Séminaires et conférences

Antisense oligomer induced spliceoform switching:  from Duchenne muscular dystrophy to common serious inherited and acquired diseases

Steve Wilton ^1,2*, Merlin Thomas³, May Aung-Htut^1,2, Craig McIntosh^1,2, Abbie Adams^1,2, Kristin Ham^1,2, Russell Johnsen², Dunhui Li^1,2, Jessica Cale², Bal Poudel^1,2

¹Centre for Molecular Medicine and Innovative Therapeutics, Murdoch University, Australia. ²Perron Institute, The University of Western Australia, Australia. ³Department of Diabetes, Monash University, Australia.

* email:

Abstract

Duchenne muscular dystrophy is an X-linked recessive disease with a high de novo mutation rate. Arising from null mutations (nonsense, frame-shifting insertions/deletions varying from a single base to multiple exons) that preclude synthesis of a functional dystrophin protein, affected boys are typically restricted to a wheelchair before the age of 12 years.  In contrast, in-frame whole exon deletions in the massive 79 exon, 14 kb mRNA dystrophin gene can present with no or only mild symptoms, indicating that many exons in this gene are not essential for near normal function.  This phenotype:genotype correlation laid the foundations for an antisense oligomer intervention during the dystrophin pre-mRNA processing. This intervention aimed to excise a specific exon during splicing to restore the reading frame around a frame-shifting deletion, or remove an intra-exonic nonsense mutation without disrupting the reading frame. The US Food and Drug Administration have now granted accelerated approval for three morpholino oligomers targeting different dystrophin exons, each relevant to certain sub-classes of genomic deletions.  The first drug approved in September 2016, (Eteplirsen), induces skipping of exon 51 and is relevant to the 10-13% of DMD patients whose genomic deletions ended with exon 50 or with DMD-causing deletions starting with exon 52.  Casimersen, the last drug approved in February 2021 targets exon 45 and is relevant to various deletions ending with exon 44 or starting with exon 46. Trials are ongoing evaluating higher doses, treating younger children and examining the “second generation morpholinos”, and eteplirsen coupled to a cell penetrating peptide that is administered monthly at lower doses. Results reported to date are most promising, with monthly injections of 30mg/kg (rather than weekly) resulting in 8-fold more dystrophin than the uncomplexed Eteplirsen !

Splice switching antisense oligomers are now offering some hope in the treatment of rare diseases and much has been learnt.  The Molecular Therapy laboratory in Perth is exploring possible antisense oligomer strategies for many different diseases, from juvenile onset Parkinson’s to adult onset Pompe’s disease, from Marfan syndrome to multiple sclerosis.  In collaboration with colleagues at Monash University, Melbourne Australia, we are also focussing on designing therapeutic strategies for much more prevalent human disorders, including asthma, diabetes and the highly relevant and topical COVID pandemic. If we can successfully develop antisense oligomers capable of increasing our COVID resistance or conferring anti-inflammatory properties where appropriate, massive demand will require a restructuring of oligomer scales of production and cost.

Keywords Antisense oligomers; Genetic Disease; Duchenne muscular dystrophy; Exon skipping; Isoform Switching, RAGE

Read more about Steve Wilton:
Professor Steve Wilton is the Director of the Centre for Molecular Medicine and Therapeutics at Murdoch University and the Perron Institute for Neurological and Translational Science (QE II Medical Centre, Western Australia).  He has positioned the Molecular Therapy Laboratory to become a pipeline of future drug development to treat many inherited and acquired diseases. The MTL is currently investigating treatments for more than 50 diseases, several of which are being undertaken with national and international collaborators.  He is committed to developing new therapeutics for many different conditions through “Therapeutic Alternative Splicing”, using antisense compounds to redirect gene expression as required for each condition: targeted exon skipping to bypass disease-causing mutations, promote retention of exons lost through splice motif mutations or disrupt expression of toxic gene products.

The US FDA granted accelerated approval for the first dystrophin exon-skipping drug (Eteplirsen) in September 2016, a second drug Golodirsen was approved in 2019 and Casimersen received accelerated approval in February 2021 as treatments for Duchenne muscular dystrophy.  With longtime colleague Prof Sue Fletcher, their work has been recognized with the 2012 Western Australian Innovator of the Year award, the 2013 Australian Museum Eureka Award for Translational Medicine, the 2014 LabGear Australia Discovery award, a finalist in the 2016 Western Australian of the Year (Professions Category) and a finalist for the Prime Minister’s Award for Science (2019).

