China Medical System Holdings Limited (CMS) announced on September 22, 2025, that it has entered into exclusive collaboration agreements with Chongqing Genrix Biopharmaceutical Co., Ltd. (Genrix Bio) for two innovative Class 1 therapeutic biological products targeting tetanus and rabies prevention. The agreements grant CMS exclusive commercialization rights in mainland China and licensing rights across the Asia-Pacific region, Middle East, and North Africa for both Vecantoxatug Injection (GR2001) and Silevimig Injection (GR1801).
Vecantoxatug: Breakthrough Tetanus Prevention Therapy
Vecantoxatug is a recombinant humanized monoclonal antibody against tetanus neurotoxin (TeNT) that binds specifically to the fragment C domain of the TeNT heavy chain. By blocking toxin entry into neurons, the therapy provides passive immunization with superior protection compared to human tetanus immunoglobulin (HTIG).
The therapy's Phase III clinical trial for passive immunization against tetanus successfully met its primary efficacy endpoint. In May 2024, Vecantoxatug received Breakthrough Therapy designation from the Center for Drug Evaluation (CDE) of China's National Medical Products Administration (NMPA), and its New Drug Application was formally accepted by the CDE on May 22, 2025.
Tetanus remains a significant global health threat, with an estimated 500,000 to 1,000,000 cases reported annually worldwide. The disease, caused by Clostridium tetani entering the body through wounds, is almost universally fatal without medical intervention, particularly among infants and the elderly. Even with active treatment, global mortality remains as high as 30-50%.
Current passive immunization agents face notable limitations in safety and accessibility, including risks of allergic reactions, potential infectious pathogen transmission, and limited availability. Vecantoxatug demonstrates excellent safety, tolerability, and low immunogenicity while providing enhanced controllability and accessibility.
Silevimig: World's First Bispecific Rabies Antibody
Silevimig represents a significant advancement as the world's first recombinant, fully human bispecific antibody against rabies virus (RABV). The therapy targets epitope I and/or epitope III of the rabies virus glycoprotein, blocking viral interaction with host receptors and preventing RABV from invading neural tissue before active vaccination provides full protection.
The molecular design aligns with World Health Organization recommendations for anti-RABV antibody development, emphasizing "cocktail" combinations of monoclonal antibodies targeting distinct antigenic sites to ensure broad effectiveness across different viral strains and genotypes.
In Phase III clinical trials for post-exposure passive immunization in adults, Silevimig met its primary efficacy endpoint, demonstrating non-inferior protective efficacy compared with human rabies immunoglobulin (HRIG), currently the most used passive immunization product in China. The New Drug Application for adult use was formally accepted by the CDE on January 14, 2025.
In July 2025, the NMPA approved a clinical trial application for Silevimig in children and adolescents aged 2 to less than 18 years requiring passive immunization following suspected rabies virus exposure. This Phase III clinical trial is currently in progress.
Addressing Critical Unmet Medical Needs
Rabies presents one of the world's deadliest diseases with a case-fatality rate approaching 100%. With no proven treatment once clinical symptoms appear, standardized Post-Exposure Prophylaxis (PEP) remains the most effective prevention strategy. Passive immunization provides immediate coverage during the 1-2 week window required for vaccine-induced antibodies to reach protective levels of ≥0.5 IU/mL.
In China, more than 40 million people are exposed to rabies annually, with approximately 40% (16 million) falling under Category III exposure according to the National Regulation for the Rabies Exposure Prophylaxis (2023 Edition). However, due to factors including limited awareness, high cost, and restricted accessibility, only about 15% of Category III cases receive passive immunization.
Current approved passive immunization options in China include human rabies immunoglobulin (HRIG) and equine rabies antiserum (ERA). HRIG must be sourced from repeatedly immunized healthy donors, making it difficult and costly to obtain, with associated risks of blood-borne infections including HIV, hepatitis B, and hepatitis C. ERA, being a heterologous protein, is prone to adverse reactions such as serum sickness and anaphylactic shock.
Strategic Partnership and Market Impact
The collaboration terms extend until ten years after both products receive marketing approvals in mainland China, with automatic renewal for successive ten-year periods unless terminated. CMS has positioned itself to leverage these innovative therapies alongside its existing product portfolio in expert networks and market resources.
Both Vecantoxatug and Silevimig can be manufactured at scale with standardized processes, demonstrating broad neutralization, low immunogenicity, minimal interference with vaccine-induced active immunity, and controlled production costs. If approved, these therapies will provide new preventive and therapeutic options for patients following tetanus and rabies exposure, addressing substantial market needs constrained by current safety and accessibility limitations.
