Meeting report: the 2020 FSHD International Research Congress,Skeletal Muscle

当前位置： X-MOL 学术 › Skelet. Muscle › 论文详情

Our official English website, www.x-mol.net, welcomes your feedback! (Note: you will need to create a separate account there.)

Meeting report: the 2020 FSHD International Research Congress
Skeletal Muscle ( IF 4.9 ) Pub Date : 2020-12-08 , DOI: 10.1186/s13395-020-00253-2
Michael Kyba ₁ , Robert J Bloch ₂ , Julie Dumonceaux ₃ , Scott Q Harper _{4,

5} , Silvère M van der Maarel ₆ , Francis M Sverdrup ₇ , Kathryn R Wagner _{8,

9} , Baziel van Engelen ₁₀ , Yi-Wen Chen _{11,

12}

Affiliation

Department of Pediatrics, University of Minnesota, Minneapolis, MN, 55104, USA.
Department of Physiology, University of Maryland School of Medicine, Baltimore, MD, 21201, USA.
NIHR Biomedical Research Centre, University College London, Great Ormond Street Institute of Child Health and Great Ormond Street Hospital NHS Trust, London, WC1N 1EH, UK.
Department of Pediatrics, The Ohio State University, Columbus, OH, 43205, USA.
Center for Gene Therapy, The Abigail Wexner Research Institute at Nationwide Children's Hospital, Columbus, OH, 43205, USA.
Department of Human Genetics, Leiden University Medical Center, Leiden, The Netherlands.
Edward A. Doisy Department of Biochemistry and Molecular Biology, Saint Louis University, Saint Louis, MO, 63104, USA.
Center for Genetic Muscle Disorders, Kennedy Krieger Institute, Baltimore, MD, 21205, USA.
Departments of Neurology and Neuroscience, Johns Hopkins School of Medicine, Baltimore, MD, 21205, USA.
Department of Neurology, Radboud University Medical Center, Nijmegen, The Netherlands.
Department of Genomics and Precision Medicine, The George Washington University, Washington, DC, 20052, USA.
Center for Genetic Medicine Research, Children's National Research Institute, Washington, DC, 20010, USA.

Facioscapulohumeral muscular dystrophy (FSHD) spent many years in a wilderness of unexplained genetic mechanism while other monogenic muscular dystrophies saw rapid progress on genetic mechanism soon after their corresponding genes were discovered, with current interventions developed based on these discoveries. While it is now the consensus of the field that aberrant expression of the DUX4 transcription factor is ultimately responsible for FSHD, the linkage of such expression to muscle degeneration through a specific pathological mechanism has proven elusive, a concerning situation for many developing therapies. The 2020 Facioscapulohumeral Muscular Dystrophy (FSHD) International Research Congress, held online, June 25–26, and involving 280 registered participants from 5 continents, revealed strides to bridge this gap, as well as steps toward therapy, including the initiation of the first clinical trial specifically targeting DUX4 expression.

Understanding which cell type DUX4 acts in, and what its pathological effects are in that cell type, benefit from investigating pathology at multiple levels, and advances highlighted in this area ranged from cell to tissue to system-wide. Major findings include the potential role of DUXA in sustaining DUX4 effects, DUX4 effects on muscle regeneration, novel circulation biomarkers, and a fish model for studying DUX4 effects.

Because DUX4 is known to impair myoblast differentiation, and has been proposed to have effects on satellite cells, Peter Zammit (Kings College, London) investigated to what extent regeneration is occurring in FSHD muscle. PAX7 and DUX4 are known to have mutually inhibitory effects on gene expression, suggesting that the expression of DUX4 in satellite cells would reduce myogenic potential. Consistent with this, myogenic and satellite cells in murine models of FSHD express DUX4. Muscle regeneration in mice carrying a DUX4-βgal reporter gene and challenged with cardiotoxin shows upregulation. PAX7+ satellite cells show similar upregulation. This suggests that DUX4 expression accompanies the activation of the myogenic program in muscle stem cells. Transcriptomic studies of regenerating healthy and FSHD muscle show that myogenic gene expression is elevated in FSHD muscles compared to controls. At the protein level, assayed by immunofluorescence, developmental myosin heavy chain was also elevated in FSHD vs controls. Most FSHD biopsies show regenerating fibers, with 0.48% of fibers in FSHD quadriceps and 1.72% of fibers in FSHD tibialis anterior muscle are regenerating. Regeneration correlates with overall severity of pathology. These results indicate that active regeneration occurs in FSHD muscle, but at low levels that are insufficient for homeostatic maintenance.

Katherine Williams (UC Irvine) has studied gene expression in nuclei of FSHD2 myoblasts and myotubes in vitro. DUX4 has been shown to spread from one nucleus to others nearby to induce target gene expression, which can persist even after DUX4 is no longer detectable. RNAseq of differentiating FSHD2 and control cell lines from myoblasts into early (day 3) myotubes identifies 54 mRNAs expressed in FSHD2 but not controls, including typical DUX4 targets as well as DUXA and LEUTX. Single nucleus analysis in myoblasts and early myotubes shows similarities between FSHD2 and control myoblasts but differences in myotubes. FSHD2 nuclei isolated from myotubes either express DUX4 or do not; they were categorized as HI or LO expressers. DUX4 target genes tend to be expressed in the HI group but not consistently, as they were also expressed at variable levels in the LO group. Their levels did not parallel levels of DUX4 in the HI group, with the exception of DUXA. Most FSHD2 myonuclei do not express DUX4, but SLC34A2 and LEUTX can be imaged at high levels in myotubes, even when DUX4 protein cannot. Differentiation for an additional 2 days (to day 5) does not significantly alter these results but shows higher levels of target gene expression. RNAseq identified ~ 1500 gene products that were elevated in expression in the HI compared to the LO group, including 6 transcription factors involved in the cell cycle. This is surprising, as nuclei in myotubes should be in G0. Suppression of expression of DUXA can suppress the expression of ZSCAN4 and LEUTX in more mature myotubes, even when DUX4 cannot be detected. This suggests that DUXA can perpetuate the abnormal gene program initiated by DUX4 expression in FSHD2.

Maria Traficante (University of Maryland Baltimore) presented preliminary evidence that serum levels of SLC34A2 are elevated in mice carrying mature FSHD human muscle. SLC34A2 is typically expressed in epithelial cells and as part of the DUX4 program in FSHD muscle. It is not found at significant levels in healthy muscle or in normal human serum. Previous work had shown that SLC34A2 could be labeled in FSHD muscle biopsies more than control biopsies and in xenografts of FSHD myogenic precursor cells (MPCs) more than control MPCs. qPCR shows higher levels of SLC34A2 mRNA in two different FSHD cell lines (15A, C6) compared to appropriate controls (15 V, A4), suggesting that its elevation is not cell-line specific. Western blots of xenografts also show elevated SLC34A2 protein. Blots of serum from mice carrying FSHD xenografts prepared with 15A MPCs also showed elevated levels of SLC34A2 protein, compared to control 15 V MPC grafts. These results suggest that SLC34A2 may be a reliable serum biomarker for FSHD.

Yuanfan (Tracy) Zhang, (Children’s Hospital, Boston) working in the Kunkel laboratory, has been examining the effects of DUX4 overexpression in zebrafish. Previous studies showed that injection of DUX4 into fish embryos results in asymmetric effects on muscle that mimic the human disease in important ways. RNAseq of injected fish show 338 genes upregulated and 10 genes downregulated, of which 55 genes show changes similar to those seen in human FSHD muscle cells. Finer regulation of DUX4 expression is achieved with a tamoxifen-inducible promoter. When expressed at low levels, DUX4 causes a milder myopathy. Screening these fish in 96-well dishes is an efficient way of identifying small molecules that can correct for the effects of DUX4. Zhang presented data to show that both herbimycin and rapamycin decrease DUX4 expression and preserve healthier muscle morphology, with reduced apoptosis and fat and fibrotic infiltration. The inducible DUX4 model in zebrafish may therefore be a good in vivo screen for drugs that suppress DUX4.

