Dystrophy Clinical Trials Research Articles

Multivariate modeling of magnetic resonance biomarkers and clinical outcome measures for Duchenne muscular dystrophy clinical trials.

Although regulatory agencies encourage inclusion of imaging biomarkers in clinical trials for Duchenne muscular dystrophy (DMD), industry receives minimal guidance on how to use these biomarkers most beneficially in trials. This study aims to identify the optimal use of muscle fat fraction biomarkers in DMD clinical trials through a quantitative disease-drug-trial modeling and simulation approach. We simultaneously developed two multivariate models quantifying the longitudinal associations between 6-minute walk distance (6MWD) and fat fraction measures from vastus lateralis and soleus muscles. We leveraged the longitudinal individual-level data collected for 10 years through the ImagingDMD study. Age of the individuals at assessment was chosen as the time metric. After the longitudinal dynamic of each measure was modeled separately, the selected univariate models were combined using correlation parameters. Covariates, including baseline scores of the measures and steroid use, were assessed using the full model approach. The nonlinear mixed-effects modeling was performed in Monolix. The final models showed reasonable precision of the parameter estimates. Simulation-based diagnostics and fivefold cross-validation further showed the model's adequacy. The multivariate models will guide drug developers on using fat fraction assessment most efficiently using available data, including the widely used 6MWD. The models will provide valuable information about how individual characteristics alter disease trajectories. We will extend the multivariate models to incorporate trial design parameters and hypothetical drug effects to inform better clinical trial designs through simulation, which will facilitate the design of clinical trials that are both more inclusive and more conclusive using fat fraction biomarkers.

Microdystrophin Expression as a Surrogate Endpoint for Duchenne Muscular Dystrophy Clinical Trials.

Duchenne muscular dystrophy (DMD) is a serious, rare genetic disease, affecting primarily boys. It is caused by mutations in the DMD gene and is characterized by progressive muscle degeneration that results in loss of function and early death due to respiratory and/or cardiac failure. Although limited treatment options are available, some for only small subsets of the patient population, DMD remains a disease with large unmet medical needs. The adeno-associated virus (AAV) vector is the leading gene delivery system for addressing genetic neuromuscular diseases. Since the gene encoding the full-length dystrophin protein exceeds the packaging capacity of a single AAV vector, gene replacement therapy based on AAV-delivery of shortened, yet, functional microdystrophin genes has emerged as a promising treatment. This article seeks to explain the rationale for use of the accelerated approval pathway to advance AAV microdystrophin gene therapy for DMD. Specifically, we provide support for the use of microdystrophin expression as a surrogate endpoint that could be used in clinical trials to support accelerated approval.

Outcome Measures in Facioscapulohumeral Muscular Dystrophy Clinical Trials.

Facioscapulohumeral muscular dystrophy (FSHD) is a debilitating muscular dystrophy with a variable age of onset, severity, and progression. While there is still no cure for this disease, progress towards FSHD therapies has accelerated since the underlying mechanism of epigenetic derepression of the double homeobox 4 (DUX4) gene leading to skeletal muscle toxicity was identified. This has facilitated the rapid development of novel therapies to target DUX4 expression and downstream dysregulation that cause muscle degeneration. These discoveries and pre-clinical translational studies have opened new avenues for therapies that await evaluation in clinical trials. As the field anticipates more FSHD trials, the need has grown for more reliable and quantifiable outcome measures of muscle function, both for early phase and phase II and III trials. Advanced tools that facilitate longitudinal clinical assessment will greatly improve the potential of trials to identify therapeutics that successfully ameliorate disease progression or permit muscle functional recovery. Here, we discuss current and emerging FSHD outcome measures and the challenges that investigators may experience in applying such measures to FSHD clinical trial design and implementation.

Meta-analyses of deflazacort versus prednisone/prednisolone in patients with nonsense mutation Duchenne muscular dystrophy.

Aim: Compare efficacies of deflazacort and prednisone/prednisolone in providing clinically meaningful delays in loss of physical milestones in patients with nonsense mutation Duchenne muscular dystrophy. Materials & methods: Placebo data from Phase IIb (ClinicalTrials.gov Identifier: NCT00592553) and ACT DMD (ClinicalTrials.gov Identifier: NCT01826487) ataluren nonsense mutation Duchenne muscular dystrophy clinical trials were retrospectively combined in meta-analyses (intent-to-treat population; for change from baseline to week 48 in 6-min walk distance [6MWD] and timed function tests). Results: Significant improvements in change in 6-min walk distance with deflazacort versus prednisone/prednisolone (least-squares mean difference 39.54m [95% CI: 13.799, 65.286; p=0.0026]). Significant and clinically meaningful improvements in 4-stair climb and 4-stair descend for deflazacort versus prednisone/prednisolone. Conclusion: Deflazacort provides clinically meaningful delays in loss of physical milestones over 48weeks compared with prednisone/prednisolone for patients withnonsense mutation Duchenne muscular dystrophy.

Quantitative muscle MRI biomarkers in Duchenne muscular dystrophy: cross-sectional correlations with age and functional tests.

Aim:Using baseline data from a clinical trial of domagrozumab in Duchenne muscular dystrophy, we evaluated the correlation between functional measures and quantitative MRI assessments of thigh muscle.Patients & methods:Analysis included timed functional tests, knee extension/strength and North Star Ambulatory Assessment. Patients (n = 120) underwent examinations of one thigh, with MRI sequences to enable measurements of muscle volume (MV), MV index, mean T2 relaxation time via T2-mapping and fat fraction.Results:MV was moderately correlated with strength assessments. MV index, fat fraction and T2-mapping measures had moderate correlations (r ∼ 0.5) to all functional tests, North Star Ambulatory Assessment and age.Conclusion:The moderate correlation between functional tests, age and baseline MRI measures supports MRI as a biomarker in Duchenne muscular dystrophy clinical trials. Trial registration: ClinicalTrials.gov, NCT02310763; registered 4 November 2014.

DMD – BIOMARKERS & OUTCOME MEASURES: P.123 Novel image analysis to assess molecular functionality of dystrophin in Duchenne muscular dystrophy clinical trials

The primary molecular endpoint for many DMD clinical trials and the proof of concept for therapeutic approaches is the induction or increase in the production of de novo dystrophin. However, it is important to not only quantify levels of restored dystrophin following treatment, but to determine its molecular functionality using unbiased methodologies. We assessed if induced dystrophin following 48 weeks treatment with an exon 53 skipping morpholino (golodirsen), which we previously demonstrated to be capable of inducing dystrophin restoration, also results in enhanced levels of dystrophin associated proteins (DAPs) and a reduction in regenerating myofibres in post treatment biopsies.

Marked motor function improvement in a 32-year-old woman with childhood-onset hypophosphatasia by asfotase alfa therapy: Evaluation based on standardized testing batteries used in Duchenne muscular dystrophy clinical trials

Hypophosphatasia (HPP) is a rare disorder resulting from biallelic loss-of-function variants or monoallelic dominant negative variants in the ALPL gene. We herein describe the clinical outcome of a 32-year-old woman with childhood-onset HPP caused by compound heterozygous variants in ALPL. Her chief complaints were severe musculoskeletal pain, muscle weakness, and impaired daily activities necessitating assistance in housework and child-rearing in addition to a history of early tooth loss and mildly short stature. Asfotase alfa therapy produced a remarkable increase in muscle strength and daily activities and markedly reduced musculoskeletal pain. Drug efficacy was clearly demonstrated through multiple test batteries (muscle strength test using microFET®2, six-minute walking test, Stair Climb Test, rising-from-floor-time test, and number-of-steps test using Actigraph®) currently adopted as standardized evaluations in Duchenne muscular dystrophy clinical trials since no test batteries for HPP have been established to date. These tests may also be promising for the assessment of HPP.

A high\u2013throughput digital script for multiplexed immunofluorescent analysis and quantification of sarcolemmal and sarcomeric proteins in muscular dystrophies

