenone periods during the EAPs. The reduced rates of decline in FVC%p and PEF%p were maintained for several years with possible beneficial effects on the rate of bronchopulmonary adverse events, time to 10% decline in FVC%p and risk of hospitalization due to respiratory cause. These long-term data provide Class IV evidence to further support the disease modifying treatment effect of idebenone previously observed in randomized, controlled trials.

Dystrophin deficiency leads to dysfunctional glutamate clearance in iPSC derived astrocytes

Duchenne muscular dystrophy (DMD) results, beside muscle degeneration in cognitive defects. As neuronal function is supported by astrocytes, which express dystrophin, we hypothesized that loss of dystrophin from DMD astrocytes might contribute to these cognitive defects. We generated cortical neuronal and astrocytic progeny from induced pluripotent stem cells (PSC) from six DMD subjects carrying different mutations and several unaffected PSC lines. DMD astrocytes displayed cytoskeletal abnormalities, defects in Ca⁺² homeostasis and nitric oxide signaling. In addition, defects in glutamate clearance were identified in DMD PSC-derived astrocytes; these deficits were related to a decreased neurite outgrowth and hyperexcitability of neurons derived from healthy PSC. Read-through molecule restored dystrophin expression in DMD PSC-derived astrocytes harboring a premature stop codon mutation, corrected the defective astrocyte glutamate clearance and prevented associated neurotoxicity. We propose a role for dystrophin deficiency in defective astroglial glutamate homeostasis which initiates defects in neuronal development.

Home-Based Monitoring of Pulmonary Function in Patients with Duchenne Muscular Dystroph

Background:

Loss of pulmonary function is a main cause of early morbidity and mortality in patients with Duchenne muscular dystrophy (DMD). Standard of care guidelines recommend regular assessment of pulmonary function by hospital-based spirometry to detect onset and monitor progression of pulmonary function decline.

Objective:

To assess the feasibility of home-based monitoring of pulmonary function by a hand-held device (HHD) in adolescent and adult patients with DMD over a period of 12 months.

Methods:

In the phase III randomized placebo-controlled DELOS trial in 10–18 year old DMD patients, peak expiratory flow (PEF) measurements were collected weekly at home by the patient (assisted by parent/caregiver) using a peak flow meter HHD. Adherence to the use of the HHD was assessed and 12-month changes in PEF as percent of predicted (PEF% p) for the idebenone (N = 31) and the placebo treatment groups (N = 33) from HHD-derived data were compared to results from hospital-based spirometry.

Results:

A total of 2689 individual HHD assessments were analysed. Overall adherence to the use of the HHD over the course of the 12-month study duration was good (75.9%, SD 21.5%) and PEF% p data obtained at the same day by HHD and standard spirometry correlated well (Spearman’s rho 0.80; p < 0.001). Several analysis methods of HHD-derived data for PEF% p consistently demonstrate that idebenone treatment slowed the decline in PEF% p compared to placebo, which supports the statistically significant difference in favour of idebenone for PEF% p measured by standard spirometry.

Conclusions:

This study demonstrates that home-based monitoring of pulmonary function in adolescent patients with DMD using a HHD is feasible, provides reliable data compared to hospital-based spirometry and is therefore suitable for use in clinical practice and for clinical trials.

Efficacy of Idebenone to Preserve Respiratory Function above Clinically Meaningful Thresholds for Forced Vital Capacity (FVC) in Patients with Duchenne Muscular Dystrophy

BACKGROUND

Patients with DMD experience progressive restrictive respiratory disease and eventual respiratory failure. Standard of care guidelines command changes in disease management when forced vital capacity percent of predicted (FVC% p) falls below clinically relevant thresholds. The Phase 3 DELOS trial in patients with DMD demonstrated that idebenone reduces the loss of peak expiratory flow and FVC compared to placebo (Buyse GM, et al.; Lancet 2015; 385 : 1748-57).

OBJECTIVE

Post-hoc analyses were conducted to assess whether treatment with idebenone could reduce the risk of patients dropping below clinically meaningful thresholds of FVC% p.

