Duchenne muscular dystrophy is a condition in boys and is characterized by progressive muscle degeneration and weakness, resulting in a decrease in respiratory function. Strategies to arrest this severe gradual deterioration are needed to extend lives and enhance the quality of life. According to a study published in the Journal of Neuromuscular Diseases, findings of the three clinical trials using eteplirsen, an exon-skipping antisense oligonucleotide, show possible results.
As genetic disorders, muscular dystrophy results in increasing weakening and breakdown of skeletal muscles. Near absence of dystrophin, a critical protein, leads to inflammation, necrosis, and eventual replacement of functional muscle tissue with fibrosis and fat. Duchenne muscular dystrophy (DMD) is a severe type of muscular dystrophy in boys that has a predictable disease course. Usually, muscle weakness begins around the age of four in the thighs and pelvis, followed by the arms. By the age of 12, most patients are unable to walk. Natural history data show that respiratory function declines linearly and predictably in the second decade of life. The respiratory decline in glucocorticoid-treated DMD patients is typically 5 percent annually in patients aged 10 to 18 years. Patients require increasing levels of clinical intervention as the disease progresses.
Navid Z. Khan, Ph.D., Senior Director, Global Medical Affairs, led the investigators, Sarepta Therapeutics, Inc., Cambridge, MA, USA, evaluated respiratory function in eteplirsen-treated patients from three clinical trials and compared them to patients matched by age range, steroid use, and genotype from the Cooperative International Neuromuscular Research Group Duchenne Natural History Study (CINRG DNHS) global database. These three trials studied eligible ambulatory DMD patients for at least four years primarily non-ambulatory DMD patients for two years, and an ongoing open-label multicenter study of ambulatory DMD patients aged seven to 16 years.
For those patients in the global patient database, they experienced the respiratory decline at rates in line with the well-established natural history of DMD. In contrast, the respiratory decline in patients treated with eteplirsen was significantly lower, and this was true across all stages of the disease evaluated. Specifically, both ambulatory and non-ambulatory patients demonstrated a slower rate of respiratory decline.
Patients need increasing levels of clinical intervention as the disease progresses, including cough assist and ventilation support, and patients are at increased risk of death once this respiratory decline reaches a critical threshold. The research demonstrates that eteplirsen may slow the rate of respiratory decline and therefore, may delay time to milestones of decline. This process may have notable positive implications on quality of life because the pulmonary decline is connected to mortality, slowing of decline may result in delayed mortality. The researchers acknowledge that they may need further follow-up.
