The Lancet: Bloodstream-delivered cell therapy slows muscle decline in young people with Duchenne muscular dystrophy, phase 3 trial finds

A cell therapy called deramiocel could slow muscle weakening in boys and young men with advanced Duchenne muscular dystrophy (DMD), and may also slow heart damage in those who already have heart muscle disease, a phase 3 clinical trial published in The Lancet has found. It is the first phase 3 trial of a cell therapy made from donor cells and administered through the bloodstream to treat a genetic disease, and the first such trial in boys and young men whose DMD is already advanced. The therapy is grown from heart cells that were donated for transplant but could not be used.

There is no cure for DMD, which is a serious genetic condition that causes the muscles, including the heart, to gradually weaken and waste away. It almost exclusively affects boys and young men, because the gene involved sits on the X chromosome. As the disease progresses, most patients lose the ability to walk and come to depend on their arms and hands for everyday tasks and independence. 

The HOPE-3 trial involved 106 boys and young men aged 10 to 22 with advanced DMD, who were treated at 20 trial sites across the USA. They were randomly assigned to receive either deramiocel (54 people) or a placebo (52 people), given as a drip into the bloodstream every three months for a year at an outpatient clinic.

After one year, participants given deramiocel were losing the use of their arms more slowly than those given the placebo. Their overall arm movement declined about 54% more slowly than in the placebo group, and their elbow movement about 65% more slowly. Across all participants, the therapy made no clear difference to how well the heart pumped blood. Among the 64 participants who already had heart muscle disease and had suitable heart scans, heart function was better preserved with deramiocel than with placebo. In a smaller group of 22 participants whose scans could be compared before and after treatment, deramiocel was also linked to less spread of heart scarring, but further research is needed to confirm this finding.

The therapy was generally safe and no deaths were reported during the trial. Allergic-type reactions were more common with deramiocel (42%) than with placebo (15%). Almost all side effects were mild or moderate and cleared up within a day or two. The most common were headache, cough, fever, nausea, and a fast heartbeat.

The authors say deramiocel has the potential to help people with any type of DMD mutation, because it targets the swelling and scarring the disease causes in the muscles rather than the gene mutation itself. Heart problems are a major cause of death in DMD, and the authors call for further studies to find out whether the heart benefits seen in this trial help people live longer.

The US Food and Drug Administration (FDA) is scheduled to discuss deramiocel at an advisory committee meeting on 29th July 2026, with a decision on whether to approve the therapy expected by 22nd August 2026: