Action Duchenne has been a leader in supporting research since its inception in 2001, pump-priming the leading international organisations, research and clinical trial teams. Here is some information on projects that we have supported.
Exon skipping in combination with BGP-15
Action Duchenne also supported a project with Professor Matthew Wood, Oxford University. This one year contract, which started in September 2013, is looking at a small molecule drug (BGP-15) which activates the heat shock response (a hsp72 agonist) and, therefore, has the ability to protect cells (e.g. muscle cells) from stress (such as that resulting from muscle degeneration). This therapy has shown benefit in the mdx mouse and dystrophin and utrophin deficient DKO mouse.
BGP-15 is currently being investigated in diabetes and a range of other disorders and has been shown to be well-tolerated. Of course such an approach cannot repair or replace dystrophin, but by helping to protect degenerating muscle cells it may help to create a much more favourable environment for other therapies, including exon skipping to work. This pump priming project therefore aims to carry out a preliminary study to determine whether or not BGP-15 has any synergistic benefit when co-administered with current state-of-the-art antisense oligonucleotides for exon skipping, peptide-conjugated PMOs.
In November 2013, Action Duchenne, provided funding for one year of an innovative cutting-edge proposal entitled: “Exosomes: a novel therapeutic approach for the treatment of dystrophinopathies.” This project will be led by Dr Mattia Calissano, Newcastle University and expert collaborators Professor George Dickson, Royal Holloway and Francesco Muntoni.
Exosomes are natural lipid particles secreted by a vast variety of cells. By using these particles experimentally loaded with wild type dystrophin protein; the investigators aim to target and restore correct amounts of the dystrophin protein. This approach could offer a new and highly physiological way to restore dystrophin expression and thus functionality in the both the skeletal and cardiac muscles.
Development of triple-transplicing technology using AAV Vectors
In 2011, Action Duchenne invested in the first programme of its kind, using adeno-associated virus via triple-transplicing technology, a form of gene therapy, to deliver the full dystrophin gene. Dr Keith Foster, Reading University, led the project entitled: “Development and evaluation of AAV vectors to restore full length dystrophin to skeletal and cardiac muscle.”
Gene therapy for Duchenne aims to compensate for the lack of dystrophin by transferring the functional dystrophin gene into muscle. Since the DMD gene is the largest gene in the body, delivery of the whole gene is difficult. Shortened versions of the gene have been developed, but full functionality of the protein expressed is compromised as a result of important parts of the protein being missing.
This approach aims to address this problem by dividing the DMD gene into three segments and packaging them into a series of novel gene carriers (known as trans‐spliced adeno-associated virus vectors). The vectors are based on harmless viruses that can carry DNA for delivery to targeted cells within the body. These vectors have been designed so that when used in combination, the different DMD gene segments join together and full length dystrophin protein is expressed (see Figure 6 for more details).
Dr Keith Foster demonstrated proof-of-concept that this methodology can work (data-led evidence that three AAV vectors can be used in concert to deliver full length dystrophin). He started to produce a second-generation viral vector to increase the efficiency of this approach and improve the levels of dystophin expression. He also plans to publish his work in the near future based on the findings of this project that repeat AAV administration results in incremental levels of gene expression.
Exon Skipping with PNAs
Action Duchenne also supported an exon-skipping project by Professor Haifang Yin in China with a three year project, which is shortly coming to an end entitled: “Developing Peptide Nucleic Acid Antisense Oligonucleotides for Duchenne Muscular Dystrophy.”
Since 2006, Haifang Yin and Wood have started to investigate alternative antisense oligonucleotide (AO) chemistries, e.g. peptide nucleic acid (PNA). PNAs are DNA/RNA analogues formed by replacing the sugar phosphate backbone of the native nucleic acid with a synthetic glycine peptide backbone, which is stable and highly resistant to proteases and nucleases with high nucleic acid binding affinity and sequence specificity. The promising data from local and systemic PNA studies indicated that more systematic studies are warranted to fully characterize and explore the clinical potential of PNA AOs for Duchenne. After lots of trials and optimization, Haifang and the team proved the feasibility of synthesizing neutral and clinically applicable PNA AOs and establish the standard protocol, paving the way for developing PNA AOs to clinic. However, the scale-up needs to be further improved for a longer-term.
While the team have been trying the best to establish the therapeutic PNA synthesis platform with a longer horizon to clinic, they have also been exploring other clinically applicable delivery approaches. The team are currently optimising novel formulations that can also facilitate the uptake of AOs in muscle.
Action Duchenne alongside other foundations supported the pre-clinical development of a novel compound called halofuginone, developed by HALO therapeutics. Halo’s HT-100, an investigational anti-fibrotic for Duchenne, is temporarily on hold in the US following a formal action from the FDA requiring Halo to stop dosing and to not enrol new boys in the phase IIa program. The study was placed on hold at the end of December and since their decision the FDA have met with the study team and they expressed their commitment to working with the lead investigators to allow the program to continue as soon as possible.
