deramiocel extension trial signals slower upper limb decline; DMD efficacy evidence awaits FDA assessment

For patients with Duchenne muscular dystrophy (DMD), preserving arm and hand function affects everyday independence, including eating, operating a wheelchair and using a phone. On October 5, Capricor Therapeutics announced new follow-up results for its cell therapy deramiocel: patients who initially received placebo showed a signal of slower upper limb functional decline after switching to treatment. This update focuses on changes in the second year, adding another layer of observation to the efficacy evidence still under review.

The HOPE-3 extension study used the PUL 2.0 upper limb function scale. According to model estimates released by the company, the delayed-treatment group declined by an average of 2.05 points during the first year on placebo and by 0.49 points during the second year after switching to deramiocel, a relative reduction in decline of 76%. This percentage describes the difference in decline between two successive years in the same group of patients. It does not mean that function recovered by 76%, nor is it a comparison with a concurrent placebo group in the second year.

The trial initially randomized 106 participants to receive treatment or placebo by intravenous infusion every three months for one year; 98 subsequently entered the extension study, in which all received deramiocel. Both the company's September conference preview and its latest announcement stated that 82 participants had month 24 assessment data, including 40 originally assigned to the treatment group and 42 originally assigned to the placebo group. Craig McDonald of the University of California, Davis presented the data at the World Muscle Society congress in Hiroshima, Japan.

Patients who received deramiocel from the outset had similar declines in scale scores in each of the two years; both groups also showed less functional decline at month 24 than predicted by a natural history model. These observations are consistent with the possibility that treatment may slow decline, but the natural history comparison involved neither matching nor statistical testing. The patient organization CureDuchenne also published a brief update noting an association between treatment and slower upper limb decline; it linked back to the company's announcement and provided no independent quantitative analysis.

The key considerations when interpreting these data are that the extension phase was no longer blinded and had no concurrent placebo control. The company explicitly stated that no significance level was allocated for statistical testing of these analyses, and the study was not designed with sufficient statistical power for the month 24 comparisons. The 76% figure is therefore an exploratory signal; determining how much of the change can be attributed to treatment still requires consideration of disease progression, incomplete follow-up data and the effects of the analytical methods.

Background

deramiocel is a cell therapy derived from allogeneic cardiac tissue, being developed to preserve muscle function by using signals secreted by the cells to modulate inflammation and reduce fibrosis. Previous controversy surrounding its review centered on the statistical analyses of the pivotal trial and whether the efficacy evidence was sufficient. These extension results provide longer-term observations, but comparisons between successive years alone cannot resolve questions about how to interpret the randomized trial evidence.

Capricor said the 24-month data have been included in a major amendment to its biologics license application, and the FDA's current target decision date is November 22, 2026. deramiocel has not yet been approved for marketing; the central question ahead is how the regulator will weigh these supportive data alongside the original randomized trial, the robustness of the analyses and the safety evidence.