HuidaGene Therapeutics Provides an Update on the HG302-01 First-in-Human Trial

SHANGHAI and MIDDLETOWN, Del. | August 5, 2026 — HuidaGene Therapeutics (“HuidaGene”) today provided an update regarding a fatal serious adverse event in HG302-01, a first-in-human investigator-initiated trial evaluating HG302, an investigational gene-editing therapy for Duchenne muscular dystrophy (DMD).

This loss saddens us deeply, and we extend our heartfelt condolences to the participant's family. We are grateful for the trust placed in this research by the participant, the family, and all study participants.

In August 2025, a participant in the high-dose cohort died following administration of HG302. Because serious clinical events require careful verification of the facts and rigorous assessment of causality, HuidaGene conducted a comprehensive clinical and scientific investigation, including laboratory, immunologic, pathological, and post-mortem analyses.

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 full findings of this investigation were submitted for peer review in January 2026, and additional scientific details will be shared upon publication.

The event was reported through the hospital's applicable ethics and study-oversight processes within the applicable reporting timeframe after the site became aware of it, in accordance with Good Clinical Practice. Initial and follow-up reports were subsequently submitted through those processes.

The participant was the final participant enrolled under the planned HG302-01 protocol. The other three participants did not develop the same severe clinical syndrome and remain under long-term follow-up in accordance with the study protocol.

Patient safety is our foremost responsibility. We are committed to learning from this event, communicating validated findings responsibly, and applying those lessons to inform safer approaches for patients with serious genetic diseases.

About HG302

HG302 is an investigational CRISPR-based gene-editing therapy designed to restore dystrophin expression in patients with DMD. HG302 has received Orphan Drug Designation from the U.S. Food and Drug Administration and was evaluated in a first-in-human clinical study.

About Duchenne Muscular Dystrophy

Duchenne muscular dystrophy is a rare, progressive genetic disorder caused by mutations in the DMD gene, resulting in little or no functional dystrophin protein. The disease primarily affects skeletal and cardiac muscle, leading to progressive muscle weakness and functional impairment. Although available treatments can help manage symptoms and slow aspects of disease progression, none can halt or cure the disease.

About HuidaGene

HuidaGene utilizes its proprietary AI-driven, CRISPR-based HG-PRECISE^Ò platform to develop potentially curative genome medicine. The company's current clinical programs include:

• HG004gene replacement therapy (ODD & RPDD from the US FDA and ODD from EMA) for RPE65-associated retinal disease (IRD)

• 'LIGHT' first-in-human trial (NCT06088992)

• China's first 'STAR' Phase 1/2 multi-national, "master protocol" clinical trial (NCT05906953)

• HG202 CRISPR/RNA-editing therapy for neovascular age-related macular degeneration (AMD)

• 'SIGHT-I' first-in-human trial (NCT06031727)  

• World's first CRISPR/RNA editing therapy 'BRIGHT' Phase 1 clinical trial (NCT06623279)

• HG204 RNA-editing therapy (ODD & RPDD from FDA and ODD by EMA) for MECP2 duplication syndrome

• World's first CRISPR/RNA-editing 'HERO' for neurodevelopment disorders first-in-human trial (NCT06615206)

• HG302 DNA-editing therapy (ODD & RPDD from FDA) for Duchenne muscular dystrophy (DMD)

• World's first CRISPR/DNA-editing 'MUSCLE' first-in-human trial (NCT06594094)

The preclinical pipelines are advancing simultaneously in HG303 CRISPR/DNA-editing for ALS and CRISPR/RNA-editing therapy for Alzheimer's and Huntington's Disease. With an extensive intellectual property portfolio, HuidaGene is a leader in genome medicines for neurology and ophthalmology. Learn more at huidagene.com or on LinkedIn.