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Handbook of Experimental Pharmacology 2020Drug development and pharmacotherapy of rare pediatric diseases have significantly expanded over the last decade, in part due to incentives and financial support... (Clinical Trial)
Clinical Trial
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.
Topics: Adrenal Cortex Hormones; Child; Dystrophin; Exons; Humans; Muscular Dystrophy, Duchenne
PubMed: 31375923
DOI: 10.1007/164_2019_256 -
Current Opinion in Pharmacology Jun 2017Duchenne muscular dystrophy (DMD) is a lethal, X-linked muscle-wasting disease caused by lack of dystrophin, essential for muscle fibre integrity. Despite extensive... (Review)
Review
Duchenne muscular dystrophy (DMD) is a lethal, X-linked muscle-wasting disease caused by lack of dystrophin, essential for muscle fibre integrity. Despite extensive pre-clinical studies, development of an effective treatment has proved challenging. More recently, significant progress has been made with the first drug approval using a genetic approach and the application of pharmacological agents which slow the progression of the disease. Drug development for DMD has mainly used two strategies: (1) the restoration of dystrophin expression or the expression of the compensatory utrophin protein as an efficient surrogate, and (2) the mitigation of secondary downstream pathological mechanisms. This review details current most promising pharmacological approaches and clinical trials aiming to tackle the pathogenesis of this multifaceted disorder.
Topics: Animals; Dystrophin; Dystrophin-Associated Protein Complex; Humans; Muscular Dystrophy, Duchenne
PubMed: 28486179
DOI: 10.1016/j.coph.2017.04.002 -
JAMA Neurology Jul 2015
Review
Topics: Adrenal Cortex Hormones; Animals; Dystrophin; Genetic Therapy; Humans; Muscular Dystrophies
PubMed: 25985443
DOI: 10.1001/jamaneurol.2014.4621 -
Acta Neuropathologica Communications Apr 2022Duchenne muscular dystrophy (DMD) is a fatal muscle-wasting disorder caused by mutations in the Dystrophin gene and for which there is currently no cure. To bridge the...
Duchenne muscular dystrophy (DMD) is a fatal muscle-wasting disorder caused by mutations in the Dystrophin gene and for which there is currently no cure. To bridge the gap between preclinical and therapeutic evaluation studies, we have generated a rat model for DMD that carries an exon 52 deletion (R-DMDdel52) causing a complete lack of dystrophin protein. Here we show that R-DMDdel52 animals recapitulated human DMD pathophysiological trajectory more faithfully than the mdx mouse model. We report that R-DMDdel52 rats displayed progressive and severe skeletal muscle loss associated with fibrotic deposition, fat infiltration and fibre type switch. Early fibrosis was also apparent in the cardiac muscle. These histological modifications led to severe muscle, respiratory and cardiac functional impairments leading to premature death around 1 year. Moreover, DMD muscle exhibited systemic inflammation with a mixed M1/M2 phenotype. A comparative single cell RNAseq analysis of the diaphragm muscle was performed, revealing cellular populations alteration and molecular modifications in all muscle cell types. We show that DMD fibroadipogenic progenitors produced elevated levels of cartilage oligomeric matrix protein, a glycoprotein responsible for modulating homeostasis of extracellular matrix, and whose increased concentration correlated with muscle fibrosis both in R-DMDdel52 rats and human patients. Fibrosis is a component of tissue remodelling impacting the whole musculature of DMD patients, at the tissue level but most importantly at the functional level. We therefore propose that this specific biomarker can optimize the prognostic monitoring of functional improvement of patients included in clinical trials.
Topics: Animals; Biomarkers; Cartilage Oligomeric Matrix Protein; Dystrophin; Fibrosis; Humans; Mice; Mice, Inbred mdx; Muscular Dystrophy, Duchenne; Rats
PubMed: 35468843
DOI: 10.1186/s40478-022-01355-2 -
Nucleic Acids Research Jul 2022Targeted chromosomal insertion of large genetic payloads in human cells leverages and broadens synthetic biology and genetic therapy efforts. Yet, obtaining large-scale...
