Orlando toddler first in Florida to get Duchenne gene therapy
The day Jaxson DeLeon got his Duchenne Muscular Dystrophy diagnosis, his mom didn’t let herself cry.
“If you cry, that’s it. You’re not going to stop crying,” Carmen Ramirez remembers thinking two years ago, when doctors told her Jaxson had this fatal, genetic condition. Duchenne has a median life expectancy of 41, according to a 2021 review.
In the last few weeks, alone in her office, Ramirez has cried without reservation.
“But it’s not because I’m upset,” she said. “I’m really that grateful.”
After decades of research, gene therapy has been approved for Duchenne Muscular Dystrophy, a degenerative muscle disease diagnosed each year in about 1 in 3,500 newborns, almost all boys. Jaxson, 4, is the first child in Florida outside of a clinical trial to receive the treatment. It was given in mid-September at Nemours Children’s Hospital in Orlando, which hosts one of eight Florida muscular dystrophy care centers that have been certified and approved by the Muscular Dystrophy Association.
Developed by Sarepta Therapeutics, Elevidys is administered by injecting a patient with a virus that treats the underlying genetic cause of Duchenne. The one-time infusion is thought to be the only approved therapy to significantly slow or even halt the progression of the uncurable disease.
“This has been a long time coming,” said the Nemours Children’s Hospital doctor who treated Jaxson, pediatric neurologist Dr. Omer Abdul Hamid.
Though the drug has potential side effects and data is limited, families are clamoring for a chance to fight the disease’s deadly outcome.
“I would do anything for my child. This will give him a chance,” Ramirez said.
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Limited data, limitless interest
The Food and Drug Administration gave Elevidys the green light in June under its Accelerated Approval Program, which allows drugs for serious conditions to be approved with less data than is normally required.
The approval was somewhat controversial. Data suggests the drug worked on 4- and 5-year-olds who were still able to walk, but there wasn’t strong evidence that it worked well in other age groups. The FDA’s advisory committee ultimately voted 8-6 in May to approve Elevidys, conditional on the success of a pending clinical trial. The drug is currently available only for certain 4- and 5-year-old patients.
The clinical trial will have data available by the end of the year, according to Sarepta spokesperson Sierra Smith. The FDA will likely broaden Elevidys’ age restrictions if the study succeeds. If data calls the drug into question, however, it could be taken off the market.
Hamid expressed his confidence in the drug, attributing the mixed results to the study’s small size.
Duchenne starts with mild physical symptoms, like clumsiness, in young children. More serious symptoms typically start when children turn 6 and get progressively worse until they lose the ability to walk and breathe on their own.
Hamid has witnessed the drug reverse some of that decline: he had a patient who regained the ability to ride his bike after his treatment.
“Anybody that’s taken care of these patients has seen the power of this treatment, and we are pretty much all in favor as neuromuscular experts across the country,” Hamid said. “I think a lot of neuromuscular experts across the country are expecting that the label for this treatment does get expanded to older age groups.”
In the months to come, Jaxson will continue to be monitored for any side effects like liver inflammation, heart inflammation, muscle inflammation and abnormal blood counts, said Hamid.
A lot of caution goes into follow-up after this treatment, said Dr. Barry Byrne, chief medical adviser for the Muscular Dystrophy Association and director of the Powell Gene Therapy Center at the University of Florida. He added that there have been fatalities in other clinical trials of therapies for Duchenne patients.
“The infusion itself, that is the simplest part of the process. It’s after that we have to be very mindful of the safety concerns,” Byrne said.
The uncertainty hasn’t stopped parents from taking a chance on this treatment.
Ramirez said the decision was a no-brainer. When she took Jaxson to the hospital, she brought bottles of champagne for the staff.
“It’s very simple. If I do nothing, I know what will happen, and I know when. And if I do something, it can change that,” Ramirez said.
So far, Jaxson has had only mild side effects, said Ramirez: a low grade fever, queasiness and a brief rash.
He has been isolating alongside her for the past several weeks, because the virus infusion has made him immunocompromised and potentially contagious to others. Ramirez said she’s nervous for the future and all the unknowns it will bring, but glad she took this chance.
“I literally feel like I’m sitting in a miracle,” she said. “I’m just praying that he’s able to pave the way for others.”
Barriers remain
Gene therapy is a rare and complicated treatment. As of June, the FDA has approved only 32 cellular and gene therapy products.
Hamid is hopeful that in future years, more gene therapies will be approved for Duchenne. Clinical trials are currently underway for several different types of gene therapy.
Elevidys’ restrictions and price tag have created some hurdles, he added. He had a patient from Georgia who was within the 5-year age limit but couldn’t get Medicaid to pre-authorize the $3.2 million treatment before he turned 6 and aged out of eligibility.
In addition, some Duchenne patients have gene mutations that disqualify them from this therapy, and those who already have antibodies for the virus injected in this treatment cannot get it.
“It’s important to realize that as exciting as this treatment is, our work is still not done. We have a lot of work to do, in terms of treating patients who aren’t eligible for this,” Hamid said.
Nemours is the only Orlando location that is offering the therapy.
Hamid said the hospital has received interest from families around the world who want to get their children this treatment before they age out of eligibility. He anticipates being able to offer the treatment to international patients in the future, but right now, it is limited to Florida residents to try to manage demand.
In addition to Nemours, two other Florida clinics are offering this treatment: one at Nicklaus Children’s Hospital in Miami and one at University of Florida Health in Gainesville.
Having an Orlando site is crucial to furthering access to this treatment and others in the future, said UF Health’s Byrne.
“It’s really important to have a site of care in Orlando,” Byrne said. “I think it’s going to be a great site for families to have easy access to if they’re coming from a distance.”
Ccatherman@orlandosentinel.com; @CECatherman Twitter