METHODS

The DELOS trial enrolled DMD patients 10-18 years of age not using glucocorticoids to receive idebenone (N = 31) or placebo (N = 33) for 12 months. Change from baseline in FVC and FVC% p was assessed by hospital spirometry and analyzed by mixed model of repeated measures and slope analysis and proportions of patients falling below clinically meaningful thresholds of FVC% p were compared.

RESULTS

The change over 1 year in FVC and FVC% p showed a consistent pattern in favor of idebenone treatment across multiple analysis methods and fewer patients in the idebenone group declined by a margin of 10% or more in FVC and FVC% p compared to placebo. There were also fewer patients in the idebenone group (15%) with a decline below FVC% p of 50% compared to the placebo group (25%) and fewer patients in the idebenone group (28%) showed a decline below FVC% p of 50% or 40% or 30% compared to the placebo group (43%).

CONCLUSIONS

These data added to the consistency and clinical meaningfulness of findings from the DELOS trial showing that idebenone can slow the loss of pulmonary function in patients with DMD.

Treatment effect of idebenone on inspiratory function in patients with Duchenne muscular dystrophy

Assessment of dynamic inspiratory function may provide valuable information about the degree and progression of pulmonary involvement in patients with Duchenne muscular dystrophy (DMD). The aims of this study were to characterize inspiratory function and to assess the efficacy of idebenone on this pulmonary function outcome in a large and well-characterized cohort of 10-18 year-old DMD patients not taking glucocorticoid steroids (GCs) enrolled in the phase 3 randomized controlled DELOS trial. We evaluated the effect of idebenone on the highest flow generated during an inspiratory FVC maneuver (maximum inspiratory flow; V'I,max(FVC)) and the ratio between the largest inspiratory flow during tidal breathing (tidal inspiratory flow; V'I,max(t)) and the V'I,max(FVC). The fraction of the maximum flow that is not used during tidal breathing has been termed inspiratory flow reserve (IFR). DMD patients in both treatment groups of DELOS (idebenone, n = 31; placebo: n = 33) had comparable and abnormally low V'I,max(FVC) at baseline. During the study period, V'I,max(FVC) further declined by -0.29 L/sec in patients on placebo (95%CI: -0.51, -0.08; P = 0.008 at week 52), whereas it remained stable in patients on idebenone (change from baseline to week 52: 0.01 L/sec; 95%CI: -0.22, 0.24; P = 0.950). The between-group difference favoring idebenone was 0.27 L/sec (P = 0.043) at week 26 and 0.30 L/sec (P = 0.061) at week 52. In addition, during the study period, IFR improved by 2.8% in patients receiving idebenone and worsened by -3.0% among patients on placebo (between-group difference 5.8% at week 52; P = 0.040). Although the clinical interpretation of these data is currently limited due to the scarcity of routine clinical practice experience with dynamic inspiratory function outcomes in DMD, these findings from a randomized controlled study nevertheless suggest that idebenone preserved inspiratory muscle function as assessed by V'I,max(FVC) and IFR in patients with DMD. Pediatr Pulmonol. 2017;52:508-515. © 2016 The Authors. Pediatric Pulmonology Published by Wiley Periodicals, Inc.

Advances in Pulmonary Care in Duchenne Muscular Dystrophy

Duchenne muscular dystrophy (DMD) is a degenerative neuromuscular disease leading to progressive muscle weakness and loss. This review discusses advances in understanding the natural history of DMD, as well as recent pharmacotherapies. Decline in expiratory and inspiratory pulmonary function results in ineffective airway clearance, sleep-disordered breathing and nocturnal and daytime respiratory failure. Routine measures of pulmonary function include forced vital capacity (FVC) and peak expiratory flow (PEF). Both measures follow parallel trajectories and relentlessly decline, reaching the lower limit of normal of 80% of predicted at early teenage years. Moreover, decline in PEF and FVC are closely correlated with respiratory complications and clinically relevant thresholds for FVC are defined in standard of care recommendations. Glucocorticoids (GCs) delay the onset of pulmonary function decline, but once patients have reached the 80% of predicted threshold the decline of FVC and PEF in GC users and patients not using GCs is comparable. In the successful phase III DELOS trial in DMD patients not using GCs, the short-chain benzoquinone idebenone (Raxone®, Santhera Pharmaceuticals, Liestal, Switzerland) has demonstrated statistically significant and clinically relevant efficacy on expiratory and inspiratory function in patients in the pulmonary function decline stage. These results indicate that idebenone can modify the natural course of respiratory disease progression, which is relevant in clinical practice where loss of respiratory function continues to be a predominant cause of early morbidity and mortality in DMD.

