oxadiazoles and Muscular-Dystrophy--Duchenne

Neuromuscular cardiopulmonary medicine is entering a new and exciting phase, with studies that assess the respiratory effect of emerging genetic and molecular therapies. In this year's neuromuscular Year in Review, we focus on Duchenne muscular dystrophy (DMD), reviewing studies that evaluate the respiratory effect of eteplirsen, the cardiopulmonary effects of ataluren, and a study comparing the use of spironolactone with eplerenone for the treatment of DMD-related cardiomyopathy.

Topics: Cardiomyopathies; Humans; Morpholinos; Muscular Dystrophy, Duchenne; Oxadiazoles; Spironolactone

Topics: Codon, Nonsense; Humans; Muscular Dystrophy, Duchenne; Oxadiazoles; Randomized Controlled Trials as Topic

To evaluate the effect of pharmacological treatments that increase the synthesis of dystrophin in Duchenne muscular dystrophy (DMD). Systematic searches were carried out in MEDLINE, EMBASE, and Web of Science, and in gray literature from inception to December 2019. Clinical trials addressing the effect of restorative treatments of dystrophin expression in children and adolescents with DMD on functional outcomes {(6-minute walking distance [6MWD], other timed functional tests [TFTs], The North Star Ambulatory Assessment)}, dystrophin expression, cardiorespiratory function, and biochemical tests were included. The DerSimonian-Laird method was used to calculate the pooled estimates for functional outcomes. Eleven studies were included in the systematic review and five in the meta-analysis. Eteplirsen showed a significant effect on 6MWD, Δ6MWD = 67.3 m (95% CI: 27.32, 107.28), and Δ6MWD = 151.0 m (95% CI: 36.15, 265.85) at 48 weeks and 3 years, respectively. In the systematic review, analyzing individually the clinical trials using Ataluren and Drisapersen showed a nonsignificant effect on 6MWD. However, the meta-analysis showed a significant effect on 6MWD for Ataluren and Drisapersen, Δ6MWD = 18.3 m (95% CI: 1.0, 35.5) and Δ6MWD = 21.5 m (95% CI: 4.7, 38.3), respectively. There were no significant differences according to baseline age for Drisapersen. Similarly, the meta-analysis showed effect in TFT with Ataluren. All drugs induced a partial synthesis of dystrophin, and exon skipping was obtained with Eteplirsen and Drisapersen. Eteplirsen also improved forced vital capacity (Δ%pFVC = 1.8%) and maximal inspiratory pressure (Δ%pMIP = 4.4%). Eteplirsen and Ataluren could modestly reduce disease progression. However, more trials are needed to confirm its efficacy, as well as quality of life and cost-utility studies.

Topics: Dystrophin; Humans; Morpholinos; Muscular Dystrophy, Duchenne; Oligonucleotides; Outcome Assessment, Health Care; Oxadiazoles

Ataluren has been approved for treating nonsense mutation Duchenne muscular dystrophy (nmDMD), and there are currently discussions concerning drug access and applications beyond the development programme. This study provides an overview of nmDMD and ataluren, stipulates clinical rules for treatment initiation and discontinuation and proposes a model for the implementation of orphan drugs in clinical practice in Sweden.. This was a targeted mini-review of the literature from 1995 to 2018, which included cohort studies, guidelines, randomised clinical trials, clinical commentaries and reviews. The review covered the pathophysiology, epidemiology and burden of nmDMD and the clinical programme for ataluren.. Based on the current evidence, and our experiences, we recommend that patients with nmDMD should be given ataluren as soon as possible after diagnosis and this treatment should continue until they reach a forced vital capacity of <30%, and, or, a score of at least six on the Brooke upper extremity scale. We propose an implementation model that comprises a coordinating specialist physician and a national expert committee responsible for providing clinical intelligence to ensure appropriate use.. Our clinical recommendations and proposed implementation model will inform the optimum medical management of nmDMD in Sweden and help ensure timely, equal access to ataluren and similar orphan drugs.

Topics: Clinical Trials as Topic; Codon, Nonsense; Cost-Benefit Analysis; Humans; Muscular Dystrophy, Duchenne; Orphan Drug Production; Oxadiazoles; Sweden

This is the second part of a two-part document intended to discuss recent therapeutic progresses in genetic neuromuscular disorders. The present review is for diseases of motor neuron and skeletal muscle, some of which reached recently the most innovative therapeutic approaches. Nusinersen, an SMN2 mRNA splicing modifier, was approved as first-ever therapy of spinal muscular atrophy (SMA) by FDA in 2016 and by EMA in 2017. The orally administered small-molecule risdiplam, which increases SMN protein levels similarly but also in peripheral organs, is tested in ongoing phase 2 and 3 trials. After positive results with phase 1 treatment with AAV9-SMN, the first gene therapy for SMA, a phase 3 clinical trial is ongoing. Ataluren is the first approved drug for Duchenne muscular dystrophy (DMD) patients with premature stop codon mutations and its indication has been recently extended since the age of 2 years. Exon skipping technology was and is currently tested in many phase 3 trials, and eteplirsen received a conditional approval by FDA for patients amenable to exon 51 skipping, but not by EMA. Many other compounds with different mechanisms of action are now tested in DMD by phase 2 and 3 trials, including phase 1 gene therapy. Other innovative approaches are under investigation, i.e., gene therapy in X-linked myotubular myopathy and Pompe disease, and antisense oligonucleotides in myotonic dystrophy type 1. Positive evidences are discussed about lamotrigine and ranolazine in non-dystrophic myotonias, chaperons in Pompe disease, and nucleosides in mitochondrial DNA depletion induced by thymidine kinase 2 deficiency.

Topics: Genetic Therapy; Glycogen Storage Disease Type II; Humans; Mitochondrial Diseases; Muscular Atrophy, Spinal; Muscular Diseases; Muscular Dystrophy, Duchenne; Myopathies, Structural, Congenital; Myotonic Dystrophy; Neuromuscular Agents; Oligonucleotides; Oxadiazoles; SMN Complex Proteins

Duchenne muscular dystrophy (DMD) is a severe type of X-linked recessive degenerative muscle disease caused by mutations in the dystrophin (

Topics: Animals; CRISPR-Cas Systems; Exons; Gene Editing; Humans; Morpholinos; Muscular Dystrophy, Duchenne; Oxadiazoles

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.

Topics: Disease Progression; Glucocorticoids; Humans; Morpholinos; Muscular Dystrophy, Duchenne; Oxadiazoles; Prednisone; Pregnenediones; Respiratory Function Tests; Respiratory Insufficiency

Duchenne muscular dystrophy (DMD) is the most common form of muscular dystrophy in childhood. Mutations of the DMD gene destabilize the dystrophin associated glycoprotein complex in the sarcolemma. Ongoing mechanical stress leads to unregulated influx of calcium ions into the sarcoplasm, with activation of proteases, release of proinflammatory cytokines, and mitochondrial dysfunction. Cumulative damage and reparative failure leads to progressive muscle necrosis, fibrosis, and fatty replacement. Although there is presently no cure for DMD, scientific advances have led to many potential disease-modifying treatments, including dystrophin replacement therapies, upregulation of compensatory proteins, anti-inflammatory agents, and other cellular targets. Recently approved therapies include ataluren for stop codon read-through and eteplirsen for exon 51 skipping of eligible individuals. The purpose of this chapter is to summarize the clinical features of DMD, to describe current outcome measures used in clinical studies, and to highlight new emerging therapies for affected individuals.

