Progress with Expanded Sarepta's Elevidys Approval, But DMD Patients Require More

In a pivotal regulatory move, the FDA has substantially broadened the application of Elevidys, a gene therapy developed by Sarepta Therapeutics for Duchenne muscular dystrophy (DMD). This expansion now includes older individuals and those who are non-ambulatory, significantly increasing the number of patients eligible for this innovative treatment. Initially, Elevidys was authorized under an accelerated approval process for ambulatory children aged 4 to 5 years with a confirmed mutation in the DMD gene. However, the latest approval extends its use to both ambulatory and non-ambulatory patients aged 4 and above, provided they have a confirmed mutation in the DMD gene.

A year ago, the FDA granted Elevidys accelerated approval even though it did not meet its primary efficacy endpoints in two studies. The FDA explained its decision by considering multiple factors, including the overall evidence, the severe and debilitating nature of DMD, and the pressing unmet medical need.

Before this extended approval, Elevidys was available to only about 3% of the DMD patient population, according to Sarepta's CEO, Doug Ingram. However, BMO Capital Markets analyst Kostas Biliouris noted that Thursday's regulatory decision now makes Elevidys accessible to over 90% of patients in the United States. In financial terms, this approval opens a significant commercial opportunity for Sarepta, with approximately 13,000 DMD patients in the U.S. now eligible for the therapy.

Tim Lugo, an analyst at William Blair, echoed this sentiment, describing the FDA’s recent decision as the "best-case scenario" for Sarepta. Lugo pointed out that many children under the age of 4 are not yet diagnosed with DMD but will eventually become eligible for Elevidys as they grow older. He also mentioned an ongoing Phase II study focusing on boys under 4 years old, which could further expand Elevidys' future market.

Elevidys, developed in collaboration with Roche, carries a hefty price tag of $3.2 million per patient, positioning it among the most expensive treatments globally. According to GlobalData, Sarepta is projected to generate $5.7 billion in sales from Elevidys by 2029.

Kostas Biliouris also mentioned that Sarepta is poised to have a monopoly in the DMD market for the next several years. This dominance is partly due to the recent setback of Pfizer’s experimental DMD gene therapy, which failed to demonstrate improved motor function compared to a placebo in a Phase III trial. Currently, Capricor Therapeutics is the only other company with a DMD treatment in Phase III trials, with results expected by the end of the year. Other DMD treatments are still in earlier development stages.

Jeff Chamberlain, president of the American Society for Gene and Cell Therapy and a prominent figure at the University of Washington School of Medicine, praised Sarepta's work on Elevidys. He noted that while some children have shown remarkable improvements, others have not benefited as significantly from the treatment. Chamberlain emphasized the importance of continuing to refine gene therapy products to enhance their effectiveness across a wider patient population.

In conclusion, the FDA's expanded approval of Elevidys marks a significant step forward in the treatment of DMD, offering new hope to a broader range of patients. However, the journey to develop more effective therapies that work for all patients is far from over.