Respiratory syncytial virus (RSV) is a common enveloped RNA virus that circulates in the winter and spring. It is mainly transmitted by direct contact with the nasal secretions and respiratory droplets of infected individuals. This virus can easily cause respiratory diseases and, if not treated promptly, can further lead to chronic respiratory and pulmonary diseases. Children, the elderly, and immunocompromised individuals are particularly susceptible high-risk groups.
The current status of RSV preventive and therapeutic drugs
In July 2023, Nirsevimab, a monoclonal antibody jointly developed by Sanofi and AstraZeneca, was approved by the FDA for sale. It is suitable for all infants at risk of RSV-related lower respiratory tract diseases, making it the world's first long-acting RSV preventive measure for all infants.
It is noteworthy that antibody drugs such as Nirsevimab do not require activation of the immune system to provide protection for infants and young children.
In contrast, Palivizumab, which can also be used for RSV prevention, is only suitable for high-risk paediatric patients with RSV diseases, covering a smaller population. In addition, currently approved RSV vaccines need to stimulate the immune system to be effective and are mainly used for preventing respiratory diseases caused by RSV in the elderly. For example, GSK's Arexvy vaccine and Pfizer's Abrysvo vaccine are used to prevent lower respiratory tract diseases caused by RSV in people aged 60 and above.
In the field of RSV-related disease treatment, there is currently no approved special antiviral drug for global markets, and patients mainly rely on supportive and palliative treatments such as interferon, bronchodilators, and corticosteroids. However, due to the significant toxic side effects, the use of these drugs is greatly limited.
Previously, the development of early RSV therapeutic drug mainly focused on nucleoside analogues, which unfortunately were not successful. In recent years, the main focus of development in this field has been on specific targets of RSV, such as various proteins involved in the replication cycle of the virus, including the RSV fusion protein (F protein), nucleoprotein (N protein), and RNA polymerase (L protein).
Huge market potential: rapid scaling of new products
In 2020, the overall global market size of RSV drugs was approximately $1.8 billion. It is estimated that by 2030, this market size may reach USD 12.8 billion, with the children's market taking the lead. The consumption of related drugs in the children's market will account for more than 90%, specifically involving the children's RSV preventive drug market, the children's RSV vaccine market, and the children's RSV infection treatment drug market.
In May of this year, GSK's Arexvy vaccine and Pfizer's Abrysvo vaccine were approved for marketing by the FDA. Due to their outstanding effectiveness and safety, these two products quickly gained market traction in the first quarter after their launch, with Arexvy achieving sales of 710 million pounds and Abrysvo achieving sales of USD 375 million.
Summary of the important milestones in the domestic RSV drug field
As of now, there are no approved RSV vaccines or drugs in China. In the corresponding niche, many enterprises including Zhifei Biological, ArkBio and advaccine are laying out new products.
ArkBio AK0529
In December 2022, the NDA registration application for AK0529, a therapeutic drug for RSV developed by ArkBio, was accepted by the NMPA and included in priority review. This RSV fusion protein small molecule inhibitor prevents virus invasion into human cells by binding to the F protein of the RSV virus.
Phase III clinical trial results show that AK0529 has a rapid onset, good dependence, and more significant clinical benefits in infant patients under 6 months, as well as good safety and tolerability. As the world's first RSV antiviral drug to successfully complete Phase III registration clinical trials, AK0529 is expected to become a heavyweight innovative drug and gold stan...
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