• Duchenne MD Groups Form International Alliance to Speed Research
• Lab Study Shows New Anti-Inflammatory Drug Helps Mice With MD
• Gene Therapy May Require Dodging Immune System
• Previously Undetected Immune System Cell May Shed Light on IBM
• FRG1 May Affect 'Final Version' of Many Genes
• Are Blood Vessels Involved in FSHD?
• George Karpati Honored
• Clinical Trials and Studies
  • PTC124 to Be Tested at Higher Doses in DMD
  • Multinational Trial to Evaluate Steroids in DMD
  • LGMD Gene Transfer Trial Still Has a Few Slots
  • Large Study Identifies Common U.S. LGMD Types
  • Heart Health Studied in Carriers of DMD, BMD
  • Various Factors May Affect Pompe's Severity

Lab Study Shows New Anti-Inflammatory Drug Helps Mice With MD

When MDA grantee Giulio Cossu at the Stem Cell Research Institute of the San Raffaele Scientific Institute of Milan (Italy), and colleagues, tested the experimental drug HCT 1026 in mouse models of Duchenne muscular dystrophy (DMD) and type 2D limb-girdle MD (LGMD2D), they found it was more effective than a corticosteroid drug in the prednisone family, and that it didn’t have the side effects of corticosteroids.

HCT 1026 is derived from flurbiprofen (Ansaid), an anti-inflammatory drug approved by the U.S. Food and Drug Administration for the treatment of arthritis. Besides easing the pain of inflammation, HCT 1026 also releases nitric oxide, which has been shown to have beneficial effects on muscle repair and regeneration.

The researchers, who published their findings in the Jan. 2 issue of Proceedings of the National Academy of Sciences, tested the compound in mice with diseases resembling DMD and LGMD2D.

In both instances, HCT 1026 maintained muscle structure and function, and reduced inflammation. The mice gained strength and performed better on tests of movement. HCT 1026 was “significantly more potent” than the corticosteroid prednisolone, with no detectable side effects. (In humans, side effects of corticosteroids, such as weight gain, can be problematic.)

The investigators say that, when they combined the drug treatment with injections of mesoangioblast stem cells into an artery, they saw better integration of the stem cells into muscle, more improvement of muscle tissue structure and better treadmill performance than they saw with stem cells alone.

Mesoangioblasts were identified by Cossu’s team and have shown promise in treating dystrophin-deficient dogs (see “Research Updates,” January-February).

An MDA-supported research team, testing gene transfer in dogs using adeno-associated viral (AAV) shells (vectors), noted an unwanted immune response, a factor they recommend be considered in human trials. The response occurred even when the vectors weren’t carrying any genes.

Until now, AAV transporters have been thought not to provoke much of an immune response.

The team, from the University of Washington and the Fred Hutchinson Cancer Research Center, both in Seattle, injected leg muscles of dogs with types 2 and 6 AAV shells, both empty and carrying various genes (though none relevant to muscular dystrophy). They found the dogs mounted a “robust” immune response sufficient to largely eliminate production of proteins from the transferred genes. The results were published online Dec. 15 in Human Gene Therapy.

In earlier studies involving mice, the immune system appears to tolerate transferred genes well, as long as the genes are active only in muscle cells, where they seem to largely escape immunologic detection.

LGMD Studies

A French team reported in the January issue of Molecular Therapy that it had successfully restored structure and function to the muscles of alpha-sarcoglycan-deficient mice, a model for human type 2D limb-girdle muscular dystrophy (LGMD2D). The investigators injected alpha-sarcoglycan genes in AAV vectors into an artery, using a synthetic molecular switch (promoter) called C5-12 to make the genes active only in muscle cells.

Using a similar strategy, MDA-supported University of Washington-Seattle scientists successfully transferred dystrophin genes via a tail vein in dystrophin-deficient mice with a disease resembling Duchenne muscular dystrophy (DMD). This group, which published results in the February issue of Molecular Therapy, used AAV vectors with a synthetic, muscle-only promoter called MHCK7.

Switches that activate therapeutic genes only in muscle cells may be sufficient to evade an unwanted immune response, but immunosuppressant medications may also be needed.

MDA grantee Dongsheng Duan at the University of Missouri-Columbia, and colleagues, published findings online Jan. 30 in Molecular Therapy showing that their “split gene” strategy is realistic for systemwide gene delivery. In this approach, large genes (like the one for dystrophin) are divided into two parts and inserted into separate vectors. The extra space gained by using two AAV shells will, they say, allow scientists to add additional regulatory switches inside each shell.

Implications for Humans

The jury is still out on the implications for humans. An unwanted immune response to AAV vectors alone, regardless of their payload, may require suppression when the vectors are injected systemically, if people respond to gene therapy as the dogs did. If the human response is similar to that of the mice, confining gene activity to the targeted tissue (such as muscle) will likely be sufficient to avoid immunologic rejection.

