Deflazacort vs prednisone treatment for Duchenne muscular dystrophy: A meta-analysis of disease progression rates in recent multicenter clinical trials

Appendicular lean mass index and motor function in ambulatory patients with Duchenne muscular dystrophy

INTRODUCTION/AIMS

Appendicular lean mass index (ALMI) has been linked to motor function in patients with Duchenne muscular dystrophy (DMD). However, quantification of the relationship between ALMI and disease-specific clinical outcome assessment trajectories is needed. The purpose of this study was to determine associations between dual-energy x-ray absorptiometry (DXA) derived estimates of ALMI and motor function in ambulatory patients with DMD.

METHODS

A retrospective analysis of longitudinal clinical visit data from 137 glucocorticoid-treated patients with DMD collected via structured motor assessment protocol evaluated associations between ALMI and motor function indexed by the North Star Ambulatory Assessment (NSAA) and 10 Meter Walk/run Test (10MWT). Body composition was assessed using DXA. ALMI was calculated by dividing arm and leg lean mass by height in m2; fat mass index (FMI) was calculated by dividing whole body fat mass by height in m2. Linear mixed-effects models were used to estimate associations between ALMI and motor function, controlling for age and FMI.

RESULTS

The full prediction model (age, age,2 ALMI, and FMI) explained 57% of the variance in NSAA scores and 63% of the variance in 10MWT speed. A 1 kg/m2 higher ALMI value predicted a 5.4-point higher NSAA score (p < .001) and 0.45 m/s faster 10MWT speed (p < .001). A 1 kg/m2 higher FMI value predicted a 1.5-point lower NSAA score (p < .001) and 0.14 meters/second slower 10MWT speed (p < .001).

DISCUSSION

DXA-derived estimates of ALMI and FMI are associated with motor function in DMD and may explain variation in DMD disease progression.

Subspecialty Health Care Utilization in Pediatric Patients With Muscular Dystrophy in the United States

Background and Objectives

Standards of care exist to optimize outcomes in Duchenne and Becker muscular dystrophy (DBMD), caused by alterations in the DMD gene; however, there are limited data regarding health care access in these patients. This study aims to characterize outpatient subspecialty care utilization in pediatric patients with DBMD.

Methods

This retrospective cohort study used administrative claims data from IBM MarketScan Medicaid and Commercial Claims and Encounters Research Databases (2013-2018). Male patients 1-18 years with an ICD-9/10 diagnosis code for hereditary progressive muscular dystrophy between January 1, 2013, and December 31, 2017, were included. Participants were stratified into 3 age cohorts: 1-6 years, 7-12 years, and 13-18 years. The primary outcome was rate of annual neurology visits. Secondary outcomes included annual follow-up rates in other subspecialties and proportion of days covered (PDC) by corticosteroids.

Results

A total of 1,386 patients met inclusion-347 (25.0%) age 1-6 years, 502 (36.2%) age 7-12 years, and 537 (38.7%) age 13-18 years. Heart failure, respiratory failure, and technology dependence increased with age (p for all<0.05). The rate of neurology visits per person-year was 0.36 and did not differ by age. Corticosteroid use was low; 30% of person-years (1452/4829) had a PDC ≥20%. Medicaid insurance was independently associated with a lower likelihood of annual neurology follow-up (OR 0.23; 95% CI 0.18-0.28).

Discussion

The rate of annual neurology follow-up and corticosteroid use in patients with DBMD is low. Medicaid insurance status was independently associated with a decreased likelihood of neurology follow-up, while age was not, suggesting that factors other than disease severity influence neurology care access. Identifying barriers to regular follow-up is critical in improving outcomes for patients with DBMD.

Effect of a Single Dose of Deflazacort on Postoperative Pain, Swelling, and Trismus after Impacted Lower Third Molar Surgery: Randomised Clinical Trial

Background and Objectives: The aim of this study was to investigate the efficacy of a single preoperative dose of deflazacort on pain, swelling, and trismus after impacted lower third molar surgery. Materials and Methods: This randomised, prospective, double-blind, split-mouth clinical study included 26 healthy individuals with bilaterally impacted lower third molars. Group 1 was given a placebo (single-dose vitamin C tablet), and group 2 was given a single 30 mg dose of deflazacort 1 h prior to surgery. Pain was evaluated using the visual analogue scale for 1 week postoperatively. Oedema (in mm) and trismus (in mm) were evaluated preoperatively and on postoperative days 2 and 7. The Mann-Whitney U test was applied for group analyses. p values < 0.05 were considered statistically significant. Results: Postoperative pain scores were significantly lower in the deflazacort group at the 6th and 12th hours after surgery (p < 0.05). There were no significant differences in trismus between the groups at any time point (p > 0.05). There was less oedema in the deflazacort group on postoperative days 2 and 7, without any statistically significant difference (p > 0.05). Conclusions: A single preoperative dose of 30 mg deflazacort was found to be clinically effective in reducing pain and oedema after extraction of impacted lower third molars.

Comparison of pharmaceutical properties and biological activities of prednisolone, deflazacort, and vamorolone in DMD disease models

Duchenne muscular dystrophy (DMD) is a progressive disabling X-linked recessive disorder that causes gradual and irreversible loss of muscle, resulting in early death. The corticosteroids prednisone/prednisolone and deflazacort are used to treat DMD as the standard of care; however, only deflazacort is FDA approved for DMD. The novel atypical corticosteroid vamorolone is being investigated for treatment of DMD. We compared the pharmaceutical properties as well as the efficacy and safety of the three corticosteroids across multiple doses in the B10-mdx DMD mouse model. Pharmacokinetic studies in the mouse and evaluation of p-glycoprotein (P-gP) efflux in a cellular system demonstrated that vamorolone is not a strong P-gp substrate resulting in measurable central nervous system (CNS) exposure in the mouse. In contrast, deflazacort and prednisolone are strong P-gp substrates. All three corticosteroids showed efficacy, but also side effects at efficacious doses. After dosing mdx mice for two weeks, all three corticosteroids induced changes in gene expression in the liver and the muscle, but prednisolone and vamorolone induced more changes in the brain than did deflazacort. Both prednisolone and vamorolone induced depression-like behavior. All three corticosteroids reduced endogenous corticosterone levels, increased glucose levels, and reduced osteocalcin levels. Using micro-computed tomography, femur bone density was decreased, reaching significance with prednisolone. The results of these studies indicate that efficacious doses of vamorolone, are associated with similar side effects as seen with other corticosteroids. Further, because vamorolone is not a strong P-gp substrate, vamorolone distributes into the CNS increasing the potential CNS side-effects.

