A first-in-human study of HuidaGene’s experimental treatment for Duchenne muscular dystrophy found evidence of gene editing and dystrophin in patients’ muscle, but reported that one boy died after a severe immune reaction to treatment.
The study, published in Cell, involved four boys who received one dose of HG302 through a vein. HG302 is a CRISPR-based therapy delivered using an AAV9 viral vector. Muscle biopsies showed gene edits at the intended site and detectable dystrophin.
Dystrophin is the protein that is missing or deficient in Duchenne muscular dystrophy. The researchers said the results were modest and came from a very small group, so they do not establish that the treatment works. Two participants completed 12 months of follow-up, and their walking assessments improved.
Overall, functional outcomes varied. The fourth participant, who received the high dose, developed a severe breathing problem known as acute respiratory distress syndrome, amid strong activity in the complement system and widespread inflammation. The participant died.
HuidaGene said the death occurred in August 2025. The company publicly disclosed it in August 2026. The researchers also said preclinical testing and existing precautions had not predicted or prevented the severe toxicity.
The findings provide early evidence that the therapy has biological activity. Its possible benefits and risks need further study.