Because most cases of FSHD do not involve specific point mutations, but rather copy number alterations of a 3.3 kb macrosatellite repeat unit leading to changes in its epigenetic regulation, genetic diagnosis can be challenging in many cases. The presentations in the genetics and epigenetics section reported new and improved approaches for determining the D4Z4 repeat number and DNA methylation state. In addition, a study reporting patients carrying shortened D4Z4 array on chromosome 10 with a distal FSHD-permissive sequence strengthened the essential role of DUX4 in the disease mechanism.

Sven Bockland (BioNano Genomics) showed results from their efforts to characterize the D4Z4 repeat by optical mapping technology. Accurate sizing and chromosome assignment is possible by optical mapping, and an automated workflow and reporting for DNA diagnostics of FSHD was presented which is currently implemented for clinical testing in several centers. The technology also allows for the detection of somatic mosaicism down to 6.25% allele fraction, and future applications include the detection of D4Z4 methylation. Next, Alexander Liu (Children’s National Washington DC) shared his experience with Oxford Nanopore long read sequencing of the D4Z4 repeat. He presented a CRISPR/Cas9-based enrichment protocol resulting in 6–150-fold enrichment of the D4Z4 repeat and sequencing of the contracted and non-contracted D4Z4 repeat from both chromosome 4 alleles in FSHD1 patients. This method also allows for methylation analysis and the first data points towards uneven methylation distribution over the entire repeat with evidence for hypomethylation of the contracted allele. In the final presentation, Richard Lemmers (Leiden University Medical Center) presented two families with evidence for linkage of FSHD with chromosome 10. In both families, de novo translocations between chromosome 4- and 10-derived repeats were detected resulting in contracted repeats on chromosome 10 ending with a typical FSHD-permissive chromosome 4 sequence that allows for stable DUX4 expression. The probands of both families have a classical FSHD phenotype and express DUX4 and DUX4 target genes in their muscle cell cultures suggesting that, independent of chromosomal localization, reactivation of DUX4 in skeletal muscle causes FSHD.

In the poster session, Nicolay Zernov presented a qPCR-based approach for FSHD1 diagnostics based on DNA digestion by EcoRI, separation by pulsed field gel electrophoresis, fragmentizing according to a size standard, and using the fragments as PCR template. Darina Šikrová presented a FSHD patient with a homozygous LRIF1 variant associated with D4Z4 hypomethylation and DUX4 expression identifying LRIF1 as novel disease gene. Jon Thomason (University of Iowa) presented a validation study of optical mapping for the molecular diagnosis of FSHD in 40 subjects emphasizing the accuracy, robustness, preciseness, and reproducibility of this technique. Another optical mapping study by Hayk Barseghyan (Children’s National Washington DC) provided proof of principle for methylation analysis of D4Z4. Experience with DNA diagnosis of FSHD by Southern blotting was presented by Sabrina Pagnoni (Catholic University of Córdoba) representing the first molecular characterization of D4Z4 alleles and haplotypes in Latin-America. Autumn Rieken (University of Iowa) presented a retrospective analysis of CLIA laboratory testing for FSHD showing an overall positive testing rate of 42%, of which 7% is testing positive for FSHD2. Finally, Russell Buttefield (University of Utah) presented a strategy for the identification of genetic modifiers of FSHD severity in a large Utah kindred first described in the 1950’s.

In spite of a well-founded understanding of the genetic cause of FSHD, the field continues to struggle with understanding which cellular phenotypes and mechanisms are most relevant downstream of DUX4, and with understanding the pathological mechanism leading from DUX4 leakage from improperly silenced D4Z4 repeats to degeneration of muscle, particularly in view of the difficulty of directly detecting the DUX4 protein in muscle sections. The pathology and disease mechanisms session addressed these issues with a diverse set of talks on both molecular and tissue-level effects of DUX4 expression. While involvement of hypoxic signaling, mis-spliced RNAs, and cell death in FHSD has been reported, new findings provided insights and details on how the pathways mediate DUX4-induced cytotoxicity. In addition, the importance of expression levels and expression patterns of DUX4 was studied and reported using animal models of FSHD.

Angela Lek of the Yale School of Medicine presented results of a whole-genome CRISPR screen for knockouts that protect DUX4-expressing myoblasts from cell death. This identified a number of genes associated with hypoxia signaling. While DUX4 has been known to enhance the sensitivity of cells to oxidative stress for some time, this is the first time that the signaling activity of the pathway itself, as opposed to the potential direct pathological effects of oxidative damage, has been shown to be deleterious. The screen was followed by experiments using chemical approaches to diminish hypoxia signaling in vitro as well as in vivo using a mouse model based on FSHD human muscle xenografts, which revealed in vivo relevance of hypoxia signaling to DUX4-induced pathology at the tissue level, possibly at the level of DUX4 protein accumulation.

Amy Campbell of the University of Colorado presented work following up on the discovery that DUX4 impairs nonsense-mediated RNA decay. She showed that transcripts bearing frameshift mutations because they are not eliminated lead to immunologically detectable neo epitopes in cells expressing DUX4, particularly of factors involved in splicing. One specific factor, a truncated form of SRSF3 derived from an alternatively spliced transcript that is normally rapidly degraded, was found to be specifically deleterious to cells when overexpressed, potentially accounting in part for the DUX4 cell death phenotype.

Julie Dumonceaux of University College London found surprisingly that while caspase inhibitors failed to protect DUX4 expressing cells from death, one necroptosis inhibitor did. She tested the in vivo relevance of the necroptosis pathway by crossing the Ripk3 knockout into the background of an FSHD mouse model based on muscle-specific DUX4 expression and found a significant diminution of the pathological phenotype.

Joel Chamberlain of the University of Washington presented experiments to test direct delivery of a human FSHD D4Z4 fragment encoding DUX4 using AAV9. The construct uses the endogenous DUX4 promoter and resulted in dose-dependent pathology of skeletal muscle, including signs of fibrosis, regeneration, and fiber splitting. Interestingly, levels of DUX4 expression were almost undetectable in the lowest dose observed to present a detectable phenotype, much like the situation in humans, where DUX4 is virtually undetectable immunohistochemically in human muscle biopsy specimens.

Michael Kyba of the University of Minnesota presented work with the iDUX4pA mouse model in which DUX4 can be expressed specifically in muscle fibers when mice are treated with doxycycline (dox). Because the system is reversible with dox withdrawal, the group investigated the long-term effects of burst (single dox injection) or pulse (10 days of dox injections) expression of DUX4. On the positive side, muscle was found to recover to relatively healthy histology several months after a pulse of DUX4 expression, supporting the therapeutic potential of inhibiting DUX4. On the disconcerting side, the group found that the fibroadiopogenic progenitor compartment does not return to normal, even after several months, and proposed a model in which long-term abnormalities in these cells lead to progressive pathology, now uncoupled from DUX4 expression, raising the question of the extent to which DUX4 suppression alone would be sufficient to treat FSHD.

This session featured presentations from several laboratories working to develop therapeutic strategies for FSHD. The main efforts focus on reduction of DUX4 transcripts directly using various strategies, including antisense oligonucleotides, CRISPR-Cas system, miRNAs, and siRNAs. In addition, strategies that modulate DUX4 expression via upstream pathways were reported, including the first clinical trial on a repurposed drug, losmapimod, that modulates DUX4 expression.

