Research provided by Professor Allan Bretag, Muscular Dystrophy South Australia, Director of Research
Other oral presentations were made in three symposium sessions, one on Glycogenosis, one on Lipid and again, it is my great pleasure to be able to write this year’s Research Report for you, albeit, for a second time, having to be written just in advance of an important clinical and scientific neuromuscular research meeting, on this occasion the 17th International Congress of the World Muscle Society (WMS 2012) that I expected to attend in Perth in early October. These reports must be prepared for the printed version of the MD South Australia Annual Report ahead of the Associations Annual General Meeting in November. Timing is, therefore, unfortunate, as the latest news from this Annual Congress cannot be included.
As a result, most of the present report will, once again, be taken up with news from earlier clinical/scientific research conferences that I have attended in the last year and from medical/scientific journal articles that I have read in the meantime.
In mid October last year, I attended the (16th) International Congress of the World Muscle Society (WMS 2011) in Almancil (near Faro) in southern Portugal. From memory there were well over 800 registered delegates in attendance. The Congress was held in a hotel complex where most attendees were also accommodated, with only a golf course and the beach (at rather more than an easy walking distance) to entice delegates away from conference sessions. For this reason, and because of the outstanding clinical and scientific advances being presented in lectures, symposia and posters, all sessions were very well attended.
Duchenne MD (DMD) – There was great interest in news of several clinical trials in DMD under way or about to begin. Pertinent lectures were given by Dr Natalie Goermans of Leuven, Belgium, Drs Matthew Wood and Steve Winder of Oxford, UK and Dr Kevin Flanigan of Columbus, Ohio, USA. Trials discussed included that by Sarepta Therapeutics of Eteplirsen (AVI-4568), their exon 51 skipping drug. This trial recently concluded with some apparently dramatic results in four treated boys who scarcely deteriorated in the six minute walk distance (6MWD) test over the 36 week trial duration compared to four boys who received a placebo. Dr Jerry Mendell of Nationwide Children’s Hospital, Columbus, Ohio described the result as an “unprecedented treatment effect”. Personally, I would wish to see these findings duplicated, or shown to be as effective in a much larger trial, before I was as convinced. Nevertheless, it does appear to be a very significant advance. Dr Natalie Goermans presented details of ongoing and future trials of the Promega exon 51 skipping drug PRO-051. As of mid August 2012, Promega/GlaxoSmithKline had completed recruitment for their phase III trial of PRO-051 (also known as GSK2402968) and now given the generic name, Drisapersen. Results are expected in mid 2013. Of particular interest was a lecture given by Dr Matthew Wood of Oxford who described a new kind of antisense oligonucleotide (AON), similar to the exon 51 skipping drugs already mentioned, but which target heart muscle and might be, therefore, extremely helpful in the cardiac complications that so frequently affect DMD boys. Newly determined paths forward for gene therapy in DMD using adeno-associated viruses (AAV) containing mini dystrophin genes were outlined by Dr Kevin Flanigan. On a different tack entirely, Dr Steve Winder has been working on the possibility of inhibiting dystroglycan phosphorylation as a way of circumventing the lack of dystrophin in Duchenne MD. Dystroglycan is a major constituent of the, so-called, DAP complex which acts as the grommet in the muscle cell membrane through which dystrophin normally attaches to the fibrous connective tissue between muscle cells to protect the delicate membrane from damage. When dystrophin is not attached to it from the inside, dystroglycan becomes phosphorylated and is then destroyed by enzymes inside the muscle cell. If unattached dystroglycan can be maintained in the cell membrane, and not destroyed, then through the DAP complex its attachment to the fibrous connective tissue could help to stabilise the otherwise excessive membrane fragility due to the absence of dystrophin. This is an entirely new concept as a potential therapy for Duchenne MD.
Spinal Muscular Atrophy (SMA) – At least three different strategies for the treatment of SMA were described by Dr Arthur Burghes of Ohio State University, USA, as a result of the understanding of the genetic cause of the disease painstakingly accumulated through years of research. These include the use of drugs that promote the read-through of stop signals in genes (similar to the strategy tried with Ataluren for DMD), the use of specially designed AON drugs (similar to the strategy being trialled for DMD) and the use of newly developed viral vectors such as scAAV9-SMN for neuron-targeted gene therapy with the Survival Motor Neurone (SMN) gene that is absent or mutated in SMA. Each of these strategies has been tested in mouse models of SMA with considerable success and clinical trials are anticipated.
