New Muscular Dystrophy Treatment Offers Hope
Study Shows Patients With Duchenne's Muscular Dystrophy Are Walking Better With PRO051 Treatment
March 23, 2011 -- Exciting findings from an early-stage clinical trial offer new hope to patients with Duchenne's muscular dystrophy, the most common but incurable and devastating form of muscular dystrophy.
Patients who received three months of weekly injections with PRO051 had a modest improvement in their ability to walk, reports a research team led by Judith C. van Deutekom, PhD, vice president for discovery at Prosensa Therapeutics, which funded the study.
"The patients are still on the product, and anecdotal evidence suggests they are functioning better in daily life," van Deutekom tells WebMD.
Duchenne's muscular dystrophy (DMD) is a very common form of the disease, striking about one in every 3,500 boys worldwide. It's a recessive genetic defect, carried by mothers but almost always striking boys.
The defect is in the gene coding for dystrophin, a protein with a major role in muscle function. Normal dystrophin acts like a shock absorber for muscle cells. The defective dystrophin in DMD leads to muscle damage and degeneration, says muscular dystrophy expert Roger W. Kula, MD, head of the neuromuscular clinic at North Shore-Long Island Jewish Health System.
"Duchenne's patients have progressive wasting of muscle," Kula, who was not involved in the PRO051 study, tells WebMD. "The disease affects walking at age 2 to 5 years, confines patients to wheelchair by age 9 to 12, and results in death from age 20 to 30. It is horrible."
Different patients with DMD have different mutations in the gene that codes for dystrophin. One of the most common mutations -- seen in about 13% of DMD patients -- is at a site called exon 51. PRO051 is a string of nucleic acids called an antisense oligonucleotide.
When the body is decoding the dystrophin gene, the drug causes the mRNA that is "reading" the gene to skip over the mutated exon 51. The result is a dystrophin protein that isn't exactly normal, but which works well enough. Muscular dystrophy patients who have naturally occurring dystrophin like this have a much milder form of the disease known as Becker's muscular dystrophy.