Two talks from Rika Maruyama (University of Alberta) and Yi-Wen Chen (Children’s National Hospital, George Washington University) described the development of gapmer antisense oligonucleotides modified with locked nucleic acid (LNA) or 2’-O-methoxy-ethyl (2’-MOE) bases, designed to knock down DUX4 mRNA using an RNAse H-mediated mechanism. Rika Maruyama presented the screening of the antisense oligonucleotides (AOs) in vitro, and Yi-Wen Chen reported data from in vivo experiments in uninduced FLExDUX4 mice that express very low levels of DUX4 and display mild myopathic phenotypes. Following subcutaneous AO delivery, FLExDUX4 mice showed increased grip strength and reduced fibrosis, while muscle weight was not affected. Future studies will be aimed at improving in vivo delivery to muscle, which is currently a barrier to translating oligonucleotide-based strategies for muscle diseases.

Two talks described AAV-based gene therapy strategies to inhibit DUX4 mRNA using different mechanisms in DUX4-expressing human cells and mouse models. In the first, Afrooz Rashnonejad (Nationwide Children’s Hospital, Columbus, Ohio) used a new type of CRISPR-Cas system that relied upon the RNA-targeting enzyme Cas13b, which can be directed to silence DUX4 mRNA without risk of cutting the genome. As Cas13b was too large to allow co-packaging of a guide RNA expression cassette in the same AAV genome, the first-generation system required injection of 2 AAVs, one expressing the guide RNA from a U6 promoter and a second carrying the Cas13b protein expression cassette. This system reduced DUX4 expression in vitro and in vivo, and improved DUX4-associated muscle histopathology in DUX4-expressing mice. The authors are now optimizing the vector to improve its efficiency and reduce off targets in vivo, and are also testing smaller versions of Cas13 that allow co-packaging with a gRNA in the same vector.

In the second gene therapy talk, Lindsay Wallace (Nationwide Children’s Hospital, Columbus, Ohio) presented advancements in the development of an AAV RNAi-based gene therapy for FSHD. This group has previously published several articles demonstrating efficacy of RNAi therapy in mouse models and is now optimizing the strategy for efficacy and safety for translation to clinical trial. Dr. Wallace reported new unpublished, long-term functional and histopathological improvements in TIC-DUX4 mice treated systemically with AAV9 and AAV6 vectors carrying their team’s lead sequence, called miDUX4.405. In addition, she summarized a blinded toxicology study in mice, which supported the safe use of miDUX4.405 at clinically relevant doses.

Katelyn Daman (UMass Medical School) presented a combined ex vivo and xenograft pipeline for FSHD drug development. Compounds targeting intersectional pathways in FSHD cells, or siRNAs targeting DUX4, were evaluated in vitro and in immunodeficient mouse muscles xenografted with FSHD patient myoblasts. Dr. Daman reported the identification of two promising compounds that led to decreased DUX4 target gene expression. Importantly, one compound is a repurposed drug already used in humans for another indication, thereby potentially accelerating its path to translation for efficacy testing in FSHD.

Finally, two noteworthy posters were presented by companies developing FSHD-focused technologies. Fulcrum Therapeutics presented a poster on the evaluation of p38α/β target engagement biomarkers in skeletal muscle in trials of losmapimod, which is a DUX4-reducing small molecule currently being tested in a Phase 2b (NCT04003974) study in FSHD patients. The microRNA therapeutics company miRecule presented the development of an anti-DUX4 modified RNA oligonucleotide conjugated to miRecule’s antibody delivery technology for the treatment of FSHD. The goal of this strategy is to improve oligonucleotide delivery to muscle when delivered systemically.

In the past couple of years, there has been increased activity in clinical research in FSHD with interventional trials, imaging studies, biomarker studies, and a large multisite natural history study. One of the most significant challenges is the slow course of the disease, which necessitates trials of long duration or large size. A key question is whether specific biomarkers can provide surrogate measures of functional efficacy and thus increase power. These studies are revealing the feasibility of clinical trials in this disease and approaches to evaluate efficacy. They have also contributed to a better understanding of FSHD

Christopher Banerji kicked off this session with a description of self-reported symptoms in the FSHD1 UK registry (n = 643). The authors described four clinical presentations of FSHD1: a classical presentation (74%) describing a descending myopathy, and three facial sparing phenotypes—a mild presentation (5%) with later facial and periscapular involvement, an early shoulder presentation (10%) with accelerated periscapular weakness, and an early foot presentation (9%) with accelerated foot dorsiflexor weakness. Interestingly, the authors also found that pregnancy and carrying multiple children to term was associated with slower onset of all muscle symptoms. Although this is contrary to anecdotal reports of many women affected with FSHD who feel that their pregnancy accelerates their symptoms, it is in line with other studies that have suggested a protective effect of estrogen on the development of weakness in FSHD. Peter Lunt presented scatter plots created from his own and others’ published data, providing a visual illustration of the interrelationships of various factors influencing phenotype. One of the most interesting findings was that these plots illustrate reduced methylation and earlier onset following grandmaternal-maternal versus grandpaternal-paternal transmission.

Rabi Tawil described the launch of a phase 2b trial of losmapimod in FSHD1. Losmapimod is a small molecule inhibitor of p38α/β which in preclinical studies resulted in dose-dependent reduction of DUX4 protein. In a RDBPC trial sponsored by Fulcrum Therapeutics, 76 individuals with genetically confirmed FSHD1, age 18 to 65, having a clinical severity score of 2 to 4 (Ricci scale 0–5), and a STIR+ skeletal muscle identified by MRI were randomized 1:1 to 15 mg losmapimod or placebo PO BID for 24 weeks. The primary outcome measure is change from baseline in DUX4 activity measured by quantitative polymerase chain reaction (qPCR) of a STIR+ skeletal muscle using a subset of DUX4-regulated gene transcripts. Michelle Mellion described the challenges that the COVID-19 pandemic has introduced into the conduct of clinical trials, particularly in the losmapimod trial (ReDUX4). The ReDUX4 protocol was amended to include safety monitoring through virtual visits, mobile phlebotomy, direct to patient shipment of investigational drug, and extension of the randomized controlled portion of the trial from 24 to 48 weeks to ensure capture of key assessments. Lucienne Ronco described results from a biomarker study to identify a set of stable DUX4-regulated gene transcripts that will provide a PD biomarker endpoint to measure losmapimod treatment effect. Sixteen subjects who met inclusion criteria similar to the ReDUX4 study were enrolled and underwent needle muscle biopsies of a STIR+ muscle 6 weeks apart. Using RNA-seq data from this and published studies, a panel of DUX4-related transcripts was identified.

Jeffrey Statland described the results of a phase 2 trial of ACE-083 in FSHD sponsored by Acceleron Pharma. ACE-083 is a locally delivered nonspecific myostatin inhibitor which induces increased muscle growth. This was a two part study: part 1 was dose-ranging (N = 37); part 2 was RDBPC for 6 months followed by a 6-month open-label period. Patients were treated with ACE-083 240 mg/muscle or placebo (1:1) injected into the tibialis anterior (TA) or biceps brachii (BB) muscles bilaterally q3 weeks (N = 58). The primary endpoint was increased in muscle mass of the TA or BB. ACE-083 was generally safe and well tolerated. There were mean increases in muscle volume of 13.8% (2.9) for ACE-083 versus 4.3% (2.7) for placebo (p = 0.01) in TA, and increases of 19.1% (2.8) for ACE-083 versus 2.7% (2.8) (p < 0.0001) for placebo in BB. Thus, the study met its primary endpoint. However, since there was no associated increase in function, development of ACE-083 for FSHD was terminated.

