AVI Biopharma hit the main goal of its most important clinical trial yet for boys with Duchenne Muscular Dystrophy, and it’s bound to raise a whole set of new questions this year about what it really means for the treatment of this disabling genetic disease.
The Bothell, WA-based biotech company (NASDAQ: AVII) said today that its RNA-based drug eteplirsen was able to help boys produce more of the dystrophin protein their muscles need to properly function. The study, which randomly assigned 12 boys to a couple different doses of the AVI drug or a placebo, showed the boys were able to produce about 22.5 percent of normal dystrophin levels after 24 weeks on the therapy, while there was no increase on the placebo. No serious adverse events were reported in patients on the experimental treatment, and no patients dropped out of the study, AVI said.
The study’s lead investigator hailed the finding as a “major advance” in an AVI statement, and the company’s CEO, Chris Garabedian, told investors today that it’s the first time anyone has shown a drug can produce “robust and consistent” increases in dystrophin in muscular dystrophy patients. But AVI also said the boost in dystrophin didn’t immediately translate into a clinical benefit, as researchers saw no difference in patients’ walking ability in a standard 6-minute walk test. Jerry Mendell of Nationwide Children’s Hospital, the study’s lead investigator, did, however, say researchers expect the drug to show a clinical benefit if it is used for a longer period of time, and AVI said it is looking forward to more data from a 48-week follow-up analysis later this year. About one out of every 3,500 boys worldwide has Duchenne Muscular Dystrophy, which usually puts them in a wheelchair before they are teenagers.
“We believe this provides tremendous promise to patients with Duchnenne Muscular Dystrophy, as we know that dystrophin is critical to healthy muscle function, and may be the key component to slow or halt the progression of the disease,” Garabedian said in a conference call with investors.
Even though AVI said the results are encouraging enough for it to advance from the second to the third and final stage of clinical trials normally required for FDA approval, investors reacted negatively, partly because of the lack of data on clinical benefit. AVI stock fell 25 percent to $1.16 at 10:48 am Eastern time.
Detailed results from the trial are expected to be presented later this month at the American Academy of Neurology meeting in New Orleans.
Scientists will surely want to review that data carefully later this month. This compound, given as a once-weekly infusion, is designed to work in a novel way by allowing patients to skip past a faulty section of gene for making dystrophin, so they can make enough of the critical protein to keep their muscles working.
The study, known as Study 201, enrolled four patients on a placebo, four more on a weight-adjusted dose of 30 milligrams per kilogram of body weight, and another four on a 50 milligram per kilogram dose. Researchers believed, based on animal trials, that it would take 24 weeks for the drug to produce dystrophin throughout enough muscle groups to be meaningful, so the main goal of the study was to see whether the AVI drug could boost dystrophin production in the 30 milligram/kilogram dose at 24 weeks. Scientists also wanted to see whether the higher dose could achieve the same goal in a shorter period of time, 12 weeks, but that didn’t work, AVI said.
AVI’s Garabedian told analysts the company is still combing through the data to look for answers on how well the drug did on its secondary goals. Since the dystrophin it found is based on muscle biopsy samples—and doctors can’t take multiple biopsies from different muscle groups at many points in time because of the procedure’s invasiveness—AVI can’t ask every single question in human trials that it can in animal studies. One of the big next steps, Garabedian said, is to wait and see what the data says from 48-week follow-up biopsies, which should give the new drug more time to help get dystrophin production up in enough muscle groups to show a clinical benefit.
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