The target of the investigational compound, fibrosis, with progressive replacement of muscle tissue, is a prominent feature in some muscular dystrophies, preventing complete regeneration and hampering muscle functions. Halofuginone, an inhibitor of Smad3 phosphorylation downstream of TGF signaling, inhibits the activation of fibroblasts and their ability to synthesize the extracellular matrix. In animal models of duchenne and other muscular dystrophies with prominent muscle fibrosis, halofuginone treatment has resulted in both prevention of collagen production in young animals and resolution of established fibrosis in older ones: the reduction in muscle collagen content was associated with improved muscle histopathology and major improvements in muscle function.
Pilot Trials Now – Sildenafil and IGF-I
Since 2011, Action Duchenne has invested in two programs of the Pilot Trials Now initiative, which ended at the end of 2013.
The first trial testing sildenafil (Revatio or Viagra), originally developed by Pfizer as a heart medication, has been shown to delay and even prevent heart failure in the DMD animal model. The prinicipal Investigator Kathryn Wagner, Kennedy Krieger Institute of Johns Hopkins University led the 12-month, double-blind, placebo-controlled REVERSE DBMD pilot trial to test if Phosphodiesterase 5 inhibition with sildenafil improved cardiac function in adults and adolescents living with Duchenne.
In August 2012, the Food and Drug Administration authority notified healthcare professionals that “use of Revatio, particularly chronic use, in children is an off-label indication, not approved by FDA and is not recommended.” The trial consequently excluded those enrolled under the age of 18.
The full data analysis of the secondary endpoints is still ongoing and is awaiting publication. This was a small study due to Data Safety Monitoring Board recommended closure; therefore this is a cautious interpretation. Overall, Sildenafil was well tolerated in DMD men, but is unlikely to provide benefit to cardiac or skeletal muscle in adult DMD. Sildenafil at 20 mg three times a day for 6 to 12 months may have adverse effects on cardiac function. The study authors concluded that the monitoring of cardiac function in future clinical trials modulating this pathway will be necessary.
The second trial from the Pilot Trials Now scheme was recombinant human insulin-like growth factor-I (IGF-I) therapy in Duchenne. IGF-I was seen as offering potential as a therapeutic agent by improving or preserve muscle function, and countering the effects of glucocorticoid steroid use in some boys, of growth failure and insulin resistance.
In this first study of IGF-I therapy in DMD boys, 6 months of once-daily IGF-I significantly increased height velocity and compared to controls, but there was no difference in motor functional outcomes.
These results were presented at the World Muscle Congress in October 2013 and are currently awaiting acceptance in a leading peer-reviewed scientific journal the European Society of Paediatric Endocrinology.
2009 £800,000 AVI Biopharma – The project with the US biopharma has three progammes: Engaging with European and US regulatory authorities to develop exon skipping as a platform medicine,Research and development of other oligos to skip exons 53, 44, 45 and further Development of
European Clinical Trial sites
2009 £35K Appointment of Dr Karen Rafferty, Treat Duchenne Muscular Dystrophy Coordinator. To support the dissemination of internationally agreed Standards of Care for Duchenne to families and clinicians in the UK.
2009 £166K Dr Matthew Wood and Dr Mike Gait – Advances in exon skipping for Duchenne muscular dystrophy: heart correction and multi-exon skipping in partnership with Duchenne lreland
2008 £80K Professor Steve Wilton University of Western Australia – Antisense Oligonucleotide Design in partnership with the James and Matthew Foundation lreland
2008 £20K Dr Mike Gait University of Cambridge, MRC Molecular Biology Laboratory – Development of peptide PNA conjugates for exon skipping
2008 £155K Dr Matthew Wood University of Oxford PNA exon skipping project
2007 £30K Profs. Volker Straub and Kate Bushby, Institute of Human Genetics, Newcastle University, Newcastle upon Tyne, UK – Effect of pharmacologically increased endothelial permeability on the uptake of antisense oligonucleotides in cardiac myocytes in mdx mice
2007 £175K Established the ZF Partnership with leading drug discovery company Summit that has helped to support the further development of a utrophin upregulation drug by Biomarin in the USA. In partnership with Charley’s Fund and Gavriel Meir Trust.
2006 £60K Professor Steve Wilton University of Western Australia – Using explants to develop Exon skipping
2006 £150K Professor Kay Davies University of Oxford Using AAV/U7 to develop exon skipping for Duchenne in partnership with ICE (Monaco and France Duchenne Parent projects)
2005 £ 100K Dr Jenny Morgan and Professor Francesco Muntoni lmperial College and UCL London – Stem cell therapy using a lentivirus to modify the faulty gene
2003 Establishing the MDEX consortium with leading UK scientists and Clinicians in partnership with the Muscular Dystrophy Campaign and Duchenne Family Support Group . Funding of 2.2m secured for the MDEX consortium from the Department of Health and the Medical Research Council