The industry panel offered an opportunity for biotechnology and pharmaceutical companies to introduce themselves, their platforms, and interests, to facilitate collaborations and partnerships with the research community. This year’s panelists included Romesh Subramanian from Dyne Therapeutics, who highlighted Dyne’s delivery technology that enables targeting therapeutics to muscle. Michelle Mellion from Fulcrum Therapeutics detailed Fulcrum’s commitment to FSHD and the company’s poster and oral presentations on topics from biomarkers and clinical trial design to initiation of a phase 2b clinical trial with the p38 inhibitor losmapimod. Anthony Saleh from miRecule discussed preclinical progress with his company’s antibody-mediated muscle-targeting platform in delivering DUX4-targeting RNA therapeutics. Finally, Jane Owens from Pfizer highlighted a poster presentation of their effort to establish relevant cell assays for FSHD and went further on to discuss unanswered questions around pathophysiology of disease and development challenges that remain.

In addition to the scientific sessions and an industry panel session, the FSHD society recognized three outstanding young FSHD investigators (Angela Lek, Yale University; Karlien Mul, Radboud University Medical Center; and Sujatha Jagannathan, University of Colorado) and gave a poster award to Darina Šikrová, Leiden University Medical Center, and Kohei Hamanaka, National Institute of Neuroscience, Japan.

As investigation into the molecular consequences of DUX4 expression matures, the myriad of altered pathways continues to grow. Methods to narrow down from those observed in experimental models to those relevant to human muscle degeneration will be necessary to determine which are most relevant or whether pathology is due to the combination of many perturbations.

Regarding therapies to inhibit DUX4, recent work has highlighted the potential of drugs that reduce DUX4 expression but that have systemic consequences in many other pathways, as well as strategies that are specific to DUX4, but challenging to effectively and specifically deliver to most relevant cell types in muscle. With the former currently in clinical trials, the field awaits eagerly the first results, while hoping for the development of approaches to advance the latter.

The 2020 FSHD International Research Consortium Congress brought together 280 participants from around the world to present research findings and exchange ideas. Scientific highlights include new insights in disease mechanisms, cutting-edge approaches for disease diagnosis, and ongoing pre-clinical and clinical studies of potential treatments for FSHD. The 2021 FSHD International Research Consortium is planned to be at Leiden, The Netherlands, highlighting the worldwide nature of the meeting.

Not applicable.

2’-MOE:: 2’-O-methoxy-ethyl
AAV:: Adeno-associated virus
AO:: Antisense oligonucleotide
BB:: Biceps brachii
BID:: Twice per day
dox:: Doxycycline
FSHD:: Facioscapulohumeral muscular dystrophy
LNA:: Locked nucleic acid
MPC:: Myogenic precursor cell
PO:: Orally
qPCR:: Quantitative polymerase chain reaction
RDBPC:: Randomized double-blind placebo-controlled
TA:: Tibialis anterior

We thank the following sponsors for supporting the 2020 FSHD International Research Congress: AFM Telethon, Avidity Biosciences, Bionano Genomics, Dyne Therapeutics, Fulcrum Therapeutics, Genomic Vision, Muscular Dystrophy Association, MiRecule, PerkinElmer Genomics, University of Massachusetts Medical School/NIH/Wellstone Center, University of Nevada School of Medicine.

Program committee and co-chairs

Jamshid Arjomand, FSHD Society

Robert Bloch, University of Maryland School of Medicine, USA

Yi-Wen Chen, Children's National Research Institute/George Washington University, USA

Julie Dumonceaux, University College of London, UK

Scott Harper, The Research Institute at Nationwide Children's Hospital, USA

June Kinoshita, FSHD Society, USA

Michael Kyba, University of Minnesota, USA

Mikell Lang, FSHD Society, USA

Mark Stone, FSHD Society, USA

Fran Sverdrup, Saint Louis University School of Medicine, USA

Silvere Silvère M. van der Maarel, Leiden University Medical Center, The Netherlands

Baziel van Engelen, Radboud University Medical Center, The Netherlands

Kathryn R. Wagner, Kennedy Krieger Institute/Johns Hopkins School of Medicine, USA

This conference was funded by the FSHD Society.

Affiliations

Department of Pediatrics, University of Minnesota, Minneapolis, MN, 55104, USA
Michael Kyba
Department of Physiology, University of Maryland School of Medicine, Baltimore, MD, 21201, USA
Robert J. Bloch
NIHR Biomedical Research Centre, University College London, Great Ormond Street Institute of Child Health and Great Ormond Street Hospital NHS Trust, London, WC1N 1EH, UK
Julie Dumonceaux
Department of Pediatrics, The Ohio State University, Columbus, OH, 43205, USA
Scott Q. Harper
Center for Gene Therapy, The Abigail Wexner Research Institute at Nationwide Children’s Hospital, Columbus, OH, 43205, USA
Scott Q. Harper
Department of Human Genetics, Leiden University Medical Center, Leiden, The Netherlands
Silvère M. van der Maarel
Edward A. Doisy Department of Biochemistry and Molecular Biology, Saint Louis University, Saint Louis, MO, 63104, USA
Francis M. Sverdrup
Center for Genetic Muscle Disorders, Kennedy Krieger Institute, Baltimore, MD, 21205, USA
Kathryn R. Wagner
Departments of Neurology and Neuroscience, Johns Hopkins School of Medicine, Baltimore, MD, 21205, USA
Kathryn R. Wagner
Department of Neurology, Radboud University Medical Center, Nijmegen, The Netherlands
Baziel van Engelen
Department of Genomics and Precision Medicine, The George Washington University, Washington, DC, 20052, USA
Yi-Wen Chen
Center for Genetic Medicine Research, Children’s National Research Institute, Washington, DC, 20010, USA
Yi-Wen Chen

Authors

Michael KybaView author publications
You can also search for this author in PubMed Google Scholar
Robert J. BlochView author publications
You can also search for this author in PubMed Google Scholar
Julie DumonceauxView author publications
You can also search for this author in PubMed Google Scholar
Scott Q. HarperView author publications
You can also search for this author in PubMed Google Scholar
Silvère M. van der MaarelView author publications
You can also search for this author in PubMed Google Scholar
Francis M. SverdrupView author publications
You can also search for this author in PubMed Google Scholar
Kathryn R. WagnerView author publications
You can also search for this author in PubMed Google Scholar
Baziel van EngelenView author publications
You can also search for this author in PubMed Google Scholar
Yi-Wen ChenView author publications
You can also search for this author in PubMed Google Scholar

Contributions

All authors contributed to writing and reviewing this report. The author(s) read and approved the final manuscript.

Corresponding author

Correspondence to Yi-Wen Chen.

Ethics approval and consent to participate

Not applicable.

Consent for publication

Not applicable.

Competing interests

The authors declare that they have no competing interests.

Publisher’s Note

Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article's Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article's Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by/4.0/. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated in a credit line to the data.