Targeted chromosomal insertion of large genetic payloads in human cells leverages and broadens synthetic biology and genetic therapy efforts. Yet, obtaining large-scale gene knock-ins remains particularly challenging especially in hard-to-transfect stem and progenitor cells. Here, fully viral gene-deleted adenovector particles (AdVPs) are investigated as sources of optimized high-specificity CRISPR-Cas9 nucleases and donor DNA constructs tailored for targeted insertion of full-length dystrophin expression units (up to 14.8-kb) through homologous recombination (HR) or homology-mediated end joining (HMEJ). In muscle progenitor cells, donors prone to HMEJ yielded higher CRISPR-Cas9-dependent genome editing frequencies than HR donors, with values ranging between 6% and 34%. In contrast, AdVP transduction of HR and HMEJ substrates in induced pluripotent stem cells (iPSCs) resulted in similar CRISPR-Cas9-dependent genome editing levels. Notably, when compared to regular iPSCs, in p53 knockdown iPSCs, CRISPR-Cas9-dependent genome editing frequencies increased up to 6.7-fold specifically when transducing HMEJ donor constructs. Finally, single DNA molecule analysis by molecular combing confirmed that AdVP-based genome editing achieves long-term complementation of DMD-causing mutations through the site-specific insertion of full-length dystrophin expression units. In conclusion, AdVPs are a robust and flexible platform for installing large genomic edits in human cells and p53 inhibition fosters HMEJ-based genome editing in iPSCs.
Topics: CRISPR-Cas Systems; Dystrophin; Endonucleases; Gene Editing; Humans; Muscle Cells; Muscular Dystrophy, Duchenne; Tumor Suppressor Protein p53
PubMed: 35776127
DOI: 10.1093/nar/gkac567 -
Cellular and Molecular Life Sciences :... Jun 2021Duchenne muscular dystrophy (DMD) is a devastating chromosome X-linked disease that manifests predominantly in progressive skeletal muscle wasting and dysfunctions in... (Review)
Review
Duchenne muscular dystrophy (DMD) is a devastating chromosome X-linked disease that manifests predominantly in progressive skeletal muscle wasting and dysfunctions in the heart and diaphragm. Approximately 1/5000 boys and 1/50,000,000 girls suffer from DMD, and to date, the disease is incurable and leads to premature death. This phenotypic severity is due to mutations in the DMD gene, which result in the absence of functional dystrophin protein. Initially, dystrophin was thought to be a force transducer; however, it is now considered an essential component of the dystrophin-associated protein complex (DAPC), viewed as a multicomponent mechanical scaffold and a signal transduction hub. Modulating signal pathway activation or gene expression through epigenetic modifications has emerged at the forefront of therapeutic approaches as either an adjunct or stand-alone strategy. In this review, we propose a broader perspective by considering DMD to be a disease that affects myofibers and muscle stem (satellite) cells, as well as a disorder in which abrogated communication between different cell types occurs. We believe that by taking this systemic view, we can achieve safe and holistic treatments that can restore correct signal transmission and gene expression in diseased DMD tissues.
Topics: Animals; Bone and Bones; Cell Communication; Dystrophin; Humans; Microvessels; Muscle, Skeletal; Muscular Dystrophy, Duchenne; Neurons; Signal Transduction
PubMed: 33825942
DOI: 10.1007/s00018-021-03821-x -
Biology Open Aug 2020Duchenne muscular dystrophy (DMD) is a progressive muscle-wasting disease caused by mutation of the gene. Pharmacological therapies that function independently of...
Duchenne muscular dystrophy (DMD) is a progressive muscle-wasting disease caused by mutation of the gene. Pharmacological therapies that function independently of dystrophin and complement strategies aimed at dystrophin restoration could significantly improve patient outcomes. Previous observations have suggested that serotonin pathway modulation ameliorates dystrophic pathology, and re-application of serotonin modulators already used clinically would potentially hasten availability to DMD patients. In our study, we used dystrophin-deficient and zebrafish models of DMD for rapid and easy screening of several classes of serotonin pathway modulators as potential therapeutics. None of the candidate drugs tested significantly decreased the percentage of zebrafish exhibiting the dystrophic muscle phenotype in the short-term birefringence assay or lengthened the lifespan in the long-term survival assay. Although we did not identify an effective drug, we believe our data is of value to the DMD research community for future studies, and there is evidence that suggests serotonin modulation may still be a viable treatment strategy with further investigation. Given the widespread clinical use of selective serotonin reuptake inhibitors, tricyclic antidepressants and reversible inhibitors of monoamine oxidase, their reapplication to DMD is an attractive strategy in the field's pursuit to identify pharmacological therapies to complement dystrophin restoration strategies.
