Efficacy and safety of deflazacort vs prednisone and placebo for Duchenne muscular dystrophy

Response Surface Optimization of Ultra-Elastic Nanovesicles Loaded with Deflazacort Tailored for Transdermal Delivery: Accentuated Bioavailability and Anti-Inflammatory Efficacy

PURPOSE

The aim of the present study was to develop deflazacort (DFZ) ultra-elastic nanovesicles (UENVs) loaded gel for topical administration to evade gastrointestinal adverse impacts accompanying DFZ oral therapy.

METHODS

UENVs were elaborated according to D-optimal mixture design employing different edge activators as Span-60, Tween-85 and sodium cholate which were incorporated into the nanovesicles to improve the deformability of vesicles bilayer. DFZ-UENVs were formulated by thin-film hydration technique followed by characterization for different parameters including entrapment efficiency (%EE), particle size, in vitro release and ex vivo permeation studies. The composition of the optimized DFZ-UENV formulation was found to be DFZ (10 mg), Span-60 (30 mg), Tween-85 (30 mg), sodium cholate (3.93 mg), L-α phosphatidylcholine (60 mg) and cholesterol (30 mg). The optimum formulation was incorporated into hydrogel base then characterized in terms of physical parameters, in vitro drug release, ex vivo permeation study and pharmacodynamics evaluation. Finally, pharmacokinetic study in rabbits was performed via transdermal application of UENVs gel in comparison to oral drug.

RESULTS

The optimum UENVs formulation exhibited %EE of 74.77±1.33, vesicle diameter of 219.64±2.52 nm, 68.88±1.64% of DFZ released after 12 h and zeta potential of -55.57±1.04 mV. The current work divulged successful augmentation of the bioavailability of DFZ optimum formulation by about 1.37-fold and drug release retardation compared to oral drug tablets besides significant depression of edema, cellular inflammation and capillary congestion in carrageenan-induced rat paw edema model.

CONCLUSION

The transdermal DFZ-UENVs can achieve boosted bioavailability and may be suggested as an auspicious non-invasive alternative platform for oral route.

The Effectiveness and Value of Deflazacort and Exon-Skipping Therapies for the Management of Duchenne Muscular Dystrophy

DISCLOSURES

Funding for this summary was contributed by Arnold Ventures, Commonwealth Fund, California Health Care Foundation, National Institute for Health Care Management (NIHCM), New England States Consortium Systems Organization, Blue Cross Blue Shield of Massachusetts, Harvard Pilgrim Health Care, Kaiser Foundation Health Plan, and Partners HealthCare to the Institute for Clinical and Economic Review (ICER), an independent organization that evaluates the evidence on the value of health care interventions. ICER's annual policy summit is supported by dues from Aetna, America's Health Insurance Plans, Anthem, Allergan, Alnylam, AstraZeneca, Biogen, Blue Shield of CA, Cambia Health Services, CVS, Editas, Express Scripts, Genentech/Roche, GlaxoSmithKline, Harvard Pilgrim, Health Care Service Corporation, Health Partners, Johnson & Johnson (Janssen), Kaiser Permanente, LEO Pharma, Mallinckrodt, Merck, Novartis, National Pharmaceutical Council, Premera, Prime Therapeutics, Regeneron, Sanofi, Spark Therapeutics, and United Healthcare. Agboola, Fluetsch, Rind, and Pearson are employed by ICER. Lin reports support from ICER during work on this economic model and grants from Mount Zion Health Fund, National Institutes of Health (National Cancer Institute and National Heart, Lung, and Blood Institute), and the Tobacco-Related Diseases Research Program, unrelated to this work. Walton reports support from ICER for work on this economic model and unrelated consulting fees from Baxter.

Effects of Bisphosphonate Therapy on Bone Mineral Density in Boys with Duchenne Muscular Dystrophy

The objective of this study was to estimate the comparative effectiveness of bisphosphonate therapy on bone mineral density (BMD) in patients with corticosteroid-treated Duchenne muscular dystrophy (DMD). A retrospective, comparative effectiveness study evaluating changes in BMD and fragility fractures in patients with DMD presenting to British Columbia Children's Hospital from 1989 to 2017 was conducted. Marginal structural generalized estimating equation models weighted by stabilized inverse-probability of treatment weights were used to estimate the comparative effectiveness of therapy on BMD. Of those treated with bisphosphonates (N = 38), 7 (18.4%), 17 (44.7%), and 14 (36.8%) cases were treated with pamidronate, zoledronic acid, or a combination of both, respectively, while 36 cases of DMD were untreated. Mean age of bisphosphonate initiation was 9.2 (SD 2.7) years. Mean fragility fractures declined from 3.5 to 1.0 following bisphosphonate therapy. Compared to the treated group, the untreated group had an additional 0.63-SD decrease (95% confidence interval [CI]: -1.18, -0.08, P = .026) in total BMD and an additional 1.04-SD decrease (95% CI: -1.74, -0.34; P = .004) in the left hip BMD, but the change in lumbar spine BMD (0.15, 95% CI: -0.36, 0.66; P = .57) was not significant. Bisphosphonate therapy may slow the decline in BMD in boys with corticosteroid-treated DMD compared to untreated counterparts. Total number of fragility fractures decreased following bisphosphonate therapy.

Metabolite V, an epoxide species is a minor circulating metabolite in humans following a single oral dose of deflazacort

Deflazacort (Emflaza) was approved in the United States in 2017 for the treatment of the Duchenne muscular dystrophy in patients aged 2 years and older. Several deflazacort metabolites were isolated and identified from rats, dogs, monkeys, and humans. Among them, 1ß,2ß-epoxy-3ß-hydroxy-21-desacetyl deflazacort, referred to as Metabolite V, was reported to be one of the major circulating metabolites in humans. However, its quantitative distribution in plasma was not fully characterized. The objective of this study was to determine deflazacort plasma pharmacokinetics, metabolite profiles and their quantitative exposures in humans following a single oral dose. Six healthy male subjects were each administered a single oral dose of 60 mg [14 C]-deflazacort. Plasma and urine were collected and deflazacort metabolites in plasma were quantified by high performance liquid chromatography radio-profiling followed by liquid chromatography-mass spectrometry characterization. Metabolite V was isolated from urine and its structure was further confirmed by nuclear magnetic resonance analysis. These analyses demonstrated that deflazacort was not detectable in plasma; of the eight circulating deflazacort metabolites identified or characterized, the pharmacologically active metabolite 21-desacetyl deflazacort and inactive metabolite 6ß-hydroxy-21-desacetyl deflazacort accounted for 25.0% and 32.9% of the 0-24 hours plasma total radioactivity, respectively, while Metabolite V, an epoxide species, was a minor circulating metabolite, representing only about 4.7% of the total plasma radioactivity.

The Effect of Deflazacort Treatment on the Functioning of Skeletal Muscle Mitochondria in Duchenne Muscular Dystrophy

Duchenne muscular dystrophy (DMD) is a severe hereditary disease caused by a lack of dystrophin, a protein essential for myocyte integrity. Mitochondrial dysfunction is reportedly responsible for DMD. This study examines the effect of glucocorticoid deflazacort on the functioning of the skeletal-muscle mitochondria of dystrophin-deficient mdx mice and WT animals. Deflazacort administration was found to improve mitochondrial respiration of mdx mice due to an increase in the level of ETC complexes (complexes III and IV and ATP synthase), which may contribute to the normalization of ATP levels in the skeletal muscle of mdx animals. Deflazacort treatment improved the rate of Ca2+ uniport in the skeletal muscle mitochondria of mdx mice, presumably by affecting the subunit composition of the calcium uniporter of organelles. At the same time, deflazacort was found to reduce the resistance of skeletal mitochondria to MPT pore opening, which may be associated with a change in the level of ANT2 and CypD. In this case, deflazacort also affected the mitochondria of WT mice. The paper discusses the mechanisms underlying the effect of deflazacort on the functioning of mitochondria and contributing to the improvement of the muscular function of mdx mice.

