FDA Expands Deflazacort Indication for Duchenne Muscular Dystrophy

The FDA has approved a supplemental new drug application for deflazacort (Emflaza; PTC Therapeutics) to expand its indication for children with Duchenne muscular dystrophy (DMD) age 2 to 5 years.¹

Deflazacort was initially approved in 2017 for patients with DMD age 5 and older.²

“We are excited to be able to bring Emflaza to younger boys living with Duchenne muscular dystrophy," said Stuart Peltz, PhD, chief executive pfficer of PTC Therapeutics, in a statement.¹ "The standard of care is to start Emflaza at the time of diagnosis. We believe that treating patients as young as possible, when they still have a substantial amount of muscle, will have the greatest benefit for patients that are two years and older.”

The expanded approval makes deflazacort, a corticosteroid, the only FDA-approved treatment for patients with DMD age 2 and older, regardless of disease-causing genetic mutation.

The original approval was based on data from a phase 3, randomized, double-blind, placebo-controlled study of 196 patients with DMD aged 5 to 15 over a 52-week period that compared treatment with deflazacort with prednisone and placebo.³

During an initial 12-week treatment period, muscle strength was significantly greater in the deflazacort group versus placebo. This treatment effect was continuously observed through week 52. Measures of motor function also favored deflazacort versus placebo.

Notably, compared with prednisone, patients who received deflazacort gained less weight—a significant adverse effect of chronic corticosteroid use. Overall, the most frequent adverse events observed were Cushingoid appearance, erythema, hirsutism, increased weight, headache, and nasopharyngitis.

PTC Therapeutics also plans to initiate a phase 3 trial of deflazacort in patients with limb-girdle muscular dystrophy (NCT03783923), with an estimated enrollment of 100 patients. The estimated completion date for that study is August, 2020.

REFERENCES

1. PTC Therapeutics receives FDA approval for the expansion of the Emflaza® (deflazacort) labeling to include patients 2-5 years of age [news release]. South Plainfield, NJ: PTC Therapeutics. June 7, 2019. www.prnewswire.com/news-releases/ptc-therapeutics-receives-fda-approval-for-the-expansion-of-the-emflaza-deflazacort-labeling-to-include-patients-2-5-years-of-age-300863988.html.

2. FDA approves drug to treat Duchenne muscular dystrophy [news release]. US Food and Drug Administration. February 9, 2017. www.fda.gov/news-events/press-announcements/fda-approves-drug-treat-duchenne-muscular-dystrophy.

3. Griggs RC, Miller JP, Greenberg CR, et al. Efficacy and safety of deflazacort vs prednisone and placebo for Duchenne muscular dystrophy. Neurology. 2016;87(20):2123-2131.