Reprints and Permissions

Cite this article

Kyba, M., Bloch, R.J., Dumonceaux, J. et al. Meeting report: the 2020 FSHD International Research Congress. Skeletal Muscle 10, 36 (2020). https://doi.org/10.1186/s13395-020-00253-2

Download citation

Received: 03 September 2020
Accepted: 16 November 2020
Published: 08 December 2020
DOI: https://doi.org/10.1186/s13395-020-00253-2

Keywords

Facioscapulohumeral muscular dystrophy
Muscular dystrophy
Meeting

中文翻译：

会议报告：2020年FSHD国际研究大会

面肩肱型肌营养不良症（FSHD）在遗传原因无法解释的荒野中度过了许多年，而其他单基因型肌营养不良症在发现其相应基因后不久就在遗传机制上获得了快速发展，目前的干预措施是基于这些发现而开发的。尽管现在已经普遍认为DUX4转录因子的异常表达最终导致FSHD，但是这种表达通过特定病理机制与肌肉变性的联系已被证明是难以捉摸的，这是许多正在发展的疗法中令人担忧的情况。于6月25日至26日在网上举行的2020年肩肱肱肌肉营养不良（FSHD）国际研究大会，来自五大洲的280名注册参与者表示，为缩小这一差距，

了解DUX4起作用的细胞类型及其在该细胞类型中的病理作用，可从多层次的病理学研究中受益，并且在该领域突出的进展涵盖了从细胞到组织再到整个系统的整个过程。主要发现包括DUXA在维持DUX4效应方面的潜在作用，DUX4对肌肉再生的作用，新型循环生物标志物以及用于研究DUX4效应的鱼类模型。

由于已知DUX4会损害成肌细胞的分化，并且已经提出DUX4对卫星细胞有影响，因此Peter Zammit（伦敦金斯学院）研究了FSHD肌肉再生的程度。已知PAX7和DUX4对基因表达具有相互抑制作用，这表明DUX4在卫星细胞中的表达会降低成肌潜能。与此相一致，FSHD鼠模型中的成肌细胞和卫星细胞表达DUX4。携带DUX4-βgal报告基因基因并受到心毒素攻击的小鼠的肌肉再生显示上调。PAX7 +卫星细胞显示出类似的上调。这表明DUX4表达伴随着肌肉干细胞中的肌源程序的激活。再生健康和FSHD肌肉的转录组研究显示，与对照组相比，FSHD肌肉中的成肌基因表达升高。在蛋白质水平上，通过免疫荧光分析，与对照相比，FSHD中发育性肌球蛋白重链也升高。大多数FSHD活检显示纤维再生，其中FSHD股四头肌中0.48％的纤维和FSHD胫前肌中1.72％的纤维正在再生。再生与病理的整体严重程度相关。这些结果表明，在FSHD肌肉中发生了主动再生，但是处于低水平，不足以维持体内平衡。FSHD股四头肌中48％的纤维和FSHD胫前肌中1.72％的纤维正在再生。再生与病理的整体严重程度相关。这些结果表明，FSHD肌肉中发生了主动再生，但是水平较低，不足以维持体内平衡。FSHD股四头肌中48％的纤维和FSHD胫前肌中1.72％的纤维正在再生。再生与病理的整体严重程度相关。这些结果表明，FSHD肌肉中发生了主动再生，但是水平较低，不足以维持体内平衡。

Katherine Williams（加州大学欧文分校）已经研究了FSHD2成肌细胞和成肌管细胞核中的基因表达。已显示DUX4从一个核扩散到附近的另一个核以诱导靶基因表达，即使不再检测到DUX4，该靶基因也可以持续存在。将FSHD2和对照细胞系从成肌细胞分化为早期（第3天）肌管的RNAseq可识别FSHD2中表达的54个mRNA，但不包含对照，包括典型的DUX4靶标以及DUXA和LEUTX。成肌细胞和早期成肌细胞中的单核分析表明，FSHD2与对照成肌细胞之间具有相似性，但成肌细胞中存在差异。从肌管分离的FSHD2核表达DUX4或不表达。它们被归类为HI或LO表示器。DUX4靶基因倾向于在HI组中表达，但不一致，因为它们在LO组中也以不同的水平表达。除DUXA外，它们的水平与HI组中DUX4的水平不平行。大多数FSHD2肌核蛋白不表达DUX4，但是即使DUX4蛋白不能表达，SLC34A2和LEUTX也可以在肌管中高水平成像。分化另外2天（至第5天）不会显着改变这些结果，但显示更高水平的靶基因表达。与LO组相比，RNAseq鉴定了HI中表达水平升高的约1500个基因产物，包括参与细胞周期的6个转录因子。这是令人惊讶的，因为肌管中的细胞核应该在G0中。即使无法检测到DUX4，抑制DUXA的表达也可以抑制ZSCAN4和LEUTX在更成熟的肌管中的表达。

马里兰巴尔的摩大学的玛丽亚·特拉菲坎特（Maria Traficante）提供了初步证据，表明在携带成熟FSHD人肌肉的小鼠中SLC34A2的血清水平升高。SLC34A2通常在上皮细胞中表达，并作为FSHD肌肉中DUX4程序的一部分表达。在健康的肌肉或正常人的血清中未发现明显的胆固醇。先前的工作表明，在FSHD肌肉活检中，SLC34A2的标记量要多于对照活检，而在FSHD肌源性前体细胞（MPC）的异种移植中，其标记量要多于对照MPC。与适当的对照（15 V，A4）相比，qPCR显示在两种不同的FSHD细胞系（15A，C6）中SLC34A2 mRNA的水平更高，表明其升高不是细胞系特异性的。异种移植物的蛋白质印迹也显示出SLC34A2蛋白升高。与15 V MPC移植物相比，携带15A MPCs制备的携带FSHD异种移植物的小鼠的血清印迹也显示SLC34A2蛋白水平升高。这些结果表明SLC34A2可能是FSHD的可靠血清生物标志物。

在Kunkel实验室工作的Yuanyuan Fan（Tracy）Zhang（波士顿儿童医院）一直在研究斑马鱼中DUX4过表达的影响。先前的研究表明，将DUX4注入鱼胚胎会导致对肌肉的不对称影响，从而在重要方面模仿人类疾病。注入鱼的RNAseq显示338个基因上调，而10个基因下调，其中55个基因显示出与人类FSHD肌肉细胞相似的变化。用他莫昔芬诱导型启动子可实现DUX4表达的更精细调节。当低水平表达时，DUX4引起轻度肌病。在96孔培养皿中筛选这些鱼是鉴定可纠正DUX4效应的小分子的有效方法。Zhang提出的数据表明，除草霉素和雷帕霉素均能降低DUX4的表达并保持更健康的肌肉形态，并减少细胞凋亡，脂肪和纤维化浸润。因此，斑马鱼中可诱导的DUX4模型对于抑制DUX4的药物可能是一个很好的体内筛选方法。

由于大多数FSHD病例不涉及特定的点突变，而是涉及3.3 kb大型卫星重复单元的拷贝数变化，从而导致其表观遗传调控发生变化，因此在许多情况下，遗传诊断可能具有挑战性。遗传学和表观遗传学部分的报告报告了确定D4Z4重复数和DNA甲基化状态的新方法和改进方法。此外，一项研究报告患者在10号染色体上携带缩短的D4Z4阵列并具有远侧FSHD允许序列，这增强了DUX4在疾病机理中的重要作用。

Sven Bockland（BioNano Genomics）展示了他们通过光学测绘技术表征D4Z4重复序列的成果。通过光学作图可以准确地确定大小和染色体，并提出了用于FSHD DNA诊断的自动化工作流程和报告，目前已在多个中心进行临床测试。该技术还允许检测低至6.25％等位基因分数的体细胞嵌合体，未来的应用包括D4Z4甲基化的检测。接下来，亚历山大·刘（儿童国家华盛顿特区）与牛津纳米孔D4Z4重复序列的长读序列分享了他的经验。他提出了一种基于CRISPR / Cas9的富集方案，导致FSHD1患者的4号染色体等位基因的D4Z4重复序列富集6至150倍，并对收缩和非收缩的D4Z4重复序列进行测序。该方法还允许进行甲基化分析，第一个数据指向整个重复序列中甲基化分布不均，并有收缩等位基因甲基化不足的证据。在最后的演讲中，理查德·莱默斯（Leiden University Medical Center）向两个家族提供了FSHD与10号染色体连锁的证据。在两个家族中，均检测到4号和10号染色体重复序列之间的从头易位，导致染色体上的重复序列收缩10以典型的FSHD允许染色体4序列结尾，该序列允许稳定的DUX4表达。