Idebenone reduces respiratory complications in patients with Duchenne muscular dystrophy

In Duchenne muscular dystrophy (DMD), progressive loss of respiratory function leads to restrictive pulmonary disease and places patients at significant risk for severe respiratory complications. Of particular concern are ineffective cough, secretion retention and recurrent respiratory tract infections. In a Phase 3 randomized controlled study (DMD Long-term Idebenone Study, DELOS) in DMD patients 10-18 years of age and not taking concomitant glucocorticoid steroids, idebenone (900 mg/day) reduced significantly the loss of respiratory function over a 1-year study period. In a post-hoc analysis of DELOS we found that more patients in the placebo group compared to the idebenone group experienced bronchopulmonary adverse events (BAEs): placebo: 17 of 33 patients, 28 events; idebenone: 6 of 31 patients, 7 events. The hazard ratios (HR) calculated "by patient" (HR 0.33, p = 0.0187) and for "all BAEs" (HR 0.28, p = 0.0026) indicated a clear idebenone treatment effect. The overall duration of BAEs was 222 days (placebo) vs. 82 days (idebenone). In addition, there was also a difference in the use of systemic antibiotics utilized for the treatment of BAEs. In the placebo group, 13 patients (39.4%) reported 17 episodes of antibiotic use compared to 7 patients (22.6%) reporting 8 episodes of antibiotic use in the idebenone group. Furthermore, patients in the placebo group used systemic antibiotics for longer (105 days) compared to patients in the idebenone group (65 days). This post-hoc analysis of DELOS indicates that the protective effect of idebenone on respiratory function is associated with a reduced risk of bronchopulmonary complications and a reduced need for systemic antibiotics.

Gain-of-function FHF1 mutation causes early-onset epileptic encephalopathy with cerebellar atrophy

OBJECTIVE

Voltage-gated sodium channel (Nav)-encoding genes are among early-onset epileptic encephalopathies (EOEE) targets, suggesting that other genes encoding Nav-binding proteins, such as fibroblast growth factor homologous factors (FHFs), may also play roles in these disorders.

METHODS

To identify additional genes for EOEE, we performed whole-exome sequencing in a family quintet with 2 siblings with a lethal disease characterized by EOEE and cerebellar atrophy. The pathogenic nature and functional consequences of the identified sequence alteration were determined by electrophysiologic studies in vitro and in vivo.

RESULTS

A de novo heterozygous missense mutation was identified in the FHF1 gene (FHF1AR114H, FHF1BR52H) in the 2 affected siblings. The mutant FHF1 proteins had a strong gain-of-function phenotype in transfected Neuro2A cells, enhancing the depolarizing shifts in Nav1.6 voltage-dependent fast inactivation, predicting increased neuronal excitability. Surprisingly, the gain-of-function effect is predicted to result from weaker interaction of mutant FHF1 with the Nav cytoplasmic tail. Transgenic overexpression of mutant FHF1B in zebrafish larvae enhanced epileptiform discharges, demonstrating the epileptic potential of this FHF1 mutation in the affected children.

CONCLUSIONS

Our data demonstrate that gain-of-function FHF mutations can cause neurologic disorder, and expand the repertoire of genetic causes (FHF1) and mechanisms (altered Nav gating) underlying EOEE and cerebellar atrophy.

Efficacy of idebenone on respiratory function in patients with Duchenne muscular dystrophy not using glucocorticoids (DELOS): a double-blind randomised placebo-controlled phase 3 trial

BACKGROUND

Cardiorespiratory failure is the leading cause of death in Duchenne muscular dystrophy. Based on preclinical and phase 2 evidence, we assessed the efficacy and safety of idebenone in young patients with Duchenne muscular dystrophy who were not taking concomitant glucocorticoids.