Myotonic Dystrophy or Myotonic Muscular Dystrophy (MMD) – MMD occurs as two distinct diseases (MMD1 and MMD2) caused by mutations in two quite different genes but producing similar symptoms of muscle stiffness (myotonia) and muscle wasting and weakness. It is also known as Dystrophia Myotonica (DM) with its two forms then designated DM1 and DM2. As for SMA, the dramatic increase in the understanding of the molecular and cellular pathology of MMD1 and MMD2 has raised the possibility of several forms of therapy. Drs Jack Puymirat from Laval University, Quebec, Canada and Andrew Leger from the University of Rochester and Genzyme Corporation, USA, announced that AON drugs specific to the disease were being developed both as standard chemical compounds and as more complex viral vectors. Since then extremely encouraging tests of the so-called “Gapmer Antisense” drug, ASO 445236, in MMD1 mice, by Drs Thurman Wheeler, Andrew Leger, Charles Thornton and their colleagues at Rochester, have found elimination of the myotonic stiffness and reduced shrinkage of muscle. Again clinical trials are expected in the foreseeable future.
Fascioscapulohumeral MD (FSHD) – Dr Lindsay Wallace from Columbus, Ohio, USA presented recent findings regarding FSHD which also suggested an approach towards therapy. In FSHD there is an over production of DUX4 protein which disrupts muscle cell structure and function.
Once again, AON drugs specific to the genetic defect loom as prospective therapeutic agents, having been successfully tested on muscle cells in tissue culture. In something of a blow to the complete understanding of FSHD, DUX4 protein has since been found, by researchers at the Boston Biomedical Research Institute in Watertown, Massachusetts, USA, to be produced in unaffected relatives of people who have FSHD. It appears that the presence of DUX4 in muscles is necessary to cause the disease but it might not be the sole cause. In those people who have DUX4 in their muscles, and are affected, some other contributing factor might be present or the unaffected relatives with DUX4 might have some protective factor. This is an area of intense research.
Limb Girdle MDs (LGMD) – For the various LGMDs progress is equally rapid according to Dr Kevin Flanagan, also from Columbus, Ohio, USA, with clinical trials of gene therapy delivered by viral vectors coming up. Of considerable interest to me was that I was able to meet and speak, for the first time, with Dr Bjarne Udd from the University of Helsinki, Finland, who has been a co-discoverer of the involvement of mutations in the gene ANO5 in LGMD type 2L and Miyoshi MD. Anoctamin-5 is the protein product of the ANO5 gene and turns out to be a muscle chloride channel activated by calcium. My own research for the last 45 years has been on the particular muscle chloride channels that are involved in the myotonic muscle stiffness diseases, Myotonia Congenita and Myotonic Dystrophy, the latter also including muscle wasting. That chloride channels are also involved in LGMD now adds to our understanding of their importance and provides additional avenues for treatment of these diseases. Dr Udd and I had hoped to collaborate on this research but, unfortunately, Dr Grigori Rychkov, my colleague at The University of Adelaide, did not obtain a research grant for 2012 that would have allowed the work to proceed.
Becker MD (BMD) – With regard to BMD it was announced that a 2000 page FDA application for a clinical trial of myostatin inhibition with Follistatin had just been approved. Myostatin is a naturally occurring protein hormone that normally stops muscle growth when other body growth is complete. If the action of this hormone is prevented in animals, huge muscle growth results. Inhibiting its action to some extent might, therefore, increase muscle growth and strength in some muscle diseases, especially where muscle cells are not too damaged, as in BMD.
Familial Amyloid Polyneuropathy (FAM) – According to Dr Maria Saraiva from the Institute of Molecular and Cellular Biology, Porto, Portugal, FAM is a very rare disease of the peripheral nervous system that, in mouse models of the disease, appears to be susceptible to treatment with the antibiotic/anti-malarial drug doxycycline in combination with tauroursadeoxycholic acid (TUDCA). Other anti-amyloid drugs are also being developed. Tafamidis stabilises the substance transthyretin slowing or preventing it from being deposited around nerves. A phase II/III controlled clinical trial has shown its ability to slow FAM stage 1 disease progression. Additional strategies include AON drugs, again, small interfering RNA and monoclonal antibodies.
Peripheral Neuropathies – In 75 to 85 % of cases of inherited Peripheral Neuropathies, such as Charcot-Marie-Tooth disease and similar conditions, the causative genetic mutation is unknown leading to problems with classification of persons with these diseases, difficulties in obtaining populations of people with the identical disease for clinical trials and inability to be sure of what treatment to use in those rare cases where treatments are available. Nevertheless, considerable hope of an improvement in the diagnostic process was predicted at the conference as a result of new technologies that allow inexpensive whole genome sequencing, perhaps for as little as $1,000 per person. This, of course, raises many ethical issues relating to knowledge of all genes and all genetic diseases or tendencies for which an individual might be at risk.
