Duchenne muscular dystrophy drug approved by FDA

The US FDA has announced the approval of a Western Australian-developed drug to treat Duchenne muscular dystrophy (DMD) — a rare and fatal muscle wasting disease affecting one in 3500 boys worldwide.

Murdoch University’s Professor Steve Wilton has been leading the development of the drug, named eteplirsen, for close to two decades now. He explained that he started back when he was based at The University of Western Australia (UWA), saying: “I came up with this crazy idea of trying to change gene expression to treat muscular dystrophy.

“Duchenne muscular dystrophy mainly affects boys, where every muscle in their body — including their heart — deteriorates, eventually leading to loss of life,” said Professor Wilton. Without treatment, affected boys are usually confined to a wheelchair before age 12 and succumb to the disease by age 30.

“Until now, however, there has been no therapy that addresses the underlying genetic defect that causes DMD,” Professor Wilton said.

Clinical trials of the drug in the United States indicate that treatment reduces the severity of the disease by delaying the loss of muscle function. Boys who have previously been told they are incurable are still able to walk into their mid to late teens and potentially beyond.

“Keeping them out of a wheelchair is crucial — that’s a real devastating milestone,” said Professor Wilton. “And if you can keep them walking, keep them upright, you reduce the scoliosis, you improve the breathing; the health and wellbeing of these kids is greatly improved.

“Through the trials we’ve seen the progression of these kids doing things they would not ordinarily be doing. Boys who would normally be in wheelchairs are instead running around playing football, jumping into cars.”

The patented treatment should be useful for DMD patients with a mutation in a particular region of the dystrophin gene, which means it will work in about one in every 10 DMD patients. However, Professor Wilton and his team have developed other ‘genetic patches’ for other dystrophin ‘spelling errors’ causing DMD and believe that treatments will eventually become available for the vast majority of DMD sufferers.

“Depending on the type of mutation, we can correct a variety of inherent diseases that have previously been considered untreatable,” said Professor Wilton.

Eteplirsen is licensed to the US pharmaceutical company Sarepta Therapeutics. It will be marketed as Exondys 51 and is now available on prescription to DMD sufferers worldwide.

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