FDA Approves First Corticosteroid, Emflaza, to Treat Range of Duchenne MD Patients

A first corticosteroid treatment for Duchenne muscular dystrophy (DMD) regardless of mutation, Emflaza (deflazacort), has been approved for use in patients ages 5 and older by U.S. Food and Drug Administration (FDA).

“We are in a new era in the treatment of Duchenne muscular dystrophy. For the first time, patients in the U.S. with Duchenne will have widespread access to an FDA approved medicine that is indicated for all genetic forms of the condition,” Timothy M. Cunniff, an executive vice president at Marathon Pharmaceuticals, the drug’s developer, said in a company press release.

Corticosteroids, including deflazacort, are widely used in many countries to slow the decline in muscle strength in boys with DMD. They work by reducing inflammation and suppressing the immune system. 

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

Emflaza will be available in tablet form and as an oral suspension. Its effectiveness in delaying DMD symptoms has been demonstrated in several clinical trials.

One Phase 3 study involved 196 DMD patients, ages 5 to 15, all with a documented mutation in the dystrophin gene and evidence of muscular weakness before 5 years old. The 12-week trial compared the effectiveness of two corticosteroids —  deflazacort (0.9 mg/kg/day) and prednisone (1.2 mg/kg/day) — against placebo.  Results showed that both drugs significantly improved muscle strength in treated patients compared to placebo, but the lower dose of deflazacort caused fewer side effects, including weight gain, while demonstrating efficacy. Significant improvements in scores of muscle strength were also maintained for a one year, the study reported. 

A two-year trial involving 29 DMD patients also showed a “numerical advantage” in average muscle strength among deflazacort treated boys compared to placebo, the FDA reported in its release. Treated patients also appeared to retain an ability to walk for a longer time than those in the placebo group. 

Common side effects associated with Emflaza included facial puffiness, weight gain, upper respiratory tract infections or coughing, and increased daytime urination.

“EMFLAZA is an important new drug with proven benefit in boys with Duchenne muscular dystrophy, increasing muscle strength and physical function,” Robert C. Griggs, MD, with the University of Rochester Medical Center and an early investigator of deflazacort, said in the Marathon release. “By undertaking the research needed to secure FDA approval … we now know more about the drug, its dosing and possible interactions. These are all advances in care for patients with Duchenne.”

The FDA previously designated Emflaza an Orphan Drug as a treatment for a rare disease with a high unmet need, and approved its use under priority review.

Marathon announced it plans further studies of Emflaza in DMD patients, including a trial examining the safety and effectiveness of different dose regimens in younger patients, and a safety and efficacy study in non-ambulatory patients.

The company will also continue to work on other DMD treatments it is developing, Cunniff said.

“We are pleased to learn that the FDA has approved EMFLAZA,” added Pat Furlong, founding president and CEO of Parent Project Muscular Dystrophy, the largest U.S. nonprofit group for Duchenne MD. “While steroids are considered standard of care for Duchenne patients, there has been no steroid specifically approved for Duchenne. The FDA approval … provides options for our families when making crucial decisions about care with their providers. We hope that this approval gives more families access to this important medication.”