Muscular Dystrophy in dogs – One quite stunning revelation about muscular dystrophy came from Dr Dianne Shelton who works at the Veterinary School of the University of California San Diego, USA. She described a group of Labrador dogs bred in Natick, Massachusetts, USA, which, like boys with DMD, have no dystrophin in their muscles. But unlike the boys, the dogs have no apparent muscle weakness or muscle wasting or functional deterioration. The race is on here to try to discover what is protecting the muscles of these dogs from the wasting that would be expected. Intriguingly, in March this year, Dr Ajit Varki who runs a Glycobiology (involvement of sugars in cell structure and function) and Human Origins Laboratory elsewhere in the University of California San Diego, came on a visit to Adelaide and I was able to talk to him about these dogs. He was very interested and proposed that dystroglycan (mentioned above – the sugar-coated protein that is central to the DAP complex attaching dystrophin to the connective tissue between muscle cells) is variable in the kind of sugar coating in different dog breeds and possibly within a single dog breed. Dr Varki had recently shown that mdx mice (lacking dystrophin but mildly affected), are much more seriously affected – more like DMD boys – if they simultaneously carry a human-type enzyme that is involved in coating proteins with sugars. These could be very important clues and could also relate to Dr Winder’s proposed therapy for DMD, as mentioned above. As a result, I emailed Dr Shelton about this and she agreed to raise the matter with Dr Varki.
Although this conference in Portugal was dominated by presenters from the USA, UK and Europe, a good number of Australians also gave lectures, presented posters and acted as chairpersons of symposia or facilitators in formal poster discussions in their particular fields of expertise. Among them were names familiar to most of you: Drs Steve Wilton (on the therapeutic use of AON drugs), Nigel Laing (on early screening for Duchenne MD), Kathy North (on several neuromuscular diseases and diagnostic procedures) and myself (on mechanisms of Myotonia Congenita).
In early June, I again attended the Annual Scientific Conference of the Asian and Oceanian Myology Center (AOMC) held this year in Kyoto, Japan. The AOMC was established as an organisation in Tokyo in 2001. Its aims and objectives have been to promote scientific and clinical research, to provide a forum to advance and distribute knowledge for the benefit of patients, to provide educational opportunities for young investigators and clinicians and to promote the achievement of high standards in clinical practice in myology and neurology as they relate to neuromuscular diseases in the Asian and Oceanian region. This year’s meeting especially commemorated Dr. Woon Chee Yee (1946-2011) who had been a founding member of AOMC, had served as Secretary of its Executive Board and, from 2007, as its Vice-President. A Senior Principal Research Scientist at the Singapore General Hospital, Dr. Yee was not only an excellent clinician, a dedicated scientist and AOMC Vice-President, but, in what spare time he had, he also served as the much-loved President of Muscular Dystrophy Association (Singapore). As a tragic irony, he succumbed to leiomyosarcoma, a very rare form of muscle cancer, on 31st August 2011, just six weeks after diagnosis. In his honour, 10 Fellowships were awarded to young scientists/clinicians to allow them to attend the Kyoto meeting. Dr. Ikuya Nonaka (AOMC President) and Dr. Ichizo Nishino (AOMC Secretary) organised the meeting for AOMC with the Japan Foundation for Neuroscience and Mental Health as co-organiser. It was attended by 148 delegates from 13 countries (94 from Japan, including Honorary AOMC President Dr. Hideo Sugita, and 20 from China), as well as, for the first time, two from Yemen and one from Iran. There were 28 speakers from Australia, China, India, Japan, Korea, Malaysia, New Zealand, Philippines, Taiwan and Thailand.
Dr. Nonaka opened the program by welcoming all delegates followed by a minute’s silence in remembrance of Dr. Woon Chee Yee, led by Dr. Rawiphan Witoonpanich. One of the two special lectures was given by Dr. Nigel Laing from Perth on the muscle disease that has been named after him, “Laing distal myopathy – where are we at in 2012″. His most striking conclusion was that there is an unusually high frequency of new mutations in this disease. The second was given by Fukutin gene discoverer, Dr. Tatsushi Toda, on “Fukuyama congenital muscular dystrophy – update”. Two additional lectures were given under the heading, Treatment of Muscular Dystrophy, the first by Dr. Shin’ichi Takeda, “Treatment of muscular dystrophy, overview” and the second by Dr. Steve Wilton, “Exon skipping and Duchenne muscular dystrophy: an update”. In a lunch-time lecture sponsored by Genzyme, Dr. Hiroyuki Ida spoke on “Pompé disease: current status and future direction”.
Mitochondrial Dysmetabolism and the other on Care and Management of Muscle Disease. In the last of these symposia, Dr Yuka Ishikawa, when speaking on “Non-invasive respiratory management in patients with Duchenne muscular dystrophy and congenital muscular dystrophy”, astonished her audience with the pronouncement that many Japanese men with Duchenne MD are now living well into their 40s and some into their 50s. Unfortunately, it was observed in other symposium presentations and general discussions that when the heart was involved in the MDs, no similarly beneficial support of cardiac function was, so far, available.