Topics: Animals; Birefringence; Drug Evaluation, Preclinical; Dystrophin; Monoamine Oxidase Inhibitors; Receptors, Serotonin; Serotonin; Serotonin Receptor Agonists; Selective Serotonin Reuptake Inhibitors; Survival Analysis; Zebrafish
PubMed: 32718931
DOI: 10.1242/bio.053363 -
Mass Spectrometry Reviews 2024The dystrophin-associated protein complex (DAPC) is a highly organized multiprotein complex that plays a pivotal role in muscle fiber structure integrity and cell... (Review)
Review
The dystrophin-associated protein complex (DAPC) is a highly organized multiprotein complex that plays a pivotal role in muscle fiber structure integrity and cell signaling. The complex is composed of three distinct interacting subgroups, intracellular peripheral proteins, transmembrane glycoproteins, and extracellular glycoproteins subcomplexes. Dystrophin protein nucleates the DAPC and is important for connecting the intracellular actin cytoskeletal filaments to the sarcolemma glycoprotein complex that is connected to the extracellular matrix via laminin, thus stabilizing the sarcolemma during muscle fiber contraction and relaxation. Genetic mutations that lead to lack of expression or altered expression of any of the DAPC proteins are associated with different types of muscle diseases. Hence characterization of this complex in healthy and dystrophic muscle might bring insights into its role in muscle pathogenesis. This review highlights the role of mass spectrometry in characterizing the DAPC interactome as well as post-translational glycan modifications of some of its components such as α-dystroglycan. Detection and quantification of dystrophin using targeted mass spectrometry are also discussed in the context of healthy versus dystrophic skeletal muscle.
Topics: Dystrophin; Dystrophin-Associated Protein Complex; Laminin; Sarcolemma; Muscle, Skeletal; Glycoproteins
PubMed: 36420714
DOI: 10.1002/mas.21823 -
Pflugers Archiv : European Journal of... May 2023The primary function of dystrophin is to form a link between the cytoskeleton and the extracellular matrix. In addition to this crucial structural function, dystrophin...
The primary function of dystrophin is to form a link between the cytoskeleton and the extracellular matrix. In addition to this crucial structural function, dystrophin also plays an essential role in clustering and organizing several signaling proteins, including ion channels. Proteomic analysis of the whole rodent brain has stressed the role of some components of the dystrophin-associated glycoprotein complex (DGC) as potential interacting proteins of the voltage-gated Ca channels of the Ca2 subfamily. The interaction of Ca2 with signaling and scaffolding proteins, such as the DGC components, may influence their function, stability, and location in neurons. This work aims to study the interaction between dystrophin and Ca2.1. Our immunoprecipitation data showed the presence of a complex formed by Ca2.1, Caαδ-1, Caβ, Dp140, and α1-syntrophin in the brain. Furthermore, proximity ligation assays (PLA) showed that Ca2.1 and Caαδ-1 interact with dystrophin in the hippocampus and cerebellum. Notably, Dp140 and α1-syntrophin increase Ca2.1 protein stability, half-life, permanence in the plasma membrane, and current density through recombinant Ca2.1 channels. Therefore, we have identified the Dp140 and α1-syntrophin as novel interaction partners of Ca2.1 channels in the mammalian brain. Consistent with previous findings, our work provides evidence of the role of DGC in anchoring and clustering Ca channels in a macromolecular complex.
Topics: Animals; Dystrophin; Mammals; Neurons; Proteomics
PubMed: 36964781
DOI: 10.1007/s00424-023-02803-1 -
Brain & Development Aug 2017Mutations in the dystrophin gene (Dmd) result in Duchenne muscular dystrophy (DMD) and Becker muscular dystrophy (BMD), which afflict many newborn boys. In 2016, Brain... (Review)
Review
Mutations in the dystrophin gene (Dmd) result in Duchenne muscular dystrophy (DMD) and Becker muscular dystrophy (BMD), which afflict many newborn boys. In 2016, Brain and Development published several interesting articles on DMD treatment with antisense oligonucleotide, kinase inhibitor, and prednisolone. Even more strikingly, three articles in the issue 6271 of Science in 2016 provide new insights into gene therapy of DMD and BMD via the clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR-associated protein 9 (Cas9). In brief, adeno-associated virus (AAV) vectors transport guided RNAs (gRNAs) and Cas9 into mdx mouse model, gRNAs recognize the mutated Dmd exon 23 (having a stop codon), and Cas9 cut the mutated exon 23 off the Dmd gene. These manipulations restored expression of truncated but partially functional dystrophin, improved skeletal and cardiac muscle function, and increased survival of mdx mice significantly. This review concisely summarized the related advancements and discussed their primary implications in the future gene therapy of DMD, including AAV-vector selection, gRNA designing, Cas9 optimization, dystrophin-restoration efficiency, administration routes, and systemic and long-term therapeutic efficacy. Future orientations, including off-target effects, safety concerns, immune responses, precision medicine, and Dmd-editing in the brain (potentially blocked by the blood-brain barrier) were also elucidated briefly. Collectively, the AAV-mediated and RNA-guided CRISPR/Cas9 system has major superiorities compared with traditional gene therapy, and might contribute to the treatment of DMD and BMD substantially in the near future.
Topics: Animals; CRISPR-Cas Systems; Dependovirus; Dystrophin; Genetic Therapy; Genetic Vectors; Humans; Male; Muscular Dystrophy, Duchenne
PubMed: 28390761
DOI: 10.1016/j.braindev.2017.03.024