Decision-Making And Selection Bias in Four Observational Studies on Duchenne and Becker Muscular Dystrophy.

BACKGROUND: Natural history data are essential for trial design in Duchenne (DMD) and Becker muscular dystrophy (BMD), but recruitment for observational studies can be challenging. OBJECTIVE: We reviewed reasons why patients or caregivers declined participation, and compared characteristics of participants and non-participants to assess possible selection bias in four observational studies, three on DMD and one on BMD. METHODS: Three pediatric DMD studies focused on cross-sectional cognitive function and brain MRI (DMDbrain, n = 35 and DMDperfusion, n = 12), and on longitudinal upper extremity function and muscle MRI (DMDarm, n = 22). One adult BMD study assessed longitudinal functioning (n = 36). Considerations for non-participation were retrospectively reviewed from screening logs. Age, travel-time, DMD gene mutations and age at loss of ambulation (DMDarm and BMD study only), of participants and non-participants were derived from the Dutch Dystrophinopathy Database and compared using nonparametric tests (p < 0.05). RESULTS: The perceived burden of the protocol (38.2%), use of MRI (30.4%), and travel-time to the study site (19.1%) were the most frequently reported considerations for non-participation. Only few patients reported lack of personal gain (0.0- 5.9%). Overall, participating patients were representative for the studied sub-populations, except for a younger age of DMDarm study participants and a complete lack of participants with a mutation beyond exon 63. CONCLUSION: Optimizing patient involvement in protocol design, improving MRI experiences, and integrating research into clinics are important factors to decrease burden and facilitate participation. Nationwide registries are essential to compare participants and non-participants and ensure representative observational research. Specific effort is needed to include patients with distal mutations in cognitive studies.

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.

Myoglobinopathy is an adult-onset autosomal dominant myopathy with characteristic sarcoplasmic inclusions.

Myoglobin, encoded by MB, is a small cytoplasmic globular hemoprotein highly expressed in cardiac myocytes and oxidative skeletal myofibers. Myoglobin binds O2, facilitates its intracellular transport and serves as a controller of nitric oxide and reactive oxygen species. Here, we identify a recurrent c.292C>T (p.His98Tyr) substitution in MB in fourteen members of six European families suffering from an autosomal dominant progressive myopathy with highly characteristic sarcoplasmic inclusions in skeletal and cardiac muscle. Myoglobinopathy manifests in adulthood with proximal and axial weakness that progresses to involve distal muscles and causes respiratory and cardiac failure. Biochemical characterization reveals that the mutant myoglobin has altered O2 binding, exhibits a faster heme dissociation rate and has a lower reduction potential compared to wild-type myoglobin. Preliminary studies show that mutant myoglobin may result in elevated superoxide levels at the cellular level. These data define a recognizable muscle disease associated with MB mutation.

Autosomal recessive limb-girdle and Miyoshi muscular dystrophies in the Netherlands: The clinical and molecular spectrum of 244 patients.

In this retrospective study, we conducted a clinico-genetic analysis of patients with autosomal recessive limb-girdle muscular dystrophy (LGMD) and Miyoshi muscular dystrophy (MMD). Patients were identified at the tertiary referral centre for DNA diagnosis in the Netherlands and included if they carried two mutations in CAPN3, DYSF, SGCG, SGCA, SGCB, SGCD, TRIM32, FKRP or ANO5 gene. DNA was screened by direct sequencing and multiplex ligand-dependent probe amplification (MLPA) analysis. A total of 244 patients was identified; 68 LGMDR1/LGMD2A patients with CAPN3 mutations (28%), 67 sarcoglycanopathy patients (LGMDR3-5/LGMD2C-E) (27%), 64 LGMDR12/LGMD2L and MMD3 patients with ANO5 mutations (26%), 25 LGMDR2/LGMD2B and MMD1 with DYSF mutations (10%), 21 LGMDR9/LGMD2I with FKRP mutations (9%) and one LGMDR8/LGMD2H patient with TRIM32 mutations (<1%). The estimated minimum prevalence of AR-LGMD and MMD in the Netherlands amounted to 14.4 × 10-6 . Thirty-three novel mutations were identified. A wide range in age of onset (0-72 years) and loss of ambulation (5-74 years) was found. Fifteen patients (6%) initially presented with asymptomatic hyperCKemia. Cardiac abnormalities were found in 35 patients (17%). Non-invasive ventilation was started in 34 patients (14%). Both cardiac and respiratory involvement occurs across all subtypes, stressing the need for screening in all included subtypes.

Visual inspection of MR relative cerebral blood volume maps has limited value for distinguishing progression from pseudoprogression in glioblastoma multiforme patients.

