Two child deaths have cast doubt on China's accelerated gene therapy research.

In China, two fatal outcomes in genome editing trials became known — they occurred in 2025 but were only disclosed in the summer of 2026.
In both cases, adeno-associated viral vectors (AAV) were used, and the deaths were preceded by a severe immune reaction.

The trials were conducted under the investigator-initiated trials (IIT) mechanism. This approach allowed the technology to be used after scientific and ethical review within a medical institution — without prior approval from the Chinese regulator responsible for drug registration (National Medical Products Administration, NMPA).

 First Case: A Rare Syndrome and Individualised Gene Therapy

The first participant was a six-year-old girl with Snijders Blok-Campeau syndrome, a rare but usually not life-threatening condition.

To correct a variant of the CHD3 gene, she received an intrathecal injection of a base editor delivered in two AAV vectors. She was the sole participant in trial NCT06860672.

Seven days later, the child died from thrombotic microangiopathy. In ClinicalTrials.gov, the relationship between the death and the therapy is assessed as definite.

According to Science and Retraction Watch, the parents provided approximately USD 860,000 to develop the therapy. In a non-public toxicology report, all four primates showed liver damage, and one also showed kidney damage. These data were not reviewed by the ethics committee prior to the start of the study in the child.

In February 2026, animal experiments were published in Nature without mentioning the clinical application, the girl's death, or the family's funding. Following the publications in Science and Retraction Watch, the journal and the university initiated investigations. The record of the death appeared in the registry only in July 2026.

Second Case: A Trial in Duchenne Muscular Dystrophy

The second case occurred in a HuidaGene Therapeutics trial in boys with Duchenne muscular dystrophy.

The product HG302 uses CRISPR/hfCas12Max in a single AAV vector to edit the DMD gene and restore dystrophin production.

The dose-escalation study included four children. No independent data monitoring committee was in place.

The final participant, who received the high dose, died in August 2025. According to HuidaGene, complement and cytokine activation led to acute respiratory distress syndrome. The other three children did not experience this complication.

The company claims it promptly reported the death to the ethical oversight authorities, but the information became public only a year later — following an investigation by STAT. The dose, clinical course, vector purity, autopsy results, and detailed analysis have not yet been published.

What Can Be Concluded Based on Available Data

The available data do not prove that the genome editing itself caused the deaths.

The primary issue appears to be a severe immune reaction to the AAV vector. At the same time, the role of dose, vector quality, manufacturing process, and individual patient immune response cannot yet be assessed due to the lack of published data.

 In Part 2, we will examine how China has changed the regulation of such trials and why the issue of transparency is becoming critical for the entire field of gene therapy.

Source: Fierce Biotech

Two Children's Deaths Raise Questions About Accelerated Gene Therapy Trials in China

Part 2

Beginning — in the previous post.

Both fatal outcomes in gene therapy trials in China occurred before the new regulation — Order No. 818 — came into force on 1 May 2026.

The new rules placed such trials under the oversight of the National Health Commission (NHC). At the same time, drug registration remains under the control of the National Medical Products Administration (NMPA).

What Has Changed in the Regulation

Now, trials using new biomedical technologies are permitted only in top-tier medical institutions.
The following have become mandatory:
— preclinical studies;
— scientific and ethical review;
— registration with the NHC;
— long-term follow-up of participants;
— immediate suspension of the trial in the event of a serious adverse reaction;
— submission of information to the NHC within five working days;
— prohibition of payments from participants.

Separate guidance requires compliance with GMP principles, vector quality control, assessment of immune toxicity, biodistribution, and off-target genome changes.

 The Main Issue Is Not Only Safety, but Also Transparency

The new rules strengthen oversight but do not require immediate public disclosure of every death or serious complication.

The delay in data disclosure became one of the key issues in both cases. It prevents other researchers from adjusting doses, protocols, inclusion criteria, and risk mitigation measures in a timely manner.
For small IITs, this is particularly important: when it comes to single patients or small groups, every serious outcome matters for the entire field of development.

Why This Matters for Rare Diseases

Gene therapy and genome editing remain among the most promising approaches for rare diseases. However, it is precisely in this area that complex regulatory dilemmas often arise:
— patients have a high unmet medical need;
— the diseases are often ultra-rare;
— standard clinical trials are difficult or impossible to conduct;
— the technologies carry specific risks, including immune toxicity and delivery-related risks;
— safety data at early stages are limited.

Therefore, accelerated development mechanisms must be accompanied not only by flexibility, but also by independent oversight, transparent registration, timely disclosure of serious adverse events, and long-term follow-up.

Conclusion
China will most likely maintain an accelerated model for the development of cell and gene technologies.

However, international recognition of data will depend on how consistently the new requirements are implemented, whether independent oversight is ensured, and whether serious complications are disclosed in a timely manner.

For the entire field of rare diseases, these cases serve as an important reminder: accelerated development should not come at the expense of transparency, risk assessment, and patient protection.

Source: Fierce Biotech