[Expert recommendation: treatment of nonambulatory patients with Duchenne muscular dystrophy]

BACKGROUND

Duchenne muscular dystrophy (DMD) is the most frequent genetic neuromuscular disease in childhood with loss of ambulation usually occurring around the age of 9-11 years.

OBJECTIVE, MATERIAL AND METHODS

Based on current guidelines and clinical trials, neuropediatric and neurological experts developed recommendations for the treatment of nonambulatory DMD patients focusing on drug treatment of adults. This advisory board was sponsored by PTC Therapeutics, the distributers of the substance ataluren.

RESULTS AND CONCLUSION

Loss of ambulation is heterogeneously defined across clinical trials. Among others, the need of a wheelchair, ambulation without mobility aids or maximum walking distance can be suitable parameters for assessment. Treatment of DMD patients at any stage of the disease is based on supportive and symptomatic measures, which should be continued after loss of ambulation. In addition, disease-modifying drugs are available for the treatment of DMD and glucocorticoids are the usual standard of care treatment even beyond the loss of ambulation. Ataluren, a potentially dystrophin restorative, disease-modifying treatment, has been approved for patients with DMD due to a nonsense mutation (nmDMD), which applies to approximately 13% of DMD patients and is usually combined with steroids. Clinical data from the STRIDE registry demonstrated a delayed disease progression even after loss of ambulation. Currently, no reliable data are available for exon skipping approaches in adult DMD patients. The antioxidant idebenone could be an option in nonambulant adolescent patients not treated with glucocorticoids and without other therapeutic options. A combination treatment of idebenone and glucocorticoids is currently being investigated in a clinical trial. Add-on treatment with idebenone in addition to ataluren may be considered for nonambulant nmDMD patients. Some of the discussed treatment options are still in clinical trials or there are not enough data for older DMD patients; therefore, these expert recommendations correspond to evidence class IV.

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.

Population-Wide Duchenne Muscular Dystrophy Carrier Detection by CK and Molecular Testing

Carrier screening of Duchenne muscular dystrophy (DMD) has not been widely evaluated. To identify definite DMD female carriers prior to or in early pregnancy, we studied a large population of reproductive age females and provided informed reproductive options to DMD carriers. 37268 females were recruited from the Hangzhou Family Planning Publicity and Technology Guidance Station/Hangzhou Health Service Center for Children and Women, Hangzhou, China, between October 10, 2017, and December 16, 2018. CK activity was measured with follow-up serum DMD genetic testing in subjects with hyperCKemia, defined as CK > 200 U/L. The calculated upper reference limit (97.5^th percentile) of serum creatine kinase (CK) for females aged 20-50 years in this study was near the reference limit recommended by the manufacturer (200 U/L), above which was defined as hyperCKemia. 427 females (1.2%) harbored initially elevated CK, among which 281 females (response rate of 65.8%) accepted CK retesting. DMD genetic testing was conducted on 62 subjects with sustained serum CK > 200 U/L and 16 females with a family history of DMD. Finally, 6 subjects were confirmed to be DMD definite carriers. The estimated DMD female carrier rate in this study was 1 : 4088 (adjusting for response rate), an underestimated rate, since only 50% to 70% of DMD female carriers manifest elevated serum CK, and carriers in this study may have been missed due to lack of follow-up or inability to detect all DMD pathogenic variants by current genetic testing.

Duchenne's Muscular Dystrophy: The Role of Induced Pluripotent Stem Cells and Genomic Editing on Muscle Regeneration

There are two types of well-known muscular dystrophies: Duchenne's muscular dystrophy (DMD) and Becker's muscular dystrophy. This article focuses on the X-linked recessive disorder of Duchenne's muscular dystrophy, which primarily affects children at age four, with a shortened life span of up to 40 years. A defective dystrophin protein lacking the gene dystrophin is the primary cause of the disease pathophysiology. This defect causes cardiac and skeletal muscle down-regulation of dystrophin, leading to weak and fibrotic muscles. The disease is currently untreatable, so most kids die due to cardiac failure in their late 30's.

This review presents current treatment options, based on previous studies conducted over the last five years. We used the PubMed database to analyze and review the most important investigations. We also included an analysis of induced pluripotent stem cell therapy vs. genetic therapy using the mdx mouse model. We have discovered promising results on mdx mouse models to date and excited about the potential for where further clinical human trials can go.

MiRNAs, Myostatin, and Muscle MRI Imaging as Biomarkers of Clinical Features in Becker Muscular Dystrophy

Becker muscular dystrophy (BMD) is an X-linked recessive disorder caused by dystrophin gene mutations. The phenotype and evolution of this muscle disorder are extremely clinical variable. In the last years, circulating biomarkers have acquired remarkable importance in their use as noninvasive biological indicators of prognosis and in monitoring muscle disease progression, especially when associated to muscle MRI imaging. We investigated the levels of circulating microRNAs (myo-miRNAs and inflammatory miRNAs) and of the proteins follistatin (FSTN) and myostatin (GDF-8) and compared results with clinical and radiological imaging data. In eight BMD patients, including two cases with evolving lower extremity weakness treated with deflazacort, we evaluated the expression level of 4 myo-miRNAs (miR-1, miR-206, miR-133a, and miR-133b), 3 inflammatory miRNAs (miR-146b, miR-155, and miR-221), FSTN, and GDF-8 proteins. In the two treated cases, there was pronounced posterior thigh and leg fibrofatty replacement assessed by muscle MRI by Mercuri score. The muscle-specific miR-206 was increased in all patients, and inflammatory miR-221 and miR-146b were variably elevated. A significant difference in myostatin expression was observed between steroid-treated and untreated patients. This study suggests that microRNAs and myostatin protein levels could be used to better understand the progression and management of the disease.

Mineralocorticoid receptor antagonism by finerenone is sufficient to improve function in preclinical muscular dystrophy

Aims

Duchenne muscular dystrophy (DMD) is an X‐linked inherited disease due to dystrophin deficiency causing skeletal and cardiac muscle dysfunction. Affected patients lose ambulation by age 12 and usually die in the second to third decades of life from cardiac and respiratory failure. Symptomatic treatment includes the use of anti‐inflammatory corticosteroids, which are associated with side effects including weight gain, osteoporosis, and increased risk of cardiovascular disease. Novel treatment options include blockade of the renin–angiotensin–aldosterone system, because angiotensin as well as aldosterone contribute to persistent inflammation and fibrosis, and aldosterone blockade represents an efficacious anti‐fibrotic approach in cardiac failure. Recent preclinical findings enabled successful clinical testing of a combination of steroidal mineralocorticoid receptor antagonists (MRAs) and angiotensin converting enzyme inhibitors in DMD boys. The efficacy of MRAs alone on dystrophic skeletal muscle and heart has not been investigated. Here, we tested efficacy of the novel non‐steroidal MRA finerenone as a monotherapy in a preclinical DMD model.

Methods and results

The dystrophin‐deficient, utrophin haploinsufficient mouse model of DMD was treated with finerenone and compared with untreated dystrophic and wild‐type controls. Grip strength, electrocardiography, cardiac magnetic resonance imaging, muscle force measurements, histological quantification, and gene expression studies were performed. Finerenone treatment alone resulted in significant improvements in clinically relevant functional parameters in both skeletal muscle and heart. Normalized grip strength in rested dystrophic mice treated with finerenone (40.3 ± 1.0 mN/g) was significantly higher (P = 0.0182) compared with untreated dystrophic mice (35.2 ± 1.5 mN/g). Fatigued finerenone‐treated dystrophic mice showed an even greater relative improvement (P = 0.0003) in normalized grip strength (37.5 ± 1.1 mN/g) compared with untreated mice (29.7 ± 1.1 mN/g). Finerenone treatment also led to significantly lower (P = 0.0075) susceptibility to limb muscle damage characteristic of DMD measured during a contraction‐induced injury protocol. Normalized limb muscle force after five lengthening contractions resulted in retention of 71 ± 7% of baseline force in finerenone‐treated compared with only 51 ± 4% in untreated dystrophic mice. Finerenone treatment also prevented significant reductions in myocardial strain rate (P = 0.0409), the earliest sign of DMD cardiomyopathy. Moreover, treatment with finerenone led to very specific cardiac gene expression changes in clock genes that might modify cardiac pathophysiology in this DMD model.

