There has been significant pharmaceutical and biotech R&D activity in Duchenne muscular dystrophy (DMD) over the last five years, and that activity has only increased with the approval of Sarepta’s Exondys 51 (eteplirsen) last September. Exondys 51 is approved to treat certain DMD patients with the mutation of the dystrophin gene amenable to exon 51 skipping, which affects about 13% of the population with DMD.
According to a new report, there are a total of 108 products in development for DMD, by 57 companies and nine academic institutions. Biotech companies focusing research and development in this disease include Sarepta Therapeutics, PTC Therapeutics, WAVE Life Sciences, Solid Biosciences, Summit Therapeutics and Catabasis Pharmaceuticals. With an approved product in Exondys 51, Sarepta is the leader with 12 pipeline products for DMD.
Although most of the companies focused on DMD are smaller biotechs, Pfizer and Merck are also active in DMD research. Pfizer just completed enrollment of a multicenter Phase 2 clinical trial of the investigational compound, domagrozumab in boys with DMD. The trial enrolled 121 patients and seeks to evaluate the safety, tolerability and efficacy of domagrozumab in boys aged 6 to less than 16 years old diagnosed with DMD regardless of genotype. The study is conducted over two years, after which participants may be eligible to continue on an open-label extension study.
Domagrozumab is an experimental, infused, anti-myostatin monoclonal antibody. Myostatin is a naturally occurring protein in muscles that helps control muscle growth; it is believed that blocking the activity of myostatin may have potential therapeutic application in treating muscle wasting diseases such as DMD.
Domagrozumab was granted Orphan Drug designation in July 2012 and Fast Track Designation in November 2012 by the U.S. Food and Drug Administration. The European Medicines Agency granted the investigational candidate Orphan Medical Product designation in February 2013.
Pfizer is also advancing a pre-clinical asset for DMD using recombinant Adeno-Associated Virus (rAAV) vector – based gene therapy, which entered Pfizer’s portfolio with the 2016 acquisition of Bamboo Therapeutics, Inc. Gene therapy is an emerging area of medical research focused on highly specialized, transformative treatments addressing the root cause of diseases caused by genetic mutation.
About Duchenne Muscular Dystrophy
Duchenne muscular dystrophy (DMD) is a genetic disorder characterized by progressive muscle degeneration and weakness. DMD is caused by an absence of dystrophin, a protein that helps keep muscle cells intact. Symptom onset is in early childhood, usually between ages of 3 and 5. The disease primarily affects boys, but in rare cases it can affect girls. Muscle weakness can begin as early as age 3, first affecting the muscles of the hips, pelvic area, thighs and shoulders, and later the skeletal (voluntary) muscles in the arms, legs and trunk. The calves often are enlarged. By the early teens, the heart and respiratory muscles are also affected.
