A child died after receiving an experimental gene editing treatment in China, but the company developing the therapy did not publicly disclose the death until nearly a year later.
Shanghai-based HuidaGene Therapeutics said on Aug. 5 that a participant in its HG302 trial died in August 2025 after receiving a high dose of the treatment for Duchenne muscular dystrophy, a progressive and life-limiting muscle disease.
The company attributed the death to acute respiratory distress syndrome that developed during a severe immune reaction following the treatment.
HuidaGene did not disclose the boy’s age, treatment date, dose, date of death, or clinical course. The trial record shows that the study enrolled four boys between the ages of 4 and 8 at Shanghai Children’s Medical Center.
The death is the second involving a child in separate experimental gene editing studies in Shanghai to become publicly known in recent weeks. Shanghai Jiao Tong University School of Medicine announced an investigation in July into an unrelated study after a 6-year-old girl died in March 2025.
In the HG302 case, neither the hospital nor Chinese health and drug authorities have publicly identified any investigation, suspension, required protocol change, sanction, or ethics determination connected to the death.
Trial Returned to Active Status Before Disclosure
HuidaGene began the HG302 study in late 2024, describing it as an investigator-initiated clinical trial evaluating a treatment designed to restore production of dystrophin, a protein lacking in patients with Duchenne muscular dystrophy.
The treatment uses CRISPR, a technology that allows scientists to alter selected sections of DNA. HuidaGene’s treatment is intended to edit the faulty gene responsible for producing dystrophin.
Under China’s rules, the participating medical institution bears primary responsibility for investigator-initiated studies, including arranging scientific and ethics reviews and monitoring the research throughout its course.
The public trial record, however, identifies HuidaGene as both the lead sponsor and the party responsible for maintaining the record. It does not name the individual who initiated the study. The company has not explained how responsibility was divided among HuidaGene, Shanghai Children’s Medical Center, and the investigators.
Changes to the public record provide a chronology of the study after the boy’s death.
The study’s status changed from “Recruiting” to “Completed” in an update submitted on Feb. 13 and posted four days later—about six months after the death. The number of participants was changed from six planned to four enrolled, and Dec. 2, 2025, was entered as the completion date.
On July 31—five days before HuidaGene publicly disclosed the death—the company submitted another update returning the study to “Active, not recruiting.”
The update changed the estimated date for completing the initial phase to Aug. 2, 2026, moved final completion to June 2, 2027, and extended follow-up for participants from 26 weeks to 104 weeks.
The record does not explain why the study was returned to active status. It contains no posted results or information about the death and says the study has no data monitoring committee.
Company Says Findings Were Submitted in January
In its statement, HuidaGene said it conducted laboratory, immune system, tissue, and post-mortem examinations after the death.
The company said the participant developed acute respiratory distress syndrome after receiving a high dose of an adeno-associated virus, or AAV, used to deliver the gene editing treatment throughout the body.
AAVs are modified viruses used to carry genetic material into patients’ cells. High doses delivered throughout the body have previously been associated with severe immune reactions and deaths in gene therapy studies.
HuidaGene said the death was reported to the hospital ethics committee and other authorities within the required period. It did not identify the authorities, provide the reporting dates, or disclose what action they took.
The company also said it submitted the findings from its investigation for peer review in January and would release further details after publication.
HuidaGene did not provide the manuscript’s title, journal, authors, or current status. No corresponding paper or preprint was publicly identifiable as of Aug. 6.
HuidaGene said the three other participants had not experienced the same severe reaction and remained under long-term follow-up.
The company did not explain why it waited until August to disclose a death that occurred the previous August and that it says it had investigated in time to submit its findings in January.
The disclosure followed repeated inquiries from STAT, a Boston-based health and science news publication that first reported the death.
STAT reported that two senior HuidaGene executives—Alvin Luk and U.S. based gene editing researcher TJ Cradick—left the company after its May 2025 presentation of early HG302 findings. HuidaGene did not address whether their departures were related to the study.
Higher Dose Followed Early Results
HuidaGene announced the first participant’s treatment in December 2024.
The treatment uses a HuidaGene-developed form of CRISPR called hfCas12Max. Delivered intravenously through an AAV vector, it is intended to alter part of the faulty dystrophin gene so the body can resume producing a functional form of the protein.
At a May 2025 meeting of the American Society of Gene and Cell Therapy, the company presented findings from the first two participants. According to STAT, the early findings did not clearly establish that the treatment had benefited the children, but Luk said the company planned to move to a higher dose.
HuidaGene has not disclosed the infusion dates or doses for all four participants, how long each child was observed before the next was treated, or what safety review took place before the higher dose was administered.
The trial record describes the study as an early safety study testing multiple dose levels. It does not identify an independent monitoring committee or specify who reviewed the accumulated safety information before the dose was increased.
No Identifiable Chinese Registry Record
No matching record for HG302, HG302-01, or the MUSCLE trial could be found in the public Chinese Clinical Trial Registry.
Registration on ClinicalTrials.gov does not establish whether HuidaGene or the hospital separately filed the study in China’s national medical research system, which is different from the public Chinese trial registry. That national filing could not be independently confirmed.
Chinese rules for investigator initiated medical research require institutional scientific and ethics reviews, registration through the national system, monitoring of serious adverse events, and updates when a study is suspended, terminated, or completed.
The rules also allow an ethics committee to require changes or recommend suspending or terminating research based on the severity of an adverse event.
No public record identifies HG302’s Chinese filing number, ethics approval number, principal investigator, or any decision by the hospital following the death.
Separate Shanghai Trial Under Investigation
The HG302 death became public shortly after reports of another child’s death in an unrelated gene editing study at Xinhua Hospital, which is also affiliated with Shanghai Jiao Tong University School of Medicine.
That study involved a 6-year-old girl with a rare neurological condition linked to the CHD3 gene. She died in March 2025 after receiving an experimental treatment delivered to the brain through an AAV vector.
Unlike Duchenne muscular dystrophy, the girl’s underlying condition generally is not considered life limiting, raising separate questions about the potential benefits and risks of a first-in-human treatment.
After her death was publicly reported in July, the medical school said it had formed a task force to investigate the study and a related scientific paper.
No comparable public investigation has been announced in the HG302 case.
HuidaGene said the three surviving participants remain under long-term follow-up. Neither the company’s statement nor the trial record identifies any conclusion from the hospital ethics committee or Chinese health authorities about the death or whether development of HG302 should continue.
