Deramiocel, a heart-derived cellular therapy, showed a slowing of muscle weakening in boys and young men with advanced Duchenne muscular dystrophy in a Phase 3 trial published in The Lancet. The HOPE-3 study enrolled 106 patients aged 10 to 22 at 20 U.S. sites and compared deramiocel administered via IV infusion every three months versus placebo over one year. The therapy was linked to slower decline in upper-limb function, with arm movement decline outpaced by about 54% relative to placebo and elbow movement decline about 65% less steep. In a subset with baseline heart disease, heart function appeared better preserved, and heart scarring spread was also reduced in a smaller evaluable group. Safety signals included more allergic-type reactions in the deramiocel arm (42%) than placebo (15%). The publication establishes a Phase 3 dataset built around clinically meaningful functional endpoints, even as regulators have continued to challenge the evidentiary framing during advisory review.