Topics: Codon, Terminator; Databases, Genetic; Dystrophin; Exons; Humans; Morpholinos; Muscle Cells; Muscular Dystrophy, Duchenne; Mutation; Oxadiazoles

According to previous reports, nearly one in 10 genetic diseases are caused by nonsense mutations around the world. Nonsense mutations lead to premature transcription terminations in cells, which in turn generate non-functional, truncated proteins. In recent years, read-through drugs are playing increasing prominent roles in the researches related to genetic diseases caused by nonsense mutations. However, due to the fact that the mechanisms lying behind translation termination still remain to be elucidated, the mechanistic research and clinical application of read-through drugs are facing new challenges. This review mainly discusses about the pathogenesis of genetic diseases caused by nonsense mutations, and then introduces the current clinical application of read-through drugs. Finally, we display some problems that remain to be solved and propose some possible coping strategies.

Topics: Aminoglycosides; Codon, Nonsense; Cystic Fibrosis; Genetic Diseases, Inborn; Humans; Muscular Dystrophy, Duchenne; Oxadiazoles

Duchenne muscular dystrophy (DMD) is a genetic, lethal, muscle disorder caused by the loss of the muscle protein, dystrophin, leading to progressive loss of muscle fibers and muscle weakness. Drug discovery efforts targeting DMD have used two main approaches: (1) the restoration of dystrophin expression or the expression of a compensatory protein, and (2) the mitigation of downstream pathological mechanisms, including dysregulated calcium homeostasis, oxidative stress, inflammation, fibrosis, and muscle ischemia. The aim of this review is to introduce the disease, its pathophysiology, and the available research tools to a drug discovery audience. This review will also detail the most promising therapies that are currently being tested in clinical trials or in advanced preclinical models.

Topics: Animals; Antioxidants; Benzoxazoles; Calcium; Disease Models, Animal; Drug Discovery; Dystrophin; Gene Expression; Humans; Muscular Dystrophy, Duchenne; Oxadiazoles

Duchenne muscular dystrophy (DMD), an X-linked inherited musclewasting disease primarily affecting young boys with prevalence of between1:3,500- 1:5,000, is a rare genetic disease caused by defects in the gene for dystrophin. Dystrophin protein is critical to the stability of myofibers in skeletal and cardiac muscle. There is currently no cure available to ameliorate DMD and/or its patho-physiology. A number of therapeutic strategies including molecular-based therapeutics that replace or correct the missing or nonfunctional dystrophin protein have been devised to correct the patho-physiological consequences induced by dystrophin absence. We will review the current in vivo experimentation status (including preclinical models and clinical trials) for two of these approaches, namely: 1) Adeno-associated virus (AAV) mediated (micro) dystrophin gene augmentation/ supplementation and 2) Antisense oligonucleotide (AON)-mediated exon skipping strategies.

Topics: Animals; Clinical Trials as Topic; Dependovirus; Disease Models, Animal; Dystrophin; Exons; Gene Transfer Techniques; Genetic Therapy; Genetic Vectors; Humans; Muscular Dystrophy, Duchenne; Oligonucleotides, Antisense; Oxadiazoles; RNA Editing

Nonsense mutations are implicated in 5-70 % of individual cases of most inherited diseases, including Duchenne muscular dystrophy (DMD) and cystic fibrosis. Ataluren (Translarna™) is an orally available, small molecule compound that targets nonsense mutations, and is the first drug in its class. Ataluren appears to allow cellular machinery to read through premature stop codons in mRNA, enabling the translation process to produce full-length, functional proteins. This article summarizes the milestones in the development of ataluren leading to its conditional first approval for nonsense mutation DMD.

Topics: Animals; Drug Approval; Humans; Molecular Conformation; Muscular Dystrophy, Duchenne; Mutation; Oxadiazoles; Small Molecule Libraries

In this paper I review the results of the treatments directed to modify the mRNA of dystrophin with the goal of converting the severe Duchenne type to the milder Becker muscular dystrophy. Antisense oligomers potential to modify Duchenne muscular dystrophy (DMD) gene expression and therapeutic strategies to induce ribosomal read-through of nonsense mutations (PTC124) are described. They are an important advance in the treatment of DMD, so far unspecific. Significant expression of new dystrophin is observed in biopsies of peripheral muscle, although the functional improvement is not so encouraging. New modification of chemistries are expected to improve the liberation, broad distribution in muscles, as well as their efficacy and safety enough to allow a positive chronic treatment of DMD.

Topics: Amino Acids, Diamino; Aminoglycosides; Animals; Clinical Trials, Phase I as Topic; Clinical Trials, Phase II as Topic; Codon, Nonsense; Disease Models, Animal; Dogs; Dystrophin; Exons; Gene Expression Regulation; Genetic Therapy; Humans; Mice; Mice, Inbred mdx; Morpholinos; Muscle, Skeletal; Muscular Dystrophy, Duchenne; Oligonucleotides; Oligonucleotides, Antisense; Oxadiazoles; Protein Biosynthesis; RNA Splicing; Suppression, Genetic

Our Translational Gene Therapy Center has used small molecules for exon skipping and mutation suppression and gene transfer to replace or provide surrogate genes as tools for molecular-based approaches for the treatment of muscular dystrophies. Exon skipping is targeted at the pre-mRNA level allowing one or more exons to be omitted to restore the reading frame. In Duchenne Muscular Dystrophy (DMD), clinical trials have been performed with two different oligomers, a 2'O-methyl-ribo-oligonucleoside-phosphorothioate (2'OMe) and a phosphorodiamidate morpholino (PMO). Both have demonstrated early evidence of efficacy. A second molecular approach involves suppression of stop codons to promote readthrough of the DMD gene. We have been able to establish proof of principle for mutation suppression using the aminoglycoside, gentamicin. A safer, orally administered, alternative agent referred to as Ataluren (PTC124) has been used in clinical trials and is currently under consideration for approval by the FDA. Using a gene therapy approach, we have completed two trials and have initiated a third. For DMD, we used a mini-dystrophin transferred in adeno-associated virus (AAV). In this trial an immune response was seen directed against transgene product, a quite unexpected outcome that will help guide further studies. For limb girdle muscular dystrophy 2D (alpha-sarcoglycan deficiency), the transgene was again transferred using AAV but in this study, a muscle specific creatine kinase promoter controlled gene expression that persisted for six months. A third gene therapy trial has been initiated with transfer of the follistatin gene in AAV directly to the quadriceps muscle. Two diseases with selective quadriceps muscle weakness are undergoing gene transfer including sporadic inclusion body myositis (sIBM) and Becker muscular dystrophy (BMD). Increasing the size and strength of the muscle is the goal of this study. Most importantly, no adverse events have been encountered in any of these clinical trials.