Conclusions

Finerenone administered as a monotherapy is disease modifying for both skeletal muscle and heart in a preclinical DMD model. These findings support further evaluation of finerenone in DMD clinical trials.

Efficacy and safety of vamorolone in Duchenne muscular dystrophy: An 18-month interim analysis of a non-randomized open-label extension study

BACKGROUND

Treatment with corticosteroids is recommended for Duchenne muscular dystrophy (DMD) patients to slow the progression of weakness. However, chronic corticosteroid treatment causes significant morbidities. Vamorolone is a first-in-class anti-inflammatory investigational drug that has shown evidence of efficacy in DMD after 24 weeks of treatment at 2.0 or 6.0 mg/kg/day. Here, open-label efficacy and safety experience of vamorolone was evaluated over a period of 18 months in trial participants with DMD.

METHODS AND FINDINGS

A multicenter, open-label, 24-week trial (VBP15-003) with a 24-month long-term extension (VBP15-LTE) was conducted by the Cooperative International Neuromuscular Research Group (CINRG) and evaluated drug-related effects of vamorolone on motor outcomes and corticosteroid-associated safety concerns. The study was carried out in Canada, US, UK, Australia, Sweden, and Israel, from 2016 to 2019. This report covers the initial 24-week trial and the first 12 months of the VBP15-LTE trial (total treatment period 18 months). DMD trial participants (males, 4 to <7 years at entry) treated with 2.0 or 6.0 mg/kg/day vamorolone for the full 18-month period (n = 23) showed clinical improvement of all motor outcomes from baseline to month 18 (time to stand velocity, p = 0.012 [95% CI 0.010, 0.068 event/second]; run/walk 10 meters velocity, p < 0.001 [95% CI 0.220, 0.491 meters/second]; climb 4 stairs velocity, p = 0.001 [95% CI 0.034, 0.105 event/second]; 6-minute walk test, p = 0.001 [95% CI 31.14, 93.38 meters]; North Star Ambulatory Assessment, p < 0.001 [95% CI 2.702, 6.662 points]). Outcomes in vamorolone-treated DMD patients (n = 46) were compared to group-matched participants in the CINRG Duchenne Natural History Study (corticosteroid-naïve, n = 19; corticosteroid-treated, n = 68) over a similar 18-month period. Time to stand was not significantly different between vamorolone-treated and corticosteroid-naïve participants (p = 0.088; least squares [LS] mean 0.042 [95% CI -0.007, 0.091]), but vamorolone-treated participants showed significant improvement compared to group-matched corticosteroid-naïve participants for run/walk 10 meters velocity (p = 0.003; LS mean 0.286 [95% CI 0.104, 0.469]) and climb 4 stairs velocity (p = 0.027; LS mean 0.059 [95% CI 0.007, 0.111]). The vamorolone-related improvements were similar in magnitude to corticosteroid-related improvements. Corticosteroid-treated participants showed stunting of growth, whereas vamorolone-treated trial participants did not (p < 0.001; LS mean 15.86 [95% CI 8.51, 23.22]). Physician-reported incidences of adverse events (AEs) for Cushingoid appearance, hirsutism, weight gain, and behavior change were less for vamorolone than published incidences for prednisone and deflazacort. Key limitations to the study were the open-label design, and use of external comparators.

CONCLUSIONS

We observed that vamorolone treatment was associated with improvements in some motor outcomes as compared with corticosteroid-naïve individuals over an 18-month treatment period. We found that fewer physician-reported AEs occurred with vamorolone than have been reported for treatment with prednisone and deflazacort, and that vamorolone treatment did not cause the stunting of growth seen with these corticosteroids. This Phase IIa study provides Class III evidence to support benefit of motor function in young boys with DMD treated with vamorolone 2.0 to 6.0 mg/kg/day, with a favorable safety profile. A Phase III RCT is underway to further investigate safety and efficacy.

TRIAL REGISTRATION

Clinical trials were registered at www.clinicaltrials.gov, and the links to each trial are as follows (as provided in manuscript text): VBP15-002 [NCT02760264] VBP15-003 [NCT02760277] VBP15-LTE [NCT03038399].

Magnetic Resonance Imaging Studies in Duchenne Muscular Dystrophy: Linking Findings to the Physical Therapy Clinic

Duchenne muscular dystrophy (DMD) is a muscle degenerative disorder that manifests in early childhood and results in progressive muscle weakness. Physical therapists have long been an important component of the multidisciplinary team caring for people with DMD, providing expertise in areas of disease assessment, contracture management, assistive device prescription, and exercise prescription. Over the last decade, magnetic resonance imaging of muscles in people with DMD has led to an improved understanding of the muscle pathology underlying the clinical manifestations of DMD. Findings from magnetic resonance imaging (MRI) studies in DMD, paired with the clinical expertise of physical therapists, can help guide research that leads to improved physical therapist care for this unique patient population. The 2 main goals of this perspective article are to (1) summarize muscle pathology and disease progression findings from qualitative and quantitative muscle MRI studies in DMD and (2) link MRI findings of muscle pathology to the clinical manifestations observed by physical therapists with discussion of any potential implications of MRI findings on physical therapy management.

Tumor Necrosis Factor Receptor SF10A (TNFRSF10A) SNPs Correlate With Corticosteroid Response in Duchenne Muscular Dystrophy

Background

Duchenne muscular dystrophy (DMD) is a rare and severe X-linked muscular dystrophy in which the standard of care with variable outcome, also due to different drug response, is chronic off-label treatment with corticosteroids (CS). In order to search for SNP biomarkers for corticosteroid responsiveness, we genotyped variants across 205 DMD-related genes in patients with differential response to steroid treatment.

Methods and Findings

We enrolled a total of 228 DMD patients with identified dystrophin mutations, 78 of these patients have been under corticosteroid treatment for at least 5 years. DMD patients were defined as high responders (HR) if they had maintained the ability to walk after 15 years of age and low responders (LR) for those who had lost ambulation before the age of 10 despite corticosteroid therapy. Based on interactome mapping, we prioritized 205 genes and sequenced them in 21 DMD patients (discovery cohort or DiC = 21). We identified 43 SNPs that discriminate between HR and LR. Discriminant Analysis of Principal Components (DAPC) prioritized 2 response-associated SNPs in the TNFRSF10A gene. Validation of this genotype was done in two additional larger cohorts composed of 46 DMD patients on corticosteroid therapy (validation cohorts or VaC1), and 150 non ambulant DMD patients and never treated with corticosteroids (VaC2). SNP analysis in all validation cohorts (N = 207) showed that the CT haplotype is significantly associated with HR DMDs confirming the discovery results.

Conclusion

We have shown that TNFRSF10A CT haplotype correlates with corticosteroid response in DMD patients and propose it as an exploratory CS response biomarker.