Quantifying Variability in Motor Function in Duchenne Muscular Dystrophy: UK Centiles for the NorthStar Ambulatory Assessment, 10 m Walk Run Velocity and Rise from Floor Velocity in GC Treated Boys

Background Boys with Duchenne Muscular Dystrophy (DMD) display heterogeneous motor function trajectory in clinics, which represents a significant obstacle to monitoring.

OBJECTIVE

In this paper, we present the UK centiles for the North Star Ambulatory Assessment (NSAA), the 10 m walk/run time (10MWR) and velocity (10MWRV), and the rise from floor time (RFF) and velocity (RFFV) created from a cohort of glucocorticoid treated DMD boys between the age of 5 and 16 years.

METHODS

Participants were included from the UK NorthStar registry if they had initiated steroids (primarily deflazacorts/prednisolone, intermittent/daily) and were not enrolled in an interventional trial. Assessments were included if the participant had a complete NSAA, the timed tests had been completed or the corresponding items were 0, or the participant was recorded as non-ambulant, in which case the NSAA was assumed 0.

RESULTS

We analysed 3987 assessments of the NSAA collected from 826 participants. Of these, 1080, 1849 and 1199 were imputed as 0 for the NSAA, RFFV and 10MWRV respectively. The 10th, 25th, 50th, 75th and 90th centiles were presented. The NSAA centiles showed a peak score of 14, 20, 26, 30 and 32 respectively, with loss of ambulation at 10.7, 12.2 and 14.3 years for the 25th, 50th and 75th centiles, respectively. The centiles showed loss of rise from floor at 8.6, 10.1 and 11.9 years and a loss of 10MWR of 0 at 8.9, 10.3 and 13.8 years for the 25th, 50th and 75th centiles, respectively. The centiles were pairwise less correlated than the raw scores, suggesting an increased ability to detect variability in the DMD cohort.

CONCLUSIONS

The NSAA, 10MWR and RFF centiles may provide insights for clinical monitoring of DMD boys, particularly in late ambulatory participants who are uniformly declining. Future work will validate the centiles in national and international natural history cohorts.

Draft Guidance for Industry Duchenne Muscular Dystrophy, Becker Muscular Dystrophy, and Related Dystrophinopathies - Developing Potential Treatments for the Entire Spectrum of Disease

Background

Duchenne muscular dystrophy (DMD) and related dystrophinopathies are neuromuscular conditions with great unmet medical needs that require the development of effective medical treatments.

Objective

To aid sponsors in clinical development of drugs and therapeutic biological products for treating DMD across the disease spectrum by integrating advancements, patient registries, natural history studies, and more into a comprehensive guidance.

Methods

This guidance emerged from collaboration between the FDA, the Duchenne community, and industry stakeholders. It entailed a structured approach, involving multiple committees and boards. From its inception in 2014, the guidance underwent revisions incorporating insights from gene therapy studies, cardiac function research, and innovative clinical trial designs.

Results

The guidance provides a deeper understanding of DMD and its variants, focusing on patient engagement, diagnostic criteria, natural history, biomarkers, and clinical trials. It underscores patient-focused drug development, the significance of dystrophin as a biomarker, and the pivotal role of magnetic resonance imaging in assessing disease progression. Additionally, the guidance addresses cardiomyopathy's prominence in DMD and the burgeoning field of gene therapy.

Conclusions

The updated guidance offers a comprehensive understanding of DMD, emphasizing patient-centric approaches, innovative trial designs, and the importance of biomarkers. The focus on cardiomyopathy and gene therapy signifies the evolving realm of DMD research. It acts as a crucial roadmap for sponsors, potentially leading to improved treatments for DMD.

Higher Prevalence of Nonsense Pathogenic DMD Variants in a Single-Center Cohort from Brazil: A Genetic Profile Study That May Guide the Choice of Disease-Modifying Treatments

Dystrophinopathies are muscle diseases caused by pathogenic variants in DMD, the largest gene described in humans, representing a spectrum of diseases ranging from asymptomatic creatine phosphokinase elevation to severe Duchenne muscular dystrophy (DMD). Several therapeutic strategies are currently in use or under development, each targeting different pathogenic variants. However, little is known about the genetic profiles of northeast Brazilian patients with dystrophinopathies. We describe the spectrum of pathogenic DMD variants in a single center in northeast Brazil. This is an observational, cross-sectional study carried out through molecular-genetic analysis of male patients diagnosed with dystrophinopathies using Multiplex Ligation-dependent Probe Amplification (MLPA) followed by Next-Generation Sequencing (NGS)-based strategies. A total of 94 male patients were evaluated. Deletions (43.6%) and duplications (10.6%) were the most recurring patterns of pathogenic variants. However, small variants were present in 47.1% of patients, most of them nonsense variants (27.6%). This is the largest South American single-center case series of dystrophinopathies to date. We found a higher frequency of treatment-amenable nonsense single-nucleotide variants than most previous studies. These findings may have implications for diagnostic strategies in less-known populations, as a higher frequency of nonsense variants may mean a higher possibility of treating patients with disease-modifying drugs.