Topics: Clinical Trials as Topic; Codon, Terminator; Creatine Kinase; Dependovirus; Dystrophin; Exons; Follistatin; Genetic Therapy; Genetic Vectors; Humans; Muscular Dystrophies; Muscular Dystrophy, Duchenne; Mutation; Myositis, Inclusion Body; Oxadiazoles; Promoter Regions, Genetic; RNA Precursors; Sarcoglycans

Duchenne muscular dystrophy (DMD) is a disease linked to the X-chromosome which affects 1 in 3,600-6,000 newborn males. It is manifested by the absence of the dystrophin protein in muscle fibres, which causes progressive damage leading to death in the third decade of life. The only medication so far shown to be effective in delaying the progression of this illness are corticosteroids, which have been shown to increase muscle strength in randomised controlled studies; long-term studies have demonstrated that they prolong walking time and retard the progression of respiratory dysfunction, dilated cardiomyopathy and scoliosis. Several potential drugs are now being investigated. Genetic therapy, involving the insertion of a dystrophin gene through a vector, has proven effective in animals but not humans. Currently under clinical study is Ataluren, a molecule that binds with ribosomes and may allow the insertion of an aminoacid in the premature termination codon, and exon-skipping, which binds with RNA and excludes specific sites of RNA splicing, producing a dystrophin that is smaller but functional. There are also studies attempting to modulate other muscular proteins, such as myostatin and utrophin, to reduce symptoms. This paper does not address cardiomyopathy treatment in DMD patients.

Topics: Aminoglycosides; Genetic Therapy; Glucocorticoids; Humans; Immunosuppressive Agents; Muscular Dystrophy, Duchenne; Myostatin; Oxadiazoles; Prednisone; Pregnenediones; Utrophin

Duchenne muscular dystrophy (DMD) is a genetic disease affecting about one in every 3,500 boys. This X-linked pathology is due to the absence of dystrophin in muscle fibers. This lack of dystrophin leads to the progressive muscle degeneration that is often responsible for the death of the DMD patients during the third decade of their life. There are currently no curative treatments for this disease but different therapeutic approaches are being studied. Gene therapy consists of introducing a transgene coding for full-length or a truncated version of dystrophin complementary DNA (cDNA) in muscles, whereas pharmaceutical therapy includes the use of chemical/biochemical substances to restore dystrophin expression or alleviate the DMD phenotype. Over the past years, many potential drugs were explored. This led to several clinical trials for gentamicin and ataluren (PTC124) allowing stop codon read-through. An alternative approach is to induce the expression of an internally deleted, partially functional dystrophin protein through exon skipping. The vectors and the methods used in gene therapy have been continually improving in order to obtain greater encapsidation capacity and better transduction efficiency. The most promising experimental approaches using pharmaceutical and gene therapies are reviewed in this article.

Topics: Dystrophin; Genetic Therapy; Gentamicins; Humans; Male; Muscle Fibers, Skeletal; Muscular Dystrophy, Duchenne; Oxadiazoles

Nucleotide changes within an exon can alter the trinucleotide normally encoding a particular amino acid, such that a new ''stop'' signal is transcribed into the mRNA open reading frame. This causes the ribosome to prematurely terminate its reading of the mRNA, leading to nonsense-mediated decay of the transcript and lack of production of a normal full-length protein. Such premature termination codon mutations occur in an estimated 10% to 15% of many genetically based disorders, including Duchenne/Becker muscular dystrophy. Therapeutic strategies have been developed to induce ribosomal read-through of nonsense mutations in mRNA and allow production of a full-length functional protein. Small-molecule drugs (aminoglycosides and ataluren [PTC124]) have been developed and are in clinical testing in patients with nonsense mutations within the dystrophin gene. Use of nonsense mutation suppression in Duchenne/Becker muscular dystrophy may offer the prospect of targeting the specific mutation causing the disease and correcting the fundamental pathophysiology.

Topics: Aminoglycosides; Child; Codon, Nonsense; Genetic Predisposition to Disease; Humans; Male; Muscular Dystrophy, Duchenne; Oxadiazoles; Suppression, Genetic

Duchenne muscular dystrophy (DMD) is the most common form of inherited muscle disease and is characterized by progressive muscle wasting ultimately resulting in death of the patients in their twenties. DMD is characterized by a deficiency of the muscle dystrophin as a result of mutations in the dystrophin gene. Currently, no effective treatment for DMD is available. Two promising treatments strategies have been proposed specifically for correcting the mutations in the dystrophin gene. Induction of exon skipping using antisense oligonucleotides is expected to correct the out-of-frame mutation into in-frame mutation of the translational reading frame of dystrophin mRNA. This strategy enables the production of truncated dystrophin production in DMD patients with out-of-frame exon-deletion mutations in the dystrophin gene. Our first treatment with antisense oligonucleotides against exon 19 was successful and resulted in the production of dystrophin in the skeletal muscle of a DMD patient with exon 20 deletion. It is anticipated that exon skipping will be applied extensively for the correction of deletion mutations. Induction of the read-through effect using gentamycin or PTC124 is expected to produce dystrophin in DMD patients with nonsense mutation. The treatment with PTC124 is currently under clinical trial. In this review, these treatments strategies have been summarized.

Topics: Animals; Clinical Trials as Topic; Codon, Nonsense; Dystrophin; Exons; Frameshift Mutation; Genetic Therapy; Gentamicins; Humans; Molecular Diagnostic Techniques; Muscular Dystrophy, Duchenne; Oligonucleotides, Antisense; Oxadiazoles; Reading Frames; RNA, Messenger

Duchenne muscular dystrophy is a progressive muscle degenerative disease caused by dystrophin mutations. The purpose of this review is to highlight two emerging therapies designed to repair the primary genetic defect, called 'exon skipping' and 'nonsense codon suppression'.. A drug, PTC124, was identified that suppresses nonsense codon translation termination. PTC124 can lead to restoration of some dystrophin expression in human Duchenne muscular dystrophy muscles with mutations resulting in premature stops. Two drugs developed for exon skipping, PRO051 and AVI-4658, result in the exclusion of exon 51 from mature mRNA. They can restore the translational reading frame to dystrophin transcripts from patients with a particular subset of dystrophin gene deletions and lead to some restoration of dystrophin expression in affected boys' muscle in vivo. Both approaches have concluded phase I trials with no serious adverse events.. These novel therapies that act to correct the primary genetic defect of dystrophin deficiency are among the first generation of therapies tailored to correct specific mutations in humans. Thus, they represent paradigm forming approaches to personalized medicine with the potential to lead to life changing treatment for those affected by Duchenne muscular dystrophy.

Topics: Codon, Terminator; Dystrophin; Exons; Humans; Morpholinos; Muscular Dystrophy, Duchenne; Mutation; Oligonucleotides; Oxadiazoles

Approximately one-third of alleles causing genetic diseases carry premature termination codons (PTCs), which lead to the production of truncated proteins. The past decade has seen considerable interest in therapeutic approaches aimed at readthrough of in-frame PTCs to enable synthesis of full-length proteins. However, attempts to readthrough PTCs in many diseases resulted in variable effects. Here, we focus on the efforts of such therapeutic approaches in cystic fibrosis and Duchenne muscular dystrophy and discuss the factors contributing to successful readthrough and how the nonsense-mediated mRNA decay (NMD) pathway regulates this response. A deeper understanding of the molecular basis for variable response to readthrough of PTCs is necessary so that appropriate therapies can be developed to treat many human genetic diseases caused by PTCs.

