A third drug developed by WA-USA partnership for Duchenne muscular dystrophy has achieved US FDA accelerated approval.

Duchenne muscular dystrophy, occurring mainly in boys, is the most common childhood form of muscle wasting. It is caused by a genetic error that prevents the body from producing dystrophin, a protein essential for maintaining muscle fibre strength and stability.   

In the absence of dystrophin, muscle is much more susceptible to damage during regular activity, leading to loss of muscle and ultimately the ability to walk and breathe. Most children with Duchenne require a wheelchair before their early teens.

Now a third treatment, Casimersen, developed by a Western Australian research team to treat the disease has received accelerated approval by the United States Food and Drug Administration (FDA). 

American biopharmaceutical company, Sarepta Therapeutics (Cambridge, MA), has announced the drug Casimersen is now available in the US. The drug has the potential to treat eight per cent of patients with Duchenne by skipping exon 45 during dystrophin expression.


“This is a special day for Duchenne patients and offers great hope for patients living with rare diseases,” said Professor Sue Fletcher, who led the development of the drug alongside long-time collaborator Professor Steve Wilton.

There are more than 7,000 rare diseases that, when combined, affect about six to eight per cent of the global population.”

“Our platform technology developed for Duchenne muscular dystrophy is currently being applied to other diseases. We are exploring the application of this approach to many serious conditions, such as asthma, motor neurone disease, multiple sclerosis and possibly even COVID-19 infections,” added Professor Wilton. 

Casimersen and the two other gene-patching drugs approved by the FDA for Duchenne were developed through the pioneering research of Professors Fletcher and Wilton at the Perron Institute and licenced through The University of Western Australia. The pair are now based at the Centre for Molecular Medicine and Innovative Therapeutics (CMMIT) at Murdoch University.Each drug is designed to treat a specific type of dystrophin gene mutation and this required testing in separate clinical trials.

Billy Ellsworth, receiving treatment with the first Duchenne drug, eteplirsen (Exondys 51) developed by Professors Fletcher and Wilton and their team, is over 20 years of age and still able to walk. This initial exon 51 skipping drug targets approximately 10-13 per cent of Duchenne patients.

In 2019 a second drug, golodirsen (Vyondys 53) received US FDA accelerated approval to treat approximately eight to ten per cent of patients with a confirmed dystrophin gene mutation amenable to exon 53 skipping.

The three drugs for Duchenne developed by Professors Fletcher and Wilton, licensed to Sarepta and now available in the US, can treat almost 30 per cent of patients diagnosed with Duchenne. 

This research supports the United Nations Sustainable Development Goal 3 to ensure healthy lives and promote well-being for all at all ages.

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