Randomized phase 2 trial and open-label extension of domagrozumab in Duchenne muscular dystrophy

We report results from a phase 2, randomized, double-blind, 2-period trial (48 weeks each) of domagrozumab and its open-label extension in patients with Duchenne muscular dystrophy (DMD). Of 120 ambulatory boys (aged 6 to <16 years) with DMD, 80 were treated with multiple ascending doses (5, 20, and 40 mg/kg) of domagrozumab and 40 treated with placebo. The primary endpoints were safety and mean change in 4-stair climb (4SC) time at week 49. Secondary endpoints included other functional tests, pharmacokinetics, and pharmacodynamics. Mean (SD) age was 8.4 (1.7) and 9.3 (2.3) years in domagrozumab- and placebo-treated patients, respectively. Difference in mean (95% CI) change from baseline in 4SC at week 49 for domagrozumab vs placebo was 0.27 (-7.4 to 7.9) seconds (p = 0.94). There were no significant between-group differences in any secondary clinical endpoints. Most patients had ≥1 adverse event in the first 48 weeks; most were mild and not treatment-related. Median serum concentrations of domagrozumab increased with administered dose within each dose level. Non-significant increases in muscle volume were observed in domagrozumab- vs placebo-treated patients. Domagrozumab was generally safe and well tolerated in patients with DMD. Efficacy measures did not support a significant treatment effect. Clinicaltrials.gov identifiers: NCT02310763 and NCT02907619.

Linkage between growth retardation and pituitary cell morphology in a dystrophin-deficient pig model of Duchenne muscular dystrophy

OBJECTIVE

Human patients with Duchenne muscular dystrophy (DMD) commonly exhibit a short stature, but the pathogenesis of this growth retardation is not completely understood. Due to the suspected involvement of the growth hormone/insulin-like growth factor 1 (GH/IGF1) system, controversial therapeutic approaches have been developed, including both GH- administration, as well as GH-inhibition. In the present study, we examined relevant histomorphological and ultrastructural features of adenohypophyseal GH-producing somatotroph cells in a porcine DMD model.

METHODS

The numbers and volumes of immunohistochemically labelled somatotroph cells were determined in consecutive semi-thin sections of plastic resin embedded adenohypophyseal tissue samples using unbiased state-of-the-art quantitative stereological analysis methods.

RESULTS

DMD pigs displayed a significant growth retardation, accounting for a 55% reduction of body weight, accompanied by a significant 50% reduction of the number of somatotroph cells, as compared to controls. However, the mean volumes of somatotroph cells and the volume of GH-granules per cell were not altered. Western blot analyses of the adenohypophyseal protein samples showed no differences in the relative adenohypophyseal GH-abundance between DMD pigs and controls.

CONCLUSION

The findings of this study do not provide evidence for involvement of somatotroph cells in the pathogenesis of growth retardation of DMD pigs. These results are in contrast with previous findings in other dystrophin-deficient animal models, such as the golden retriever model of Duchenne muscular dystrophy, where increased mean somatotroph cell volumes and elevated volumes of intracellular GH-granules were reported and associated with DMD-related growth retardation. Possible reasons for the differences of somatotroph morphology observed in different DMD models are discussed.

Modeling disease trajectory in Duchenne muscular dystrophy

OBJECTIVE

To quantify disease progression in individuals with Duchenne muscular dystrophy (DMD) using magnetic resonance biomarkers of leg muscles.

METHODS

MRI and magnetic resonance spectroscopy (MRS) biomarkers were acquired from 104 participants with DMD and 51 healthy controls using a prospective observational study design with patients with DMD followed up yearly for up to 6 years. Fat fractions (FFs) in vastus lateralis and soleus muscles were determined with ¹H MRS. MRI quantitative T₂ (qT₂) values were measured for 3 muscles of the upper leg and 5 muscles of the lower leg. Longitudinal changes in biomarkers were modeled with a cumulative distribution function using a nonlinear mixed-effects approach.

RESULTS

MRS FF and MRI qT₂ increased with DMD disease duration, with the progression time constants differing markedly between individuals and across muscles. The average age at half-maximal muscle involvement (μ) occurred 4.8 years earlier in vastus lateralis than soleus, and these measures were strongly associated with loss-of-ambulation age. Corticosteroid treatment was found to delay μ by 2.5 years on average across muscles, although there were marked differences between muscles with more slowly progressing muscles showing larger delay.

CONCLUSIONS

MRS FF and MRI qT₂ provide sensitive noninvasive measures of DMD progression. Modeling changes in these biomarkers across multiple muscles can be used to detect and monitor the therapeutic effects of corticosteroids on disease progression and to provide prognostic information on functional outcomes. This modeling approach provides a method to transform these MRI biomarkers into well-understood metrics, allowing concise summaries of DMD disease progression at individual and population levels.

CLINICALTRIALSGOV IDENTIFIER

NCT01484678.

Fractures and Linear Growth in a Nationwide Cohort of Boys With Duchenne Muscular Dystrophy With and Without Glucocorticoid Treatment: Results From the UK NorthStar Database

Importance

Based on studies with relatively small sample size, fragility fractures are commonly reported in glucocorticoid (GC)-treated boys with Duchenne muscular dystrophy (DMD).

Objective

To determine the fracture burden and growth impairment in a large contemporary cohort of boys with DMD in the United Kingdom and in relation to GC regimen.

Design, Setting, and Participants

A retrospective review of fracture morbidity and growth from 832 boys with DMD in the UK NorthStar database (2006-2015), which systematically captures information from 23 participating centers. A total of 564 boys had more than 1 visit. No numbers of boys who refused were collected, but informal data from 2 centers in London and from Scotland show that refusal is very low. Data were analyzed between October 2006 and October 2015.

Main Outcomes and Measures

Fracture incidence rate per 10 000 person-years was determined. Cox regression analysis was used to identify factors associated with first fracture.

Results

Median age at baseline was 6.9 years (interquartile range, 4.9-7.2 years). At baseline, new fractures were reported in 7 of 564 participants (1.2%). During a median follow-up of 4 years (interquartile range, 2.0-6.0 years), incident fractures were reported in 156 of 564 participants (27.7%), corresponding to an overall fracture incidence rate of 682 per 10 000 person-years (95% CI, 579-798). The highest fracture incidence rate was observed in those treated with daily deflazacort at 1367 per 10 000 person-years (95% CI, 796-2188). After adjusting for age at last visit, mean hydrocortisone equivalent dose, mobility status, and bisphosphonate use prior to first fracture, boys treated with daily deflazacort had a 16.0-fold increased risk for first fracture (95% CI, 1.4-180.8; P = .03). Using adjusted regression models, change in height standard deviation scores was -1.6 SD lower (95% CI, -3.0 to -0.1; P = .03) in those treated with daily deflazacort compared with GC-naive boys, whereas there were no statistical differences in the other GC regimen.

Conclusions and Relevance

In this large group of boys with DMD with longitudinal data, we document a high fracture burden. Boys treated with daily deflazacort had the highest fracture incidence rate and the greatest degree of linear growth failure. Clinical trials of primary bone protective therapies and strategies to improve growth in boys with DMD are urgently needed, but stratification based on GC regimen may be necessary.

A Review of Deflazacort for Patients With Duchenne Muscular Dystrophy

Objective: The objective of this article is to review the pharmacology, pharmacokinetics, efficacy, safety, dosage and administration, and formulary considerations of deflazacort. Data Sources: A search of MEDLINE and EMBASE (1946 to December 31, 2019) was conducted using the terms deflazacort and Duchenne muscular dystrophy (DMD). Results were limited to clinical trials, humans, and English. Additional sources and data were obtained from the references of included articles and prescribing information. Study Selection and Data Extraction: All articles published after July 2014 related to pharmacology, pharmacokinetics, efficacy, or safety of the therapy in human subjects were included. Data Synthesis: Deflazacort 0.9 mg/kg/d is a once-daily oral corticosteroid and is the first drug of its class to be Food and Drug Administration (FDA) approved for DMD. Studies with deflazacort show improved functional outcomes, delayed onset of cardiomyopathy, reduction in scoliosis surgery, and improved survival, but these improvements are supported by relatively weak evidence. Relevance to Patient Care and Clinical Practice: This review presents data from studies published after the most recent DMD 2016 treatment guidelines and offers prescribing considerations, including pharmacology, pharmacokinetics, adverse effects, formulary considerations, and areas of uncertainty. Conclusions: Deflazacort presents an additional, FDA-approved corticosteroid option for patients that offers improved quality of life for DMD patients. However, there is weak evidence to support these benefits; a full risk-benefit analysis considering adverse events, efficacy, cost, and previous trials of steroid therapy is necessary when selecting therapy. Further research will help clarify deflazacort's optimal dose, duration of treatment, and impact on quality of life.