Topics: Alleles; Codon, Nonsense; Cystic Fibrosis; Genetic Diseases, Inborn; Humans; Models, Biological; Muscular Dystrophy, Duchenne; Oxadiazoles; RNA Stability; RNA, Messenger

Topics: Codon, Nonsense; Humans; Muscular Dystrophy, Duchenne; Oxadiazoles; Walking

Ataluren is a unique small molecule developed for the treatment of diseases caused by nonsense mutations, which result in premature termination of ribosomal translation and lack of full-length protein production. This study investigated the in vivo metabolism and disposition of ataluren in mice, rats, dogs, and humans. After single oral administration of [

Topics: Administration, Oral; Adolescent; Adult; Animals; Codon, Nonsense; Dogs; Female; Healthy Volunteers; Humans; Male; Metabolic Clearance Rate; Mice; Mice, Transgenic; Middle Aged; Muscular Dystrophy, Duchenne; Oxadiazoles; Peptide Chain Termination, Translational; Rats; Tissue Distribution; Young Adult

Topics: Humans; Muscular Dystrophy, Duchenne; Oxadiazoles; Treatment Outcome

Duchenne muscular dystrophy (DMD) is a severe, progressive, and rare neuromuscular, X-linked recessive disease. Dystrophin deficiency is the underlying cause of disease; therefore, mutation-specific therapies aimed at restoring dystrophin protein production are being explored. We aimed to assess the efficacy and safety of ataluren in ambulatory boys with nonsense mutation DMD.. We did this multicentre, randomised, double-blind, placebo-controlled, phase 3 trial at 54 sites in 18 countries located in North America, Europe, the Asia-Pacific region, and Latin America. Boys aged 7-16 years with nonsense mutation DMD and a baseline 6-minute walk distance (6MWD) of 150 m or more and 80% or less of the predicted normal value for age and height were randomly assigned (1:1), via permuted block randomisation (block size of four) using an interactive voice-response or web-response system, to receive ataluren orally three times daily (40 mg/kg per day) or matching placebo. Randomisation was stratified by age (<9 years vs ≥9 years), duration of previous corticosteroid use (6 months to <12 months vs ≥12 months), and baseline 6MWD (<350 m vs ≥350 m). Patients, parents and caregivers, investigational site personnel, PTC Therapeutics employees, and all other study personnel were masked to group allocation until after database lock. The primary endpoint was change in 6MWD from baseline to week 48. We additionally did a prespecified subgroup analysis of the primary endpoint, based on baseline 6MWD, which is reflective of anticipated rates of disease progression over 1 year. The primary analysis was by intention to treat. This study is registered with ClinicalTrials.gov, number NCT01826487.. Between March 26, 2013, and Aug 26, 2014, we randomly assigned 230 patients to receive ataluren (n=115) or placebo (n=115); 228 patients comprised the intention-to-treat population. The least-squares mean change in 6MWD from baseline to week 48 was -47·7 m (SE 9·3) for ataluren-treated patients and -60·7 m (9·3) for placebo-treated patients (difference 13·0 m [SE 10·4], 95% CI -7·4 to 33·4; p=0·213). The least-squares mean change for ataluren versus placebo in the prespecified subgroups was -7·7 m (SE 24·1, 95% CI -54·9 to 39·5; p=0·749) in the group with a 6MWD of less than 300 m, 42·9 m (15·9, 11·8-74·0; p=0·007) in the group with a 6MWD of 300 m or more to less than 400 m, and -9·5 m (17·2, -43·2 to 24·2; p=0·580) in the group with a 6MWD of 400 m or more. Ataluren was generally well tolerated and most treatment-emergent adverse events were mild to moderate in severity. Eight (3%) patients (n=4 per group) reported serious adverse events; all except one event in the placebo group (abnormal hepatic function deemed possibly related to treatment) were deemed unrelated to treatment.. Change in 6MWD did not differ significantly between patients in the ataluren group and those in the placebo group, neither in the intention-to-treat population nor in the prespecified subgroups with a baseline 6MWD of less than 300 m or 400 m or more. However, we recorded a significant effect of ataluren in the prespecified subgroup of patients with a baseline 6MWD of 300 m or more to less than 400 m. Baseline 6MWD values within this range were associated with a more predictable rate of decline over 1 year; this finding has implications for the design of future DMD trials with the 6-minute walk test as the endpoint.. PTC Therapeutics.

Topics: Adolescent; Child; Codon, Nonsense; Double-Blind Method; Dystrophin; Global Health; Humans; Male; Muscular Dystrophy, Duchenne; Oxadiazoles; Treatment Outcome; Walking

Dystrophinopathy is a rare, severe muscle disorder, and nonsense mutations are found in 13% of cases. Ataluren was developed to enable ribosomal readthrough of premature stop codons in nonsense mutation (nm) genetic disorders.. Randomized, double-blind, placebo-controlled study; males ≥ 5 years with nm-dystrophinopathy received study drug orally 3 times daily, ataluren 10, 10, 20 mg/kg (N=57); ataluren 20, 20, 40 mg/kg (N=60); or placebo (N=57) for 48 weeks. The primary endpoint was change in 6-Minute Walk Distance (6MWD) at Week 48.. Ataluren was generally well tolerated. The primary endpoint favored ataluren 10, 10, 20 mg/kg versus placebo; the week 48 6MWD Δ=31.3 meters, post hoc P=0.056. Secondary endpoints (timed function tests) showed meaningful differences between ataluren 10, 10, 20 mg/kg, and placebo.. As the first investigational new drug targeting the underlying cause of nm-dystrophinopathy, ataluren offers promise as a treatment for this orphan genetic disorder with high unmet medical need.

Topics: Adolescent; Child; Child, Preschool; Codon, Nonsense; Dose-Response Relationship, Drug; Double-Blind Method; Dystrophin; Humans; International Cooperation; Male; Muscular Dystrophy, Duchenne; Outcome Assessment, Health Care; Oxadiazoles; Prospective Studies; Time Factors; Walking

An international clinical trial enrolled 174 ambulatory males ≥5 years old with nonsense mutation Duchenne muscular dystrophy (nmDMD). Pretreatment data provide insight into reliability, concurrent validity, and minimal clinically important differences (MCIDs) of the 6-minute walk test (6MWT) and other endpoints.. Screening and baseline evaluations included the 6-minute walk distance (6MWD), timed function tests (TFTs), quantitative strength by myometry, the PedsQL, heart rate-determined energy expenditure index, and other exploratory endpoints.. The 6MWT proved feasible and reliable in a multicenter context. Concurrent validity with other endpoints was excellent. The MCID for 6MWD was 28.5 and 31.7 meters based on 2 statistical distribution methods.. The ratio of MCID to baseline mean is lower for 6MWD than for other endpoints. The 6MWD is an optimal primary endpoint for Duchenne muscular dystrophy (DMD) clinical trials that are focused therapeutically on preservation of ambulation and slowing of disease progression.

Topics: Disease Progression; Exercise Test; Heart Rate; Humans; Male; Muscular Dystrophy, Duchenne; Outcome Assessment, Health Care; Oxadiazoles; Reproducibility of Results; Time Factors; Walking

Duchenne muscular dystrophy (DMD) subjects ≥5 years with nonsense mutations were followed for 48 weeks in a multicenter, randomized, double-blind, placebo-controlled trial of ataluren. Placebo arm data (N = 57) provided insight into the natural history of the 6-minute walk test (6MWT) and other endpoints.. Evaluations performed every 6 weeks included the 6-minute walk distance (6MWD), timed function tests (TFTs), and quantitative strength using hand-held myometry.. Baseline age (≥7 years), 6MWD, and selected TFT performance are strong predictors of decline in ambulation (Δ6MWD) and time to 10% worsening in 6MWD. A baseline 6MWD of <350 meters was associated with greater functional decline, and loss of ambulation was only seen in those with baseline 6MWD <325 meters. Only 1 of 42 (2.3%) subjects able to stand from supine lost ambulation.. Findings confirm the clinical meaningfulness of the 6MWD as the most accepted primary clinical endpoint in ambulatory DMD trials.