From Meaningful Outcomes to Meaningful Change Thresholds: A Path to Progress for Establishing Digital Endpoints

This paper examines the use of digital endpoints (DEs) derived from digital health technologies (DHTs), focusing primarily on the specific considerations regarding the determination of meaningful change thresholds (MCT). Using DHTs in drug development is becoming more commonplace. There is general acceptance of the value of DHTs supporting patient-centric trial design, capturing data outside the traditional clinical trial setting, and generating DEs with the potential to be more sensitive to change than conventional assessments. However, the transition from exploratory endpoints to primary and secondary endpoints capable of supporting labeling claims requires these endpoints to be substantive with reproducible population-specific values. Meaningful change represents the amount of change in an endpoint measure perceived as important to patients and should be determined for each digital endpoint and given population under consideration. This paper examines existing approaches to determine meaningful change thresholds and explores examples of these methodologies and their use as part of DE development: emphasizing the importance of determining what aspects of health are important to patients and ensuring the DE captures these concepts of interest and aligns with the overarching endpoint strategy. Examples are drawn from published DE qualification documentation and responses to qualification submissions under review by the various regulatory authorities. It is the hope that these insights will inform and strengthen the development and validation of DEs as drug development tools, particularly for those new to the approaches to determine MCTs.

Duchenne muscular dystrophy: disease mechanism and therapeutic strategies

Duchenne muscular dystrophy (DMD) is a severe, progressive, and ultimately fatal disease of skeletal muscle wasting, respiratory insufficiency, and cardiomyopathy. The identification of the dystrophin gene as central to DMD pathogenesis has led to the understanding of the muscle membrane and the proteins involved in membrane stability as the focal point of the disease. The lessons learned from decades of research in human genetics, biochemistry, and physiology have culminated in establishing the myriad functionalities of dystrophin in striated muscle biology. Here, we review the pathophysiological basis of DMD and discuss recent progress toward the development of therapeutic strategies for DMD that are currently close to or are in human clinical trials. The first section of the review focuses on DMD and the mechanisms contributing to membrane instability, inflammation, and fibrosis. The second section discusses therapeutic strategies currently used to treat DMD. This includes a focus on outlining the strengths and limitations of approaches directed at correcting the genetic defect through dystrophin gene replacement, modification, repair, and/or a range of dystrophin-independent approaches. The final section highlights the different therapeutic strategies for DMD currently in clinical trials.

Disease progression rates in ambulatory Duchenne muscular dystrophy by steroid type, patient age and functional status

Aim: To examine benefits of corticosteroids for Duchenne muscular dystrophy (DMD) by age and disease progression. Methods: Data from daily steroid users (placebo-treated) were pooled from four phase 2b/3 trials in DMD. Outcomes assessed overall and among subgroups included changes from baseline to 48 weeks in six-minute walk distance (6MWD), timed function tests and North Star Ambulatory Assessment total score. Results: Among 231 patients receiving deflazacort (n = 127) or prednisone (n = 104), observed differences in 6MWD favoring deflazacort over prednisone were significant for patients with relatively older age (≥8-years-old), greater disease progression (baseline timed stand from supine ≥5 s), or longer corticosteroid use (>3 years). Conclusion: Daily deflazacort had greater benefits than daily prednisone particularly among older/more progressed patients.

Duchenne muscular dystrophy: Current treatment and emerging exon skipping and gene therapy approach

Duchenne muscular dystrophy (DMD) is an X-linked recessive neuromuscular disorder that causes debilitating muscle weakness and atrophy due to a loss of the dystrophin protein. Patients with DMD are commonly diagnosed at about 3-5 years of age and progressively decline until complications of the disease often result in death at about 20 years of age. While there is no current cure for DMD, several treatment options focus on improving the quality of life and slowing progression of symptoms associated with the disease. The current treatment for DMD is glucocorticoids and physical therapy. Respiratory therapy, cardiac management, bone health maintenance, orthopedic interventions, and dietary considerations are also utilized in managing DMD patients. Emerging therapeutic approaches include gene transfer therapy, using adeno-associated virus (AAV) vectors, and exon skipping agents. Both approaches have been shown to be relatively safe, with few significant side effects. Even though exon skipping agents produce a smaller dystrophin protein, they effectively preserve a significant portion of its function. Exon skipping agents have clinical advantages over traditional therapies, such as corticosteroids, because they slow the progression of DMD in addition to relieving symptoms. This review discusses the pathogenesis of DMD and explores the current treatment options as well as new and emerging therapies.

Functional and Clinical Outcomes Associated with Steroid Treatment among Non-ambulatory Patients with Duchenne Muscular Dystrophy1

BACKGROUND

Evidence on the long-term efficacy of steroids in Duchenne muscular dystrophy (DMD) after loss of ambulation is limited.

OBJECTIVE

Characterize and compare disease progression by steroid treatment (prednisone, deflazacort, or no steroids) among non-ambulatory boys with DMD.

METHODS

Disease progression was measured by functional status (Performance of Upper Limb Module for DMD 1.2 [PUL] and Egen Klassifikation Scale Version 2 [EK] scale) and by cardiac and pulmonary function (left ventricular ejection fraction [LVEF], forced vital capacity [FVC] % -predicted, cough peak flow [CPF]). Longitudinal changes in outcomes, progression to key disease milestones, and dosing and body composition metrics were analyzed descriptively and in multivariate models.

RESULTS

This longitudinal cohort study included 86 non-ambulatory patients with DMD (mean age 13.4 years; n = 40 [deflazacort], n = 29 [prednisone], n = 17 [no steroids]). Deflazacort use resulted in slower average declines in FVC % -predicted vs. no steroids (+3.73 percentage points/year, p < 0.05). Both steroids were associated with significantly slower average declines in LVEF, improvement in CPF, and slower declines in total PUL score and EK total score vs. no steroids; deflazacort was associated with slower declines in total PUL score vs. prednisone (all p < 0.05). Both steroids also preserved functional abilities considered especially important to quality of life, including the abilities to perform hand-to-mouth function and to turn in bed at night unaided (all p < 0.05 vs. no steroids).

CONCLUSIONS

Steroid use after loss of ambulation in DMD was associated with delayed progression of important pulmonary, cardiac, and upper extremity functional deficits, suggesting some benefits of deflazacort over prednisone.

