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Gene therapy for Duchenne muscular dystrophy doesn’t meet primary endpoint in Phase 3 clinical trial

Pharmaceutical company Sarepta has announced the results of its EMBARK trial of gene therapy delandistrogene moxeparvovec (known as the brand Elevidys) to treat Duchenne muscular dystrophy (DMD).

The results show that in a Phase 3 trial, it didn’t achieve a statistically significant difference in the key measure chosen to test its effectiveness (primary endpoint), the NorthStar Ambulatory Assessment, which measures motor function in people with DMD. However, other measures of the trial (secondary endpoints) were met.

Gene therapy in DMD

DMD gene therapy aims to deliver a working version of the dystrophin gene, so that the body can produce functioning dystrophin. The potential benefits of this include protecting the muscles and preventing the progression of the DMD.

Delandistrogene moxeparvovec (Elevidys) is a gene therapy that uses gene transfer. Gene transfer involves delivering the treatment by using a carrier or ‘vector’, such as a virus, which carries the working gene to the affected cells in the body.

The EMBARK study

The study involved 125 patients with DMD who were aged 4 to 7. It was a placebo controlled, randomised trial, in which patients either received delandistrogene moxeparvovec (Elevidys) or a placebo (a substance that has no therapeutic effect).

After 52 weeks, researchers recorded an increase in the NorthStar Ambulatory Assessment of the participants. Patients treated with the gene therapy experienced a 2.6-point increase in NorthStar Ambulatory Assessment, compared with 1.9 for those on placebo. However, this result wasn’t statistically significant to meet the primary endpoint for the trial.

The trial did meet several secondary endpoints. This included an improvement in a patient’s time to rise from the floor and a change in their 10-metre walk or run time.

On the time to rise from the floor, patients treated with the drug experienced a 0.64 second improvement versus placebo. On the 10-metre distance test, the drug was associated with a 0.42-second improvement versus placebo.

What the results mean for gene therapy for DMD

While gene therapy brings a lot of hope, there is still a lot more that we need to understand about it and how it can be optimised as a treatment.

You can find more information about gene therapy in DMD here.

Pharmaceutical company Roche, who has the commercial rights to Elevidys in the UK, issued this global statement about the results, and this letter to the patient community in the UK.

Special webinar to discuss the results of the trial

We are holding a webinar for people with DMD and their families to discuss the results of the trial.

It will be led by Professor Francesco Muntoni, Professor of Paediatric Neurology at Great Ormond Street Hospital, who will discuss the results. There will be an opportunity to ask questions at the end.

We are running it jointly with the NorthStar Network of DMD specialists, Muscular Dystrophy UK and Action Duchenne, and it will take place at 7-7.45pm, on Thursday 2 November.

It will be via Zoom and you can join via this link: https://ucl.zoom.us/j/98764219567 (you won’t need a password)

The North Star Network and Roche (the pharmaceutical company that has the commercial rights to Elevidys in the UK) have prepared this background on the therapy and trial, which you might find useful to read ahead of the webinar.

Published on 31 October 2023

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