Two 2025 Pediatric Deaths in China Linked to Experimental Gene-Therapy Trials Raise Transparency Questions

Two pediatric deaths tied to separate experimental gene-therapy studies in China occurred in 2025 but were not disclosed publicly until 2026, drawing fresh scrutiny to how such studies are monitored and when serious adverse events are communicated.

One case involved a 6-year-old girl identified in reporting as Mei, who died after receiving an experimental brain-targeted base-editing therapy at Xinhua Hospital, which is affiliated with Shanghai Jiao Tong University School of Medicine. Science and Retraction Watch reported on July 23, 2026, that the girl died in March 2025, seven days after an intrathecal infusion, after developing a severe immune reaction. The second case involved Shanghai-based HuidaGene Therapeutics, which said in an Aug. 5, 2026, press release that “in August 2025, a participant in the high-dose cohort died following administration of HG302” in its first-in-human HG302-01 trial for Duchenne muscular dystrophy, a genetic muscle-wasting disease.

The timing is central to why the cases are now receiving attention. Both deaths happened in 2025. Neither became public that year. Mei’s death entered the public record through investigative reporting in July 2026. The HuidaGene fatality was disclosed the following month in the company’s own public statement. Together, the cases have sharpened questions about transparency, safety oversight and reporting practices in China’s system for investigator-initiated trials, or studies run through hospitals and researchers rather than through the conventional sponsor-led drug approval pathway.

In Mei’s case, Science and Retraction Watch said the death had not been publicly disclosed at the time and reported broader questions about related preclinical data and disclosure. Shanghai Jiao Tong University School of Medicine later said it had established a special task force to investigate the reporting and the related research and clinical work. Separately, Nature attached an Editor’s Note on July 29, 2026, to a Feb. 18, 2026, paper, “In vivo base editing of Chd3 rescues behavioural abnormalities in mice,” which lists researcher Zilong Qiu among the co-authors. The note said: “Readers are alerted that concerns have been raised regarding this article, including with the data presented. Further editorial action will be taken if appropriate as soon as the investigation into the concerns is complete and all parties have been given an opportunity to respond in full.”

HuidaGene’s account came directly from the company. In its Aug. 5 statement, the biotech said the participant’s death followed high-dose systemic administration of an adeno-associated virus, or AAV, vector, a commonly used gene-delivery system. “Based on the available clinical and scientific evidence, the participant developed acute respiratory distress syndrome in the setting of severe complement and cytokine activation following high-dose systemic administration of an adeno-associated virus vector,” the company said. It added that the event was reported through the hospital’s ethics and oversight processes and said other enrolled participants did not develop the same syndrome and remain in long-term follow-up. HuidaGene also said the full findings of its investigation were submitted for peer review in January 2026 and that more details would be shared upon publication.

The cases have landed amid changes to China’s oversight framework for advanced biomedical research. Before a recent rule change, China operated with a dual-track system: conventional sponsor-led registration trials regulated under national drug rules, and a broader set of investigator-initiated trials overseen mainly through hospitals and ethics committees. Those investigator-led studies have now come under closer examination because both 2025 deaths were linked to that broader clinical research environment rather than to a standard public drug approval process.

China’s State Council Decree No. 818, issued on Sept. 28, 2025, and effective May 1, 2026, created a national framework for “biomedical new technologies,” including gene editing and in-vivo gene therapy. The measure introduced filing, oversight and reporting requirements. Its timing is notable: It took effect after both deaths had already occurred, but before either case became public.

The HuidaGene death also fits into a wider safety discussion around AAV-based treatments. High systemic doses of AAV vectors are already recognized internationally as a safety risk. In 2025, the U.S. Food and Drug Administration, which regulates medicines in the United States, investigated deaths from acute liver failure in non-ambulatory Duchenne muscular dystrophy patients treated with AAV-based therapies. That broader context does not resolve what happened in either China case, where investigations are still ongoing and no final public findings from the university inquiry or Nature’s editorial review were available in the material provided.