Results from a phase 3, 65-participant trial of idebenone (brand names are Catena and Raxone) in boys with Duchenne muscular dystrophy (DMD) show the drug reduced the decline in respiratory function compared to a placebo, potentially paving the way toward regulatory approval.
The trial was conducted in the U.S. and several other countries in patients who were 10 to 18 years old and were not using corticosteroids, such as prednisone, which are widely prescribed to treat DMD but can have serious side effects.
Idebenone (Catana, Raxone), in development to treat DMD and other disorders by the Swiss company Santhera Pharmaceuticals, is an oral medication designed to preserve function in the energy-producing parts of calls known as mitochondria. This, in turn, may protect cells from a type of damage known as oxidative stress. Idebenone has received temporary approval in France for the treatment of an optic nerve disorder.
Idebenone group did better than placebo group on respiratory measures
In a May 13, 2014, announcement, Santhera said idebenone appeared safe and well tolerated in the phase 3 trial and that there was a difference between the idebenone-treated group and a placebo group in the change in "peak expiratory flow" over a year's time. Peak expiratory flow, a measure of respiratory muscle strength, is a person's maximal speed of exhalation. Loss of respiratory muscle strength and decline in respiratory function are a leading cause of death in DMD.
The encouraging results were further strengthened in a May 22, 2014, announcement, in which Santhera said that other respiratory function endpoints also showed a benefit for idebenone compared to a placebo and provided additional detail on the peak expiratory flow results.
The company said the average one-year decline in peak expiratory flow, measured at a hospital-based study site, was 9 percent for the placebo group but was only 3.1 percent for the idebenone group.
On a measure known as "forced expiratory volume in one second" (the amount of air that can be forcibly exhaled in one second), the results also showed a benefit for idebenone. On this measure, the placebo group declined by 10.7 percent during the year, while the idebenone group showed a 2.4 percent decline.
In addition, "forced vital capacity" (the amount of air that can be exhaled after a fully inhaled breath) declined by 9 percent in the placebo group compared to 5.7 percent in the idebenone group.
"We are very excited to observe this treatment benefit for Catena/Raxone in delaying respiratory deterioration in DMD, as evidenced by the significant outcome for the primary peak expiratory flow endpoint in DELOS [the phase 3 trial]," said Nick Coppard, senior vice president of development at Santhera. "The positive result of secondary outcomes, in addition to the primary endpoint, are clearly supportive and establish the clinical meaningfulness of Catena/Raxone treatment. … Having demonstrated a significant and clinically relevant benefit without safety concerns, we believe we are well positioned to discuss regulatory approval with the authorities."