AIM: We examined whether visual interpretation of relative cerebral blood volume (rCBV) color maps made with dynamic susceptibility-weighted perfusion MRI can reliably distinguish progressive disease (PD) from pseudoprogression (PsPD) in glioblastoma patients during treatment with temozolomide chemoradiation. MATERIALS & METHODS: Magnetic resonance (MR) perfusion-weighted images were evaluated based on visual inspection of rCBV maps. Sensitivity and specificity were calculated to assess if rCBV can reliably differentiate between PD and PsPD, during standard chemoradiation therapy. RESULTS: Evaluation of dynamic susceptibility-weighted contrast-enhanced perfusion MRI by visual interpretation of rCBV maps did not differentiate PD from PsPD (sensitivity = 72%; specificity = 23%). Furthermore, the interpretation of the rCBV maps had no prognostic value regarding survival. CONCLUSION: Qualitative rCBV-based dynamic susceptibility-weighted contrast-enhanced perfusion MRI does not reliably differentiate PD from PsPD, and is not prognostic for survival in glioblastoma multiforme patients during treatment with temozolomide chemoradiation.

Proton Magnetic Resonance Spectroscopy Indicates Preserved Cerebral Biochemical Composition in Duchenne Muscular Dystrophy Patients.

BACKGROUND: Duchenne muscular dystrophy (DMD) is caused by the absence of dystrophin. DMD is associated with specific learning and behavioural disabilities. In the brain, dystrophin is associated with GABAA receptors and aquaporin-4 in neurons and astrocytes, respectively, but little is known about its function. OBJECTIVE AND METHODS: In this study we aimed to compare the biochemical composition between patients and healthy controls in brain regions that are naturally rich in dystrophin using magnetic resonance spectroscopy. Given previous conflicting results obtained at clinical field strengths, we obtained data using a 7 Tesla system with associated higher signal-to-noise ratio and spectral resolution. RESULTS: Results indicated unchanged biochemical composition in all regions investigated, and increased variance in glutamate in the frontal cortex.

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.

Decreased cerebral perfusion in Duchenne muscular dystrophy patients.

Duchenne muscular dystrophy is caused by dystrophin gene mutations which lead to the absence of the protein dystrophin. A significant proportion of patients suffer from learning and behavioural disabilities, in addition to muscle weakness. We have previously shown that these patients have a smaller total brain and grey matter volume, and altered white matter microstructure compared to healthy controls. Patients with more distal gene mutations, predicted to affect dystrophin isoforms Dp140 and Dp427, showed greater grey matter reduction. Now, we studied if cerebral blood flow in Duchenne muscular dystrophy patients is altered, since cerebral expression of dystrophin also occurs in vascular endothelial cells and astrocytes associated with cerebral vasculature. T1-weighted anatomical and pseudo-continuous arterial spin labeling cerebral blood flow images were obtained from 26 patients and 19 age-matched controls (ages 8-18 years) on a 3 tesla MRI scanner. Group comparisons of cerebral blood flow were made with and without correcting for grey matter volume using partial volume correction. Results showed that patients had a lower cerebral blood flow than controls (40.0 ± 6.4 and 47.8 ± 6.3 mL/100 g/min respectively, p = 0.0002). This reduction was independent of grey matter volume, suggesting that they are two different aspects of the pathophysiology. Cerebral blood flow was lowest in patients lacking Dp140. There was no difference in CBF between ambulant and non-ambulant patients. Only three patients showed a reduced left ventricular ejection fraction. No correlation between cerebral blood flow and age was found. Our results indicate that cerebral perfusion is reduced in Duchenne muscular dystrophy patients independent of the reduced grey matter volume.

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.

Diagnosis of becker muscular dystrophy: Results of Re-analysis of DNA samples.

INTRODUCTION: The phenotype of Becker muscular dystrophy (BMD) is highly variable, and the disease may be underdiagnosed. We searched for new mutations in the DMD gene in a cohort of previously undiagnosed patients who had been referred in the period 1985-1995. METHODS: All requests for DNA analysis of the DMD gene in probands with suspected BMD were re-evaluated. If the phenotype was compatible with BMD, and no deletions or duplications were detected, DNA samples were screened for small mutations. RESULTS: In 79 of 185 referrals, no mutation was found. Analysis could be performed on 31 DNA samples. Seven different mutations, including 3 novel ones, were found. Long-term clinical follow-up is described. CONCLUSIONS: Refining DNA analysis in previously undiagnosed cases can identify mutations in the DMD gene and provide genetic diagnosis of BMD. A delayed diagnosis can still be valuable for the proband or the relatives of BMD patients.

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.

Reduced cerebral gray matter and altered white matter in boys with Duchenne muscular dystrophy.

OBJECTIVE: Duchenne muscular dystrophy (DMD) is characterized by progressive muscle weakness caused by DMD gene mutations leading to absence of the full-length dystrophin protein in muscle. Multiple dystrophin isoforms are expressed in brain, but little is known about their function. DMD is associated with specific learning and behavioral disabilities that are more prominent in patients with mutations in the distal part of the DMD gene, predicted to affect expression of shorter protein isoforms. We used quantitative magnetic resonance (MR) imaging to study brain microstructure in DMD. METHODS: T1-weighted and diffusion tensor images were obtained on a 3T MR scanner from 30 patients and 22 age-matched controls (age = 8-18 years). All subjects underwent neuropsychological examination. Group comparisons on tissue volume and diffusion tensor imaging parameters were made between DMD patients and controls, and between 2 DMD subgroups that were classified according to predicted Dp140 isoform expression (DMD_Dp140(+) and DMD_Dp140(-) ). RESULTS: DMD patients had smaller total brain volume, smaller gray matter volume, lower white matter fractional anisotropy, and higher white matter mean and radial diffusivity than healthy controls. DMD patients also performed worse on neuropsychological examination. Subgroup analyses showed that DMD_Dp140(-) subjects contributed most to the gray matter volume differences and performed worse on information processing. INTERPRETATION: Both gray and white matter is affected in boys with DMD at a whole brain level. Differences between the DMD_Dp140(-) subgroup and controls indicate an important role for the Dp140 dystrophin isoform in cerebral development.