Therapies that are available and under development for Duchenne muscular dystrophy: What about lung function?

BACKGROUND

Respiratory failure is the principal source of morbidity and mortality among patients with Duchenne muscular dystrophy exerting a negative influence on their total quality of life. The aim of this review is to provide systematically current literature evidence about the effects of different treatment options (available or under development) for Duchenne muscular dystrophy on the pulmonary function of these patients.

METHODS

A comprehensive search was undertaken using multiple health-related databases, while two independent reviewers assessed the eligibility of studies. A third person addressed any disagreements between reviewers. The quality of the methodology of the included studies was also assessed.

RESULTS

A total of 19 original research papers (nine evaluating the role of steroids, six idebenone, three eteplirsen, one stem-cell therapy, and one ataluren) were found to fulfill our selection criteria with the majority of them (14 of 19) being prospective studies, not always including a control group. Endpoints mainly used in these studies were values of pulmonary function tests. Current and under development treatments proved to be safe and no significant adverse events were reported. A beneficial impact on pulmonary function was described by authors in the majority of these studies. The principal effect was slowing of lung disease progress, as expressed by spirometric values. However, the risk of bias was introduced in many of the above studies, while high heterogeneity in terms of treatment protocols and outcome measures limits the comparability of the results.

CONCLUSION

Glucocorticoids remain the best-studied pharmacologic therapy for Duchenne muscular dystrophy and very likely delay the expected decline in lung function. With regard to new therapeutic agents, initial study results are encouraging. However, larger clinical trials are needed that minimize the risk of study bias, optimize the comparability of treatment groups, examine clinically meaningful pulmonary outcome measures, and include long-term follow up.

Real-world outcomes of long-term prednisone and deflazacort use in patients with Duchenne muscular dystrophy: experience at a single, large care center

Aim: To assess outcomes among patients with Duchenne muscular dystrophy receiving deflazacort or prednisone in real-world practice. Methods: Clinical data for 435 boys with Duchenne muscular dystrophy from Cincinnati Children’s Hospital Medical Center were studied retrospectively using time-to-event and regression analyses. Results: Median ages at loss of ambulation were 15.6 and 13.5 years among deflazacort- and prednisone-initiated patients, respectively. Deflazacort was also associated with a lower risk of scoliosis and better ambulatory function, greater % lean body mass, shorter stature and lower weight, after adjusting for age and steroid duration. No differences were observed in whole body bone mineral density or left ventricular ejection fraction. Conclusion: This single center study adds to the real-world evidence associating deflazacort with improved clinical outcomes.

Glucocorticoids counteract hypertrophic effects of myostatin inhibition in dystrophic muscle

Duchenne muscular dystrophy (DMD) is a devastating genetic muscle disease resulting in progressive muscle degeneration and wasting. Glucocorticoids, specifically prednisone/prednisolone and deflazacort, are commonly used by DMD patients. Emerging DMD therapeutics include those targeting the muscle-wasting factor, myostatin (Mstn). The aim of this study was to investigate how chronic glucocorticoid treatment impacts the efficacy of Mstn inhibition in the D2.mdx mouse model of DMD. We report that chronic treatment of dystrophic mice with prednisolone (Pred) causes significant muscle wasting, entailing both activation of the ubiquitin-proteasome degradation pathway and inhibition of muscle protein synthesis. Combining Pred with Mstn inhibition, using a modified Mstn propeptide (dnMstn), completely abrogates the muscle hypertrophic effects of Mstn inhibition independently of Mstn expression or SMAD3 activation. Transcriptomic analysis identified that combining Pred with dnMstn treatment affects gene expression profiles associated with inflammation, metabolism, and fibrosis. Additionally, we demonstrate that Pred-induced muscle atrophy is not prevented by Mstn ablation. Therefore, glucocorticoids interfere with potential muscle mass benefits associated with targeting Mstn, and the ramifications of glucocorticoid use should be a consideration during clinical trial design for DMD therapeutics. These results have significant implications for past and future Mstn inhibition trials in DMD.

MRI vastus lateralis fat fraction predicts loss of ambulation in Duchenne muscular dystrophy

Objective

We studied the potential of quantitative MRI (qMRI) as a surrogate endpoint in Duchenne muscular dystrophy by assessing the additive predictive value of vastus lateralis (VL) fat fraction (FF) to age on loss of ambulation (LoA).

Methods

VL FFs were determined on longitudinal Dixon MRI scans from 2 natural history studies in Leiden University Medical Center (LUMC) and Cincinnati Children's Hospital Medical Center (CCHMC). CCHMC included ambulant patients, while LUMC included a mixed ambulant and nonambulant population. We fitted longitudinal VL FF values to a sigmoidal curve using a mixed model with random slope to predict individual trajectories. The additive value of VL FF over age to predict LoA was calculated from a Cox model, yielding a hazard ratio.

Results

Eighty-nine MRIs of 19 LUMC and 15 CCHMC patients were included. At similar age, 6-minute walking test distances were smaller and VL FFs were correspondingly higher in LUMC compared to CCHMC patients. Hazard ratio of a percent-point increase in VL FF for the time to LoA was 1.15 for LUMC (95% confidence interval [CI] 1.05–1.26; p = 0.003) and 0.96 for CCHMC (95% CI 0.84–1.10; p = 0.569).

Conclusions

The hazard ratio of 1.15 corresponds to a 4.11-fold increase of the instantaneous risk of LoA in patients with a 10% higher VL FF at any age. Although results should be confirmed in a larger cohort with prospective determination of the clinical endpoint, this added predictive value of VL FF to age on LoA supports the use of qMRI FF as an endpoint or stratification tool in clinical trials.

The SINE Compound KPT-350 Blocks Dystrophic Pathologies in DMD Zebrafish and Mice

Duchenne muscular dystrophy (DMD) is an X-linked muscle wasting disease that is caused by the loss of functional dystrophin protein in cardiac and skeletal muscles. DMD patient muscles become weakened, leading to eventual myofiber breakdown and replacement with fibrotic and adipose tissues. Inflammation drives the pathogenic processes through releasing inflammatory cytokines and other factors that promote skeletal muscle degeneration and contributing to the loss of motor function. Selective inhibitors of nuclear export (SINEs) are a class of compounds that function by inhibiting the nuclear export protein exportin 1 (XPO1). The XPO1 protein is an important regulator of key inflammatory and neurological factors that drive inflammation and neurotoxicity in various neurological and neuromuscular diseases. Here, we demonstrate that SINE compound KPT-350 can ameliorate dystrophic-associated pathologies in the muscles of DMD models of zebrafish and mice. Thus, SINE compounds are a promising novel strategy for blocking dystrophic symptoms and could be used in combinatorial treatments for DMD.