As usual, there was a Muscle Pathology Case Conference at the meeting during which seven interesting and unusual cases were presented. These sessions are invariably greatly appreciated and enthusiastically received by both novices and experienced researchers, frequently with extensive discussion and divergent opinions before reaching a final diagnosis or concluding that further information/biochemistry/genetic analysis is required. Also, on this occasion, 66 abstracts were submitted for poster presentations in five categories: Muscular Dystrophies, Myopathies, Myotonic Disorders and Channelopathies, Metabolic Myopathies and Other Neuromuscular Diseases. These were individually the site of considerable animated discussion as viewers were led from poster to poster by facilitators during the poster session. A prize was awarded for the best poster (and presentation by its authors) in each category, as judged by the facilitators.
From the recent scientific and medical literature
A treatment that I first mentioned in MDSA Research Reports from several years ago is proving beneficial in further animal tests. The cell membrane sealing agent Poloxamer 188, now known as “Carmeseal”, has recently been found to improve function of the diaphragm muscle in muscular dystrophy mice as well as reducing damage to heart muscle in muscular dystrophy dogs.
New leads for treating Emery-Dreifus MD and LGMD type 1B have recently been reported. Among these are the drugs Selumetinib, Temsirolimus (Torisel) and Rapamycin (Rapamune) the last two of which are already in use in humans for the chemotherapy of kidney cancer and to prevent rejection of transplanted kidneys, respectively. These findings come from the laboratories of Drs Howard Worman at Columbia University, New York and Fresnida Ramos at the University of Washington, Seattle, USA. Already being in use can mean that the time taken to bring these drugs to clinical trials for MDs can be reduced.
In a totally new approach, gene therapy to increase frataxin production in Friedreich’s Ataxia (FA) and untrophin as a dystrophin substitute in Duchenne MD, is being tackled by utilising synthetically engineered “transcription activation-like effectors” (TALE). Human cells in tissue culture treated with the appropriate TALE produce two to three times more frataxin than untreated cells. If able to be replicated in the nervous system of people affected by FA, this would be sufficient to provide an effective, long-term treatment.
I have written and spoken on the subject of newborn screening for Duchenne MD since about 1980, advocating its introduction, along with genetic counselling, as a possible way of allowing parents to escape the burden of long delays in diagnosis and of multiple further births of boys with the disease in the time before a first diagnosis is confirmed. As mentioned above, Dr Nigel Laing from Perth has become a recent lobbyist for, and vocal supporter of, neonatal testing. Now the MDA of the USA is conducting a survey to examine the future possibility of newborn screening for NMDs, especially in diseases for which there are rapid advances in therapy development.
In one of the most exciting announcements since the completion of the Human Genome project some 10 years ago, the results so far of the subsequent ENCODE (Encyclopaedia Of DNA Elements) project have just been published in a number of research papers in the scientific journal, Nature, with simultaneous companion publications in other research journals. Basically, an international consortium of hundreds of scientists has been working towards the determination of all of the genetic information (encoded by DNA) that is needed to build all types of cells, body organs and, indeed, a whole person from a single genome. Remarkably, the consortium has reported that 80% of the human genome contains elements (DNA sequences) that are linked to biochemical function. This negates the widely held view that most of the human genome is “junk DNA” and only a small portion of it (the 2% which contains our 30,000 or so genes) is important. It appears that the space between genes is far from irrelevant but is filled with modifiers of gene expression, such as, “enhancers” and “promoters”, and numerous previously overlooked regions that encode RNA transcripts but are not genes as they do not code for proteins. Rather these RNA transcripts are likely, themselves, to have regulatory roles, facilitating, inhibiting or modulating gene expression or protein production. In all, 1,640 genome-wide data sets from147 different cell types have been prepared. So far, these include data from skeletal muscle cells, heart muscle cells, smooth muscle cells and some brain cells. Already the results show that many DNA mutations associated with certain diseases are found in or near the newly-found regulatory regions of DNA rather than within genes. Like the Human Genome project, the ENCODE project will provide an enormous leap forward in understanding diseases and developing strategies for their treatment. Unlike much other scientific and medical information, data sets from the project are being made freely available to researchers anywhere. The Neuromuscular Diseases will certainly be among the beneficiaries of this new knowledge.
Finally, I expect to be able to report on the latest research developments from the WMS 2012 Congress in Perth at some time after my return.
Professor Allan Bretag
Director of Research
Past Research Reports from Professor Allan Bretag, Muscular Dystrophy South Australia’s Director of Research
MDSA Brief Annual Research Report 2011: click here to view
MDSA Annual Research Report 2010: click here to view
MDSA Annual Research Report 2009: click here to view
World Alliance of Neuromuscular Disorder Assciations Prospectus 2009-2012: click here to view