The Food and Drug Administration said Monday that Capricor Therapeutics’ stem cell treatment for Duchenne muscular dystrophy did not meet the objectives of a Phase 3 trial — contrary to the company’s claims last year.

Capricor said in December that the drug, known as deramiocel, met both the primary and secondary endpoints in a large, randomized study. It was a striking result in a fatal, childhood disease that has proven stubbornly difficult to treat, despite immense advances in genetic medicine. 

The data were also notable for coming primarily in teenagers and young men who have already lost the ability to walk, a population with few options. The drug appeared to both preserve their upper-arm function and stave off the heart failure most patients eventually experience, Capricor had said.