FDA Sets Date for Full Approval, Broader Indication for Elevidys

The FDA has granted priority review for Sarepta Therapeutics' supplemental biologics license application for the gene therapy Elevidys (delandistrogene moxeparvovec-rokl) and set a review goal date of June 21, 2024. Elevidys was granted an accelerated approval in June 2023 to treat ambulatory patients aged 4 through 5 years with Duchenne muscular dystrophy who have a confirmed mutation in the dystrophin gene.

The supplemental application seeks to convert the accelerated approval to a full approval and expand the indication to treat Duchenne muscular dystrophy patients with a confirmed mutation in the DMD gene.

Elevidys is a one-time therapy that delivers a gene to muscle that codes for a shortened, functional form of dystrophin, which is mutated in Duchenne muscular dystrophy. Duchenne causes the muscles in the body to become weak and damaged over time and is eventually fatal. Duchenne affects about 1 in 3,500 to 5,000 males born worldwide.

Elevidys launched with a wholesale acquisition cost (WAC) of $3.2 million. A cost-effectiveness analysis sponsored by Sarepta indicated the value of Elevidys between $5 million and $13 million compared with standard of care alone, with a willingness-to-pay threshold of $500,000. The analysis found that Elevidys increases quality of life and equal value of life years gained, a measure used to determine how much a treatment can extend life.

In its preliminary earnings release issued in January 2024, Elevidys’ net product revenue is expected to be $131.3 million for the fourth quarter of 2023 and $200.4 million for full-year 2023.

The efficacy supplement is supported by results from EMBARK, a phase 3 clinical study in patients with Duchenne between the ages of 4 through 7 years and data from ENDEAVOR, an open-label clinical study in patients with Duchenne in patients ages 2 years and older.

Topline results of EMBARK were announced in October 2023. In the study, Elevidys-treated patients improved 2.6 points on their North Star Ambulatory Assessment (NSAA) total score 52 weeks after treatment compared with 1.9 points in placebo-treated patients. The difference of 0.65-points between treated and placebo groups did not reach statistical significance. In a press release, Sarepta officials said the results favored Elevidys across all endpoints in the study, including achieving statistical significance on all pre-specified key secondary endpoints and in each age subgroup of the key secondary endpoints.

Sarepta is also conducting trials of other treatments for Duchene’s. One is vesleteplirsen (SRP-5051), a drug to treat patients with Duchenne muscular dystrophy who are amenable to exon 51 skipping, which would allow for increased dystrophin production. A phase 2 trial is ongoing. Data from part B of the study were reported in January and found that patients treated with vesleteplirsen had consistent dystrophin expression in ambulatory and non-ambulatory patients at 28 weeks.

Additionally, Sarepeta has begun screening for a phase 3 trial of bidridistrogene xeboparvovec (SRP-9003), a gene therapy to treat patients with limb-girdle muscular dystrophy Type 2E, a rare condition that causes weakness and wasting in the muscles in the shoulder and legs.