The primary molecular endpoint for many Duchenne muscular dystrophy (DMD) clinical trials is the induction, or increase in production, of dystrophin protein in striated muscle. For accurate endpoint analysis, it is essential to have reliable, robust and objective quantification methodologies capable of detecting subtle changes in dystrophin expression. In this work, we present further development and optimisation of an automated, digital, high-throughput script for quantitative analysis of multiplexed immunofluorescent (IF) whole slide images (WSI) of dystrophin, dystrophin associated proteins (DAPs) and regenerating myofibres (fetal/developmental myosin-positive) in transverse sections of DMD, Becker muscular dystrophy (BMD) and control skeletal muscle biopsies. The script enables extensive automated assessment of myofibre morphometrics, protein quantification by fluorescence intensity and sarcolemmal circumference coverage, colocalisation data for dystrophin and DAPs and regeneration at the single myofibre and whole section level. Analysis revealed significant variation in dystrophin intensity, percentage coverage and amounts of DAPs between differing DMD and BMD samples. Accurate identification of dystrophin via a novel background subtraction method allowed differential assessment of DAP fluorescence intensity within dystrophin positive compared to dystrophin negative sarcolemma regions. This enabled surrogate quantification of molecular functionality of dystrophin in the assembly of the DAP complex. Overall, the digital script is capable of multiparametric and unbiased analysis of markers of myofibre regeneration and dystrophin in relation to key DAPs and enabled better characterisation of the heterogeneity in dystrophin expression patterns seen in BMD and DMD alongside the surrogate assessment of molecular functionality of dystrophin. Both these aspects will be of significant relevance to ongoing and future DMD and other muscular dystrophies clinical trials to help benchmark therapeutic efficacy.

The Value of Imaging and Composition-Based Biomarkers in Duchenne Muscular Dystrophy Clinical Trials.

As the drug development pipeline for Duchenne muscular dystrophy (DMD) rapidly advances, clinical trial outcomes need to be optimized. Effective assessment of disease burden, natural history progression, and response to therapy in clinical trials for Duchenne muscular dystrophy are critical factors for clinical trial success. By choosing optimal biomarkers to better assess therapeutic efficacy, study costs and sample size requirements can be reduced. Currently, functional measures continue to serve as the primary outcome for the majority of DMD clinical trials. Quantitative measures of muscle health, including magnetic resonance imaging and spectroscopy, electrical impedance myography, and ultrasound, sensitively identify diseased muscle, disease progression, and response to a therapeutic intervention. Furthermore, such non-invasive techniques have the potential to identify disease pathology prior to onset of clinical symptoms. Despite robust supportive evidence, non-invasive quantitative techniques are still not frequently utilized in clinical trials for Duchenne muscular dystrophy. Non-invasive quantitative techniques have demonstrated the ability to quantify disease progression and potential response to therapeutic intervention, and should be used as a supplement to current standard functional measures. Such methods have the potential to significantly accelerate the development and approval of therapies for DMD.

P.307Heterogeneous distribution of fatty infiltration - an important consideration in Becker muscular dystrophy clinical trials

P.307Heterogeneous distribution of fatty infiltration - an important consideration in Becker muscular dystrophy clinical trials

EP.70Annual prevalence of pneumothorax in neuromuscular disorders: results of questionnaire survey of institutions registered in muscular dystrophy clinical trial network in Japan

Pneumothorax associated with Duchenne muscular dystrophy (DMD) was reported in 1994, but there have been only few case reports since then. This study describes the current prevalence of pneumothorax secondary to DMD and other neuromuscular diseases. In November 2018, we sent a questionnaire survey by e-mail to 40 institutions registered in the muscular dystrophy clinical trial network (MDCTN), a Japanese network for clinical research and clinical trials for neuromuscular diseases established in 2012.

P.146Novel high-throughput digital analysis to quantify the amount of functional sarcolemmal dystrophin and myofibre regeneration in Duchenne muscular dystrophy clinical trial samples (exon 53 skipping with golodirsen)

P.146Novel high-throughput digital analysis to quantify the amount of functional sarcolemmal dystrophin and myofibre regeneration in Duchenne muscular dystrophy clinical trial samples (exon 53 skipping with golodirsen)

The Direct Cost of Managing a Rare Disease: Assessing Medical and Pharmacy Costs Associated with Duchenne Muscular Dystrophy in the United States.

