While Thursday’s label expansion and traditional approval for the gene therapy is an important milestone, many challenges still face the Duchenne muscular dystrophy community.
In a much-anticipated regulatory decision on Thursday, the FDA significantly expanded the label and use of Elevidys, Sarepta Therapeutics’ gene therapy for Duchenne muscular dystrophy (DMD). Most exciting, perhaps, is the expansion of Elevidys’ label to include older individuals as well as non-ambulatory ones, broadening the spectrum of patients eligible for this breakthrough therapy. While Elevidys was previously approved under accelerated approval for ambulatory individuals 4 through 5 years with a confirmed mutation in the DMD gene, Thursday’s expanded approval includes ambulatory and non-ambulatory patients 4 years of age and older with a confirmed mutation in the DMD gene.
It was a year ago that the regulator granted accelerated approval for Elevidys as the first FDA-approved gene therapy for DMD—despite falling short of its primary efficacy endpoint in two studies. In making its decision, the FDA on Thursday said it “considered the totality of the evidence, including the potential risks associated with the product, the life-threatening and debilitating nature of the disease and the urgent unmet medical need.”
Under its previous label, Elevidys was limited to only about 3% of the total DMD population, according to Sarepta CEO Doug Ingram. However, BMO Capital Markets analyst Kostas Biliouris, in a note to investors, said that with Thursday’s approval, the FDA has effectively opened Elevidys’ label to more than 90% of patients in the U.S.
Elevidys is now approved to treat a population that “includes ~13,000 DMD patients (~90% of total prevalence), creating a significant commercial opportunity for [Sarepta],” Biliouris wrote.
William Blair analyst Tim Lugo agreed, writing in an investor note that Thursday’s FDA approval is the “best-case scenario for Sarepta since many patients below age 4 are not yet diagnosed but will age into the label, opening the DMD market to all current and future patients who will be eligible for treatment.” Lugo also highlighted the fact that Sarepta has an ongoing Phase II study for boys under the age of 4.
It’s also worth mentioning that Elevidys—developed and commercialized in partnership with Roche—has a $3.2 million per patient price tag, making it one of the world’s most expensive medicines. Data analysis firm GlobalData said it expects Sarepta to pocket $5.7 billion in Elevidys sales by 2029.
Sarepta’s Monopoly in DMD
Biliouris said in his investors’ note that Sarepta will have a “monopoly in DMD for the next ~4+years.” That 4+ years of monopoly is thanks in part to the stumble by Pfizer’s experimental DMD gene therapy, which was found not to improve motor function versus placebo in a Phase III trial last week.
Indeed, there is only one other company with a DMD candidate in Phase III: Capricor Therapeutics’ cell therapy CAP-1002. The company expects topline data from the ongoing trial by the end of this year. Other DMD treatments are all in earlier stages of development.
Jeff Chamberlain, president of the American Society for Gene and Cell Therapy and the McCaw Chair in Muscular Dystrophy at the University of Washington School of Medicine, told BioSpace last month that Sarepta has done a “fantastic job” on Elevidys, with some children treated with the gene therapy “doing tremendously well,” while others he said are “not doing quite as well.”
In the coming years, it is critical to overcome the challenges with the first generation of micro-dystrophin gene therapy products, according to Chamberlain. “Just because we have an approved therapy doesn’t mean you can stop and go home,” Chamberlain said. “We want something that’s going to be more effective; that’s going to work on all patients, not just some of them.”
Greg Slabodkin is the news editor at BioSpace. You can reach him at greg.slabodkin@biospace.com. Follow him on LinkedIn.