Update of the Brazilian consensus recommendations on Duchenne muscular dystrophy

In the last few decades, there have been considerable improvements in the diagnosis and care of Duchenne muscular dystrophy (DMD), the most common childhood muscular dystrophy. International guidelines have been published and recently reviewed. A group of Brazilian experts has developed a standard of care based on a literature review with evidence-based graded recommendations in a two-part publication. Implementing best practice management has helped change the natural history of this chronic progressive disorder, in which the life expectancy for children of the male sex in the past used to be very limited. Since the previous publication, diagnosis, steroid treatment, rehabilitation, and systemic care have gained more significant insights with new original work in certain fields. Furthermore, the development of new drugs is ongoing, and some interventions have been approved for use in certain countries. Therefore, we have identified the need to review the previous care recommendations for Brazilian patients with DMD. Our objective was to create an evidence-based document that is an update on our previous consensus on those topics.

Limb-girdle muscular dystrophy type 2B causes HDL-C abnormalities in patients and statin-resistant muscle wasting in dysferlin-deficient mice

Limb-girdle muscular dystrophy (MD) type 2B (LGMD2B) and Duchenne MD (DMD) are caused by mutations to the Dysferlin and Dystrophin genes, respectively. We have recently demonstrated in typically mild dysferlin- and dystrophin-deficient mouse models that increased plasma cholesterol levels severely exacerbate muscle wasting, and that DMD patients display primary dyslipidemia characterized by elevated plasma cholesterol and triglycerides. Herein, we investigate lipoprotein abnormalities in LGMD2B and if statin therapy protects dysferlin-deficient mice (Dysf) from muscle damage. Herein, lipoproteins and liver enzymes from LGMD2B patients and dysferlin-null (Dysf) mice were analyzed. Simvastatin, which exhibits anti-muscle wasting effects in mouse models of DMD and corrects aberrant expression of key markers of lipid metabolism and endogenous cholesterol synthesis, was tested in Dysf mice. Muscle damage and fibrosis were assessed by immunohistochemistry and cholesterol signalling pathways via Western blot. LGMD2B patients show reduced serum high-density lipoprotein cholesterol (HDL-C) levels compared to healthy controls and exhibit a greater prevalence of abnormal total cholesterol (CHOL)/HDL-C ratios despite an absence of liver dysfunction. While Dysf mice presented with reduced CHOL and associated HDL-C and LDL-C-associated fractions, simvastatin treatment did not prevent muscle wasting in quadriceps and triceps muscle groups or correct aberrant low-density lipoprotein receptor (LDLR) and 3-hydroxy-3-methylglutaryl coenzyme A reductase (HMGCR) protein expression. LGMD2B patients present with reduced serum concentrations of HDL-C, a major metabolic comorbidity, and as a result, statin therapy is unlikely to prevent muscle wasting in this population. We propose that like DMD, LGMD2B should be considered as a new type of genetic dyslipidemia.

Current Strategies of Muscular Dystrophy Therapeutics: An Overview

Muscular dystrophies are a group of genetic disorders characterized by varying degrees of progressive muscle weakness and degeneration. They are clinically and genetically heterogeneous but share the common histological features of dystrophic muscle. There is currently no cure for muscular dystrophies, which is of particular concern for the more disabling and/or lethal forms of the disease. Through the years, several therapies have encouragingly been developed for muscular dystrophies and include genetic, cellular, and pharmacological approaches. In this chapter, we undertake a comprehensive exploration of muscular dystrophy therapeutics under current development. Our review includes antisense therapy, CRISPR, gene replacement, cell therapy, nonsense suppression, and disease-modifying small molecule compounds.

Prognostic factors, disease course, and treatment efficacy in Duchenne muscular dystrophy: A systematic review and meta-analysis

INTRODUCTION/AIMS

Prognostic factors in Duchenne muscular dystrophy (DMD) predict the disease course and may help individualize patient care. The aim was to summarize the evidence on prognostic factors that may support treatment decisions.

METHODS

We searched six databases for prospective studies that each included ≥50 DMD patients with a minimum follow-up of 1 y. Primary outcomes were age at loss of ambulation (LoA), pulmonary function (forced vital capacity percent of predicted, FVC%p), and heart failure.

RESULTS

Out of 5074 references, 59 studies were analyzed. Corticosteroid use was associated with a delayed LoA (pooled effect hazard ratio [HR] 0.42, 95% confidence interval [CI] 0.23-0.75, I2 94%), better pulmonary function tests (higher peak FVC%, prolonged time with FVC%p > 50%, and reduced need for assisted ventilation) and delayed cardiomyopathy. Longer corticosteroid treatment was associated with later LoA (>1 y compared to <1 y; pooled HR: 0.50, 95% CI 0.27-0.90) and early treatment start (aged <5 y) may be associated with early cardiomyopathy and higher fracture risk. Genotype appeared to be an independent driver of LoA in some studies. Higher baseline physical function tests (e.g., 6-minute walk test) were associated with delayed LoA. Left ventricular dysfunction and FVC <1 L increased and the use of angiotensin-converting enzyme (ACE) inhibitors reduced the risk of heart failure and death. Fusion surgery in scoliosis may potentially preserve pulmonary function.

DISCUSSION

Prognostic factors that may inform clinical decisions include age at corticosteroid treatment initiation and treatment duration, ACE-inhibitor use, baseline physical function tests, pulmonary function, and cardiac dysfunction.

Perspectives on the advances in the pharmacotherapeutic management of Duchenne muscular dystrophy

INTRODUCTION

: Duchenne muscular dystrophy (DMD) is a progressive genetic disease characterized by muscular weakness with a global prevalence of 7.1 cases per 100,000 males. DMD is caused by mutations of the dystrophin gene on the X chromosome which is responsible for dystrophin protein production. Dystrophin is a cytoskeletal protein that contributes to structural support in muscle cells. DMD mutations result in dystrophin protein deficiency which leads to muscle damage and the associated clinical presentation.

AREAS COVERED

: Corticosteroids such as prednisone and deflazacort are routinely given to patients to treat inflammation, but their use is limited by the occurrence of side effects and a lack of standardized prescribing. Exon-skipping medications are emerging as treatment options for a small portion of DMD patients even though efficacy is uncertain. Many new therapeutics are under development that target inflammation, fibrosis, and dystrophin replacement.

EXPERT OPINION

: Because of side effects associated with corticosteroid use, there is need for better alternatives to the standard of care. Excessive cost is a barrier to patients receiving medications that have yet to have established efficacy. Additional therapies have the potential to help patients with DMD, although most are several years away from approval for patient use.