A Duchenne muscular dystrophy (DMD) cohort was identified using a claims-based algorithm to estimate health care utilization and costs for commercially insured DMD patients in the United States. Previous analyses have used broad diagnosis codes that include a range of muscular dystrophy types as a proxy to estimate the burden of DMD. To estimate DMD-associated resource utilization and costs in a sample of patients identified via a claims-based algorithm using diagnosis codes, pharmacy prescriptions, and procedure codes unique to DMD management based on DMD clinical milestones. DMD patients were selected from a commercially insured claims database (2000-2009). Patients with claims suggestive of a non-DMD diagnosis or who were aged 30 years or older were excluded. Each DMD patient was matched by age, gender, and region to controls without DMD in a 1:10 ratio (DMD patients n = 75; controls n = 750). All-cause health care resource utilization, including emergency department, inpatient, outpatient, and physician office visits, and all-cause health care costs were examined over a minimum 1-year period. Costs were computed as total health-plan and patient-paid amounts of adjudicated medical claims (in annualized U.S. dollars). The average age of the DMD cohort was 13 years. Patients in the DMD cohort had a 10-fold increase in health care costs compared with controls ($23,005 vs. $2,277, P < 0.001). Health care costs were significantly higher for the DMD cohort across age strata and, in particular, for DMD patients aged 14-29 years ($40,132 vs. $2,746, P < 0.001). In the United States, resource use and medical costs of DMD are substantial and increase with age. Funding for this study (GHO-10-4441) was provided by GlaxoSmithKline (GSK). Optum was contracted by GSK to conduct the study. Thayer was an employee of Optum Health Economics and Outcomes Research at the time of this study and was not compensated for her participation as an author of this manuscript. Bell is an employee and shareholder of GSK. McDonald has been a consultant for GSK, Sarepta, PTC Therapeutics, Biomarin, and Catabasis on clinical trials regarding Duchenne muscular dystrophy clinical trial design, endpoint selection, and data analysis; Mitobridge for drug development; and Eli Lilly as part of a steering committee for clinical trials. Study concept and design were contributed primarily by Bell, along with Thayer and McDonald. Thayer collected the data, and data interpretation was performed by Thayer and Bell, along with McDonald. The manuscript was written by Thayer and Bell, along with McDonald, and revised by all the authors.

The 100-meter timed test: Normative data in healthy males and comparative pilot outcome data for use in Duchenne muscular dystrophy clinical trials

Timed walking tests are often used to measure function in boys with Duchenne muscular dystrophy (DMD). Our objective was to evaluate the 100 meter timed test (100m), a fixed distance test of maximal performance, for use in DMD. To this end, we sought to establish normative 100m performance in healthy controls, compare DMD performance to controls, and evaluate the reliability of 100m. Seventy-two boys with DMD (18 steroid-naïve, 54 on steroids) and 599 controls (4–14 years) completed the 100m as speedily as possible on a 25-meter track. Repeat testing was completed between 1 and 42 days later and again at 1 year in a subgroup of 96 control boys. Additionally 35 DMD boys were followed longitudinally (5–19 months). Descriptive statistics are presented by age and cohort. There was a significant difference in performance between groups (p < 0.01). Age and body mass index (BMI) significantly influenced 100m (p < 0.0001) in the control cohort. Test–retest reliability was excellent for both cohorts (ICC > 0.90, p < 0.001). Normative data can be used to determine percent-predicted 100m times to quantify the severity of running impairment in children with a motor deficit. Performance of 100m follows the natural history established by other outcome measures in DMD.

Clinical trial network for the promotion of clinical research for rare diseases in Japan: muscular dystrophy clinical trial network.

BackgroundDuchenne muscular dystrophy (DMD) is the most commonly inherited neuromuscular disease. Therapeutic agents for the treatment of rare disease, namely “orphan drugs”, have recently drawn the attention of researchers and pharmaceutical companies. To ensure the successful conduction of clinical trials to evaluate novel treatments for patients with rare diseases, an appropriate infrastructure is needed. One of the effective solutions for the lack of infrastructure is to establish a network of rare diseases.MethodsTo accomplish the conduction of clinical trials in Japan, the Muscular dystrophy clinical trial network (MDCTN) was established by the clinical research group for muscular dystrophy, including the National Center of Neurology and Psychiatry, as well as national and university hospitals, all which have a long-standing history of research cooperation.ResultsThirty-one medical institutions (17 national hospital organizations, 10 university hospitals, 1 national center, 2 public hospitals, and 1 private hospital) belong to this network and collaborate to facilitate clinical trials. The Care and Treatment Site Registry (CTSR) calculates and reports the proportion of patients with neuromuscular diseases in the cooperating sites. In total, there are 5,589 patients with neuromuscular diseases in Japan and the proportion of patients with each disease is as follows: DMD, 29 %; myotonic dystrophy type 1, 23 %; limb girdle muscular dystrophy, 11 %; Becker muscular dystrophy, 10 %. We work jointly to share updated health care information and standardized evaluations of clinical outcomes as well. The collaboration with the patient registry (CTSR), allows the MDCTN to recruit DMD participants with specific mutations and conditions, in a remarkably short period of time.ConclusionCounting with a network that operates at a national level is important to address the corresponding national issues. Thus, our network will be able to contribute with international research activity, which can lead to an improvement of neuromuscular disease treatment in Japan.