Topics: Adolescent; Child; Child, Preschool; Double-Blind Method; Electromyography; Exercise Test; Glucocorticoids; Hand Strength; Humans; Longitudinal Studies; Male; Muscular Dystrophy, Duchenne; Observation; Outcome Assessment, Health Care; Oxadiazoles; Predictive Value of Tests; Time Factors; Walking

Approximately 13% of boys with Duchenne muscular dystrophy (DMD) have a nonsense mutation in the dystrophin gene, resulting in a premature stop codon in the corresponding mRNA and failure to generate a functional protein. Ataluren (PTC124) enables ribosomal readthrough of premature stop codons, leading to production of full-length, functional proteins.. This Phase 2a open-label, sequential dose-ranging trial recruited 38 boys with nonsense mutation DMD. The first cohort (n = 6) received ataluren three times per day at morning, midday, and evening doses of 4, 4, and 8 mg/kg; the second cohort (n = 20) was dosed at 10, 10, 20 mg/kg; and the third cohort (n = 12) was dosed at 20, 20, 40 mg/kg. Treatment duration was 28 days. Change in full-length dystrophin expression, as assessed by immunostaining in pre- and post-treatment muscle biopsy specimens, was the primary endpoint.. Twenty three of 38 (61%) subjects demonstrated increases in post-treatment dystrophin expression in a quantitative analysis assessing the ratio of dystrophin/spectrin. A qualitative analysis also showed positive changes in dystrophin expression. Expression was not associated with nonsense mutation type or exon location. Ataluren trough plasma concentrations active in the mdx mouse model were consistently achieved at the mid- and high- dose levels in participants. Ataluren was generally well tolerated.. Ataluren showed activity and safety in this short-term study, supporting evaluation of ataluren 10, 10, 20 mg/kg and 20, 20, 40 mg/kg in a Phase 2b, double-blind, long-term study in nonsense mutation DMD.. ClinicalTrials.gov NCT00264888.

Topics: Child; Codon, Nonsense; Dystrophin; Humans; Male; Muscular Dystrophy, Duchenne; Oxadiazoles

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

Topics: Acetylcysteine; Adenosine Triphosphate; Cell Differentiation; Cell Survival; CRISPR-Cas Systems; Dystrophin; Gene Editing; Humans; Induced Pluripotent Stem Cells; Mitochondria; Muscular Dystrophy, Duchenne; Myocytes, Cardiac; NADPH Oxidase 4; Oxadiazoles; Oxidative Stress; Reactive Oxygen Species

Duchenne muscular dystrophy (DMD) is a severe, progressive X-linked recessive disorder, caused by the absence of the dystrophin protein. A resolutive therapy for DMD is not yet available. The first approved drug for DMD patients with nonsense mutations is ataluren, approved for the treatment of children aged ≥ 2 yrs, that seems effective in slowing the disease progression. An earlier introduction of ataluren seems to give better results. We report the case of a 14-year-old DMD patient with a nonsense mutation in exon 70, still ambulant, who started taking ataluren at 12 years and remained stable for the following two years. The patient was on steroid since the age of 6, with beneficial effects. At two-years follow-up, an optimal disease evolution was observed, associated with a constant decrease of creatine kinase blood levels. Despite the late start of the treatment, ataluren seems to have significantly contributed to the stabilization of the functional status in this patient though it cannot be excluded that the result may have been influenced by the previous favorable course of the disease. However, further studies should be planned in patients with similar age treated with ataluren to better evaluate the treatment's results compared to the natural course of the disease.

Topics: Adolescent; Child; Codon, Nonsense; Dystrophin; Exons; Humans; Male; Muscular Dystrophy, Duchenne; Oxadiazoles

Ataluren is a relatively new treatment for male patients with Duchenne muscular dystrophy (DMD) due to a premature stop codon. Long-term longitudinal data as well as efficacy data on non-ambulant patients are still lacking. Here we present the results from a long-term follow-up study of all DMD patients treated with ataluren and followed at the Queen Silvia Children's Hospital in Gothenburg, Sweden, with focus on the evolution of patients' upper motor and respiratory function over time.. This is a retrospective longitudinal case-series study of all male DMD patients treated with ataluren and followed at the Queen Silvia Children's Hospital in Gothenburg, Sweden, since 2008.. Our eleven patients had a median exposure to ataluren of 2312 days which is almost a fourfold higher than previous studies. Loss of ambulation occurred at a median age of 13.2 years. Patients who lost ambulation prior to 13.2 years of age had received ataluren for 5 years, whereas patients who continued to be ambulatory after 13.2 years of age had received ataluren for 6.5 years until loss of ambulation or last follow-up if still ambulatory. Four of six non ambulatory patients had Performance of the Upper Limb scores above the expected mean values over time. All but one patient maintained a pulmonary decline above the expected over time. All ambulatory patients increased in their predicted forced vital capacity (FVC) with 2.8 to 8.2% annually. Following loss of ambulation, 5 of 6 patients declined in predicted FVC (%), with annual rate of decline varying from 1.8 to 21.1%. The treatment was safe and well tolerated throughout the follow-up period.. This is the first study to present long-term cumulative treatment outcomes over a median period of 6.3 years on ataluren treatment. Our results indicate a delay in loss of ambulation, as well as a slower decline in FVC and upper limb motor function even after loss of ambulation. We suggest that treatment with ataluren should be initiated as soon as the diagnosis is confirmed, closely monitored and, in case of sustainable benefit, continued even after loss of ambulation.

Topics: Adolescent; Child; Child, Preschool; Follow-Up Studies; Humans; Male; Muscular Dystrophy, Duchenne; Oxadiazoles; Retrospective Studies; Sweden

Duchenne's muscular dystrophy (DMD) is an X-linked neuromuscular disorder caused by deletions (75%), duplications (15-20%) and point mutations (5-10%) in the dystrophin gene. Among the latter, stop-codon point mutations are rare. Female carriers of dystrophin gene mutations are usually asymptomatic as they are "protected" by the second X-chromosome, which produces a normal dystrophin protein. However, about 8-10% of them can present symptoms that set the clinical picture of the manifesting or symptomatic carrier. Although no causative cure there is for DMD, therapies are available to slow the decline of muscle weakness and delay the onset of heart and respiratory involvement. However, there is limited data in the literature documenting the treatment of symptomatic carriers, often entrusted to the sensitivity of individual doctors. In this paper, we report the follow-up outcomes of four European symptomatic nmDMD carriers treated with ataluren, overall followed for 193 months. Annual assessment of muscle strength, pulmonary lung function tests, and echocardiography, indicate a mild attenuation of disease progression under treatment.. There were no adverse clinical effects or relevant abnormalities in routine laboratory tests. We can conclude that ataluren appears to stabilize, if not slightly improve, the clinical course of patients with a good safety profile, especially if we consider that the treatment was late for 3/4 patients, at a mean age of 36.6 ± 10.6 years.