Comparing Deflazacort and Prednisone in Duchenne Muscular Dystrophy

Deflazacort and prednisone/prednisolone are the current standard of care for patients with Duchenne muscular dystrophy (DMD) based on evidence that they improve muscle strength, improve timed motor function, delay loss of ambulation, improve pulmonary function, reduce the need for scoliosis surgery, delay onset of cardiomyopathy, and increase survival. Both have been used off-label for many years (choice dependent on patient preference, cost, and geographic location) before FDA approval of deflazacort for DMD in 2017. In this review, we compare deflazacort and prednisone/prednisolone in terms of their key pharmacological features, relative efficacy, and safety profiles in patients with DMD. Differentiating features include lipid solubility, pharmacokinetics, changes in gene expression profiles, affinity for the mineralocorticoid receptor, and impact on glucose metabolism. Evidence from randomized clinical trials, prospective studies, meta-analyses, and post-hoc analyses suggests that patients receiving deflazacort experience similar or slower rates of functional decline compared with those receiving prednisone/prednisolone. Regarding side effects, weight gain and behavior side effects appear to be greater with prednisone/prednisolone than with deflazacort, whereas bone health, growth parameters, and cataracts appear worse with deflazacort.

Deflazacort dose optimization and safety evaluation in Duchenne muscular dystrophy (DOSE): A randomized, double-blind non-inferiority trial

BACKGROUND

US food and drug administration has recently approved deflazacort for Duchenne muscular dystrophy (DMD) and recommended the dosage of 0.9 mg/kg/d for patients aged ≥5years. However, data assessing the minimal efficacious dose and need of dose-titration based on age or disease severity is limited.

OBJECTIVE

To determine whether deflazacort 0.45 mg/kg/d (proposed lower dosage) is non-inferior to 0.9 mg/kg/d among newly diagnosed patients with DMD.

METHOD

A double-blinded, non-inferiority, randomized trial, conducted between December 2018 and July 2020. Newly diagnosed patient aged 5-15 years with genetic or muscle biopsy confirmed DMD and baseline 6-min walk distance (6MWD) > 150 m were screened. Patients were randomly assigned (1:1), stratified to prespecified subgroups by age (≤7years and >7years), and baseline 6MWD (≤350 m and >350 m), to receive either 0.45 mg/kg/d or 0.9 mg/kg/d regimens. The primary endpoint was the change in 6MWD, from baseline to week-24 of intervention. The trial was powered with a predefined, non-inferiority margin of 30 m. The analyses were by modified intention-to-treat (mITT).

RESULT

A total of 97 patients were enrolled, 40 receiving 0.45 mg/kg/d and 45 receiving 0.9 mg/kg/d deflazacort comprised of mITT population. For primary endpoint analysis the mean (SD) change in 6MWD from baseline to week-24 was 9.7 m (41.5) in deflazacort 0.45 mg/kg/d, and 34.7 m (43.5) for 0.9 mg/kg/d. The mean difference in change in 6MWD across the group was 24.8 m (95% CI 6.7 to 43, p value 0.008). The mean difference in change in 6MWD in the subgroups of boys ≤7 years of age was 21.8 m (95% CI -0.82, 44.5, p = 0.059), with baseline 6MWD of >350 m was 19.9 m (95% CI -2.4, 42.4; p = 0.08). The incidence of combined moderate to severe treatment-related adverse events was significant in the 0.9 mg/kg/d group by week 24 (odds ratio 0.36 [95% CI, 0.14 to 0.89], p = 0.03).

DISCUSSION

The efficacy of proposed low dose deflazacort in comparison to the standard dose did not meet the prespecified criteria for non-inferiority. The low dose deflazacort was non-inferior in subgroup of patients with age ≤7 years and baseline 6MWD of >350 m.

TRIAL REGISTRATION

Clinical Trial Registry-India Identifier: CTRI/2019/02/017388.

Direct costs of adhering to selected Duchenne muscular dystrophy Care Considerations: Estimates from a midwestern state

INTRODUCTION/AIMS

The multidisciplinary Duchenne muscular dystrophy (DMD) Care Considerations were developed to standardize care and improve outcomes. We provide cumulative cost estimates for selected key preventive (ie, excluding new molecular therapies and acute care) elements of the care considerations in eight domains (neuromuscular, rehabilitation, respiratory, cardiac, orthopedic, gastrointestinal, endocrine, psychosocial management) independent of completeness of uptake or provision of nonpreventive care.

METHODS

We used de-identified insurance claims data from a large midwestern commercial health insurer during 2018. We used Current Procedural Terminology and national drug codes to extract unit costs for clinical encounters representing key preventive elements of the DMD Care Considerations. We projected per-patient cumulative costs from ages 5 to 25 years for these elements by multiplying a schedule of recommended frequencies of preventive services by unit costs in 2018 US dollars.

RESULTS

Assuming a diagnosis at age 5 years, independent ambulation until age 11, and survival until age 25, we estimated 670 billable clinical events. The 20-year per-patient cumulative cost was $174 701 with prednisone ($2.3 million with deflazacort) and an expected total of $12 643 ($29 194) for out-of-pocket expenses associated with those events and medications.

DISCUSSION

Standardized monitoring of disease progression and treatments may reduce overall costs of illness. Costs associated with these services would be needed to quantify potential savings. Our approach demonstrates a method to estimate costs associated with implementation of preventive care schedules.

Prognostic indicators of disease progression in Duchenne muscular dystrophy: A literature review and evidence synthesis

BACKGROUND

Duchenne muscular dystrophy (DMD) is a rare, severely debilitating, and fatal neuromuscular disease characterized by progressive muscle degeneration. Like in many orphan diseases, randomized controlled trials are uncommon in DMD, resulting in the need to indirectly compare treatment effects, for example by pooling individual patient-level data from multiple sources. However, to derive reliable estimates, it is necessary to ensure that the samples considered are comparable with respect to factors significantly affecting the clinical progression of the disease. To help inform such analyses, the objective of this study was to review and synthesise published evidence of prognostic indicators of disease progression in DMD. We searched MEDLINE (via Ovid), Embase (via Ovid) and the Cochrane Library (via Wiley) for records published from inception up until April 23 2021, reporting evidence of prognostic indicators of disease progression in DMD. Risk of bias was established with the grading system of the Centre for Evidence-Based Medicine (CEBM).