Muscular dystrophy clinical trial network: establishment and promotion of clinical research for neuromuscular diseases in Japan

Muscular dystrophy clinical trial network: establishment and promotion of clinical research for neuromuscular diseases in Japan

Dystrophin quantification

Objective:We formed a multi-institution collaboration in order to compare dystrophin quantification methods, reach a consensus on the most reliable method, and report its biological significance in the context of clinical trials.Methods:Five laboratories with expertise in dystrophin quantification performed a data-driven comparative analysis of a single reference set of normal and dystrophinopathy muscle biopsies using quantitative immunohistochemistry and Western blotting. We developed standardized protocols and assessed inter- and intralaboratory variability over a wide range of dystrophin expression levels.Results:Results from the different laboratories were highly concordant with minimal inter- and intralaboratory variability, particularly with quantitative immunohistochemistry. There was a good level of agreement between data generated by immunohistochemistry and Western blotting, although immunohistochemistry was more sensitive. Furthermore, mean dystrophin levels determined by alternative quantitative immunohistochemistry methods were highly comparable.Conclusions:Considering the biological function of dystrophin at the sarcolemma, our data indicate that the combined use of quantitative immunohistochemistry and Western blotting are reliable biochemical outcome measures for Duchenne muscular dystrophy clinical trials, and that standardized protocols can be comparable between competent laboratories. The methodology validated in our study will facilitate the development of experimental therapies focused on dystrophin production and their regulatory approval.

Composite Biomarkers for Assessing Duchenne Muscular Dystrophy: An Initial Assessment

BackgroundCompared with individual parameters, composite biomarkers may provide a more effective means for monitoring disease progression and the effects of therapy in clinical trials than single measures. In this study, we built composite biomarkers for use in Duchenne muscular dystrophy by combining values from two objective measures of disease severity: electrical impedance myography and quantitative ultrasound and evaluating how well they correlated to standard functional measures. MethodsUsing data from an ongoing study of electrical impedance myography and quantitative ultrasound in 31 Duchenne muscular dystrophy and 26 healthy boys aged 2-14 years, we combined data sets by first creating z scores based on the normal subject data and then using simple mathematical operations (addition and multiplication) to create composite measures. These composite scores were then correlated to age and standard measures of function including the 6-minute walk test, the North Star Ambulatory Assessment, and handheld dynamometry. ResultsCombining data sets resulted in stronger correlations with all four outcomes than for either electrical impedance myography or quantitative ultrasound alone in six of eight instances. These improvements reached statistical significance (P < 0.05) in several cases. For example, the correlation coefficient for the composite measure with the North Star Ambulatory Assessment was 0.79 but was only 0.66 and 0.67 (respectively) for gray scale level and electrical impedance myography separately. ConclusionsArithmetically derived composite scores can provide stronger correlations to functional measures than isolated biomarkers. Longitudinal study of such composite markers in Duchenne muscular dystrophy clinical trials is warranted.

G.P.303: Influences on parental decision making about participation in Duchenne and Becker muscular dystrophy clinical trials

Introduction: Parents’ decisions about enrolling children in Duchenne/Becker muscular dystrophy (DBMD) clinical trials (CTs) may be influenced by hopes and expectations, which when unrealistic may challenge informed consent. We explore influences on decision-making. Methods: The study team employed a community-based participatory research approach. Parents of children in CTs in U.S. or Canada were recruited for an online survey through Parent Project Muscular Dystrophy and clinics. Participants viewed a series of benefit and worry statements and rated each statement’s influence on decision-making, and how much they expected and hoped or worried about each. Results: Among the first 61 participants, CT decision-making was influenced by potential altruistic and individual benefits: learning generalizable information (97% slightly to strongly agree), CT resulting in a drug that works (82%), leading to better future for other children (82%), improving quality-of-life for their child (82%), and parent doing everything to help their child (82%). CT worries most affecting decision-making were: child would be bothered by side effects (39%), child’s eligibility for a competing trial (36%), and child not liking the trial (29%). Expectation and hope ratings were highly correlated with ratings of factors that influenced decision-making ( r = 0.5–0.8, p

P16 Towards a consensus on biochemical outcome measures for Duchenne muscular dystrophy clinical trials

P16 Towards a consensus on biochemical outcome measures for Duchenne muscular dystrophy clinical trials