Stephen Tapscott at the Hutchinson Center, a member of the dog study team, suggests that the different responses of the two animals may have to do with the similar genetics of lab-bred rodents, compared to greater genetic diversity in randomly bred dogs. Tapscott, a member of MDA’s Scientific Advisory Committee, believes medications to suppress the immune system may be needed in at least some human gene therapy trials.

“We are currently exploring immunosuppressive regimens,” he said.


Previously Undetected Immune System Cell May Shed Light on IBM

Recent findings by researchers at Harvard Medical School, Brigham and Wo-men’s Hospital, and Children’s Hospital, all in Boston, have identified a type of immune system cell previously undetected in the biopsy samples of people with inclusion-body myositis (IBM).

MDA grantee Steven A. Greenberg at Harvard and Brigham and Women’s, and colleagues, who published their findings in the January issue of Muscle & Nerve, say the results suggest new hypotheses about IBM, as well as new potential treatment possibilities.

The cells, called dendritic cells, haven’t been previously reported in IBM muscle samples, because their identification requires looking at muscle specimens using specific markers, Greenberg says. Previous studies have used a more general type of marker and have misidentified many of the dendritic cells as T-cells, a better known immune system cell.

“Until the last decade, the study of dendritic cells has been relatively neglected in immunology and particularly in autoimmune disease,” Greenberg says, referring to diseases in which the body’s immune system mistakenly attacks its own tissue. Polymyositis (PM) and Dermatomyositis (DM), in which dendritic cells have previously been noted, have long been classified as autoimmune disorders. Experts have disagreed about how to classify IBM, although most believe the immune system is involved in some way.

“These [dendritic] cells are now recognized as central to the initiation and development of specific immune responses,” Greenberg says. One type, myeloid dendritic cells, is particularly abundant in IBM muscle tissue.

“Myeloid dendritic cells activate other immune system cells, particularly T-cells that are believed to be a major cause of muscle damage in IBM and polymyositis. Their presence in IBM and PM muscle provides a means by which these T-cells become activated and attack muscle.”

Greenberg says new therapies for autoimmune diseases aimed at disrupting the function of dendritic cells and their interaction with T-cells could be considered for future trials in myositis, given these findings. He notes that two drugs — abatacept (Orencia) and efalizumab (Raptiva), both of which interfere with dendritic cell-T-cell interactions — are already approved by the Food and Drug Administration for other conditions.

FRG1 May Affect ‘Final Version’ of Many Genes

Researchers at Leiden University in the Netherlands have added to existing knowledge about the FRG1 protein, which is made from a gene strongly implicated in Facioscapulohumeral MD (FSHD) by some prominent investigators (see “Impossible Things”).

Silvana van Koningsbruggen and colleagues, including MDA-funded Silvere van der Maarel, say their experiments demonstrate the probable role of FRG1 in RNA splicing, a cellular process that takes “rough draft” genetic instructions to their final version.

Their paper, published online Nov. 14 in Chromosoma, reports identification of several splicing-related proteins associated with FRG1.

Are Blood Vessels Involved in FSHD?

A research group that included  Charles Thornton and Rabi Tawil, MDA clinic co-directors at the University of Rochester (N.Y.) Medical Center, have found evidence that blood vessel abnormalities may be involved in facioscapulohumeral muscular dystrophy (FSHD).

When they analyzed gene activity in people with FSHD, myotonic dystrophy (MMD) and no muscular dystrophy, they found that 44 genes were specifically overactive (upregulated) in early FSHD, and that 11 of these (32 percent) had a role in blood vessel structure or function.

These findings may help explain why retinal blood vessel abnormalities sometimes are part of FSHD. The researchers, who published their findings online Dec. 6 in Neurology, speculate that blood flow irregularities inside muscle fibers could also be a contributing factor in FSHD.

PTC124 to Be Tested at Higher Doses in DMD

New Jersey company PTC Thera-peutics will test a higher dose of its experimental compound PTC124 in approximately 12 boys with Duchenne muscular dystrophy (DMD) caused by a premature stop codon mutation. The drug is designed to coax muscle cells to ignore these mutations and make functional dystrophin.

In October, the company announced that, in a trial of 26 boys with DMD, the drug appeared safe and well tolerated. Results showed significant decreases in serum creatine kinase (CK), which leaks out of damaged muscle tissue, and increases in dystrophin.

In the higher-dose study, boys will take the drug at 20 milligrams per kilogram of body weight at breakfast and lunch and 40 milligrams per kilogram at dinner for 28 days. They’ll be followed closely for an additional 28 days and periodically after that.

Contact Kerri Donnelly at PTC Therapeutics at (908) 222-7000, ext. 112, or kdonnelly@ptcbio.com.