Bryan J. Traynor is a neurologist and Senior Investigator at the National Institute on Aging, and adjunct faculty at Johns Hopkins University and Queen Square Institute of Neurology, UCL. He is best known for his work to understand the genetic etiology of amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD). He led the international consortium that identified pathogenic repeat expansions in C9orf72 as a common cause of ALS and FTD. Other genes discovered by his laboratory as causes of ALS and FTD include VCP, MATR3, KIF5A and HTT. His principal interests are in ALS, FTD, myasthenia gravis, and genomics.

Summary: I will discuss how genomics has advanced our understanding of amyotrophic lateral sclerosis (ALS) by finding new genes and providing us with the tools to unlock the mysteries of this disease first described Charcot all those years ago.

Bryan Traynor’s CV

Adeno-associated virus vector-based in vivo gene therapy – State of the art, challenges and strategies for mitigation

Guangping Gao, PhD, Horae Gene Therapy Center & Weibo Li Institute for Rare Diseases Research, University of Massachusetts Medical School.

This presentation will provide an overview on the key principles, state of the art, challenges, and potential strategies to mitigate in AAV in vivo gene therapy. The presentation will also showcase AAV capsid discovery and engineering to modulate target tissue tropism, therapeutic gene expression cassette design and optimization to enhance transduction efficiency, tissue/cell type specify and reduce immunogenicity, and examples of AAV gene therapy development: from proof-of-concept preclinical studies to first-in-human clinical evaluation.

Speaker Short Bio

 Guangping Gao, PhD is the Director, Horae Gene Therapy Center and Viral Vector Core, Co-Director, Li Weibo Institute for Rare Diseases Research, Professor of Microbiology and Physiological Systems, Penelope Booth Rockwell Professor in Biomedical Research, University of Massachusetts Medical School; Elected fellows, both the US National Academy of Inventors  (NAI) and American Academy of Microbiology; Past president, American Society of Gene and Cell Therapy.

Dr. Gao is an internationally well recognized gene therapy researcher, instrumental in the discovery and characterization of a new family of adeno-associated virus (AAV) serotypes, which revitalized the field of gene therapy. Dr. Gao’s research primarily focuses on gene therapy platform technologies and product development.

Dr. Gao has published more 310+ research papers, 6 book chapters, and 5 edited books. Dr. Gao holds 191 patents with 401 more patent applications pending.  He serves as Executive Editor-In-Chief of Human Gene Therapy, Senior Editor of the Gene and Cell Therapy book series, Associate Editor of Signal Transduction and Targeted Therapy, and on Editorial Boards of several other gene therapy and virology journals. Dr. Gao was ranked as the World Top 20 Translational Researchers by Nature Biotechnology.

Biosketch

More information on Charlotte A. Peterson and on her laboratory

Adam J. Engler is a Professor and Vice-Chair of Bioengineering at UC San Diego, where he has been on the faculty since 2008. He also is a resident scientist at the Sanford Consortium for Regenerative Medicine and Associate Director of the Medical-Scientist Training Program (MSTP).

Dr. Engler previously trained with Dr. Dennis Discher at the University of Pennsylvania, where he earned his PhD studying how ECM stiffness regulated stem cell fate. He also trained as a postdoc with Dr. Jean Schwarzbauer at Princeton University’s Department of Molecular Biology where he studied the mechanics of extracellular matrix assembly.

Dr. Engler’s current research focuses on how physical and chemical properties of the niche influence or misregulate cell function and modify genetic mechanisms of disease. In particular, his lab studies this phenomenon in the context of cardiovascular diseases and cancer. To accomplish this, his lab makes natural and synthetic matrices with unique spatiotemporal properties to mimic niche conditions, improve stem cell behavior and commitment in vitro, or direct them for therapeutic use in vivo. He currently has published over 100 manuscripts with an H-index of 52, holds 3 patents, and has a start-up company focused on stem cell research products.

Dr. Engler has received numerous awards in recognition of this research, including young investigator or mid-career awards from International Society for Matrix Biology (2008), Biomedical Engineering Society (2008), American Society of Matrix Biology (2014), American Society of Mechanical Engineering (2015), and American Society for Engineering Education (2018). Dr. Engler is a 2018 fellow of the American Institute for Biomedical Engineering and recipient of an NIH New Innovator Award grant (2009).

More information on Adam J. Engler’CV.

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More information on Shin’Ichi Takeda’s biosktech.