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FDA Okays Marathon's Emflaza for DMD

— Corticosteroids already commonly used to treat the condition

MedpageToday

The FDA has okayed deflazacort (Emflaza) for the treatment of Duchenne muscular dystrophy (DMD) in patients ages 5 and up, the agency announced.

The drug is far less controversial than other DMD treatments that have made headlines recently, particularly eteplirsen (Exondys 51). Deflazacort does not involve exon-skipping technology; it's simply a corticosteroid.

FDA acknowledged that corticosteroids are commonly used around the world to treat DMD. A showed they improved muscle strength and function over one year, and strength alone for up to two years, in randomized controlled trials.

Deflazacort, however, is the first corticosteroid to seek and win FDA approval for the condition, which affects 1 in 3,600 boys worldwide.

An email sent to a spokesperson for deflazacort drugmaker Marathon Pharmaceuticals regarding pricing for the drug was not returned as of press time. Corticosteroids are frequently generic and inexpensive.

FDA said the effectiveness of deflazacort was demonstrated in a clinical study of 196 male patients who were 5 to 15 years old at the beginning of the trial. All had a documented mutation of the dystrophin gene and onset of weakness before age 5.

At week 12, those on deflazacort had improvements in a clinical assessment of muscle strength across a number of muscles compared with those on placebo. Average muscle strength remained stable through the 52 weeks of the study for those on the corticosteroid, the agency said.

In another, 104-week trial with 29 male patients, deflazacort showed a "numerical advantage over placebo on an assessment of average muscle strength," according to the FDA press release, which also noted that patients on deflazacort "appeared to lose the ability to walk later than those treated with placebo," although this was not statistically controlled for multiple comparisons.

Common side effects include facial puffiness (Cushingoid appearance), weight gain, increased appetite, upper respiratory tract infection, cough, extraordinary daytime urinary frequency (pollakiuria), unwanted hair growth (hirsutism), and excessive fat around the stomach (central obesity).

Other side effects that are less common include problems with endocrine function, increased susceptibility to infection, elevation in blood pressure, risk of gastrointestinal perforation, serious skin rashes, behavioral and mood changes, diminished bone density, and vision problems such as cataracts.

Patients who get immunosuppressive doses of corticosteroids should not be given live or live attenuated vaccines, the FDA warned.

Marathon scored fast track designation, priority review, and orphan drug designation for deflazacort for DMD. The company also gets a pediatric disease priority review voucher that can be redeemed at a later date for a different product; FDA says this is the ninth such voucher it has doled out.