Special report: US biotech Sarepta Therapeutics last month released promising test results for a potential treatment of a rare and horrifying disease, Duchenne Muscular Dystrophy.

Sarepta’s shares surged 50 per cent, adding more than $US4 billion to its market capitalisation before settling back to $US135 per share.

Watching on was a small Melbourne biotech called Antisense Therapeutics (ASX:ANP), which suspects it could have a treatment that may also be a game-changer.

Duchenne Muscular Dystrophy, or DMD, is a genetic disease affecting boys.

It starts showing symptoms in little boys aged 3 and 5 years, eating away at their muscles until they become wheelchair-bound usually by age 10. Sufferers’ survive only into their 20s.

A man on the inside

The data from a Phase 1/2a trail reported by Sarepta suggests that its experimental gene therapy may slow the disease.

Antisense director William Goolsbee believes Antisense’s treatment may make that Sarepta drug, that is already on the market for DMD, work even better.

That’s because Mr Goolsbee came from Sarepta where he served as a non-executive director until 2016.

He can see the pathway for Antisense’s drug from the Phase 2 trials to be conducted at the Royal Children’s Hospital in Melbourne, to a drug with sales worth over $150 million in the US that the Sarepta drug Exondys 51 is already achieving.

“I joined the board of Sarepta in 2007. We were in a very similar circumstance as Antisense,” he told Stockhead.

“We had a low market cap, we had low cash balance, we were fighting to get to the point where we could prove out our drug. Now look at what’s changed in the last 10 years. That’s what we’re trying to achieve at Antisense.”

DMD is rare – estimated at only one in 3,500 births.

The 20,000 boys with DMD in the US allowed Sarepta to access the FDA’s early-to-market orphan drug program and this is where Antisense is also aiming.

“My goal everyday is to keep a boy walking and healthy. The further we can push their ambulation and lifespans the more time we give them while we work towards an ultimate breakthrough, like we hope we’re having with HIV where people now reasonably talk about a cure,” Mr Goolsbee said.

Doubling down

But what Antisense is doing is quite different to the Sarepta drug.

“There we had a disease modifying drug that modified protein expression in the body and changed the course of the disease,” Mr Goolsbee said.

But in a vicious circle, while the Sarepta drug may slow the progression of the disease it can’t stop the disease-created inflammation that keeps attacking the muscle.

The Antisense treatment is designed to treat the inflammation that exacerbates muscle fibre damage.

This can be managed by using cortico-steroids but these come with a whole range of side effects including excessive weight gain — precisely the wrong thing for boys who already have limited movement.

“What we want to do is add our treatment ATL1102 on top of that drug and eliminate a substantial portion of continued muscle degeneration, so whatever the period of ambulation is for that boy would be longer – years is our expectation,” Mr Goolsbee said.

“We can almost create a position of stasis of the disease.”

Fixing the boys

This year Antisense is beginning a Phase 2 DMD trial at the Royal Melbourne Children’s Hospital where it is recruiting 10 boys between 10 years and 18 years, weighing 25kg to 60kg.

The trial will assess the safety and tolerability of ATL1102, but also its efficacy in terms of its effects on the blood and imaging markers of inflammation and muscle damage.

Dosing of patients in the trial is forecast to finish by March next year with results by June.

The DMD treatment is the same as that previously used by the company in a Multiple Sclerosis trial, which showed significant activity in reducing the number of newly formed inflammatory brain lesions.

The company is trialing a lower dose on DMD patients with the rationale that it may have a similar beneficial effect on inflammatory processes in DMD patients as it showed in Multiple Sclerosis.

 

This special report is brought to you by Antisense Therapeutics.

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