Topics: Adult; Dystrophin; Female; Follow-Up Studies; Humans; Middle Aged; Muscular Dystrophy, Duchenne; Mutation; Oxadiazoles

Duchenne muscular dystrophy (DMD) is an X-linked myopathy caused by mutations, in most cases deletions and duplications, in the dystrophin gene. Point mutations account for 13% and stop codon mutations are even rarer. Ataluren was approved for the treatment of DMD caused by nonsense mutations in 2014, and several clinical trials documented its efficacy and safety. However, few real-life experience data is available, especially in pediatric age. We report the case of a 2-year- ambulant child affected by DMD caused by the stop-codon mutation c.10801C > T, p.Gln3601X in exon 76, who was early treated with Ataluren at a dosage of 40 mg/kg/die, and presented a rapid improvement in both muscle strength and cognitive and social skills.

Topics: Child; Child, Preschool; Codon, Nonsense; Dystrophin; Exons; Humans; Male; Muscular Dystrophy, Duchenne; Mutation; Oxadiazoles

This study was undertaken to determine whether a low residual quantity of dystrophin protein is associated with delayed clinical milestones in patients with DMD mutations.. We performed a retrospective multicentric cohort study by using molecular and clinical data from patients with DMD mutations registered in the Universal Mutation Database-DMD France database. Patients with intronic, splice site, or nonsense DMD mutations, with available muscle biopsy Western blot data, were included irrespective of whether they presented with severe Duchenne muscular dystrophy (DMD) or milder Becker muscular dystrophy (BMD). Patients were separated into 3 groups based on dystrophin protein levels. Clinical outcomes were ages at appearance of first symptoms; loss of ambulation; fall in vital capacity and left ventricular ejection fraction; interventions such as spinal fusion, tracheostomy, and noninvasive ventilation; and death.. Of 3,880 patients with DMD mutations, 90 with mutations of interest were included. Forty-two patients expressed no dystrophin (group A), and 31 of 42 (74%) developed DMD. Thirty-four patients had dystrophin quantities < 5% (group B), and 21 of 34 (61%) developed BMD. Fourteen patients had dystrophin quantities ≥ 5% (group C), and all but 4 who lost ambulation beyond 24 years of age were ambulant. Dystrophin quantities of <5%, as low as <0.5%, were associated with milder phenotype for most of the evaluated clinical outcomes, including age at loss of ambulation (p < 0.001).. Very low residual dystrophin protein quantity can cause a shift in disease phenotype from DMD toward BMD. ANN NEUROL 2021;89:280-292.

Topics: Adolescent; Adrenal Cortex Hormones; Adult; Age of Onset; Angiotensin-Converting Enzyme Inhibitors; Blotting, Western; Child; Cohort Studies; Disease Progression; Dystrophin; Humans; Male; Mobility Limitation; Mortality; Muscle, Skeletal; Muscular Dystrophy, Duchenne; Noninvasive Ventilation; Oxadiazoles; Phenotype; Proportional Hazards Models; Retrospective Studies; Severity of Illness Index; Spinal Fusion; Stroke Volume; Tracheostomy; Vital Capacity; Young Adult

During protein synthesis, nonsense mutations, resulting in premature stop codons (PSCs), produce truncated, inactive protein products. Such defective gene products give rise to many diseases, including cystic fibrosis, Duchenne muscular dystrophy (DMD), and some cancers. Small molecule nonsense suppressors, known as TRIDs (translational read-through-inducing drugs), stimulate stop codon read-through. The best characterized TRIDs are ataluren, which has been approved by the European Medicines Agency for the treatment of DMD, and G418, a structurally dissimilar aminoglycoside. Previously [1], we applied a highly purified in vitro eukaryotic translation system to demonstrate that both aminoglycosides like G418 and more hydrophobic molecules like ataluren stimulate read-through by direct interaction with the cell's protein synthesis machinery. Our results suggested that they might do so by different mechanisms. Here, we pursue this suggestion through a more-detailed investigation of ataluren and G418 effects on read-through. We find that ataluren stimulation of read-through derives exclusively from its ability to inhibit release factor activity. In contrast, G418 increases functional near-cognate tRNA mispairing with a PSC, resulting from binding to its tight site on the ribosome, with little if any effect on release factor activity. The low toxicity of ataluren suggests that development of new TRIDs exclusively directed toward inhibiting termination should be a priority in combatting PSC diseases. Our results also provide rate measurements of some of the elementary steps during the eukaryotic translation elongation cycle, allowing us to determine how these rates are modified when cognate tRNA is replaced by near-cognate tRNA ± TRIDs.

Topics: Aminoglycosides; Animals; Artemia; Codon, Nonsense; Codon, Terminator; Cystic Fibrosis; Muscular Dystrophy, Duchenne; Oxadiazoles; Peptide Chain Elongation, Translational; Protein Biosynthesis; Protein Synthesis Inhibitors; Ribosomes; RNA, Transfer; Saccharomyces

The aim was to assess 3-year longitudinal data using 6MWT in 26 ambulant boys affected by DMD carrying nonsense mutations and to compare their results to other small mutations. We also wished to establish, within the nonsense mutations group, patterns of change according to several variables. Patients with nonsense mutations were categorized according to the stop codon type newly created by the mutation and also including the adjacent 5' (upstream) and 3' (downstream) nucleotides. No significant difference was found between nonsense mutations and other small mutations (p > 0.05) on the 6MWT. Within the nonsense mutations group, there was no difference in 6MWT when the patients were subdivided according to: Type of stop codon, frame status of exons involved, protein domain affected. In contrast, there was a difference when the stop codon together with the 3' adjacent nucleotide ("stop+4 model") was considered (p < 0.05) with patients with stop codon TGA and 3' adjacent nucleotide G (TGAG) having a more rapid decline. Our finding suggest that the stop+4 model may help in predicting functional changes. This data will be useful at the time of interpreting the long term follow up of patients treated with Ataluren that are becoming increasingly available.

Topics: Belgium; Child; Child, Preschool; Codon, Nonsense; Dystrophin; Exons; Humans; Italy; Longitudinal Studies; Male; Muscular Dystrophy, Duchenne; Mutation; Oxadiazoles; Walk Test

Little is known of the impact of ataluren on health status and utility in patients with nonsense mutation Duchenne muscular dystrophy (nmDMD). In this work we sought to investigate the clinical expert consensus of these topics in a Delphi panel study.. Six Swedish neuromuscular experts participated in this study. Consensus was investigated for responses to the Health Utilities Index (HUI) and a visual analog scale (VAS) for ambulatory and nonambulatory patients treated with ataluren plus best supportive care vs best supportive care alone.. Consensus was obtained after three panel rounds across treatments and disease stages, except for HUI question 10 (ability to use hands and fingers) for nonambulatory patients. Utility differences between treatments were 0.31 for ambulatory patients, and 0.15 to 0.18 for nonambulatory patients, respectively. The corresponding VAS differences were 12 and 13.. The outcomes of this study support the association of ataluren for the treatment of nmDMD with improved health status and utility.