METHODS

In a multicentre phase 3 trial in Belgium, Germany, the Netherlands, Switzerland, France, Sweden, Austria, Italy, Spain, and the USA, patients (age 10-18 years old) with Duchenne muscular dystrophy were randomly assigned in a one-to-one ratio with a central interactive web response system with a permuted block design with four patients per block to receive idebenone (300 mg three times a day) or matching placebo orally for 52 weeks. Study personnel and patients were masked to treatment assignment. The primary endpoint was change in peak expiratory flow (PEF) as percentage predicted (PEF%p) from baseline to week 52, measured with spirometry. Analysis was by intention to treat (ITT) and a modified ITT (mITT), which was prospectively defined to exclude patients with at least 20% difference in the yearly change in PEF%p, measured with hospital-based and weekly home-based spirometry. This study is registered with ClinicalTrials.gov, number NCT01027884.

FINDINGS

31 patients in the idebenone group and 33 in the placebo group comprised the ITT population, and 30 and 27 comprised the mITT population. Idebenone significantly attenuated the fall in PEF%p from baseline to week 52 in the mITT (-3·05%p [95% CI -7·08 to 0·97], p=0·134, vs placebo -9·01%p [-13·18 to -4·84], p=0·0001; difference 5·96%p [0·16 to 11·76], p=0·044) and ITT populations (-2·57%p [-6·68 to 1·54], p=0·215, vs -8·84%p [-12·73 to -4·95], p<0·0001; difference 6·27%p [0·61 to 11·93], p=0·031). Idebenone also had a significant effect on PEF (L/min), weekly home-based PEF, FVC, and FEV1. The effect of idebenone on respiratory function outcomes was similar between patients with previous corticosteroid use and steroid-naive patients. Treatment with idebenone was safe and well tolerated with adverse event rates were similar in both groups. Nasopharyngitis and headache were the most common adverse events (idebenone, eight [25%] and six [19%] of 32 patients; placebo, nine [26%] and seven [21%] of 34 patients). Transient and mild diarrhoea was more common in the idebenone group than in the placebo group (eight [25%] vs four [12%] patients).

INTERPRETATION

Idebenone reduced the loss of respiratory function and represents a new treatment option for patients with Duchenne muscular dystrophy.

FUNDING

Santhera Pharmaceuticals.

Idebenone as a Novel Therapeutic Approach for Duchenne Muscular Dystrophy

Progressive loss of pulmonary function leads to early morbidity and mortality in Duchenne muscular dystrophy (DMD) due to both expiratory impairment with ineffective airway clearance, and inspiratory impairment leading to nocturnal and daytime hypoventilation and respiratory failure. Glucocorticoid steroids have become a mainstay of DMD therapy with well-documented efficacy on muscle strength and respiratory function. However, the side-effect profile restricts their long-term use, particularly in non-ambulant patients. Idebenone improves secondary mitochondrial dysfunction caused by dystrophin deficiency, intracellular calcium accumulation and increased reactive oxygen species (ROS). Idebenone-mediated improved bioenergetics leads to enhanced adenosine triphosphate (ATP) production and reduced ROS. Based on this rationale, idebenone has been investigated clinically for efficacy on reducing respiratory function decline in exploratory phase II (DELPHI) and confirmatory phase III (DELOS) trials. Idebenone significantly reduced the loss of respiratory function in 8–18-year-old DMD patients who were not using concomitant glucocorticoids. These results indicate that idebenone can modify the natural course of respiratory disease progression in DMD, which is relevant in clinical practice where loss of respiratory function continues to be a predominant cause of early morbidity and mortality in DMD.