Multinational Trial to Evaluate Steroids in DMD

Some 300 boys with Duchenne muscular dystrophy (DMD) may soon be invited to participate in a multinational, multiyear study of three corticosteroid medication regimens.

Although corticosteroids such as prednisone have been used for many years to slow the course of DMD, and have been recommended by the American Academy of Neurology since 2005, there remains much debate about which steroids to use, how much to give, on what schedule and for what length of time.

Set to launch in 2008, with funding from the U.S. National Institutes of Health, the trial is expected to encompass approximately 59 sites in 11 countries.

Kate Bushby, professor of neuromuscular genetics at the International Centre for Life in Newcastle Upon Tyne, United Kingdom, and Robert Griggs, professor of neurology at the University of Rochester (N.Y.)
Medical Center, are the principal investigators.

The doctors will test three regimens, using prednisone and deflazacort, in boys 4 to 7 years old for at least three years. They’ll compare the children’s muscle and respiratory functions, and their parents’ satisfaction with the treatment.

LGMD Gene Transfer Trial Still Has a Few Slots

A gene therapy trial for alpha-sarcoglycan-deficient Limb-girdle muscular dystrophy (LGMD) is close to starting, says principal investigator Jerry Mendell at Columbus (Ohio) Children’s Research Institute. There are a few slots open for additional patients.

In the first phase of the trial, an alpha-sarcoglycan gene will be injected into a leg muscle to test the safety of the procedure.

“These initial gene therapy trials lay the foundation for moving to the next level of gene transfer, where the gene can be given through the circulation to reach many muscles,” Mendell said.

The investigators are seeking people with known alpha-sarcoglycan deficiency, but will work with those who don’t know what type of LGMD they have.

Contact Xiomara Rosales-Quintero, Columbus Children’s Research Institute and Gene Therapy Center, at (614) 722-6961 or rosalesx@ccri.net.

Large Study Identifies Common U.S. LGMD Types

The first large-scale study to assess the relative frequency of different types of Limb-girdle muscular dystrophy (LGMD) has found that the most common LGMDs in the United States involve deficiencies of calpain, dysferlin, sarcoglycans and dystroglycan.

The study, supported in part by MDA, drew participants from six MDA clinics.

The investigators, who published their results in the October issue of the Journal of Neuropathology and Experimental Neurology, examined muscle samples from 266 people with diagnoses of LGMD based on symptoms and family history. They found a reduction or absence of the dysferlin protein in 18 percent; of a sarcoglycan in 15 percent; of dystroglycan in 15 percent; and of caveolin in 1.5 percent.

Protein abnormalities, however, don’t always correspond to gene abnormalities, because one gene abnormality can affect more than one protein. The researchers note that several new therapies on the horizon will require accurate protein and DNA diagnoses in LGMD.

The Jain Foundation, a group dedicated to research on dysferlin gene mutations, which can cause type 2B LGMD or Miyoshi myopathy, a type of distal MD, is urgently seeking participants for its patient registry, a database that it hopes will speed understanding of these disorders. To register online, go to www.jain-foundation.org, and click on Patient Registration. Or contact Plavi Mittal at plavimittal@jain-foundation.org. All information will be kept confidential.

Heart Health Studied in Carriers of DMD, BMD

A questionnaire-based study of beliefs and practices related to cardiac health in genetic carriers of Duchenne and Becker muscular dystrophies (DMD, BMD) closed Dec. 31. The study, funded by the U.S. Centers for Disease Control and Prevention, also asked about the impact of the disease on the lives of carriers and their families.

A total of 1,348 women submitted usable research data, which are being analyzed.

Various Factors May Affect Pompe’s Severity

It looks like there’s more to predicting the severity and onset of acid maltase deficiency (AMD), or Pompe’s disease, than knowing the makeup of a person’s acid maltase genes.

Arnold Reuser at Erasmus Medical Center-Rotterdam, the Netherlands, with colleagues at other Dutch institutions, and Genzyme, a Massachusetts pharmaceutical company, studied 98 people with Pompe’s disease. All of them had a common AMD mutation in one of their two acid maltase genes and a highly deleterious mutation in the other acid maltase gene.

The common mutation allows production of about 10 percent of the normal level of the enzyme acid maltase. The researchers selected patients whose second acid maltase gene led to no enzyme production.

The onset and course of the disease varied in these study participants far more than the investigators had anticipated. The age of symptom onset varied from less than a year to 52 years; the age of first wheelchair use ranged from 18 to 64 years; and first ventilator use from 14 to 68 years.

The authors, who published their findings in the Jan. 9 issue of Neurology, say that, when some acid maltase can be made, other genes or environmental factors influence disease severity. For example, a study published in the Jan. 9 issue of Muscle & Nerve showed that a high-protein, low-carbohydrate diet, coupled with daily treadmill exercise, can stabilize or even improve muscle function in at least some adult-onset Pompe’s patients.