Topics: Codon, Nonsense; Delphi Technique; Health Status; Humans; Muscular Dystrophy, Duchenne; Oxadiazoles; Treatment Outcome

Topics: Child; Creatine Kinase; Delayed Diagnosis; Early Diagnosis; Female; Humans; Male; Muscular Dystrophy, Duchenne; Oxadiazoles; Patient Care Team; Quality of Life; Referral and Consultation; Sex Factors

Topics: Adolescent; Aged; Animals; Child; Child, Preschool; Guinea Pigs; Humans; Infant; Male; Muscular Dystrophy, Duchenne; Oxadiazoles; Rabbits; Registries

Duchenne and Becker muscular dystrophies (DMD/BMD) are X-linked recessive neuromuscular disorders characterized by progressive irreversible muscle weakness and atrophy that affect both skeletal and cardiac muscles. DMD/BMD is caused by mutations in the Dystrophin gene on the X chromosome, leading to the absence of the essential muscle protein Dystrophin in DMD. In BMD, Dystrophin is partially functioning with a shorter protein product. Recent advances in molecular therapies for DMD require precise genetic diagnoses because most therapeutic strategies are mutation-specific. Hence, early diagnosis is crucial to allow appropriate planning for patient care and treatment. In this study, data from DMD/BMD patients who attended the Kuwait Medical Genetic Center during the last 20 years was retrieved from a Kuwait neuromuscular registry and analyzed. We combined multiplex PCR and multiplex ligation-dependent probe amplification (MLPA) with Sanger sequencing to detect Dystrophin gene mutations. A total of 35 different large rearrangements, 2 deletion-insertions (Indels) and 4 substitution mutations were identified in the 68 unrelated families. The deletion and duplication rates were 66.2% and 4.4%, respectively. The analyzed data from our registry revealed that 11 (16%) of the DMD families will benefit from newly introduced therapies (Ataluren and exon 51 skipping). At the time of submitting this paper, two cases have already enrolled in Ataluren (Tranlsarna™) therapy, and one case has been enrolled in exon 51 skipping therapy.

Topics: Adolescent; Adult; Child; DNA Mutational Analysis; Dystrophin; Exons; Family; Female; Gene Expression; Genetic Therapy; Humans; INDEL Mutation; Kuwait; Male; Multiplex Polymerase Chain Reaction; Muscular Dystrophy, Duchenne; Mutation, Missense; Oxadiazoles; Precision Medicine; Sequence Deletion

Duchenne muscular Dystrophy (DMD) is a X-linked degenerative disorder affecting skeletal muscles and myocardium caused by mutations in the dystrophin gene, mainly deletions and duplications. Point-mutations account for 13% and stop codon mutations are even more unfrequent. A drug treatment for patients with DMD caused by stop codon gene mutations and still ambulant, has become recently available, based on the clear demonstration of its efficacy in slowing the course of the disease. The drug is able to read through the stop codon; furthermore it has the advantage of an oral administration and a better patient's compliance. We report a case of a still ambulant 27 year-old DMD symptomatic carrier with a stop-codon mutation in exon 53 (c.7792C > T; p.Gln2598Stop), who started the treatment with Ataluren at a dosage of 2,250 mg/die, reporting a prompt subjective improvement in muscle strength. Unfortunately two months after, the patient discontinued taking the drug for a traumatic femur fracture requiring surgical repair and prolonged rehabilitation. With the resumption of the drug intake in February 2018, the patient reported almost immediately an improvement in motor skills, including the possibility of recovering walking, first with support and then unsupported. These results seem even more encouraging, as Duchenne patients hardly recover the ability to walk following a fracture at this age and extend the possibility to treat with ataluren also the symptomatic Duchenne carriers who have nonsense dystrophin gene mutations. Furthermore the case here reported supports the concept that symptomatic DMD female carriers must enjoy the same therapeutic opportunities offered to males.

Topics: Administration, Oral; Adult; Dystrophin; Female; Humans; Muscle, Skeletal; Muscular Dystrophy, Duchenne; Oxadiazoles; Patient Reported Outcome Measures; Point Mutation; Symptom Assessment; Walking

Topics: Child; Delivery of Health Care; Drug Industry; Humans; Ireland; Male; Muscular Dystrophy, Duchenne; Oxadiazoles; Primary Health Care; State Medicine

Topics: Clinical Trials as Topic; Drug Approval; Humans; Muscular Dystrophy, Duchenne; Oxadiazoles; United States; United States Food and Drug Administration

Topics: Adolescent; Adult; Child; Child, Preschool; Clinical Trials, Phase II as Topic; Codon, Nonsense; Drug Approval; Dystrophin; Humans; Male; Muscular Dystrophy, Duchenne; Oxadiazoles; Randomized Controlled Trials as Topic; Treatment Outcome; Young Adult

Topics: Child; Dystrophin; Exons; Humans; Male; Muscular Dystrophy, Duchenne; Oligonucleotides; Oxadiazoles; RNA Splicing; Ubiquinone

Topics: Administration, Oral; Child, Preschool; Codon, Nonsense; Humans; Muscular Dystrophy, Duchenne; Oxadiazoles; Suspensions

The social context of rare disease research is changing, with increased community engagement around drug development and clinical trials. This engagement may benefit patients and families but may also lead to heightened trial expectations and therapeutic misconception. Clinical investigators are also susceptible to harboring high expectations. Little is known about parental motivations and expectations for clinical trials for rare pediatric disorders.. We describe the experience of parents and clinical investigators involved in a phase II clinical trial for Duchenne and Becker muscular dystrophy: their expectations, hopes, motivations, and reactions to the termination of the trial.. This qualitative study was based on interviews with clinical investigators and parents of sons with Duchenne and Becker muscular dystrophy (DBMD) who participated in the phase IIa or IIb ataluren clinical trial in the United States. Interviews were transcribed and coded for thematic analysis.. Participants were 12 parents of affected boys receiving active drug and 9 clinical investigators. High trial expectations of direct benefit were reported by parents and many clinicians. Investigators described monitoring and managing parents' expectations; several worried about their own involvement in increasing parents' expectations. Most parents were able to differentiate their expectations from their optimistic hopes for a cure. Parents' expectations arose from other parents, advocacy organizations, and the sponsor. All parents reported some degree of clinical benefit to their children. Secondary benefits were hopefulness and powerful feelings associated with active efforts to affect the disease course. Parents and clinical investigators reported strong, close relationships that were mutually important. Parents and clinicians felt valued by the sponsor for the majority of the trial. When the trial abruptly stopped, they described loss of engagement, distress, and feeling unprepared for the possibility of trial termination.. This was a retrospective study of one clinical trial. We were unable to recruit participants whose children received placebo. The interviews occurred during a time of significant uncertainty and distress for many of the participants.. This pilot study reflects complex outcomes of strong community engagement. The findings highlight a need for renewed education about, and support for, clinical trial termination and loss of drug access. The primary positive outcome was demonstration of strong relationships among committed parents and study teams. These relationships were highly valued by both parties and may suggest an ideal intervention opportunity for efforts to improve psychological well-being. A negative outcome attributed, in part, to community engagement was inappropriately high trial expectations. More optimistically, high expectations were attributed, in part, to the importance of hope and powerful feelings associated with active efforts to affect the disease course.