Pharmacotherapy of Duchenne Muscular Dystrophy

Drug development and pharmacotherapy of rare pediatric diseases have significantly expanded over the last decade, in part due to incentives and financial support provided by governments, regulators, and nonprofit foundations. Duchenne muscular dystrophy (DMD) is among the most common rare pediatric disorders, and clinical trials of therapeutic approaches have seen dramatic expansion. Pharmacotherapeutic standard of care has been limited to off-label prescription of high-dose, daily corticosteroids (prednisone, deflazacort). Deflazacort received FDA approval for DMD in 2016, although the price increases associated with formal FDA approval and the severe side effects associated with corticosteroid use have limited patient/physician uptake and insurance coverage in the USA. In Europe, EMA has given conditional marketing authorization for prescription of Translarna (a stop codon read-through drug prescribed to ~10% of DMD patients), although there is not yet evidence of clinical efficacy. The FDA awarded conditional approval to etiplirsen, an exon-skipping oligonucleotide drug, based on accelerated pathways (increased dystrophin production in patient muscle). Evidence of clinical efficacy remains the focus of post-marketing studies. There are many innovative pharmacotherapies under clinical development for DMD (Phase I, II, and III clinical trials). All are "disease modifying" in the sense that none seek to replace the full-length, normal DMD gene or dystrophin protein, but instead either seek to introduce an abnormal "Becker-like" version of the gene or protein or target pathophysiological pathways downstream of the primary defect. It is envisioned that the most significant benefit to DMD patients will be through multidrug approaches simultaneously aiming to introduce partially functional dystrophin in patient muscle while also targeting both chronic inflammation and the fibrofatty replacement of muscle.

Pediatric neuromuscular disorders: Care considerations during the COVID-19 pandemic

COVID-19, the respiratory and frequently systemic disease caused by the novel SARS-COV-2 virus, was first recognized in December 2019 and quickly spread to become a pandemic and world-wide public health emergency over the subsequent 3-4 months. While COVID-19 has a very low morbidity rate across approximately 80% of the population, it has a high morbidity and mortality rate in the remaining 20% of the population.1 These numbers have put a significant strain on medical systems around the world. Patients with neuromuscular diseases such as those with Duchenne muscular dystrophy (DMD) and spinal muscular atrophy (SMA), tend to be more medically fragile and have higher health care needs than the general population. Respiratory insufficiency, cardiac disease, obesity, and immunocompromised status due to chronic steroid treatments in certain patient populations with neuromuscular conditions are specific risk factors for severe COVID-19 disease. In general, the pediatric population has shown to be less severely impacted with lower infection rates and lower morbidity and mortality rates than the adult population, however, as expected, children with underlying medical conditions are at higher risk of morbidity from COVID-19 than their peers.2 Many patients with neuromuscular disease also rely heavily on caregiver support through their lifetime and thus maintaining the health of their primary caregivers is also a significant consideration in the health and well-being of the patients. This paper will address routine and emergency medical care, rehabilitation services, and other considerations for the pediatric patient with a neuromuscular condition during the COVID-19 pandemic.

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.

Progress in treatment and newborn screening for Duchenne muscular dystrophy and spinal muscular atrophy

BACKGROUND

Advances in treatment for Duchenne muscular dystrophy (DMD) and spinal muscular atrophy (SMA) hold promise for children with these disorders. Accurate genetic diagnosis, early in the disease process, will allow these treatments to be most effective. Newborn screening (NBS) for SMA has been recommended in the United States, and a pilot DMD NBS program is underway in Hangzhou, China.

DATA SOURCES

A PubMed search, limited to the past 5 years, was conducted to identify: (1) therapeutic advancements for DMD/SMA approved by the United States Food and Drug Administration or the European Medicine Agency and (2) The status of NBS for DMD/SMA.

RESULTS

We review the current state of approved treatments for DMD/SMA. We present recommendations regarding the future of NBS for these diseases, with a focus on the outcomes and challenges of SMA NBS in New York, USA, and the DMD NBS pilot program in Hangzhou, China.

CONCLUSIONS

Approved treatments for DMD and SMA may change the natural history of these diseases. Long-term studies of these treatments are underway. To avoid the known diagnostic delay associated with these disorders and provide optimal effectiveness of these treatments, early identification of patients through NBS will be necessary. Establishing comprehensive follow-up plans for positively identified patients will need to be in place for NBS programs to be successful.

Human induced pluripotent stem cell models for the study and treatment of Duchenne and Becker muscular dystrophies

Duchenne and Becker muscular dystrophies are the most common muscle diseases and are both currently incurable. They are caused by mutations in the dystrophin gene, which lead to the absence or reduction/truncation of the encoded protein, with progressive muscle degeneration that clinically manifests in muscle weakness, cardiac and respiratory involvement and early death. The limits of animal models to exactly reproduce human muscle disease and to predict clinically relevant treatment effects has prompted the development of more accurate in vitro skeletal muscle models. However, the challenge of effectively obtaining mature skeletal muscle cells or satellite stem cells as primary cultures has hampered the development of in vitro models. Here, we discuss the recently developed technologies that enable the differentiation of skeletal muscle from human induced pluripotent stem cells (iPSCs) of Duchenne and Becker patients. These systems recapitulate key disease features including inflammation and scarce regenerative myogenic capacity that are partially rescued by genetic and pharmacological therapies and can provide a useful platform to study and realize future therapeutic treatments. Implementation of this model also takes advantage of the developing genome editing field, which is a promising approach not only for correcting dystrophin, but also for modulating the underlying mechanisms of skeletal muscle development, regeneration and disease. These data prove the possibility of creating an accurate Duchenne and Becker in vitro model starting from iPSCs, to be used for pathogenetic studies and for drug screening to identify strategies capable of stopping or reversing muscular dystrophinopathies and other muscle diseases.

Variability and trends in corticosteroid use by male United States participants with Duchenne muscular dystrophy in the Duchenne Registry

Background

Treatment options for Duchenne muscular dystrophy remain limited, although consensus treatment guidelines recommend corticosteroid use.

Methods

This retrospective analysis assessed corticosteroid use in ambulatory and nonambulatory US males with Duchenne, age 35 and under, or Becker muscular dystrophy, who enrolled in The Duchenne Registry from 2007 to 2016 (formerly DuchenneConnect).

Results

The mean (SD) age of corticosteroid use initiation was 5.9 (2.5) years, and deflazacort use (54%) was slightly more common than prednisone/prednisolone (46%). Among all responses from those with Duchenne, 63% were currently on corticosteroids, 12% were no longer on corticosteroids, and 25% had never been on corticosteroids. Among those who were nonambulatory, 49% were currently on corticosteroids, 28% had discontinued corticosteroids, and 23% had never used corticosteroids. Primary reasons for never initiating therapy were that corticosteroids were not prescribed or recommended and concerns about side effects. Corticosteroid use was maximal at age 8 (84% on corticosteroids) and gradually declined from age 10 to 19. The primary reasons for corticosteroid discontinuation were problems with side effects (65%) or not enough benefit (28%). Average doses of corticosteroids were below recommended doses. In the 159 responses with Becker muscular dystrophy, 20% were currently using corticosteroids.

Conclusions

Recognizing the self-selected nature of participation, it appears that a considerable proportion of US participants registered with The Duchenne Registry were either not on corticosteroids or not on recommended doses despite consensus recommendations. Side effects were a consideration in initiating and discontinuing treatment.

These data reinforce the need for additional treatment options for those affected by Duchenne.

Pulmonary function and clinical correlation in DMD

Duchenne muscular dystrophy [DMD] is the most common inherited myopathy and is caused by a defect in the dystrophin gene on the X chromosome causing production of a dysfunctional dystrophin protein. Over the last decade there have been advances in disease modifying pharmacotherapy beyond the widely used strategy of corticosteroids into products to impact both dystrophin production itself and also some of the downstream effects of absent of dysfunctional dystrophin. This manuscript will explore the respiratory progression of DMD including some proposed functional and clinical correlations and the overlap between loss of function in different muscle groups. Options for symptomatic treatment and support are presented and direction as to when the different options should be considered is provided. The manuscript will also review the currently available and late phase developmental pharmacotherapies for DMD.