在发布者会议上，Nicolay Zernov提出了基于qPCR的FSHD1诊断方法，该方法基于EcoRI进行的DNA消化，脉冲场凝胶电泳分离，根据大小标准进行片段化以及将片段用作PCR模板。DarinaŠikrová向一名FSHD患者介绍了纯合的LRIF1变异体，该变异体与D4Z4低甲基化和DUX4表达相关，可鉴定LRIF1作为新的疾病基因。爱荷华州大学的乔恩·托马森（Jon Thomason）在40名受试者中进行了光学映射对FSHD分子诊断的验证研究，强调了该技术的准确性，鲁棒性，准确性和可重复性。Hayk Barseghyan（儿童国家华盛顿特区）的另一项光学制图研究为D4Z4的甲基化分析提供了原理证明。Sabrina Pagnoni（科尔多瓦天主教大学）介绍了通过Southern印迹法对FSHD进行DNA诊断的经验，代表了拉丁美洲的D4Z4等位基因和单倍型的首次分子表征。美国爱荷华州大学的Autumn Rieken对FSHD的CLIA实验室测试进行了回顾性分析，显示总阳性率为42％，其中7％为FSHD2阳性。最后，

尽管对FSHD的遗传原因有充分的了解，但该领域仍在努力了解哪些细胞表型和机制与DUX4的下游最相关，以及理解由DUX4泄漏导致的病理机制，其中DUX4的沉默是由于DHD4重复沉默导致的。尤其是考虑到直接检测肌肉切片中DUX4蛋白的困难，导致肌肉变性。病理学和疾病机制会议通过一系列有关DUX4表达的分子和组织水平影响的讲座解决了这些问题。虽然已经报道了FHSD中涉及缺氧信号传导，错剪的RNA和细胞死亡，但新发现为途径如何介导DUX4诱导的细胞毒性提供了见识和细节。此外，

耶鲁大学医学院的安吉拉·莱克（Angela Lek）展示了全基因组CRISPR筛选的结果，该筛选用于保护表达DUX4的成肌细胞免受细胞死亡的敲除。这确定了许多与缺氧信号传导相关的基因。尽管已知DUX4在一段时间内增强了细胞对氧化应激的敏感性，但这是该途径本身的信号传导活性与潜在的直接氧化损伤的潜在病理性相反，这是首次有害。在筛选之后进行的实验是使用化学方法在体外以及体内使用基于FSHD人肌肉异种移植物的小鼠模型来减少体内的缺氧信号传导，该实验揭示了体内缺氧信号传导与DUX4诱导的病理学在组织水平上的相关性在DUX4蛋白质积累水平上。

科罗拉多大学的艾米·坎贝尔（Amy Campbell）介绍了有关DUX4损害无意义介导的RNA衰变的发现的后续工作。她表明，带有移码突变的转录本由于未消除而导致在表达DUX4的细胞中产生免疫学上可检测到的新表位，尤其是涉及剪接的因子。发现一种特定因子，即从通常迅速降解的剪接转录本衍生而来的截短形式的SRSF3，在过表达时对细胞特别有害，可能部分解释了DUX4细胞死亡表型。

伦敦大学学院的朱莉·杜蒙索（Julie Dumonceaux）惊奇地发现，尽管半胱天冬酶抑制剂未能保护表达DUX4的细胞免于死亡，但一种坏死病抑制剂却能做到。她通过将Ripk3基因敲入基于肌肉特异性DUX4表达的FSHD小鼠模型的背景，测试了坏死病途径的体内相关性，并发现病理表型显着减少。

华盛顿大学的乔尔·张伯伦（Joel Chamberlain）进行了实验，以测试使用AAV9直接递送编码DUX4的人FSHD D4Z4片段。该构建体使用内源性DUX4启动子，并导致骨骼肌的剂量依赖性病理，包括纤维化，再生和纤维分裂的迹象。有趣的是，在观察到的最低剂量下，DUX4的表达水平几乎无法检测到，从而呈现出可检测的表型，这与人类的情况非常相似，在人体中，DUX4在人体肌肉活检样本中实际上是免疫组织化学检测不到的。

明尼苏达大学的Michael Kyba介绍了iDUX4pA小鼠模型的工作，其中当用强力霉素（dox）处理小鼠时，DUX4可以在肌肉纤维中特异性表达。由于该系统可通过撤消dox来逆转，因此该小组研究了DUX4突发（单次dox注入）或脉冲（dox注入10天）表达的长期影响。从积极的一面，发现在DUX4表达脉冲数月后，肌肉恢复到相对健康的组织学，支持了抑制DUX4的治疗潜力。在令人不安的方面，该小组发现，即使在数月后，纤维异常致祖细胞仍无法恢复正常，并提出了一种模型，其中这些细胞的长期异常导致进行性病理，现已脱离DUX4表达，

本次会议的特色是来自几个致力于制定FSHD治疗策略的实验室的演讲。主要工作集中在使用各种策略直接减少DUX4转录本，包括反义寡核苷酸，CRISPR-Cas系统，miRNA和siRNA。此外，已报道了通过上游途径调节DUX4表达的策略，包括关于可调节DUX4表达的改用药物losmapimod的首次临床试验。

来自亚伯达大学（University of Alberta）的丸山梨香（Rika Maruyama）和乔治华盛顿大学儿童国家医院的陈一文（Yi-Wen Chen）的两个演讲描述了用锁核酸（LNA）或2'-O-甲氧基-乙基（2 '-MOE）碱基，旨在使用RNA酶H介导的机制敲低DUX4 mRNA。Rika Maruyama提出了体外反义寡核苷酸（AOs）的筛选方法，Yi-Wen Chen报告了来自未诱导的FLExDUX4小鼠体内实验的数据，这些小鼠表达非常低的DUX4水平并表现出轻度的肌病性表型。皮下AO递送后，FLExDUX4小鼠显示出增强的握力和减少的纤维化，而肌肉重量未受影响。未来的研究将致力于改善体内向肌肉的递送，

两个演讲描述了在表达DUX4的人细胞和小鼠模型中使用不同机制抑制DUX4 mRNA的基于AAV的基因治疗策略。首先，Afrooz Rashnonejad（俄亥俄州哥伦布市全国儿童医院）使用了一种新型的CRISPR-Cas系统，该系统依赖于RNA靶向酶Cas13b，该酶可以沉默DUX4 mRNA而不会切割基因组。由于Cas13b太大，无法在同一AAV基因组中共同包装指导RNA表达盒，因此第一代系统需要注射2支AAV，其中一种表达来自U6启动子的指导RNA，第二种携带Cas13b蛋白表达卡带。该系统在体内和体外降低了DUX4的表达，并改善了表达DUX4的小鼠中DUX4相关的肌肉组织病理学。

在第二次基因治疗讲座中，林赛·华莱士（Lindsay Wallace）（俄亥俄州哥伦布市全国儿童医院）介绍了针对FSHD的基于AAV RNAi的基因治疗的开发进展。该小组先前已发表了几篇文章，证明了RNAi治疗在小鼠模型中的功效，现在正在优化将功效和安全性翻译至临床试验的策略。Wallace博士报告了TIC-DUX4小鼠的新未发表的长期功能和组织病理学改善，这些小鼠经过AAV9和AAV6载体系统治疗，该载体带有其团队的前导序列，称为miDUX4.405。此外，她总结了在小鼠中进行的盲式毒理学研究，该研究支持以临床相关剂量安全使用miDUX4.405。

