Recently,the research team of Genecradle Therapeutics published an important achievement titled"Preclinical Study of AAV9-coSMN1 Gene Therapy for Spinal Muscular Atrophy:Efficacy and Safety Validation in Mouse and Non-Human Primate Models"in the international authoritative journal Molecular Medicine(IF 6.0).This study systematically presents the preclinical research of GC101 gene therapy,focusing on the innovative design of AAV9-coSMN1 gene therapy,the mild SMA mouse model,drug efficacy evaluation,and safety evaluation.As the Phase III pivotal clinical trial of GC101 Injection for Type 2 SMA is officially launched,the publication of these research findings is timely,providing important references and perspectives for the academic and industrial communities to better understand this therapy.

Paper link:https://molmed.biomedcentral.com/articles/10.1186/s10020-025-01207-4

Research Highlights:Three Major Innovative Breakthroughs

• Codon optimization technology significantly enhances SMN protein expression.

The research team optimized the codon adaptation index and GC content of the SMN1 gene to construct an efficient expression vector.Experiments confirmed that the protein expression level of coSMN1 in neuronal cells was 3-6 times higher than that of the wild type,laying a molecular foundation for therapeutic breakthroughs.

• First proof of long-term efficacy in Type 3 SMA animal models.

In Type 3 SMA mouse models,the lack of SMN protein leads to the loss of spinal cord anterior horn motor neurons,and the tail gradually atrophies and necroses 4-6 weeks after birth.However,newborn model animals treated with a single injection of AAV9-coSMN1 can significantly and durably retain tail length(tail length maintained for at least 1 year),and the number of spinal cord motor neurons is significantly rescued and maintained at normal levels.This result suggests that if treated in time,AAV9-coSMN1 can effectively prevent the loss of spinal cord motor neurons.

In addition,this study found that the lack of SMN and the loss of motor neurons lead to mitochondrial dysfunction in skeletal muscles.Although this has not yet significantly affected the active movement ability of Type 3 SMA mice,significant reductions in mitochondrial number and activity can be observed through special tissue pathological staining techniques.Notably,after a single central nervous system administration,the pathological characteristics of skeletal muscles in treated mice were significantly improved,indicating that AAV9-mediated central nervous system therapy can not only act on spinal cord anterior horn motor neurons but also have a positive effect on skeletal muscles.

• Intrathecal injection strategy demonstrates excellent safety.

According to data disclosed by the FDA,zolgensma,at a dose of 3E+13 vg/animal,caused severe toxic reactions in cynomolgus monkeys after a single intrathecal injection,including pathological features such as single neuron necrosis.This has led to concerns and attention regarding the risk of side effects from central nervous system delivery.

To further investigate the in vivo safety of AAV9-coSMN1,this study prepared GMP-grade products using the Bac to AAV production system and administered a single intrathecal injection to cynomolgus monkeys at a dose of 4.7E+13 vg/animal,observing various safety indicators,including pathology,under GLP conditions.

The results showed that after a single intrathecal injection,the physiological and safety indicators of the cynomolgus monkeys were normal.Notably,no pathological changes were detected in the spinal cord or dorsal root ganglia of the treated monkeys,indicating that the AAV9-coSMN1 gene therapy product prepared using the Bac to AAV system has good safety characteristics,laying an important data foundation and confidence in safety for its clinical translation application.




Clinical Significance:Rewriting the SMA Treatment Landscape



✧Precise targeting of the central nervous system for systemic benefits,covering multiple phenotypes of patients.Compared to traditional intravenous administration,intrathecal injection can directly deliver the SMN1 gene to motor neurons,avoiding liver overload and potentially overcoming the age and weight limitations of Zolgensma®,benefiting a broader patient population.

✧"One-time treatment,long-term benefits."A single dose can achieve sustained expression in the CNS,significantly improving treatment convenience and patient compliance compared to the repeated intrathecal injections of antisense oligonucleotides(such as nusinersen).

Expert Opinion

Professor Wu Xiaobing,the corresponding author of this study and the founder of Genecradle Therapeutics,said:"GC101 Injection(AAV9-coSMN1)has achieved dual breakthroughs in efficacy and safety through innovative design.Currently,the clinical trials based on these results have made milestone progress in China and have been recognized by the CDE as a breakthrough therapy based on significant safety and efficacy data.Recently,the Phase III pivotal clinical trial of GC101 for Type 2 SMA has been officially launched,and we look forward to this therapy offering a better choice for global SMA patients."


About GC101 Adeno-Associated Virus Injection

GC101 Injection is the first domestically developed AAV gene therapy product for intrathecal administration to treat SMA.The indications cover Types 1,2,and 3 of 5q SMA.The successful completion of the I/II phase clinical trial of the GC101-2 Type IND project has laid the foundation for the Phase III pivotal clinical trial.Clinical trial data have shown positive and significant therapeutic effects in Type 2 SMA subjects treated with GC101 Injection,with several subjects achieving breakthroughs in motor milestones.Compared to existing treatments,GC101 Injection's potential for"one-time treatment,long-term efficacy"demonstrates a differentiated advantage.In December 2024,GC101 Injection was included in the breakthrough therapy drug directory by the CDE in recognition of its outstanding performance.