FDA Approves Drug to Treat Duchenne Muscular Dystrophy, but Congress Has Problems

The FDA has approved the drug Emflaza (deflazacort) to treat patients 5 and older with Duchenne muscular dystrophy (DMD). The drug is available as both a tablet and an oral suspension.

Although already in use to treat DMD around the world, this is the first corticosteroid approved by the FDA to treat DMD in the United States, and the first approval of deflazacort for any use. Emflaza is marketed by Marathon Pharmaceuticals of Northbrook, IL.

DMD is the most common type of muscular dystrophy. It predominantly affects males-about one in 3,600 male infants worldwide and is caused by an absence of dystrophin, a protein that helps keep muscle cells intact.

In a clinical study of 196 male patients, deflazacort was found to be effective. At week 12, patients demonstrated improvements in muscle strength across several muscle groups. An overall stability in average muscle strength was maintained at week 52.

In a longer trial with 29 male patients, deflazacort was found to be better than placebo in improving average muscle strength. Though not statistically controlled for multiple comparisons, it also appeared that patients taking deflazacort were capable of walking longer than those treated with a placebo.

The drug was granted fast track designation and priority review by the FDA. It also received an orphan drug designation. In addition, Marathon is receiving a rare pediatric disease priority voucher, which provides additional incentives for finding drugs to treat rare diseases in children.

However, just a few days after its acceptance, two members of Congress, Sen. Bernie Sanders (I-VT) and Rep. Elijah Cummings (D-MD), criticized the price of the new drug. Marathon had planned to sell the drug for $89,000 a year. The company faced criticism because the drug is sold in other parts of the world for about $1,500 a year.

The criticism has led Marathon to hold up on its rollout of the drug. In a letter posted on Cureduchenne.com, a DMD advocacy website, Jeff Aronin, CEO of Marathon, announced that the company will be “pausing our commercialization efforts in order to meet with Duchenne community leaders and explain our commercialization plans, review their concerns, discuss all options, and move forward with commercialization based on the resulting plan of action.”

Aronin said that the price of the drug was due to the “the resources we invested to get to this point.”

Sanders and Cummings, however, criticized Marathon’s price for Emflaza because it has been available and researched elsewhere. They accused the company of abusing the orphan drug program, and are calling for a lower price.

The common side effects of deflazacort are similar to those of other corticosteroids: cushingoid appearance, weight gain, increased appetite, upper respiratory tract infection, cough, frequent urination, hirsutism, and central obesity. Less common side effects include problems with endocrine function, increased susceptibility to infection, elevated blood pressure, risk of gastrointestinal perforation, serious skin rashes, behavioral and mood changes, loss of bone mass, and cataract formation. Patients receiving immunosuppressive doses of corticosteroids should not be given live or live attenuated vaccines.

Click here to read the full FDA press release