RESULTS

Our search included 135 studies involving 25,610 patients from 18 countries across six continents (Africa, Asia, Australia, Europe, North America and South America). We identified a total of 23 prognostic indicators of disease progression in DMD, namely age at diagnosis, age at onset of symptoms, ataluren treatment, ATL1102, BMI, cardiac medication, DMD genetic modifiers, DMD mutation type, drisapersen, edasalonexent, eteplirsen, glucocorticoid exposure, height, idebenone, lower limb surgery, orthoses, oxandrolone, spinal surgery, TAS-205, vamorolone, vitlolarsen, ventilation support, and weight. Of these, cardiac medication, DMD genetic modifiers, DMD mutation type, and glucocorticoid exposure were designated core prognostic indicators, each supported by a high level of evidence and significantly affecting a wide range of clinical outcomes.

CONCLUSION

This study provides a current summary of prognostic indicators of disease progression in DMD, which will help inform the design of comparative analyses and future data collection initiatives in this patient population.

Jumping Mechanography is a Suitable Complementary Method to Assess Motor Function in Ambulatory Boys with Duchenne Muscular Dystrophy

OBJECTIVE

The number of clinical trials for Duchenne muscular dystrophy (DMD) has increased substantially lately, therefore appropriate clinical instruments are needed to measure disease progression and drug efficacy. Jumping mechanography is a medical diagnostic method for motion analysis, which allows to quantify physical parameters. In this study, we compared mechanography with timed function tests (TFTs).

METHODS

41 ambulatory DMD patients performed a total of 95 chair rising tests (CRT) and a total of 76 single two-legged jumps (S2LJ) on a mechanography ground reaction force platform. The results were correlated with a 6-minute walk test (6MWT) and the time required to run 10 meters, stand up from a supine position, and climb four stairs, all performed in the same setting.

RESULTS

Our measurements show a high correlation between mechanography and the TFTs: S2LJ/10-m run, r = 0.62; CRT/10-m run, r = 0.61; S2LJ/standing up from supine, r = 0.48; CRT/standing up from supine, r = 0.58; S2LJ/climb four stairs, r = 0.55; CRT/climb four stairs, r = 0.51. The correlation between mechanography and the 6MWT was only moderate with r = 0.38 for S2LJ/6MWT and r = 0.39 for CRT/6MWT.

INTERPRETATION

Jumping mechanography is a reliable additional method, which can be used for physical endpoint measurements in clinical trials. We confirmed our assumption, that the method provides additional information concerning performance at movement with higher power output. We suggest using the S2LJ as a first-choice tandem tool combined with the 6MWT. In patients with higher disability, the CRT is an alternative measuring method, because with the progression of the disease this is longer feasible.

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 39.54 m [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 48 weeks compared with prednisone/prednisolone for patients with nonsense mutation Duchenne muscular dystrophy.

Effect of Tadalafil Administration on Redox Homeostasis and Polyamine Levels in Healthy Men with High Level of Physical Activity

Background: The phosphodiesterase type 5 inhibitor (PDE5I) tadalafil, in addition to its therapeutic role, has shown antioxidant effects in different in vivo models. Supplementation with antioxidants has received interest as a suitable tool for preventing or reducing exercise-related oxidative stress, possibly leading to the improvement of sport performance in athletes. However, the use/abuse of these substances must be evaluated not only within the context of amateur sport, but especially in competitions where elite athletes are more exposed to stressful physical practice. To date, very few human studies have addressed the influence of the administration of PDE5Is on redox balance in subjects with a fitness level comparable to elite athletes; therefore, the aim of this study was to investigate for the first time whether acute ingestion of tadalafil could affect plasma markers related to cellular damage, redox homeostasis, and blood polyamines levels in healthy subjects with an elevated cardiorespiratory fitness level. Methods: Healthy male volunteers (n = 12), with a VO_2max range of 40.1–56.0 mL/(kg × min), were administered with a single dose of tadalafil (20 mg). Plasma molecules related to muscle damage and redox-homeostasis, such as creatine kinase (CK), lactate dehydrogenase (LDH), total antioxidant capacity (TAC), reduced/oxidized glutathione ratio (GSH/GSSG), free thiols (FTH), antioxidant enzyme activities (superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPx)), as well as thiobarbituric acid reactive substances (TBARs), protein carbonyls (PrCAR), and polyamine levels (spermine (Spm) and spermidine (Spd)) were evaluated immediately before and 2, 6 and 24 hours after the acute tadalafil administration. Results: A single tadalafil administration induced an increase in CK and LDH plasma levels 24 after consumption. No effects were observed on redox homeostasis or antioxidant enzyme activities, and neither were they observed on the oxidation target molecules or polyamines levels. Conclusion: Our results show that in subjects with an elevated fitness level, a single administration of tadalafil induced a significant increase in muscle damage target without affecting plasma antioxidant status.

[Update on Duchenne muscular dystrophy]

Duchenne muscular dystrophy, DMD*(ICD-9-C: 359.1; ICD-10-ES: G71.01, ORPHA: 98896) is a dystrophic type, autosomal recessive myopathy linked to the X chromosome, low incidence 1/3300, with full penetrance and multi-organ involvement (neuro-muscular, respiratory, digestive and metabolic). It has great clinical variability. Symptoms begin in pediatric age (mobility limitation and early respiratory complications). Respiratory complications reduce the life expectancy of those affected. There is no treatment that modifies its evolution, although corticosteroids and new gene therapies are increasing the half-life of this disease. The role of the Primary Care Physician (PCP) is decisive in the monitoring and control of the complications of DMD, either coordinating the different specialties involved in it.

A Combined Prospective and Retrospective Comparison of Long-Term Functional Outcomes Suggests Delayed Loss of Ambulation and Pulmonary Decline with Long-Term Eteplirsen Treatment

Background:

Studies 4658-201/202 (201/202) evaluated treatment effects of eteplirsen over 4 years in patients with Duchenne muscular dystrophy and confirmed exon-51 amenable genetic mutations. Chart review Study 4658-405 (405) further followed these patients while receiving eteplirsen during usual clinical care.