Topics: Attitude of Health Personnel; Attitude to Health; Clinical Trials, Phase II as Topic; Early Termination of Clinical Trials; Female; Hope; Humans; Interviews as Topic; Male; Motivation; Muscular Dystrophy, Duchenne; Neuromuscular Agents; Oxadiazoles; Parents; Pilot Projects; Professional-Family Relations; Qualitative Research; Research Personnel; Retrospective Studies; Social Values

Sapje zebrafish carry a mutation in the dystrophin gene, which results in a premature stop codon, and a severe muscle phenotype. They display several of the structural characteristics of Duchenne muscular dystrophy (DMD). Ataluren (PTC124) is proposed to cause readthrough of premature stop codons and has been introduced as a potential treatment of genetic disorders. Clinical trials in DMD have shown promise, although with complex dose dependency. We have established physiology techniques, enabling high resolution of contractile function in skeletal muscle of zebrafish larvae. We aimed to provide a mechanical analysis of sapje larval muscle and examine effects of ataluren. Homozygous 5 d postfertilization (dpf) sapje larvae exhibited structural defects with 50% decrease in active tension. Ataluren (0.1-1 μM, 3-5 dpf) improved contractile function (~60% improvement of force at 0.5 μM) and dystrophin expression. Controls were not affected. Higher doses (5 μM, 35 μM) impaired contractile function, an effect also observed in controls, suggesting unspecific negative effects at high concentrations. In summary, Sapje larvae exhibit impaired contractile performance and provide a relevant DMD model for functional studies. Ataluren significantly improves skeletal muscle function in the sapje larvae, most likely reflecting an observed increase in dystrophin expression. The bell-shaped dose dependence in sapje resembles that previously reported in clinical DMD studies.

Topics: Animals; Blotting, Western; Dose-Response Relationship, Drug; Dystrophin; Humans; Larva; Muscle, Skeletal; Muscular Dystrophy, Animal; Muscular Dystrophy, Duchenne; Mutation; Oxadiazoles; Stress, Mechanical; Zebrafish; Zebrafish Proteins

Topics: Drug Approval; Europe; Humans; Male; Muscular Dystrophy, Duchenne; Oxadiazoles

Topics: Drug Industry; Humans; Muscular Dystrophy, Duchenne; Oxadiazoles

Molecules that induce ribosomal read-through of nonsense mutations in mRNA and allow production of a full-length functional protein hold great therapeutic potential for the treatment of many genetic disorders. Two such read-through compounds, RTC13 and RTC14, were recently identified by a luciferase-independent high-throughput screening assay and were shown to have potential therapeutic functions in the treatment of nonsense mutations in the ATM and the dystrophin genes. We have now tested the ability of RTC13 and RTC14 to restore dystrophin expression into skeletal muscles of the mdx mouse model for Duchenne muscular dystrophy (DMD). Direct intramuscular injection of compound RTC14 did not result in significant read-through activity in vivo and demonstrated the levels of dystrophin protein similar to those detected using gentamicin. In contrast, significant higher amounts of dystrophin were detected after intramuscular injection of RTC13. When administered systemically, RTC13 was shown to partially restore dystrophin protein in different muscle groups, including diaphragm and heart, and improved muscle function. An increase in muscle strength was detected in all treated animals and was accompanied by a significant decrease in creatine kinase levels. These studies establish the therapeutic potential of RTC13 in vivo and advance this newly identified compound into preclinical application for DMD.

Topics: Animals; Codon, Nonsense; Disease Models, Animal; Dose-Response Relationship, Drug; Drug Evaluation, Preclinical; Dystrophin; Furans; Gentamicins; Injections, Intramuscular; Injections, Intraperitoneal; Male; Mice; Mice, Inbred C57BL; Mice, Inbred mdx; Muscle Fibers, Skeletal; Muscle Strength; Muscle, Skeletal; Muscular Dystrophy, Duchenne; Oxadiazoles; Phenols; Protein Synthesis Inhibitors; Reading Frames; Schiff Bases; Thiazolidines; Transcription, Genetic

Topics: Clinical Trials as Topic; Cystic Fibrosis; Humans; Muscular Dystrophy, Duchenne; Oxadiazoles; RNA Processing, Post-Transcriptional

Topics: Clinical Trials as Topic; Codon, Nonsense; Cystic Fibrosis; Drug Design; Drug Industry; Humans; Muscular Dystrophy, Duchenne; Oxadiazoles; Therapies, Investigational

Topics: Animals; Codon, Nonsense; Dystrophin; Gene Expression; Humans; Losartan; Marfan Syndrome; Mice; Muscular Dystrophy, Duchenne; Oxadiazoles; PPAR alpha; Transforming Growth Factor beta

Topics: Animals; Codon, Nonsense; Humans; Mice; Mice, Inbred mdx; Muscular Dystrophy, Duchenne; Oxadiazoles

Alterations of gastric mechanical activity have been reported in mdx mouse, animal model for Duchenne muscular dystrophy. This study examined if alterations in the vasoactive intestinal polypeptide (VIP) system are present in mdx stomach. Gastric mechanical activity was recorded in vitro as changes of endoluminal pressure and neurally or pharmacologically evoked relaxations were analysed in mdxvs normal stomach. Reverse-transcription polymerase chain reaction was used to detect inducible nitric oxide synthase (iNOS) expression. Relaxations to sodium nitroprusside in mdx stomach showed no difference in comparison with normal preparations. In normal stomach, VIP produced relaxation, which was reduced by VIP6-28, antagonist of VIP receptors, but was not modified by Nomega-nitro-L-arginine methyl ester (L-NAME), 1-H-oxodiazol-[1,2,4]-[4,3-a]quinoxaline-1-one (ODQ) or by N-(3-(aminomethyl)-benzyl)acetamidine (1400W) and aminoguanidine, inhibitors of iNOS. In contrast, in mdx stomach VIP responses were antagonized not only by VIP6-28, but also by L-NAME, ODQ, 1400W or aminoguanidine. In normal stomach, the slow relaxation evoked by stimulation at high frequency was reduced by VIP6-28, but it was unaffected by 1400W or aminoguanidine. In mdx stomach, it was reduced by VIP6-28 or 1400W, which did not show additive effects. iNOS mRNA was expressed only in mdx stomach. The results suggest that in mdx gastric preparations, iNOS is functionally expressed, being involved in the slow relaxation induced by VIP.

Topics: Animals; Disease Models, Animal; Enzyme Inhibitors; Imines; Male; Mice; Mice, Inbred mdx; Muscle Relaxation; Muscle, Smooth; Muscular Dystrophy, Duchenne; NG-Nitroarginine Methyl Ester; Nitric Oxide Synthase Type II; Organ Culture Techniques; Oxadiazoles; Quinoxalines; Receptors, Vasoactive Intestinal Peptide; Reverse Transcriptase Polymerase Chain Reaction; RNA, Messenger; Stomach; Vasoactive Intestinal Peptide

PTC-124, a 1,2,4-oxadiazole compound, is in development by PTC Therapeutics Inc as an orally active small molecule that can override nonsense stop translation signals to produce full-length proteins. PTC-124 is currently being evaluated in phase II clinical trials against cystic fibrosis (CF) and Duchenne muscular dystrophy (DMD). The functional properties of PTC-124 are similar to the aminoglycoside antibiotic gentamicin, but the two compounds are chemically distinct and PTC-124 does not exhibit any antibiotic characteristics. In vitro experiments showed PTC-124 to be superior to gentamicin at ribosomal read-through of nonsense mutations. In vivo investigations revealed that PTC-124 was effective in restoring the production of full-length protein in animal models of CF and DMD. Phase I clinical trials reported that PTC-124 was well tolerated in healthy patients. The author concludes that the encouraging results observed to date make PTC-124 an attractive option for further well-designed, long-term human studies on larger sample populations. The author also predicts that if results continue to be positive, PTC-124 could also be trialed in other single gene disorders with nonsense mutations such as hemophilia, neurofibromatosis, retinitis pigmentosa, bullous skin diseases and lysosomal storage disorders.

Topics: Animals; Clinical Trials as Topic; Cystic Fibrosis; Humans; Muscular Dystrophy, Duchenne; Oxadiazoles; Protein Synthesis Inhibitors