AB&B BIO-TECH-B (02627) announced that the group has recently initiated Phase I and Phase II clinical trials for its self-developed adjuvanted recombinant Respiratory Syncytial Virus (RSV) vaccine (CHO cell). The company obtained clinical trial approval for this vaccine from the National Medical Products Administration of China in August 2025.
Respiratory Syncytial Virus (RSV) is a highly contagious RNA virus and a significant pathogen causing respiratory infections in infants, the elderly, and immunocompromised individuals. Clinically, it primarily manifests as symptoms of acute respiratory infection, mainly affecting the lower respiratory tract, with severe cases being life-threatening. According to data from the Chinese Center for Disease Control and Prevention, from 2009 to 2019, RSV ranked as the second leading cause of acute respiratory infections among adults and the leading cause among children in China. Given the current lack of specific therapeutic drugs in clinical practice, management relies mainly on supportive care for acute infections, making vaccination the preferred clinical solution for RSV prevention and control.
The group's adjuvanted recombinant RSV vaccine (CHO cell) is developed using CHO cells to express a modified pre-F protein. Through extensive screening, the company has obtained a high-yield monoclonal cell line capable of stably expressing the pre-F protein. In the company's preclinical studies, this candidate demonstrated higher pre-F expression levels, better thermal stability, and superior immunogenicity compared to marketed recombinant RSV vaccines.
According to previously disclosed results, the expression level of the pre-F protein in marketed recombinant RSV vaccines ranges between 600 mg/L and 800 mg/L. In contrast, the company's high-yield cell line produces pre-F protein at approximately 1,000 mg/L to 1,500 mg/L. Preclinical studies showed that after storage at 40°C for 14 days, the activity of the company's pre-F protein remained above 95%, whereas the protein activity of marketed products decreased to around 50%. Due to this stability, unlike approved products, the company's candidate utilizes a liquid formulation instead of a lyophilized one.
In preclinical immunogenicity tests conducted in mice, the geometric mean titer of neutralizing antibodies for the company's investigational vaccine was significantly higher than that of comparable marketed products. The candidate also demonstrated favorable safety in the company's toxicity studies and active systemic anaphylaxis tests.
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