Objective:

To compare long-term clinical outcomes of eteplirsen-treated patients from Studies 201/202/405 with those of external controls.

Methods:

Median total follow-up time was approximately 6 years of eteplirsen treatment. Outcomes included loss of ambulation (LOA) and percent-predicted forced vital capacity (FVC%p). Time to LOA was compared between eteplirsen-treated patients and standard of care (SOC) external controls and was measured from eteplirsen initiation in 201/202 or, in the SOC group, from the first study visit. Comparisons were conducted using univariate Kaplan-Meier analyses and log-rank tests, and multivariate Cox proportional hazards models with regression adjustment for baseline characteristics. Annual change in FVC%p was compared between eteplirsen-treated patients and natural history study patients using linear mixed models with repeated measures.

Results:

Data were included from all 12 patients in Studies 201/202 and the 10 patients with available data from 405. Median age at LOA was 15.16 years. Eteplirsen-treated patients experienced a statistically significant longer median time to LOA by 2.09 years (5.09 vs. 3.00 years, p < 0.01) and significantly attenuated rates of pulmonary decline vs. natural history patients (FVC%p change: –3.3 vs. –6.0 percentage points annually, p < 0.0001).

Conclusions:

Study 405 highlights the functional benefits of eteplirsen on ambulatory and pulmonary function outcomes up to 7 years of follow-up in comparison to external controls.

Human dystrophin expressing chimeric (DEC) cell therapy ameliorates cardiac, respiratory, and skeletal muscle's function in Duchenne muscular dystrophy

Duchenne muscular dystrophy (DMD) is a progressive and lethal disease, caused by X‐linked mutations of the dystrophin encoding gene. The lack of dystrophin leads to muscle weakness, degeneration, fibrosis, and progressive loss of skeletal, cardiac, and respiratory muscle function resulting in premature death due to the cardiac and respiratory failure. There is no cure for DMD and current therapies neither cure nor arrest disease progression. Thus, there is an urgent need to develop new approaches and safer therapies for DMD patients. We have previously reported functional improvements which correlated with increased dystrophin expression following transplantation of dystrophin expressing chimeric (DEC) cells of myoblast origin to the mdx mouse models of DMD. In this study, we demonstrated that systemic‐intraosseous transplantation of DEC human cells derived from myoblasts of normal and DMD‐affected donors, increased dystrophin expression in cardiac, respiratory, and skeletal muscles of the mdx/scid mouse model of DMD. DEC transplant correlated with preservation of ejection fraction and fractional shortening on echocardiography, improved respiratory function on plethysmography, and improved strength and function of the limb skeletal muscles. Enhanced function was associated with improved muscle histopathology, revealing reduced mdx pathology, fibrosis, decreased inflammation, and preserved muscle morphology and architecture. Our findings confirm that DECs generate a systemic protective effect in DMD‐affected target organs. Therefore, DECs represents a novel therapeutic approach with the potential to preserve or enhance multiorgan function of the skeletal, cardiac, and respiratory muscles critical for the well‐being of DMD patients.

Steroid switching in dystrophinopathy treatment: a US chart review of patient characteristics and clinical outcomes

Aim: To describe reasons for switching from prednisone/prednisolone to deflazacort and associated clinical outcomes among patients with Duchenne and Becker muscular dystrophy (DMD and BMD, respectively) in the USA. Methods: A chart review of patients with DMD (n = 62) or BMD (n = 30) who switched from prednisone to deflazacort (02/2017-12/2018) collected demographic/clinical characteristics, reasons for switching, outcomes and common adverse events. Results: The mean ages at switch were 20.1 (DMD) and 9.2 (BMD) years. The primary physician-reported reasons for switching were 'to slow disease progression' (DMD: 83%, BMD: 79%) and 'tolerability' (67 and 47%). Switching was 'very' or 'somewhat' effective at addressing the primary reasons in 90-95% of patients. Conclusion: Physician-reported outcomes were consistent with deflazacort addressing patients' primary reasons for switching.

Therapeutic Approaches for Duchenne Muscular Dystrophy: Old and New

Duchenne muscular dystrophy (DMD) is marked by pathogenic variants in the DMD gene, leading to reduced or absent dystrophin translation, muscle fiber destruction, loss of ambulation, cardiomyopathy, respiratory failure, and eventually death. Disease progression is slowed with use of prednisone or other corticosteroid agents. Gene replacement therapy, which is one of the focus points of this review, has emerged as the most promising potential treatment for DMD, though alternative RNA-based strategies have been employed for patients with specific pathogenic variants. While challenges remain, many of these novel therapeutic approaches hold promise for treating this devastating disease.

In vitro cytochrome P450- and transporter-mediated drug interaction potential of 6β-hydroxy-21-desacetyl deflazacort-A major human metabolite of deflazacort

6β-Hydroxy-21-desacetyl deflazacort (6β-OH-21-desDFZ) is a major circulating but not biologically active metabolite of deflazacort (DFZ). In vitro studies were performed to evaluate cytochrome P450 (CYP)- and transporter-mediated drug interaction potentials of 6β-OH-21-desDFZ. Up to 50 µM, the highest soluble concentration in the test system, 6β-OH-21-desDFZ weakly inhibited (IC₅₀  > 50 µM) the enzyme activity of CYPs 1A2, 2B6, 2C8, 2C9, and 2D6, while moderately inhibiting CYP2C19 and CYP3A4 with IC₅₀ values of approximately 50 and 35 μM, respectively. The inhibition was neither time-dependent nor metabolism-based. Incubation of up to 50 µM 6β-OH-21-desDFZ with plated cryopreserved human hepatocytes for 48 h resulted in no meaningful concentration-dependent induction of either mRNA levels or enzyme activity of CYP1A2, CYP2B6, or CYP3A4. In transporter inhibition assays, 6β-OH-21-desDFZ, up to 50 µM, did not show interaction with human OAT1, OAT3, and OCT2 transporters. It weakly inhibited (IC₅₀  > 50 µM) human MATE1, MATE2-K, and OCT1 transporter activity, and moderately inhibited human MDR1, OATP1B1, and OATP1B3 transporter activity with IC₅₀ values of 19.81 μM, 37.62 μM, and 42.22 μM, respectively. ¹⁴ C-6β-OH-21-desDFZ was biosynthesized using bacterial biotransformation and the subsequent study showed that 6β-OH-21-desDFZ was not a substrate for human BCRP, MDR1, MATE1, MATE2-K, OAT1, OATP1B1, OATP1B3, and OCT2 transporters, but appeared to be an in vitro substrate for the human OAT3 uptake transporter. At plasma concentrations of 6β-OH-21-desDFZ seen in the clinic, CYP- and transporter-mediated drug-drug interactions are not expected following administration of a therapeutic dose of DFZ in Duchenne muscular dystrophy (DMD) patients.