Development, Implementation, and Use of a Neurology Therapeutics Committee

Innovative therapeutics are transforming care of children with previously untreatable neurological disorders. However, there are challenges in the use of new therapies: the medicine may not be effective in all patients, administration may not be tolerated, and matching therapy choice to patient is complex. Finally, costs are high, which imposes financial burdens on insurance companies, families, and the health-care system. Our objective was to address challenges for clinical implementation of the new therapeutics. We sought to develop a process that would be personalized for patient and disease, encourage appropriate use of a therapeutic agent while mitigating pressure on a clinician to prescribe the therapy in all instances, and assist third-party payers in approving therapeutic use based on safety and efficacy. We report our creation of a Neurology Therapeutics Committee for pediatric patients. We review the committee’s mechanisms, describe its use and report outcomes, and suggest the Neurology Therapeutics Committee’s broader applicability.

Vamorolone targets dual nuclear receptors to treat inflammation and dystrophic cardiomyopathy

Cardiomyopathy is a leading cause of death for Duchenne muscular dystrophy. Here, we find that the mineralocorticoid receptor (MR) and glucocorticoid receptor (GR) can share common ligands but play distinct roles in dystrophic heart and skeletal muscle pathophysiology. Comparisons of their ligand structures indicate that the Δ9,11 modification of the first-in-class drug vamorolone enables it to avoid interaction with a conserved receptor residue (N770/N564), which would otherwise activate transcription factor properties of both receptors. Reporter assays show that vamorolone and eplerenone are MR antagonists, whereas prednisolone is an MR agonist. Macrophages, cardiomyocytes, and CRISPR knockout myoblasts show vamorolone is also a dissociative GR ligand that inhibits inflammation with improved safety over prednisone and GR-specific deflazacort. In mice, hyperaldosteronism activates MR-driven hypertension and kidney phenotypes. We find that genetic dystrophin loss provides a second hit for MR-mediated cardiomyopathy in Duchenne muscular dystrophy model mice, as aldosterone worsens fibrosis, mass and dysfunction phenotypes. Vamorolone successfully prevents MR-activated phenotypes, whereas prednisolone activates negative MR and GR effects. In conclusion, vamorolone targets dual nuclear receptors to treat inflammation and cardiomyopathy with improved safety.

Chemistry and Pharmacology of Deflazacort: A Novel Bioactive Compound for the Treatment of Duchenne Muscular Dystrophy-A Mini Review

Objective:

Firstly, Deflazacort was synthesized in 1969 and has the structural similarity with cortisol. The present review is an attempt to summarize the updated information related to chemistry and pharmacology of Deflazacort.

Development:

Deflazacort a synthetic compound synthesized by derivatization in the chemical structure of prednisolone with an aim to improve its potency. Deflazacort is under global development with Marathon Pharmaceuticals, was approved by the U.S. Food and Drug Administration in year 2017 to treat patients with Duchenne muscular dystrophy (DMD).

Chemistry and Pharmacology:

DMD is one of the rare and genetic disorders with the symptoms of progressive degeneration of muscle tissue. Chemically, it is deacetylated at position 21 to produce active metabolite 21-desacetyl deflazacort (21-desDFZ), which acts through the glucocorticoid receptor. The predominant side effects are cushingoid appearance, increased appetite, upper respiratory tract infection (URTI), pollakiuria, hirsutism, and nasopharyngitis.

Conclusion:

The present article summarizes the available updated information and work done so far on Deflazacort with special emphasis on its chemistry, pharmacology with detailed mechanism of action, pharmacodynamics, pharmacokinetics, metabolism and clinical trials etc.

sPIF promotes myoblast differentiation and utrophin expression while inhibiting fibrosis in Duchenne muscular dystrophy via the H19/miR-675/let-7 and miR-21 pathways

Duchenne muscular dystrophy (DMD) is a progressive, lethal, X-linked disease of skeletal and cardiac muscles caused by mutations in the dystrophin gene. Loss of dystrophin leads to muscle fiber damage and impairment of satellite cell asymmetric division, which are essential for muscle regeneration. These processes ultimately result in muscle wasting and the replacement of the degenerating muscles by fibrogenic cells, a process that leads to the generation of fibrotic tissues. Preimplantation factor (PIF) is an evolutionary conserved 15-amino acid peptide secreted by viable mammalian embryos. Synthetic PIF (sPIF) reproduces the protective/regenerative effects of the endogenous peptide in immune disorders and transplantation models. In this study, we demonstrated that sPIF treatment promoted mouse and human myoblast differentiation and inhibited the expression of collagen 1A1, collagen 1A2, and TGF-β in DMD patient-derived myoblasts. Additionally, sPIF increased the expression of utrophin, a homolog of dystrophin protein. sPIF effects were mediated via the upregulation of lncRNA H19 and miR-675 and downregulation of let-7. sPIF also inhibited the expression of miR-21, a major fibrosis regulator. The administration of sPIF in mdx mice significantly decreased serum creatine kinase and collagen I and collagen IV expression in the diaphragm, whereas it increased utrophin expression in the diaphragm, heart and quadriceps muscles. In conclusion, sPIF promoted the differentiation of DMD myoblasts, increased utrophin expression via the H19/miRNA-675/let-7 pathway, and reduced muscle fibrosis possibly via the upregulation of miR-675 and inhibition of miR-21 expression. These findings strongly support pursuing sPIF as a potential therapeutic agent for DMD. Moreover, the completion of an sPIF phase I safety trial will further promote the use of sPIF for the treatment of muscular dystrophies.

Emerging Strategies in the Treatment of Duchenne Muscular Dystrophy

Duchenne muscular dystrophy (DMD) is a progressive X-linked degenerative muscle disease due to mutations in the DMD gene. Genetic confirmation has become standard in recent years. Improvements in the standard of care for DMD have led to improved survival. Novel treatments for DMD have focused on reducing the dystrophic mechanism of the muscle disease, modulating utrophin protein expression, and restoring dystrophin protein expression. Among the strategies to reduce the dystrophic mechanisms are 1) inhibiting inflammation, 2) promoting muscle growth and regeneration, 3) reducing fibrosis, and 4) facilitating mitochondrial function. The agents under investigation include a novel steroid, myostatin inhibitors, idebenone, an anti-CTGF antibody, a histone deacetylase inhibitor, and cardiosphere-derived cells. For utrophin modulation, AAV-mediated gene therapy with GALGT2 is currently being investigated to upregulate utrophin expression. Finally, the strategies for dystrophin protein restoration include 1) nonsense readthrough, 2) synthetic antisense oligonucleotides for exon skipping, and 3) AAV-mediated micro/minidystrophin gene delivery. With newer agents, we are witnessing the use of more advanced biotechnological methods. Although these potential breakthroughs provide significant promise, they may also raise new questions regarding treatment effect and safety.

Phase IIa trial in Duchenne muscular dystrophy shows vamorolone is a first-in-class dissociative steroidal anti-inflammatory drug

We report a first-in-patient study of vamorolone, a first-in-class dissociative steroidal anti-inflammatory drug, in Duchenne muscular dystrophy. This 2-week, open-label Phase IIa multiple ascending dose study (0.25, 0.75, 2.0, and 6.0 mg/kg/day) enrolled 48 boys with Duchenne muscular dystrophy (4 to <7 years), with outcomes including clinical safety, pharmacokinetics and pharmacodynamic biomarkers. The study design included pharmacodynamic biomarkers in three contexts of use: 1. Secondary outcomes for pharmacodynamic safety (insulin resistance, adrenal suppression, bone turnover); 2. Exploratory outcomes for drug mechanism of action; 3. Exploratory outcomes for expanded pharmacodynamic safety. Vamorolone was safe and well-tolerated through the highest dose tested (6.0 mg/kg/day) and pharmacokinetics of vamorolone were similar to prednisolone. Using pharmacodynamic biomarkers, the study demonstrated improved safety of vamorolone versus glucocorticoids as shown by reduction of insulin resistance, beneficial changes in bone turnover (loss of increased bone resorption and decreased bone formation only at the highest dose level), and a reduction in adrenal suppression. Exploratory biomarkers of pharmacodynamic efficacy showed an anti-inflammatory mechanism of action and a beneficial effect on plasma membrane stability, as demonstrated by a dose-responsive decrease in serum creatine kinase activity. With an array of pre-selected biomarkers in multiple contexts of use, we demonstrate the development of the first dissociative steroid that preserves anti-inflammatory efficacy and decreases steroid-associated safety concerns. Ongoing extension studies offer the potential to bridge exploratory efficacy biomarkers to clinical outcomes.

