Boy Dies in Chinese DMD Gene-Editing Trial, Renewing Scrutiny of Accelerated Clinical Pathway

An early-stage trial originally intended to demonstrate that gene editing could alter the course of Duchenne muscular dystrophy now leaves a more urgent question: When therapies that permanently modify DNA enter pediatric wards, who is responsible for applying the brakes as risks rise, and when should serious adverse events be disclosed to the public? According to STAT, Chinese biotechnology company HuidaGene has confirmed that a boy participating in the HG302 trial died in August 2025.

HG302 uses an engineered adeno-associated virus (AAV) as a vector to deliver the CRISPR-hfCas12Max editing system into muscle cells, editing the splice site of exon 51 of the DMD gene in hopes of restoring dystrophin through exon skipping. The open-label, dose-escalation study, named MUSCLE, was conducted at Shanghai Children’s Medical Center, affiliated with Shanghai Jiao Tong University School of Medicine, and enrolled ambulatory boys aged 4 to 8.

The report states that the boy who died was the fourth and final participant to receive treatment, at a dose higher than those used in the earlier groups. HuidaGene had previously said that only a small amount of dystrophin was detected in the first low-dose participant. However, there is currently insufficient publicly available information for an independent assessment of how the trial subsequently increased the dose, what symptoms appeared before the death, or the causal relationship between the treatment and the death.

The public trial record changed the study’s status to “completed” in February 2026 but did not post any results. After announcing at the end of 2024 that the first participant had been treated, HuidaGene also claimed that a lower AAV dose was expected to reduce immune-related risks. Before the boy’s death came to light, the public still could not access complete safety data. This information gap is especially consequential for a Phase 1 dose-escalation trial enrolling only a small number of children, because a single serious event could change decisions about subsequent doses and the entire development program.

The case also highlights China’s dual-track system for cell and gene therapies. Some studies initiated by hospital researchers may begin after institutional review without first undergoing a full review by the national drug regulator. This pathway can accelerate the entry of rare-disease therapies into human trials, but if serious adverse-event reporting, cross-institutional oversight, and public registration are not strengthened at the same time, speed may come at the cost of participant protection and public trust.

### Background

The death in this DMD trial and another recently disclosed case are not the same incident. The latter involved a 6-year-old girl with a CHD3-related neurodevelopmental disorder who died seven days after receiving an intrathecal dual-AAV base-editing therapy in 2025. The hospital ethics committee determined that the death was related to the treatment, but neither the trial record nor the subsequently published animal study disclosed the human trial or the death. Nature has added an editor’s note to the related paper, and Shanghai Jiao Tong University School of Medicine has also announced an investigation.

The diseases, technical designs, and research teams in the two cases were different and cannot, without evidence, be treated as involving the same safety mechanism. Their common features, however, are clear: the participants were children, both therapies used AAV to deliver gene-editing tools, and major outcomes entered public view only after the fact. What now truly needs to be disclosed is not only the causes of death, but also the dose-selection decisions, independent safety reviews, regulatory reporting timelines, and follow-up outcomes for the other participants.