Duchenne muscular dystrophy

Duchenne muscular dystrophy is a severe, progressive, muscle-wasting disease that leads to difficulties with movement and, eventually, to the need for assisted ventilation and premature death. The disease is caused by mutations in DMD (encoding dystrophin) that abolish the production of dystrophin in muscle. Muscles without dystrophin are more sensitive to damage, resulting in progressive loss of muscle tissue and function, in addition to cardiomyopathy. Recent studies have greatly deepened our understanding of the primary and secondary pathogenetic mechanisms. Guidelines for the multidisciplinary care for Duchenne muscular dystrophy that address obtaining a genetic diagnosis and managing the various aspects of the disease have been established. In addition, a number of therapies that aim to restore the missing dystrophin protein or address secondary pathology have received regulatory approval and many others are in clinical development.

Mechanisms and Clinical Applications of Glucocorticoid Steroids in Muscular Dystrophy

Glucocorticoid steroids are widely used as immunomodulatory agents in acute and chronic conditions. Glucocorticoid steroids such as prednisone and deflazacort are recommended for treating Duchenne Muscular Dystrophy where their use prolongs ambulation and life expectancy. Despite this benefit, glucocorticoid use in Duchenne Muscular Dystrophy is also associated with significant adverse consequences including adrenal suppression, growth impairment, poor bone health and metabolic syndrome. For other forms of muscular dystrophy like the limb girdle dystrophies, glucocorticoids are not typically used. Here we review the experimental evidence supporting multiple mechanisms of glucocorticoid action in dystrophic muscle including their role in dampening inflammation and myofiber injury. We also discuss alternative dosing strategies as well as novel steroid agents that are in development and testing, with the goal to reduce adverse consequences of prolonged glucocorticoid exposure while maximizing beneficial outcomes.

Comparison of Serum Pharmacodynamic Biomarkers in Prednisone-Versus Deflazacort-Treated Duchenne Muscular Dystrophy Boys

Prednisone (Pred) and Deflazacort (Dfz) are commonly used glucocorticoids (GCs) for Duchenne muscular dystrophy (DMD) treatment and management. While GCs are known to delay the loss of ambulation and motor abilities, chronic use can result in onerous side effects, e.g., weight gain, growth stunting, loss of bone density, etc. Here, we use the CINRG Duchenne natural history study to gain insight into comparative safety of Pred versus Dfz treatment through GC-responsive pharmacodynamic (PD) biomarkers. Longitudinal trajectories of SOMAscan® protein data obtained on serum of DMD boys aged 4 to 10 (Pred: n = 7; Dfz: n = 8) were analyzed after accounting for age and time on treatment. Out of the pre-specified biomarkers, seventeen candidate proteins were differentially altered between the two drugs (p < 0.05). These include IGFBP-2 and AGER associated with diabetes complications, and MMP-3 associated with extracellular remodeling. As a follow-up, IGFBP-2, MMP-3, and IGF-I were quantified with an ELISA using a larger sample size of DMD biosamples (Dfz: n = 17, Pred: n = 12; up to 76 sera samples) over a longer treatment duration. MMP-3 and IGFBP-2 validated the SOMAscan® signal, however, IGF-I did not. This study identified GC-responsive biomarkers, some associated with safety, that highlight differential PD response between Dfz and Pred.

Gene doping and genomic science in sports: where are we?

The misuse of sport-related gene transfer methods in elite athletes is a real and growing concern. The success of gene therapy in the treatment of hereditary diseases has been most evident since targets in gene therapy products can be used in healthy individuals to improve sports performance. Performing these practices threatens the sporting character of competitions and may pose potential health hazards. Since the World Anti-Doping Agency pronouncement on the prohibition of such practices in 2003, several researchers have been trying to address the challenge of developing an effective method for the detection of genetic doping. This review presents an overview of the published methods developed for this purpose, the advantages and limitations of technologies and the putative target genes. At last, we present the perspective related to the application of the detection methods in the doping control field.

Deflazacort vs prednisone treatment for Duchenne muscular dystrophy: A meta-analysis of disease progression rates in recent multicenter clinical trials

INTRODUCTION

In this study we characterized disease progression over 48 weeks among boys receiving deflazacort vs prednisone/prednisolone placebo arm treatment in two recent Duchenne muscular dystrophy (DMD) clinical trials.

METHODS

Ambulatory boys with DMD receiving placebo in the phase 3 ataluren (N = 115) and tadalafil (N = 116) trials were included. The trials required at least 6 months of prior corticosteroid use and stable baseline dosing. Associations between corticosteroid use and 48-week changes in ambulatory function were estimated using mixed models. Adjusted differences between corticosteroid groups were pooled in a meta-analysis.

RESULTS

In the meta-analysis, deflazacort-treated patients vs prednisone/prednisolone-treated patients experienced, on average, lower declines of 28.3 meters on 6-minute walk distance (95% confidence interval [CI], 5.7, 50.9; 2.9 seconds on rise from supine [95% CI, 0.9, 4.9 seconds]; 2.3 seconds on 4-stair climb [95% CI, 0.5, 4.1 seconds]; and 2.9 [95% CI, 0.1, 5.8] points on the North Star Ambulatory Assessment linearized score).

DISCUSSION

Deflazacort-treated patients experienced significantly lower functional decline over 48 weeks.