Deflazacort versus prednisone/prednisolone for maintaining motor function and delaying loss of ambulation: A post HOC analysis from the ACT DMD trial

Introduction: ACT DMD was a 48‐week trial of ataluren for nonsense mutation Duchenne muscular dystrophy (nmDMD). Patients received corticosteroids for ≥6 months at entry and stable regimens throughout study. This post hoc analysis compares efficacy and safety for deflazacort and prednisone/prednisolone in the placebo arm. Methods: Patients received deflazacort (n = 53) or prednisone/prednisolone (n = 61). Endpoints included change from baseline in 6‐minute walk distance (6MWD), timed function tests, estimated age at loss of ambulation (extrapolated from 6MWD). Results: Mean changes in 6MWD were ‐39.0 m (deflazacort; 95% confidence limit [CL], ‐68.85, ‐9.17) and ‐70.6 m (prednisone/prednisolone; 95% CL, ‐97.16, ‐44.02). Mean changes in 4‐stair climb were 3.79 s (deflazacort; 95% CL, 1.54, 6.03) and 6.67 s (prednisone/prednisolone; 95% CL, 4.69, 8.64). Conclusions: This analysis, limited by its post hoc nature, suggests greater preservation of 6MWD and 4‐stair climb with deflazacort vs. prednisone/prednisolone. A head‐to‐head comparison will better define these differences. Muscle Nerve58: 639–645, 2018

DMD genotype correlations from the Duchenne Registry: Endogenous exon skipping is a factor in prolonged ambulation for individuals with a defined mutation subtype

Antisense oligonucleotide (AON)-mediated exon skipping is an emerging therapeutic for individuals with Duchenne muscular dystrophy (DMD). Skipping of exons adjacent to common exon deletions in DMD using AONs can produce in-frame transcripts and functional protein. Targeted skipping of DMD exons 8, 44, 45, 50, 51, 52, 53, and 55 is predicted to benefit 47% of affected individuals. We observed a correlation between mutation subgroups and age at loss of ambulation in the Duchenne Registry, a large database of phenotypic and genetic data for DMD (N = 765). Males amenable to exon 44 (N = 74) and exon 8 skipping (N = 18) showed prolonged ambulation compared to other exon skip groups and nonsense mutations (P = 0.035 and P < 0.01, respectively). In particular, exon 45 deletions were associated with prolonged age at loss of ambulation relative to the rest of the exon 44 skip amenable cohort and other DMD mutations. Exon 3-7 deletions also showed prolonged ambulation relative to all other exon 8 skippable mutations. Cultured myotubes from DMD patients with deletions of exons 3-7 or exon 45 showed higher endogenous skipping than other mutations, providing a potential biological rationale for our observations. These results highlight the utility of aggregating phenotypic and genotypic data for rare pediatric diseases to reveal progression differences, identify potentially confounding factors, and probe molecular mechanisms that may affect disease severity.

Biological scaffold-mediated delivery of myostatin inhibitor promotes a regenerative immune response in an animal model of Duchenne muscular dystrophy

Recent studies have reported that the immune system significantly mediates skeletal muscle repair and regeneration. Additionally, biological scaffolds have been shown to play a role in polarizing the immune microenvironment toward pro-myogenic outcomes. Moreover, myostatin inhibitors are known to promote muscle regeneration and ameliorate fibrosis in animal models of Duchenne muscular dystrophy (DMD), a human disease characterized by chronic muscle degeneration. Biological scaffolds and myostatin inhibition can potentially influence immune-mediated regeneration in the dystrophic environment, but have not been evaluated together. Toward this end, here we created an injectable biological scaffold composed of hyaluronic acid and processed skeletal muscle extracellular matrix. This material formed a cytocompatible hydrogel at physiological temperatures in vitro When injected subfascially above the tibialis anterior muscles of both WT and dystrophic mdx-5^Cv mice, a murine model of DMD, the hydrogel spreads across the entire muscle before completely degrading at 3 weeks in vivo We found that the hydrogel is associated with CD206⁺ pro-regenerative macrophage polarization and elevated anti-inflammatory cytokine expression in both WT and dystrophic mice. Co-injection of both hydrogel and myostatin inhibitor significantly increased FoxP3⁺ regulatory T cell modulation and Foxp3 gene expression in the scaffold immune microenvironment. Finally, delivery of myostatin inhibitor with the hydrogel increased its bioactivity in vivo, and transplantation of immortalized human myoblasts with the hydrogel promoted their survival in vivo This study identifies a key role for biological scaffolds and myostatin inhibitors in modulating a pro-regenerative immune microenvironment in dystrophic muscle.

Development of a New Self-Reporting Instrument Measuring Benefits and Side Effects of Corticosteroids in Duchenne Muscular Dystrophy: Report from a Pilot Study

BACKGROUND

There is no cure for Duchenne Muscular Dystrophy (DMD); treatment is symptomatic and corticosteroids slow the progression. Side effects of corticosteroids - especially the physical effects - have been described, however patients' and caregivers perception on chronic corticosteroid treatment and their side effects is less well known, in particular with regards to cognition, behaviour, and emotional functioning.

OBJECTIVE

The primary aim of this pilot study was to (i) construct a self-report questionnaire to assess the perceived benefits and side effects of corticosteroids for patients with DMD and their parents. Furthermore we aimed to (ii) investigate the psychometric qualities of this questionnaire, (iii) whether there was a difference between parents' and patient's perceptions, and finally (iv) to what extent reported side effects may alter over time.

METHODS

A 23-item questionnaire (SIDECORT: side effect of corticosteroids) was constructed to assess the perception of these benefits and side effects in a systematic manner.

RESULTS

In total, 86 patients (aged 5 - 28 years) and 125 of their parents completed the questionnaire. Internal consistency was good. Using factor analyses on the side effect items as reported by parents, two underlying factors were found, with the first factor describing cognitive, behavioural and emotional functioning, and the second factor describing physical functioning. The potential benefits of corticosteroids were highly rated among both parents and patients, although parents rated the importance of the benefits higher than their sons (p = 0.002). Similarly, parents rated the severity of the side effects generally higher than their sons (p = 0.011), especially with regards to the physical side effects (p = 0.014). Based on the parent's perception, the neurodevelopmental side effects generally appeared to decline the longer corticosteroids were used.

CONCLUSIONS

To our knowledge, this is the first explicit study on perceived cognitive-, behavioural-, and emotional side effects and the allocation of benefits to corticosteroids in DMD. On the basis of our research we suggest a short form questionnaire, which proves to be reliable and valid for research- and clinical practice. This questionnaire could provide useful insights for the care of boys and men with DMD.

How to prevent the next Marathon Pharmaceuticals

In recent years, several drug companies have exploited U.S. regulatory policies to acquire exclusive rights to cheap therapies and substantially raise their prices, and Federal agencies and state governments are exploring various ways to prevent or punish such behavior in the future. Among these cases, however, Marathon Pharmaceuticals’ handling of Emflaza (deflazacort) is unique, because the drug was previously only available abroad, and was never previously sold in the U.S. before the company obtained FDA approval for it. Thus, laws and policies designed to address price hikes on already-marketed drugs are unlikely to prevent additional Marathon-like scenarios. In this article, we describe in more detail the unique features of Emflaza compared with these other recent cases of drug price increases, determine the likelihood that similar situations will arise in the future, and explore legislative and administrative options to specifically prevent such behavior.