凯瑟琳·达曼（Katelyn Daman）（马萨诸塞大学医学院）介绍了用于FSHD药物开发的体外和异种移植组合管道。在体外和在FSHD患者成肌细胞异种移植后的免疫缺陷小鼠肌肉中评估了靶向FSHD细胞中交叉途径的化合物或靶向DUX4的siRNA。Daman博士报告了鉴定出两种有前景的化合物，这些化合物导致DUX4靶基因表达降低。重要的是，一种化合物是已在人类中用于另一种适应症的改用药物，从而有可能加速其转化为FSHD进行功效测试的途径。

最后，开发以FSHD为重点的技术的公司展示了两个值得注意的海报。Fulcrum Therapeutics在losmapimod试验中介绍了评估骨骼肌中p38α/β靶标参与生物标志物的海报，losmapimod是目前正在FSHD患者的2b期（NCT04003974）2期试验中测试的一种DUX4还原小分子。microRNA治疗公司miRecule展示了抗DUX4修饰的RNA寡核苷酸的开发，该寡核苷酸偶联了miRecule的抗体递送技术，用于治疗FSHD。该策略的目的是在全身递送时改善寡核苷酸向肌肉的递送。

在过去的几年中，通过干预性试验，影像学研究，生物标志物研究以及大型的多场所自然史研究，FSHD的临床研究活动有所增加。最重大的挑战之一是该疾病的病程缓慢，这需要长期或大剂量的试验。一个关键的问题是特定的生物标记物是否可以提供功能功效的替代指标，从而增加功效。这些研究揭示了对该疾病进行临床试验的可行性以及评估疗效的方法。他们还有助于更好地了解FSHD

Christopher Banerji在本次会议上以FSHD1 UK注册表中自我报告症状的描述开始了会议（n = 643). The authors described four clinical presentations of FSHD1: a classical presentation (74%) describing a descending myopathy, and three facial sparing phenotypes—a mild presentation (5%) with later facial and periscapular involvement, an early shoulder presentation (10%) with accelerated periscapular weakness, and an early foot presentation (9%) with accelerated foot dorsiflexor weakness. Interestingly, the authors also found that pregnancy and carrying multiple children to term was associated with slower onset of all muscle symptoms. Although this is contrary to anecdotal reports of many women affected with FSHD who feel that their pregnancy accelerates their symptoms, it is in line with other studies that have suggested a protective effect of estrogen on the development of weakness in FSHD. Peter Lunt presented scatter plots created from his own and others’ published data, providing a visual illustration of the interrelationships of various factors influencing phenotype. One of the most interesting findings was that these plots illustrate reduced methylation and earlier onset following grandmaternal-maternal versus grandpaternal-paternal transmission.

Rabi Tawil描述了FSHD1中洛沙马莫德2b期临床试验的启动。Losmapimod是p38α/β的小分子抑制剂，在临床前研究中导致DUX4蛋白的剂量依赖性降低。在Fulcrum Therapeutics赞助的RDBPC试验中，将76例经遗传学确诊的FSHD1，年龄18至65，临床严重度评分为2至4（Ricci评分0-5），并通过MRI鉴定为STIR +骨骼肌的患者随机分为1组： 1至15毫克losmapimod或安慰剂PO BID，持续24周。主要结局指标是使用DUX4调控基因转录子集通过STIR +骨骼肌的定量聚合酶链反应（qPCR）测量的DUX4活性相对于基线的变化。Michelle Mellion描述了COVID-19大流行对临床试验带来的挑战，特别是在losmapimod试用版（ReDUX4）中。对ReDUX4协议进行了修订，包括通过虚拟访问，移动静脉放血，直接向患者运送研究药物以及将试验的随机对照部分从24周扩展到48周来确保安全性，以确保获得关键评估。Lucienne Ronco描述了生物标志物研究的结果，以鉴定一组稳定的DUX4调控的基因转录物，这些转录物将提供PD生物标志物终点来测量losmapimod治疗效果。入选了16个达到与ReDUX4研究相似的入选标准的受试者，每6周进行一次STIR +肌肉的穿刺活检。使用来自本研究和已发表研究的RNA-seq数据，鉴定出一组与DUX4相关的转录本。对ReDUX4协议进行了修订，包括通过虚拟访问，移动静脉放血，直接向患者运送研究药物以及将试验的随机对照部分从24周扩展到48周来确保安全性，以确保获得关键评估。Lucienne Ronco描述了生物标志物研究的结果，以鉴定一组稳定的DUX4调控的基因转录物，这些转录物将提供PD生物标志物终点来测量losmapimod治疗效果。入选了16个达到与ReDUX4研究相似的入选标准的受试者，每6周进行一次STIR +肌肉的穿刺活检。使用来自本研究和已发表研究的RNA-seq数据，鉴定出一组与DUX4相关的转录本。对ReDUX4协议进行了修订，包括通过虚拟访问，移动静脉放血，直接向患者运送研究药物以及将试验的随机对照部分从24周扩展到48周来确保安全性，以确保获得关键评估。Lucienne Ronco描述了生物标志物研究的结果，以鉴定一组稳定的DUX4调控的基因转录物，这些转录物将提供PD生物标志物终点来测量losmapimod治疗效果。入选了16个达到与ReDUX4研究相似的入选标准的受试者，每6周进行一次STIR +肌肉的穿刺活检。使用来自本研究和已发表研究的RNA-seq数据，鉴定出一组与DUX4相关的转录本。并将试验的随机对照部分从24周延长至48周，以确保获得关键评估。Lucienne Ronco描述了生物标志物研究的结果，以鉴定一组稳定的DUX4调控的基因转录物，这些转录物将提供PD生物标志物终点来测量洛马斯莫德治疗效果。入选了16个达到与ReDUX4研究相似的入选标准的受试者，每6周进行一次STIR +肌肉的穿刺活检。使用来自本研究和已发表研究的RNA-seq数据，鉴定出一组与DUX4相关的转录本。并将试验的随机对照部分从24周延长至48周，以确保获得关键评估。Lucienne Ronco描述了生物标志物研究的结果，以鉴定一组稳定的DUX4调控的基因转录物，这些转录物将提供PD生物标志物终点来测量losmapimod治疗效果。入选了16个达到与ReDUX4研究相似的入选标准的受试者，每6周进行一次STIR +肌肉的穿刺活检。使用来自本研究和已发表研究的RNA-seq数据，鉴定出一组与DUX4相关的转录本。Lucienne Ronco描述了生物标志物研究的结果，以鉴定一组稳定的DUX4调控的基因转录物，这些转录物将提供PD生物标志物终点来测量losmapimod治疗效果。入选了16个达到与ReDUX4研究相似的入选标准的受试者，每6周进行一次STIR +肌肉的穿刺活检。使用来自本研究和已发表研究的RNA-seq数据，鉴定出一组与DUX4相关的转录本。Lucienne Ronco描述了生物标志物研究的结果，以鉴定一组稳定的DUX4调控的基因转录物，这些转录物将提供PD生物标志物终点来测量losmapimod治疗效果。入选了16个达到与ReDUX4研究相似的入选标准的受试者，每6周进行一次STIR +肌肉的穿刺活检。使用来自本研究和已发表研究的RNA-seq数据，鉴定出一组与DUX4相关的转录本。

Jeffrey Statland介绍了Acceleron Pharma赞助的FSHD ACE-083的2期试验结果。ACE-083是一种局部递送的非特异性肌肉生长抑制素抑制剂，可诱导肌肉增长。这是一个分为两部分的研究：第一部分是剂量范围（N = 37）；第二部分是剂量范围。第2部分是RDBPC，为期6个月，然后是6个月的开放标签期。患者每三周向双侧胫骨前肌（TA）或肱二头肌（BB）肌肉注射ACE-083 240 mg /肌肉或安慰剂（1：1）（N = 58）。主要终点指标是TA或BB的肌肉质量增加。ACE-083通常是安全的，并且耐受性良好。ACE-083的肌肉体积平均增加13.8％（2.9），而安慰剂则为4.3％（2.7）（pTA中的= 0.01），而ACE-083的增幅为19.1％（2.8），而BB中的安慰剂为2.7％（2.8）（p <0.0001）。因此，该研究达到了其主要终点。但是，由于没有相关的功能增加，因此终止了用于FSHD的ACE-083的开发。

