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Marathon Pharmaceuticals Announces Neurology Publication of Pivotal Phase 3 Data for Deflazacort for Duchenne Muscular Dystrophy

  • Deflazacort associated with improved muscle strength compared to placebo
  • Deflazacort currently undergoing Priority Review by the U.S. FDA

Northbrook, Ill. – August 30, 2016 – Marathon Pharmaceuticals LLC announced the publication of pivotal Phase 3 data evaluating the investigational drug deflazacort for the treatment of Duchenne muscular dystrophy in the journal Neurology. Data are currently available online and will appear in the print edition this fall.

The data from this Phase 3, double-blind, randomized, placebo-controlled, multicenter study of 196 boys aged 5-15 years showed that patients who received either deflazacort (in two dose strengths: 0.9 mg/kg/day and 1.2 mg/kg/day) or prednisone (0.75 mg/kg/day) demonstrated significant improvement in muscle strength compared with placebo at 12 weeks, meeting the primary endpoint of the study. Deflazacort was also associated with less weight gain than prednisone at 12 weeks; there were significant increases in weight and body mass index (BMI) with prednisone versus placebo (weight: LS mean 3.23 kg versus 1.23 kg, P=.0459, 95% CI 0.03-3.97; BMI: LS means 1.47 kg versus 0.16, P=.0041, 95% CI 0.35-2.29) but no significant differences between the deflazacort groups and placebo.

A secondary analysis of change in muscle strength from 12 to 52 weeks demonstrated a significant improvement in average muscle strength score in the deflazacort 0.9 mg/kg/day group compared with the prednisone-treated group.

“Corticosteroids are the only treatment that increases muscle strength in boys with Duchenne muscular dystrophy. Importantly, this study showed that both deflazacort and prednisone increase strength over placebo, and deflazacort is associated with less weight gain than prednisone,” said study investigator and lead author Robert C. Griggs, M.D., Professor in the Department of Neurology at the University of Rochester. “With currently no FDA-approved treatment for Duchenne and no cure, deflazacort may provide an important treatment option for delaying the progression of Duchenne.”

The three most commonly reported treatment-related adverse events in all groups were Cushingoid appearance (136/196 participants; 69.4%), erythema (82/196 participants; 41.8%), and hirsutism (77/196 participants, 39.3%).1 Adverse events that may be associated with long term steroid use were not evaluated due to the 52-week duration of this study.

The Phase 3 study examined the efficacy of deflazacort vs. placebo. The study also compared the efficacy and safety of deflazacort to prednisone. Eligible participants were randomly assigned to one of four study arms, receiving treatment with either deflazacort 0.9 mg/kg/day, deflazacort 1.2 mg/kg/day, prednisone 0.75 mg/kg/day or placebo for 12 weeks. After 12 weeks, placebo participants were randomly assigned to one of the three active treatment groups and followed through 52 weeks.1 The Neurology publication is available at

This pivotal study is one of two clinical trials exclusively licensed by Marathon, which also conducted a full clinical pharmacology program for deflazacort, including eight clinical pharmacology and safety studies and nine preclinical studies. Data from this Phase 3 trial helped form the basis for two New Drug Applications (NDAs) for deflazacort, one for an immediate-release tablet formulation (6 mg, 18 mg, 30 mg and 36 mg) and one for an oral suspension formulation (22.75 mg/mL), from Marathon, a biopharmaceutical company developing treatments for rare diseases. The NDAs are currently under Priority Review by the U.S. Food and Drug Administration (FDA).

“As with too many rare diseases, patients and families living with Duchenne muscular dystrophy have limited treatment options and a dire need for reliable therapies. These very encouraging data underscore the merits of bringing deflazacort through the FDA review process, in the hopes of making deflazacort broadly available to patients who could benefit from it in the U.S.,” said Dr. Tim Cunniff, Executive Vice President of Research and Development, Marathon Pharmaceuticals.

About Deflazacort

Deflazacort, an investigational drug, is a glucocorticoid with anti-inflammatory and immunosuppressant properties.2 Deflazacort is not currently approved in the United States for any indication. Versions of deflazacort are available in some countries outside the United States where it is approved for a number of indications, but not for Duchenne. If approved, deflazacort will be among the first commercially available treatments indicated for Duchenne in the United States. As of the date of this data publication, there is no cure for Duchenne and currently no FDA-approved treatment.

Based on data contained in the NDAs and in published clinical studies, it appears that deflazacort may be an important treatment option for patients with Duchenne, if approved by the FDA.
Side effects that could occur with Deflazacort use include:

Facial puffiness or Cushingoid appearance, skin redness, unwanted hair growth, weight gain, central obesity, headache and increased appetite.

Other important side effects include: a decrease in the density of the bones (osteopenia) or fragility of the bones (osteoporosis) which may lead to fractures, acne, stomach upset or irritation to the stomach lining, cataracts (which can impair vision), increased susceptibility to infection, sugar intolerance and aggravation of diabetes, elevation in blood pressure, behavioral and mood changes, effects on growth and development such as short stature.

Deflazacort use is not recommended for patients who have a systemic fungal infection or are allergic to deflazacort or any of the inactive ingredients in deflazacort, have had recent or ongoing infections or have recently received a vaccine or are scheduled for a vaccination.

About Marathon Pharmaceuticals

Marathon Pharmaceuticals, LLC, is a biopharmaceutical company that develops treatments for rare diseases, with a focus on patients who currently have no treatment options. The company’s pipeline of new medicines includes treatments for rare neurological and movement disorders. Marathon is headquartered in Northbrook, Illinois, with offices in Chicago, New Jersey and Washington D.C.