FDA Expands Approval of Delandistrogene Moxeparvovec-rokl for Duchenne Muscular Dystrophy

The FDA has expanded the approval of delandistrogene moxeparvovec-rokl (Elevidys; Sarepta Therapeutics Inc) for Duchenne muscular dystrophy (DMD) to include ambulatory and non-ambulatory individuals 4 years of age and older with DMD and a confirmed mutation in the DMD gene.¹

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In June 2023, delandistrogene moxeparvovec-rokl was approved under an accelerated approval for ambulatory individuals 4 through 5 years of age with DMD who had a confirmed mutation in the DMD gene.² The action from the FDA grants traditional approval for ambulatory individuals 4 years of age or older, in addition to accelerated approval for non-ambulatory individuals in that same age range.

“Today’s approval broadens the spectrum of patients with Duchenne muscular dystrophy eligible for this therapy, helping to address the ongoing, urgent treatment need for patients with this devastating and life-threatening disease,” Peter Marks, MD, PhD, director of the FDA’s Center for Biologics Evaluation and Research, said in a news release.¹

Delandistrogene moxeparvovec-rokl is a recombinant gene therapy that delivers to the body a gene leading to the production of Elevidys micro-dystrophin, which is a shortened protein containing selected domains of the dystrophin protein that is present in normal muscle cells.¹

In deciding whether to expand approval of delandistrogene moxeparvovec-rokl, the FDA considered the debilitating nature of DMD and the unmet medical need for patients. The drug was originally approved through the accelerated approval pathway, which allows the FDA to approve drugs for serious diseases when the drug is reasonably likely to provide clinical benefits to patients.¹

The treatment’s efficacy was evaluated in 2 double-blind studies and 2 open-label studies, which enrolled a total of 218 male patients with confirmed disease-causing mutation in the DMD gene.¹

In one, the North Star Ambulatory Assessment (NSAA), a scale used to rate motor function in males with DMD who are capable of walking, was utilized to evaluate the effect of delandistrogene moxeparvovec-rokl. Although the primary end point of improvement versus placebo in the NSAA in that study failed, the FDA found the results surrounding the secondary end points indicated a clinical benefit compared to the placebo, leading to delandistrogene moxeparvovec-rokl’s traditional approval.

When considering whether to grant accelerated approval for non-ambulatory individuals aged 4 and older, the FDA considered clinical data from a study in 4- to 7-year-old children, in addition to a study in 4- to-5-year-old children, that indicated a correlation of delandistrogene moxeparvovec-rokl micro-dystrophin levels with positive clinical outcomes.

DMD primarily affects males, with about 1 in every 3300 boys impacted by the disorder. Life-threatening respiratory and heart problems can occur because of weakening of respiratory muscles involved in lung function. Symptoms typically begin in childhood, and oftentimes patients die in their 20s or 30s due to respiratory or heart failure.

Although the expanded approval of delandistrogene moxeparvovec-rokl is a positive step in meeting this unmet gap in care, the cost of gene therapies may still inhibit patients from receiving proper treatment. Sophia Humphreys, PharmD, MHA, BCBBS, noted in an issue of Pharmacy Practice in Focus: Health Systems that individual cost for gene therapies could exceed $3 million per patient for novel agents.³

Additionally, analyses of the cost of gene therapies have found that the annual cost will exceed $20 billion, which is a conservative estimate. Health systems must ensure that an adequate supply of gene therapies such as delandistrogene moxeparvovec-rokl is available and do what they can to lower the financial burden on individuals with DMD.

References

1. FDA. FDA expands approval of gene therapy for patients with Duchenne muscular dystrophy. Press release. Published June 20, 2024. Accessed June 21, 2024. https://content.govdelivery.com/accounts/USFDA/bulletins/3a3fabc

2. Gallagher A. FDA grants accelerated approval to Elevidys for Duchenne muscular dystrophy. Pharmacy Times. Published June 22, 2023. Accessed June 21, 2024. https://www.pharmacytimes.com/view/fda-grants-accelerated-approval-to-elevidys-for-duchenne-muscular-dystrophy

3. Haas C. Considering financial perspectives with gene therapy breakthroughs. Pharmacy Times/Pharmacy Practice in Focus: Health Systems (Vol. 13, Issue 3). Published May 9, 2024. Accessed June 21, 2024. https://www.pharmacytimes.com/view/considering-financial-perspectives-with-gene-therapy-breakthroughs