The contribution of platelet studies to the understanding of disease mechanisms in complex and monogenetic neurological disorders

Platelets, known for their role in primary haemostasis, prevent excessive bleeding after injury. The study of platelets has, therefore, traditionally focused on bleeding disorders. It has recently become evident, however, that platelet research can contribute to unravelling the disease mechanisms that underlie neuropathological disorders that have a subtle subclinical platelet phenotype. Platelets and neurosecretory cells have common gene expression profiles and share several biological features. This review provides a literature update on the use of platelets as easily accessible cells to study neurological disorders. We provide examples of the use of different platelet-based tests to understand the underlying pathophysiological mechanisms for both complex and monogenetic neuropathological disorders. In addition to the well-studied regulated granule secretion and serotonin metabolism, more recent studies have shown that defects in transcription factors, membrane transporters, G-protein signal transduction, and cytoskeletal proteins can be investigated using platelets to gain information on their role in neuropathology.

Effects of glucocorticoids and idebenone on respiratory function in patients with duchenne muscular dystrophy

In Duchenne muscular dystrophy (DMD) progressive weakness of respiratory muscles leads to a restrictive pulmonary syndrome that contributes to early morbidity and mortality. Currently no curative treatment exists for DMD. In a Phase II randomized placebo-controlled study (DELPHI) in 21 DMD boys at age 8-16 years, idebenone (450 mg/d) showed trends of efficacy for cardiac and respiratory endpoints. Since the DELPHI study population comprised both glucocorticoid-naïve subjects and glucocorticoid-users, we now report a post-hoc analysis investigating the effects of glucocorticoids and idebenone on markers of respiratory weakness, particularly peak expiratory flow (PEF) percent predicted (PEF%p). Baseline values of PEF%p correlated well with the percent predicted values for maximal inspiratory mouth pressure (MIP%p), forced vital capacity (FVC%p), and forced expired volume in 1 sec (FEV1%p). Baseline PEF%p and FVC%p were significantly higher in patients on concomitant glucocorticoids compared to glucocorticoid-naïve patients. In the latter subgroup, idebenone caused a 8.0 ± 12.1% improvement in PEF%p, whilst patients on placebo declined by -12.3 ± 17.9% (P < 0.05) in the course of the 12 month study. In patients receiving concomitant glucocorticoids, PEF%p remained stable (-0.4 ± 14.6%) in the idebenone group compared to a decline by -6.2 ± 12.4% (P = 0.24) in the placebo group. Idebenone showed a trend for efficacy on FVC%p only in glucocorticoid-naïve patients. Because of the study limitations, these data are exploratory and preclude any firm conclusions. In conclusion, PEF appears to be a sensitive respiratory function parameter that could be a valid and clinically relevant endpoint in intervention studies in DMD. In DELPHI the effect size of idebenone on PEF%p was significantly larger in steroid-naive patients, possibly indicating a maximum treatment effect reached by steroids or steroid-mediated suppression of idebenone's effects. The impact of standard care glucocorticoids on respiratory function will have to be considered in the planning of future interventional trials in DMD.

Regulated granule trafficking in platelets and neurons: a common molecular machinery

Platelet function in primary hemostasis involves the secretion of granules upon activation, providing the localized delivery of effector proteins at sites of vascular injury. The sequential process of regulated secretion in platelets, from the biogenesis of the granules, through their transport and up to the exocytotic fusion process at the acceptor membrane, involves a complex molecular machinery conserved between some other specialized cells such as neurons. Mutations in genes encoding proteins involved in this process of granule trafficking have helped towards demystification of the underlying secretory mechanisms. Human diseases of trafficking encompass a broad symptomatology including a platelet-related bleeding diathesis and neuronal problems. In this review, we want to highlight the similarities in granule biology between platelets and neurons and further focus on some granule trafficking disorders that result in bleeding and neuropathology. This review provides evidence that platelet research can be expanded from traditional studies of isolated thrombopathies to the field of neuropathologies that include a platelet secretion defect.

