FDA Approves Corticosteroid Drug to Treat Duchenne Muscular Dystrophy

Just months after Sarepta Therapeutics’ Exondys 51 became the first US Food and Drug Administration (FDA) approved drug to treat Duchenne muscular dystrophy (DMD), the agency has approved Marathon Pharmaceuticals’ Emflaza (deflazacort). The drug has been approved to treat the rare genetic disorder in patients five years of age and older.

DMD is a disease characterized by progressive muscle weakness and deterioration, which primarily affects young boys. Emflaza is a corticosteroid designed to reduce inflammation and dampen the actions of the immune system. While corticosteroids are already in use for the treatment of DMD in other countries, the approval of Emflaza marks the first corticosteroid approval for this indication in the US.

“This is the first treatment approved for a wide range of patients with Duchenne muscular dystrophy,” said Dr. Billy Dunn, director of the Division of Neurology Products in the FDA’s Center for Drug Evaluation and Research. “We hope that this treatment option will benefit many patients with DMD.”

A clinical trial involving 196 male patients between the ages of five and 15 years old was conducted to assess the effectiveness of deflazacort. All patients had a confirmed mutation in the dystrophin gene, the protein product of which is responsible for stabilizing muscle fibers.

After 12 weeks of being treated with deflazacort, the DMD patients saw improvements in muscle strength, compared to those taking the placebo. According to the FDA, patients on deflazacort also lost the ability to walk later compared to the placebo group, although this result was not statistically controlled for multiple comparisons.

“Today we celebrate FDA approval of Emflaza as a treatment option for kids and adults living with Duchenne muscular dystrophy,” said Steven M. Derks, President and CEO of the Muscular Dystrophy Association (MDA). “This approval follows decades of MDA research — including early-stage development and testing of Emflaza in DMD patients — that was made possible by the hard work, dedication and unwavering commitment of our donors and sponsors.

“Drugs like Emflaza aren’t developed in silos, but rather through the combined efforts of biotechs and drug companies, patient organizations like MDA, corporate partners and donors, and the families who are there every step of the way to see it through. We are grateful to be part of such a welcome new development in the DMD landscape — and, more importantly, to belong to such a giving and dedicated community.”

In September of 2016, Exondys 51 became the first drug to be approved to treat DMD. Just three months later, the FDA approved Spinraza for the treatment of spinal muscular atrophy, another rare neuromuscular disease.