A spokesman for Sarepta told ABCNews.com that the "path forward" for eteplirsen will depend on its discussions with the FDA later this year.
In a statement, the company said it "... understands the urgent need of boys with DMD and their families," but cannot publicly speak about patients in its clinical trials.
"We have aligned with the DMD community in the fight against this disease for many years, and we are committed to finding the most expeditious regulatory path forward to bring eteplirsen quickly and responsibly to all of the boys who may benefit from it," the statement said. "Our priority is to gather and analyze the safety and efficacy data from the ongoing Phase IIb study, which will form the basis of discussions with the FDA to determine the most appropriate path for eteplirsen."
Duchenne muscular dystrophy affects one in 3,500 male births, about 20,000 children in the United States and 300,000 worldwide, according to Cure Duchenne, one of three organizations that have funded the clinical trial.
The muscular disease strikes between the ages of 3 and 5 as boys progressively lose their ability to walk. Eventually, they are wheelchair bound, their upper body strength fails, and, like Austin, they eventually cannot raise their arms to feed themselves.
Later, their breathing is affected and they require tracheotomies and breathing assistance. Eventually, the heart and lungs fail.
The drug is not a cure, but shows promise, according to Cure Duchenne founder Debra Miller, who has a 15-year-old with the disease. It is the first to target specific mutations in the gene that makes dystrophin, the protein that helps strengthen muscle fibers.
"We want to do everything we can to get this drug for all the boys and we are working with Sarepta," she said. "My son is still walking, but I can definitely see the weakness and it's like a stab in the stomach. The worst part is that every year he can do less than the year before."
But with only 12 research subjects having access to the drug right now, "It's a good news, bad news story," she said.
"We lived our life thinking this was a hopeless disease, but we have a good feeling about this drug," said Miller. "We are very hopeful and very cautious."
Her son is not in the clinical trial because the drug does not target his specific genetic mutation. But, she said, this trial has given other families the "proof of principle" that this type of drug can work.
As for the Mcnarys' children, Austin was diagnosed at the age of 3, when Max was already 3 months old -- too late for genetic testing. When Mcnary wanted more children, she was found not to be a carrier. Rather, she had a spontaneous mutation in her eggs.
"This can happen in any family," said Mcnary, who has six children in all, the Leclaire boys, who are from a previous relationship, her husband's twins and two healthy children from their marriage together, aged 4 and 1.
In the last year, the family has been "torn emotionally," according to Mcnary.
"I am clearly happy for Max because he is doing so well and exceeding our expectations for this drug," said Mcnary. "But it's taking much longer than we ever thought for the drug company to at least grant access to his brother [Austin] who is sitting home watching his brother get treatment."
"For the longest time, I felt so scared, because in the beginning, we weren't allowed to say anything about the clinical trial," she said.
But now Mcnary her husband, Craig, who runs a Roto-Rooter franchise, have been talking to whomever will listen. For the past six months, they have been emailing Sarepta's executives.
"I am like a broken record," said Mcnary. "I congratulate the drug company who are now public and doing well. Their stocks are going up. We are not just looking out for Austin. We have a lot of friends in the (muscular dystrophy) community. People are losing their upper body strength just waiting for this. This is urgent right now."