|A new clinical trial may offer insight into the cause of some cases of Duchenne MD.|
A clinical trial to test the effects of the compound PTC124 is now open to boys with Duchenne muscular dystrophy (DMD).
Prospective participants must be at least 5 years old, be able to walk, have a “nonsense” mutation (premature stop codon) in the gene for the dystrophin protein, and meet other study criteria, according to PTC Therapeutics of South Plainfield, N.J.
For study details, see the clinical trials database on the MDA Web site at www.mda.org/research/ctrials.aspx. (Select “Duchenne muscular dystrophy” from the disease list.)
The biotechnology company developed PTC124 as a synthetic compound designed to allow muscle cells to ignore certain DMD-causing mutations in the dystrophin gene. MDA contributed $1.5 million to PTC Therapeutics for the compound’s development. A phase 1 trial in healthy subjects has shown that oral PTC124 is safe and well tolerated. (See “Research Updates,” July-August 2005.)
Nonsense mutations prematurely end the synthesis of a protein — in this case dystrophin — leading to a small, nonfunctional protein that can’t perform its cellular role. It’s been estimated that nonsense mutations cause some 15 percent of DMD cases.
Prospective participants in the PTC124 trial can find out whether they have a nonsense mutation through DNA testing conducted by the University of Utah. For details, go to www.genome.utah.edu/DMD; or call Karin Dent, genetic counselor, at (801) 581-6956.
Testing costs range from $400 to $1,175 but may be free for families participating in the Utah Dystrophinopathy Project.
|Qi Long Lu|
The PTC124 trial is being held at Cincinnati Children’s Hospital Medical Center, Children’s Hospital of Philadelphia and the University of Utah in Salt Lake City.
A pilot trial of antisense oligonucleotides (AONs) in older boys with Duchenne muscular dystrophy (DMD) is slated to open this spring in England in London and Newcastle Upon Tyne.
Nine boys, ages 14 to 18, will participate in the study, which will inject AONs into a foot muscle at three dosage levels.
AONs are designed to cause exon skipping, a mechanism that coaxes cells to alter their processing of genetic instructions. In experiments in mice and in cells derived from DMD patients, AONs led cells to “skip” the faulty portion of the muscle protein dystrophin that leads to the disease.
Stephen Wilton at the University of Western Australia in Perth and Qi Long Lu at Carolinas Medical Center in Charlotte, have MDA funding to develop exon skipping for DMD (see “Changing the Code,” March-April 2005). Wilton says similar clinical trials will likely begin in the United States and Australia if the British trial is encouraging.
For details on the British trial, go to www.clinicaltrials.gov, search for “antisense oligonucleotides,” and select the trial for Duchenne muscular dystrophy.
MDA-supported researchers at Ohio State University in Columbus recently found no benefit from the drug diltiazem in the treatment of facioscapulohumeral muscular dystrophy (FSHD). Anecdotal reports from people with FSHD had suggested the drug might improve strength in this disorder.
Neurologist John Kissel, co-director of the MDA clinic at OSU Medical Center, reported the negative results at a conference for MDA clinic directors held in Tucson, Ariz., in November.
Diltiazem, a calcium channel blocker, relaxes blood vessels by interfering with the entry of calcium into blood vessel cells. It’s approved by the U.S. Food and Drug Administration to treat high blood pressure and chest pain from blocked coronary arteries (angina).
The team tested 19 adults ages 21 to 60 with chromosome 4-re-lated FSHD, who took diltiazem (Cardizem) at doses of 30 milligrams three times a day for six months. At the end of the study period, manual muscle testing showed no change in strength compared to baseline values; and X-ray scanning showed no change in lean body mass between the study’s beginning and end.
The investigators say the lack of change in either strength or muscle mass argues against the involvement of abnormal cellular calcium handling in FSHD-related weakness or wasting.