On February 14, 2025, in the clinical research ward of the Zengcheng Campus at Guangzhou Women and Children’s Medical Center, China, the father of a young Rett syndrome (RTT) patient from Shanxi Province, referred to as “Xixi”, expressed cautious optimism. After years of struggling with a devastating neurological disorder, Xixi has recently shown encouraging signs of improvement — including the ability to actively express her needs through crying and behavioral cues.
This milestone represents an early positive outcome from the first investigator-initiated clinical study of RTT gene therapy in Central-Southern China. The study is being jointly led by the team of Professor Wenhao Zhou at Guangzhou Women and Children’s Medical Center and Professor Zilong Qiu at the Songjiang Research Institute of Shanghai Jiao Tong University School of Medicine. PackGene is honored to support this IIT program and contribute to its journey from research and development through clinical translation.
Gene Therapy Offers New Hope for RTT Patients
Now six years old, Xixi had shown normal early development and could say simple words such as “mom” and “dad” around her first birthday. However, in 2021, her parents noticed a dramatic regression. She developed repetitive hand-wringing behaviors and teeth grinding and gradually lost her ability to walk and speak.
After visiting multiple hospitals over a two-year period, genetic testing at a Beijing hospital ultimately confirmed a diagnosis of Rett syndrome.
RTT is an ultra-rare neurodevelopmental disorder affecting approximately 1 in every 10,000–15,000 individuals and predominantly impacts females. Often referred to as an “unsolved disease,” RTT patients experience severe developmental regression characterized by loss of speech and motor abilities, cognitive decline, and stereotypic hand movements. Since the first RTT case was diagnosed in China in 1988, treatment options have remained extremely limited. Traditional rehabilitation approaches offer only modest benefit, while recently approved therapies abroad remain difficult to access and financially challenging for many families.
Following nearly two years of searching for specialists and treatment opportunities, Xixi’s family finally found hope. On February 14, 2024, she became the first child in Central-Southern China to receive RTT gene therapy.
One month after treatment, notable improvements were observed in motor function, feeding ability, and her capacity to communicate needs.
The investigational therapy was developed based on nearly two decades of research by Professor Qiu’s team. The approach utilizes a proprietary adeno-associated virus (AAV) vector carrying a functional copy of the MECP2 gene, delivered directly into the cerebrospinal fluid through a one-time intrathecal administration.
PackGene provided high-quality AAV vector support for the program, leveraging extensive experience and technical expertise in gene therapy development to facilitate successful clinical translation.
Conceptually, the AAV vector functions like a highly targeted delivery vehicle, transporting the therapeutic gene directly to affected neurons in the brain, where it can restore missing or dysfunctional gene activity and potentially improve neurological function.
Clinical Trial Plans to Enroll Six Patients
“One-time administration has the potential to generate long-term therapeutic benefit, substantially reducing treatment burden and economic pressure for patients and families,” said Professor Qiu.
Preclinical studies of the MECP2 gene therapy candidate, RETT-001, demonstrated favorable efficacy and safety profiles compared with similar programs worldwide, including prolonged survival and significant improvements in motor function in animal models.
The current investigator-initiated clinical study plans to enroll six RTT patients between the ages of four and ten.
To support the study, Guangzhou Women and Children’s Medical Center established a dedicated clinical research ward integrating ethics oversight, risk monitoring, and standardized operating procedures. Multidisciplinary collaboration among pediatric, neurology, and critical care specialists provides continuous monitoring to ensure treatment safety and protocol compliance.
Professor Zhou noted that investigators will continue tracking changes in language, cognition, and behavior, alongside electroencephalography and immune monitoring assessments. The team also plans to expand future clinical studies to develop more mature and broadly accessible treatment options for RTT patients.
PackGene is honored to support RETT-001 program through its integrated end-to-end CDMO platform, and also witness the progress made possible through collaborative efforts among researchers, clinicians, and patient communities.
Moving forward, PackGene remains committed to advancing CGT delivery technologies and strengthening technical capabilities to support gene therapy innovation, with the mission of making gene therapy more affordable and accessible to patients.