Idebenone as a novel, therapeutic approach for Duchenne muscular dystrophy: results from a 12 month, double-blind, randomized placebo-controlled trial

Early mortality in Duchenne muscular dystrophy (DMD) is related to cardiac and respiratory complications. A phase IIa double-blind randomized placebo-controlled clinical trial was conducted to investigate the tolerability and efficacy of idebenone therapy in children with DMD. Twenty-one DMD patients (aged 8-16 years) were randomly assigned to daily treatment with 450 mg idebenone (Catena®) (n=13) or placebo (n=8) for 12 months. All subjects completed the study and idebenone was safe and well tolerated. Idebenone treatment resulted in a trend (p=0.067) to increase peak systolic radial strain in the left ventricular inferolateral wall, the region of the heart that is earliest and most severely affected in DMD. A significant respiratory treatment effect on peak expiratory flow was observed (p=0.039 for PEF and p=0.042 for PEF percent predicted). Limitations of this study were the small sample size, and a skewed age distribution between treatment groups. Data from this study provided the basis for the planning of a confirmatory study.

Long-term blinded placebo-controlled study of SNT-MC17/idebenone in the dystrophin deficient mdx mouse: cardiac protection and improved exercise performance

AIMS

Duchenne muscular dystrophy (DMD) is a severe and still incurable disease, with heart failure as a leading cause of death. The identification of a disease-modifying therapy may require early-initiated and long-term administration, but such type of therapeutic trial is not evident in humans. We have performed such a trial of SNT-MC17/idebenone in the mdx mouse model of DMD, based on the drug's potential to improve mitochondrial respiratory chain function and reduce oxidative stress.

METHODS AND RESULTS

In this study, 200 mg/kg bodyweight of either SNT-MC17/idebenone or placebo was given from age 4 weeks until 10 months in mdx and wild-type mice. All evaluators were blinded to mouse type and treatment groups. Idebenone treatment significantly corrected cardiac diastolic dysfunction and prevented mortality from cardiac pump failure induced by dobutamine stress testing in vivo, significantly reduced cardiac inflammation and fibrosis, and significantly improved voluntary running performance in mdx mice.

CONCLUSION

We have identified a novel potential therapeutic strategy for human DMD, as SNT-MC17/idebenone was cardioprotective and improved exercise performance in the dystrophin-deficient mdx mouse. Our data also illustrate that the mdx mouse provides unique opportunities for long-term controlled prehuman therapeutic studies.

The neurogenic bladder: medical treatment

Neurogenic bladder sphincter dysfunction (NBSD) can cause severe and irreversible renal damage and bladder-wall destruction years before incontinence becomes an issue. Therefore, the first step in adequate management is to recognize early the bladder at risk for upper- and lower-tract deterioration and to start adequate medical treatment proactively. Clean intermittent catheterization combined with anticholinergics (oral or intravesical) is the standard therapy for NBSD. Early institution of such treatment can prevent both renal damage and secondary bladder-wall changes, thereby potentially improving long-term outcomes. In children with severe side effects or with insufficient suppression of detrusor overactivity despite maximal dosage of oral oxybutynin, intravesical instillation is an effective alternative. Intravesical instillation eliminates systemic side effects by reducing the first-pass metabolism and, compared with oral oxybutynin, intravesical oxybutynin is a more potent and long-acting detrusor suppressor. There is growing evidence that with early adequate treatment, kidneys are saved and normal bladder growth can be achieved in children so they will no longer need surgical bladder augmentation to achieve safe urinary continence in adolescence and adulthood.

CINRG pilot trial of oxatomide in steroid-naïve Duchenne muscular dystrophy

The authors report a pilot open-label two-center therapeutic trial of oxatomide in 14 steroid-naive DMD boys aged 5-10 years. Comparison of linear evolutions between 3 months medication-free lead-in periods and 6 months treatment periods showed no significant differences in quantitative (QMT) and manual (MMT) measurements of muscle strength and timed functional tests. A modest mitigation of strength deterioration over time cannot be excluded.

Neuroleptic malignant syndrome in juvenile neuronal ceroid lipofuscinosis associated with low-dose risperidone therapy

We present a patient with juvenile neuronal ceroid lipofuscinosis who developed a neuroleptic malignant syndrome when treated for hallucinations with a very low dose of risperidone, an atypical neuroleptic medication with usually few extrapyramidal side-effects. The loss of dopaminergic neurons in this condition may make these patients more vulnerable to this severe adverse effect.