该行业小组为生物技术和制药公司提供了自我介绍，平台和兴趣的机会，以促进与研究界的合作和伙伴关系。今年的小组成员包括Dyne Therapeutics的Romesh Subramanian，他着重介绍了Dyne的递送技术，该技术可将治疗剂靶向肌肉。Fulcrum Therapeutics的Michelle Mellion详细介绍了Fulcrum对FSHD的承诺以及该公司的海报和口头报告，涉及从生物标志物和临床试验设计到使用p38抑制剂losmapimod进行2b期临床试验的主题。miRecule的Anthony Saleh讨论了他公司的抗体介导的肌肉靶向平台在提供靶向DUX4的RNA治疗剂方面的临床前进展。最后，

除了科学会议和行业座谈会之外，FSHD学会还表彰了三位杰出的FSHD青年研究人员（耶鲁大学的安格拉·莱克；拉德布德大学医学中心的Karlien Mul；科罗拉多大学的Sujatha Jagannathan）并向日本莱顿大学医学中心的DarinaŠikrová和日本国立神经科学研究所的Kohei Hamanaka。

随着对DUX4表达分子后果的研究逐渐成熟，无数种途径的改变继续增长。从实验模型中观察到的与人类肌肉变性相关的方法缩小的方法对于确定哪种方法最相关或病理是否是由于许多微扰的结合是必要的。

关于抑制DUX4的疗法，最近的工作强调了降低DUX4表达但在许多其他途径中具有系统性后果的药物的潜力，以及针对DUX4的策略，但难以有效，特异性地递送至大多数相关细胞类型在肌肉中。由于前者目前正在临床试验中，因此该领域急切期待第一个结果，同时希望开发出一些方法来推进后者。

2020年FSHD国际研究联合会大会汇集了来自世界各地的280名参与者，以介绍研究结果并交流思想。科学亮点包括对疾病机制的新见解，用于疾病诊断的前沿方法以及正在进行的针对FSHD潜在疗法的临床前和临床研究。计划于2021年召开的FSHD国际研究联合会将在荷兰的莱顿举行，重点是会议的全球性。

不适用。

2'-MOE：: 2'-O-甲氧基-乙基
AAV：: 腺相关病毒
AO：: 反义寡核苷酸
BB：: 肱二头肌
出价：: 每天两次
dox：: 强力霉素
FSHD：: 面肩肱型肌营养不良
LNA：: 锁核酸
MPC：: 成肌前体细胞
PO：: 口头
定量PCR: 定量聚合酶链反应
RDBPC：: 随机双盲安慰剂对照
TA：: 胫前肌

我们感谢以下赞助商支持2020 FSHD国际研究大会：AFM Telethon，Avidity Biosciences，Bionano Genomics，Dyne Therapeutics，Fulcrum Therapeutics，Genomic Vision，肌肉营养不良协会，MiRecule，PerkinElmer Genomics，马萨诸塞大学医学院/ NIH / Wellstone内华达大学医学院中心。

计划委员会和联合主席

FSHD协会的Jamshid Arjomand

罗伯特·布洛赫（Robert Bloch），美国马里兰大学医学院

陈宜文，儿童国家研究所/乔治华盛顿大学，美国

朱莉·杜蒙索（Julie Dumonceaux），英国伦敦大学学院

斯科特·哈珀（Scott Harper），美国全国儿童医院研究所

美国FSHD学会June Kinoshita

Michael Kyba，美国明尼苏达大学

美国FSHD协会的Mikell Lang

美国FSHD协会的Mark Stone

Fran Sverdrup，美国圣路易斯大学医学院

荷兰莱顿大学医学中心的SilvereSilvèreM.van der Maarel

荷兰拉德布德大学医学中心的Baziel van Engelen

凯瑟琳·瓦格纳（Kathryn R.Wagner），肯尼迪·克里格研究所/约翰·霍普金斯医学院

这次会议是由FSHD协会资助的。

隶属关系

美国明尼苏达州明尼阿波利斯大学儿科，美国明尼苏达州55104
迈克尔·基巴（Michael Kyba）
马里兰大学医学院生理学系，马里兰州巴尔的摩，美国21201
罗伯特·布洛赫
英国伦敦大学学院，大奥蒙德街儿童保健研究所和大奥蒙德街医院NIHR生物医学研究中心NHS Trust，伦敦，WC1N 1EH，英国
朱莉·杜蒙索
俄亥俄州立大学儿科，俄亥俄州哥伦布，43205，美国
斯科特·哈珀
美国俄亥俄州哥伦布市儿童医院Abigail Wexner研究所基因治疗中心，美国43205
斯科特·哈珀
莱顿大学医学中心人类遗传学系，荷兰莱顿
西尔维尔·范·德·马雷尔
爱德华·杜伊斯（Edward A. Doisy），圣路易斯大学生物化学与分子生物学系，美国密苏里州圣路易斯，邮编：63104
弗朗西斯·斯维尔德鲁普
肯尼迪·克里格研究所遗传肌肉疾病中心，马里兰州巴尔的摩，美国21205
凯瑟琳·瓦格纳
约翰霍普金斯医学院神经病学和神经科学系，马里兰州巴尔的摩，美国21205
凯瑟琳·瓦格纳
荷兰奈梅亨，拉德布德大学医学中心神经内科
巴塞尔·范·恩格伦
美国华盛顿特区，乔治华盛顿大学，基因组学和精密医学系，20052
陈宜文
儿童国家研究所遗传医学研究中心，华盛顿特区，20010，美国
陈宜文

Michael Kyba查看作者出版物
您也可以在PubMed Google学术搜索中搜索该作者
Robert J. Bloch查看作者出版物
您也可以在PubMed Google学术搜索中搜索该作者
Julie Dumonceaux查看作者出版物
您也可以在PubMed Google学术搜索中搜索该作者
Scott Q. Harper查看作者出版物
您也可以在PubMed Google学术搜索中搜索该作者
SilvèreM. van der Maarel查看作者出版物
您也可以在PubMed Google学术搜索中搜索该作者
Francis M. Sverdrup查看作者出版物
您也可以在PubMed Google学术搜索中搜索该作者
Kathryn R. Wagner查看作者出版物
您也可以在PubMed Google学术搜索中搜索该作者
Baziel van Engelen查看作者出版物
您也可以在PubMed Google学术搜索中搜索该作者
陈以文查看作者出版物
您也可以在PubMed Google学术搜索中搜索该作者

会费

所有作者都为撰写和审阅本报告做出了贡献。作者阅读并批准了最终手稿。

通讯作者

对应于陈以文。

道德规范的批准和同意参加

不适用。

同意发表

不适用。

利益争夺

作者宣称他们没有竞争利益。

发行人注意

对于出版的地图和机构隶属关系中的管辖权主张，Springer Nature保持中立。

开放存取本文是根据知识共享署名4.0国际许可许可的，该许可允许以任何媒介或格式使用，共享，改编，分发和复制，只要您对原始作者和出处提供适当的信誉，链接到知识共享许可，并指出是否进行了更改。本文的图像或其他第三方材料包含在该文章的知识共享许可中，除非在该材料的信用额度中另有说明。如果该材料未包含在该文章的创用CC许可中，并且您的预期用途未得到法律法规的许可或超出了许可的用途，则您需要直接获得版权所有者的许可。要查看此许可证的副本，请访问http://creativecommons.org/licenses/by/4.0/。

转载和许可