ANO5 mutations in the Dutch limb girdle muscular dystrophy population.

A Dutch cohort of 105 limb girdle muscular dystrophy (LGMD) patients were subject to subsequent genetic investigations. In half the families a causative mutation was found. Recently mutations were identified in ANO5 causing LGMD2L and Miyoshi-like myopathy (MMD3), but could also be found in patients with hyperCKemia only. Therefore, we analysed the index cases of the remaining 31 as yet undiagnosed families from our previously described cohort of LGMD patients for the presence of ANO5 mutations. Detailed history and neurological examination were available for all patients. Serum creatine kinase (CK) activity, skeletal muscle computed tomography (CT) and cardiological investigations were performed. Mutations in ANO5 were found in 16% of the families: 11 index patients and two sibs, eight males and five females. The founder mutation c.191dupA was present in 8 out of 13 patients. Ten different pathogenic mutations were identified of which seven were novel: five missense and two splice site mutations. The age of these patients ranged from 26 to 69 years and the age of onset varied from 21 to 57 years. Symptoms at onset were related to proximal leg weakness. The weakness was slowly progressive. Calf hypertrophy was present in three patients. Males were more severely affected than females. Serum CK activity was highly elevated in the early stage of disease and moderately increased in later stages. Muscle biopsy showed predominantly dystrophic changes. One patient had hypertrophic cardiomyopathy, two others had intraventricular septum thickening.

Dystrophin quantification and clinical correlations in Becker muscular dystrophy: implications for clinical trials.

Duchenne muscular dystrophy is caused by mutations in the DMD gene that disrupt the open reading frame and prevent the full translation of its protein product, dystrophin. Restoration of the open reading frame and dystrophin production can be achieved by exon skipping using antisense oligonucleotides targeted to splicing elements. This approach aims to transform the Duchenne muscular dystrophy phenotype to that of the milder disorder, Becker muscular dystrophy, typically caused by in-frame dystrophin deletions that allow the production of an internally deleted but partially functional dystrophin. There is ongoing debate regarding the functional properties of the different internally deleted dystrophins produced by exon skipping for different mutations; more insight would be valuable to improve and better predict the outcome of exon skipping clinical trials. To this end, we have characterized the clinical phenotype of 17 patients with Becker muscular dystrophy harbouring in-frame deletions relevant to on-going or planned exon skipping clinical trials for Duchenne muscular dystrophy and correlated it to the levels of dystrophin, and dystrophin-associated protein expression. The cohort of 17 patients, selected exclusively on the basis of their genotype, included 4 asymptomatic, 12 mild and 1 severe patient. All patients had dystrophin levels of >40% of control and significantly higher dystrophin (P = 0.013), ß-dystroglycan (P = 0.025) and neuronal nitric oxide synthase (P = 0.034) expression was observed in asymptomatic individuals versus symptomatic patients with Becker muscular dystrophy. Furthermore, grouping the patients by deletion, patients with Becker muscular dystrophy with deletions with an end-point of exon 51 (the skipping of which could rescue the largest group of Duchenne muscular dystrophy deletions) showed significantly higher dystrophin levels (P = 0.034) than those with deletions ending with exon 53. This is the first quantitative study on both dystrophin and dystrophin-associated protein expression in patients with Becker muscular dystrophy with deletions relevant for on-going exon skipping trials in Duchenne muscular dystrophy. Taken together, our results indicate that all varieties of internally deleted dystrophin assessed in this study have the functional capability to provide a substantial clinical benefit to patients with Duchenne muscular dystrophy.

Prednisone 10 days on/10 days off in patients with Duchenne muscular dystrophy.

Corticosteroids are effective in improving motor function in Duchenne muscular dystrophy (DMD) patients within 6 months-2 years of treatment initiation, but there is as yet no consensus on which treatment scheme is the best. We retrospectively analyzed data of 35 DMD patients who were treated with prednisone 0.75 mg/kg per day intermittently 10 days on/10 days off. Prednisone was started during the ambulant phase at age 3.5-9.7 years (median 6.5 years). The median period of treatment was 27 months (range 3-123 months). The median age at which ambulation was lost was 10.8 years (mean 10.9 years; 95% confidence interval 10.0-11.8 years). Nine patients (26%) had excessive weight gain. Eight boys (21%) had a bone fracture, which was when four of these eight children lost the ability to walk. Treatment was stopped in two obese patients, two hyperactive boys and one patient following a fracture. Our data suggest that prednisone 10 on/10 off has relatively few side effects and extends the ambulant phase by 1 year compared to historical controls.